---END PERSONAL NOPUSH DIVIDER---

--
2.42.0

doc/org-manual.org

@@ -11377,7 +11377,7 @@ pretty output for a number of export backends.
 :END:
 #+cindex: @LaTeX{} fragments
 
-#+vindex: org-format-latex-header
+#+vindex: org-latex-preview-header
 Org mode can contain LaTeX math fragments, and it supports ways to
 process these for several export backends.  When exporting to LaTeX,
 the code is left as it is.  When exporting to HTML, Org can use either
@@ -11434,20 +11434,19 @@ lines:
 :END:
 #+cindex: @LaTeX{} fragments, preview
 
-#+vindex: org-preview-latex-default-process
+#+vindex: org-latex-preview-process-default
 If you have a working LaTeX installation and =dvipng=, =dvisvgm= or
 =convert= installed[fn:38], LaTeX fragments can be processed to
 produce images of the typeset expressions to be used for inclusion
 while exporting to HTML (see [[*LaTeX fragments]]), or for inline
 previewing within Org mode.
 
-#+vindex: org-format-latex-options
-#+vindex: org-format-latex-header
-You can customize the variables ~org-format-latex-options~ and
-~org-format-latex-header~ to influence some aspects of the preview.
-In particular, the ~:scale~ (and for HTML export, ~:html-scale~)
-property of the former can be used to adjust the size of the preview
-images.
+#+vindex: org-latex-preview-appearance-options
+#+vindex: org-latex-preview-header
+You can customize the variables ~org-latex-preview-appearance-options~ and
+~org-latex-preview-header~ to influence some aspects of the preview.
+In particular, the ~:scale~ and ~:zoom~ properties of the former can
+be used to adjust the size of the preview images.
 
 - {{{kbd(C-c C-x C-l)}}} (~org-latex-preview~) ::
   #+kindex: C-c C-x C-l
@@ -11471,6 +11470,24 @@ To disable it, simply use
 
 : #+STARTUP: nolatexpreview
 
+#+vindex: org-latex-preview-numbered
+When generating previews, Org mode can track equation numbers and keep
+them consistent by regenerating previews when necessary.  This
+behavior is controlled by the variable ~org-latex-preview-numbered~.
+
+Org mode can automatically preview LaTeX fragments as you type them,
+and hide and reveal preview images as the cursor moves into or out of
+them.  To enable this, turn on the minor mode
+~org-latex-preview-auto-mode~.
+
+
+- (~org-latex-preview-auto-mode~) ::
+  #+findex: org-latex-preview-auto-mode
+
+  Generate previews of LaTeX fragments as they are entered in the
+  buffer.  Previews will be generated when there is any change to the
+  buffer that includes the insertion of a LaTeX environment or
+  fragment.
 *** Using CDLaTeX to enter math
 :PROPERTIES:
 :DESCRIPTION: Speed up entering of formulas.
@@ -16796,6 +16813,378 @@ user-friendly improvements.  See
 <https://orgmode.org/worg/dev/org-export-reference.html> for more
 details.
 
+*** Export features
+**** The underlying idea
+
+Across export backends it is common to want to include certain chunks
+of content that are only relevant in particular situations.
+
+With static export templates, one is forced to choose between
+including everything that /might/ be wanted, or including very little
+by default and requiring common content to be manually added every
+time it is wanted.
+
+"Export features" allow for a third option, a much more sophisticated
+method of resolving this dilemma. At the start of the export process,
+the buffer being exported and the export communication plist (~info~)
+are scanned to determine which capabilities are relevant to the
+current export. During the construction of the final output this list
+of capabilities is used to produce snippets of content to be included.
+
+This can be thought of as the construction of a graph between conditions,
+features, and feature implementations. For example, say we have three conditions
+we want to support:
++ Say that images need some extra setup to be supported well, we can
+  just include it when image links are found in the buffer.
++ Say we can better support emojis by treating them as images in a
+  particular export backend. We could look for a signal in the buffer
+  that emojis should be handled as images, and then make use of some
+  "image support" and "emoji support" snippets.
++ Say that LaTeX maths requires some extra setup, we can just
+  do this when inline LaTeX fragments are found.
+This situation can be crudely drawn with the following graph:
+
+#+begin_example
+ condition            feature       implementation
+ =========            =======       ===============
+
+ [emoji] -----------> emoji ------> [emoji plist]
+         \
+          '---->----.
+                     \
+ [image link] ------> image ------> [image plist]
+
+ [inline LaTeX] ----> maths ------> [maths plist]
+
+ \____________________/   \__________________/
+        phase 1                 phase 2
+#+end_example
+
+In phase 1 "feature detection" the relevant features are determined, and in
+phase 2 "feature implementation" how those features can be provided is worked
+out.
+
+**** Feature detection
+
+After the expansion of =#+include= statements and the removal of
+comments, the export communication plist (~info~) is annotated. At the
+very end of the annotation process, ~org-export-detect-features~ is
+run to determine the list of capabilities relevant to the current export.
+
+This operates by merging the global feature condition alist
+(~org-export-conditional-features~) with the ~feature-conditions~ slot
+of the current backend and each of its parents. This produces the
+total feature conditions alist, which has the form:
+
+#+begin_example
+((condition . implied-features)
+ ...)
+#+end_example
+
+Where =condition= is a test that implies that =implied-features= are
+relevant. While =implied-features= is always a list of feature
+symbols, for convenience =condition= can take a number of forms,
+namely:
++ A regexp which is searched for in the export buffer.
++ A variable, if a string it is used as a regexp search, otherwise any
+  non-nil value is taken to imply =implied-features=.
++ A (unary) function, which is called with on the export communication
+  plist (~info~). A returned string is used as a regexp search,
+  otherwise any non-nil value is taken to imply =implied-features=.
+
+As an example, a feature conditions alist which checks whether any
+headings exist, and if the word "hello" appears could take the
+following form:
+
+#+begin_example
+(((lambda (info)
+   (org-element-map (plist-get info :parse-tree) 'heading
+    #'identity info t))
+  headlines)
+ ("hello" has-greeting))
+#+end_example
+
+Conditions are inherited from parent export backends and (for conditions general
+enough to apply across backends) the variable ~org-export-conditional-features~.
+
+#+begin_example
+                                                    ,--> beamer
+                                                   /
+  html <----.                      ,----> latex --'
+             \                    /
+        org-export-conditional-features
+             /                    \
+ ascii <----'                      '----> odt
+#+end_example
+
+**** Feature implementations
+
+The other half of the export feature system is of course producing
+snippets of content from the list of features. Export backends can do
+this at any point via ~org-export-expand-feature-snippets~. This
+operates on a /feature implementation alist/. The implementation alist
+is essentially a mirror of the condition alist, instead of =(condition
+. feature-list)= elements it takes =(feature . implementation-plist)=
+elements. This reversal of order may seem a bit odd, but it should
+help make the condition--feature--implementation graph more apparent.
+
+For example, considering this example condition alist and implementation alist
+would be represented as the earlier graph.
+
+#+begin_example
+;; The condition alist
+(([emoji predicate] emoji image)
+ ([image predicate] image)
+ ([inline LaTeX predicate] maths))
+;; The implementation alist
+((emoji [plist])
+ (image [plist])
+ (maths [plist])
+#+end_example
+
+The implementation plist recognises a number of keywords, but the
+primary keyword is ~:snippet~. The snippet value provides the snippet
+content used to provide the feature's capability. Much like
+~condition~, it accepts a number of forms for convenience, namely:
++ A string, which is passed on.
++ A variable symbol, the value of which must be a string.
++ A (unary) function, which is called on the export communication
+  plist (~info~), and must return a string.
+
+Note that no keys are mandatory in the implementation plist (not even
+~:snippet~).
+
+Like conditions, implementations are also inherited from parent backends, but
+there is no "root" global list of implementations, as they are always
+backend-specific.
+
+#+begin_example
+                                     ,--> beamer
+                                    /
+  html <---o         o---> latex --'
+
+ ascii <---o         o---> odt
+#+end_example
+
+**** Feature dependency and incompatibility
+
+While just connecting features with snippets satisfies most use cases,
+this system is designed to also allow for complex configurations of
+inter-dependent snippets.
+
+In slightly more complex examples, we may run across implementations
+which either (a) only make sense when another feature is active, or
+(b) require another implementation to be used in order to work. These
+two situations are covered by the ~:when~ and ~:requires~ keywords
+respectively. The accept either a single feature symbol or a list of
+feature symbols.
+
+For example, if an implementation contains ~:when featA~, it will only
+be used when =featA= is active. If the implementation contains ~:when
+(featA featB)~ it will require /both/ =featA= and =featB= to be
+active. The ~:requires~ keyword works in the same way, but
+unconditionally requires implementations instead of testing for them.
+
+Occasionally one implementation may be incompatible with another. For
+example, in LaTeX loading the same package with different options will
+often produce an "options clash" error. To ensure that incompatible
+implementations are not used, the ~:prevents~ keyword makes it as if
+the feature were never used in the first place.
+
+Circular ~:requires~ and ~:prevents~, or features that are
+simultaneously required and prevented result in undefined behaviour.
+Similarly, the behaviour of mutual ~:when~​s (e.g. ~(a :when b) (b
+:when a)~ is also undefined.
+
+**** Feature ordering
+
+In many scenarios it is not only /which/ snippets are included that
+matters, but the /order/ in which they are placed. A requirement for a
+certain snippet to appear before/after others can be specified through
+the ~:before~ and ~:after~ keywords. Like ~:when~, ~:requires~, and
+~:prevents~ they accept either a single feature symbol or a list of
+feature symbols.
+
+As an example, should an implementation plist contain ~:before featA
+:after (featB featC)~ it will be placed after =featA= but before
+=featB= and =featC=. It is possible to accidentally create circular
+dependencies, in which case an error will be raised.
+
+While ~:before~ and ~:after~ work well for specifying relative
+ordering, it can also be useful to specify the /absolute/ ordering,
+for instance to put something first or last. This can be controlled
+via the ~:order~ keyword. Each implementation has an ~:order~ of zero
+by default. Implementations with a higher ~:order~ come later.
+
+# REVIEW maybe give a convention on :order ranges?
+# Perhaps take inspiration from ~add-hook~.
+
+-----
+
+The overall ordering behaviour can be characterized as a ascending
+sort of ~:order~ followed by a stable [[https://en.wikipedia.org/wiki/Topological_sorting][topological sort]] based on
+~:before~ and ~:after~.
+
+**** Adding or editing export features
+
+The export features of a backend can be modified via the convenience
+macro ~org-export-update-features~. This is invoked with the following
+form:
+
+#+begin_example
+(org-export-update-features 'BACKEND
+ (FEATURE-NAME
+  :PROPERTY VALUE
+  ...)
+ ...)
+#+end_example
+
+For each feature mentioned, it sets the each =:PROPERTY= to =VALUE= in
+the implementation plist. The one exception to this is ~:condition~ in
+which case the backend's feature condition alist is modified so that
+the condition is taken to imply the feature.
+
+Setting ~:condition t~ will thus make the feature enabled by default. This is not
+a special case, but rather an instance of the general behaviour of obtaining the
+value of any non-function symbol provided, and as ~(symbol-value 't)~ is always
+non-nil, the associated features will always be considered active. Conversely
+setting ~:condition nil~ will make it so no conditions imply the feature. This is
+possible thanks to special behavior that removes the feature from all other
+conditions' associations when ~nil~ is given.
+
+Since having a anonymous function (lambda) is expected to be
+reasonably common with ~:condition~ and ~:snippet~, for those keywords
+and sexp given is implicitly wrapped with ~(lambda (info) SEXP)~.
+
+If the backend is not available at the time the feature update is run,
+an error will be raised.
+
+**** Custom export feature examples
+
+To make the usage of ~org-export-update-features~ and the capabilities
+of the export feature system clearer, here are a few examples
+~org-export-update-features~ invocations.
+
+Say you want to apply the [[https://ctan.org/pkg/chickenize][chickenize]] package to the word "wacky" when
+the title starts with "wacky". We can implement that by testing for
+the regexp =^#\\+title: Wacky= and including
+src_latex{\usepackage[chickenstring[1]='wacky']{chickenize}} when it is
+found.
+
+#+begin_example
+(org-export-update-features 'latex
+ (wacky-chicken
+  :condition "^#\\+title: Wacky"
+  :snippet "\\usepackage[chickenstring[1]='wacky']{chickenize}"))
+#+end_example
+
+However, if =#+title: Wacky= is placed inside an example block, this
+regexp will match even though the match isn't actually parsed as a
+keyword. To be more robust, we can inspect ~info~ instead.
+
+#+begin_example
+(org-export-update-features 'latex
+ (wacky-chicken
+  :condition (and (car (plist-get info :title))
+                  (string-match-p "^Wacky" (car (plist-get info :title))))
+  :snippet "\\usepackage[chickenstring[1]='wacky']{chickenize}"))
+#+end_example
+
+=chickenize= is a LuaLaTeX only package, and so trying to use this
+when compiling with pdfLaTeX or XeLaTeX will cause issues. This may
+well apply to other snippets too, so it could make sense to make a
+=lualatex= feature to indicate when LuaLaTeX is being used.
+
+#+begin_example
+(org-export-update-features 'latex
+ (lualatex
+  :condition (equal (plist-get info :latex-compiler) "lualatex")))
+#+end_example
+
+To only use the chickenize snippet with LuaLaTeX, we can now add
+=lualatex= as a ~:when~ clause.
+
+#+begin_example
+(org-export-update-features 'latex
+ (wacky-chicken
+  :when lualatex))
+#+end_example
+
+Hopefully this has given you an impression of how ~:condition~, ~:when~, and
+~:snippet~ can look in practice. To demonstrate ~:requires~, ~:prevents~, and
+~:after~ we will consider another LaTeX example.
+
+Say that you wanted a few named special blocks to automatically export nicely,
+such as =#+begin_warning=, =#+begin_info=, and =#+begin_note=. All three of
+these can be individually detected and handled appropriately. For the sake of
+simplicity, a crude regexp will be used here, however examining the parse tree
+would be a more robust solution.
+
+#+begin_example
+(org-export-update-features 'latex
+ (box-warning
+  :condition "^[ \t]*#\\+begin_warning"
+  :snippet "\\mysetupbox{warning}"
+  :requires mysetupbox
+  :after mysetupbox)
+ (box-info
+  :condition "^[ \t]*#\\+begin_info"
+  :snippet "\\mysetupbox{info}"
+  :requires mysetupbox
+  :after mysetupbox)
+ (box-note
+  :condition "^[ \t]*#\\+begin_note"
+  :snippet "\\mysetupbox{note}"
+  :requires mysetupbox
+  :after mysetupbox)
+ (mysetupbox
+  :snippet "\newcommand{\mysetupbox}...")
+#+end_example
+
+Here, all three box types make use of LaTeX command ~\mysetupbox~ which is
+provided by the =mysetupbox= feature implementation. By using a ~:requires~ for
+this, we can make sure it is availible that it is loaded once, and thanks to the
+~:after mysetupbox~ lines the specific box setup invocations will occur after
+the ~\newcommand{\mysetupbox}...~ definition.
+
+Say that when using beamer you use a package that defines its own
+warning/info/note environments and you'd like to use those. In that case one can
+make an on-by-default beamer feature that prevents the box features from being
+used.
+
+#+begin_example
+(org-export-update-features 'beamer
+ (no-custom-boxes
+  :condition t
+  :prevents (box-warning box-info box-note)))
+#+end_example
+
+**** Detailed explanation of the implementation resolution process
+
+The previous descriptions of the "export feature" behaviour should give a clear
+overview of how this feature works. In case more detail is wanted, or should
+there be any ambiguity, here is a more technical description of the overall
+feature implementation resolution process.
+
+1. The list of detected features is used to obtain all applicable corresponding
+   feature implementations. Detected feature symbols may have /no/ corresponding
+   implementation.
+2. The list of feature implementations is sorted according to ~:order~.
+3. Using a queue, all required features (~:requires~) are added to the list of feature
+ implementations, as are their requirements recursively. Should a feature that
+   has no implementation be required, an ~org-missing-feature-dependency~ error is raised.
+4. The implementations with a ~:when~ condition are scanned and marked as
+   confirmed when all of the ~:when~ conditions are known to be satisfied. This is
+   repeated until there is no change in the list of confirmed implementations,
+   at which point all non-confirmed implementations are removed.
+5. For each of the feature implementations in turn, prevented features
+   (~:prevents~) are removed from the list. Feature implementations that are only
+   present because of a feature that has now been removed are themselves
+   removed, recursively.
+6. The list of feature implementations is sorted according to ~:order~, again.
+7. A stable topological sort is performed using ~:before~ and ~:after~. Should any
+   circular dependencies be found, a ~org-circular-feature-dependency~ error is raised.
+
 ** Export Region
 :PROPERTIES:
 :DESCRIPTION: Author tables and lists in Org syntax.
@@ -23160,7 +23549,7 @@ used to create images, any LaTeX environment is handled.
 [fn:38] These are respectively available at
 [[https://sourceforge.net/projects/dvipng/]], [[http://dvisvgm.bplaced.net/]]
 and from the ImageMagick suite.  Choose the converter by setting the
-variable ~org-preview-latex-default-process~ accordingly.
+variable ~org-latex-preview-process-default~ accordingly.
 
 [fn:39] This works automatically for the HTML backend (it requires
 version 1.34 of the =htmlize.el= package, which you need to install).

etc/ORG-NEWS

@@ -569,6 +569,157 @@ constant.
 If you still want to use python-mode with ob-python, you might
 consider [[https://gitlab.com/jackkamm/ob-python-mode-mode][ob-python-mode-mode]], where the code to support python-mode
 has been ported to.
+*** The LaTeX preview system has been overhauled
+
+Org's LaTeX preview system has been overhauled
+
+
+Org mode's LaTeX preview system has been rewritten with several improvements and new features.
+
+- LaTeX Previews are generated in bulk, and hundreds of LaTeX fragments can be processed per second.
+- Images are placed in the buffer continuously as they are generated.
+- Preview generation is asynchronous and will not block Emacs.
+- Inline previews are aligned and scaled to match the font baseline and size.
+- Previews scale along with text when the text scale is changed.
+- Previews are coloured to match surrounding text and the active theme.
+- SVG previews automatically change colors when the active theme changes.
+- Error encountered when compiling LaTeX fragments can be accessed by mousing over preview images.
+- Preview overlays can hide and show themselves dynamically based on cursor position.
+- Org mode can auto-generate LaTeX previews as you type or edit the text of existing ones.
+- Org mode can keep equation numbering consistent by regenerating previews as needed.
+
+**** New features
+
+***** New minor mode ~org-latex-preview-auto-mode~
+
+When this mode is turned on, LaTeX preview overlays in the buffer can be temporarily disabled by moving the cursor into them.  Moving the cursor out will display the LaTeX preview image overlay again.  Additionally, editing LaTeX fragments that have previews will cause the preview images to be updated.
+
+If the option ~org-latex-preview-auto-track-inserts~ is non-nil (which see), previews for LaTeX fragments will be auto-generated as you type.
+
+
+**** New options
+
+***** A new option ~org-latex-preview-compiler-command-map~ for setting precompile commands
+
+This alist maps compilers in ~org-latex-compilers~ to command strings
+used for LaTeX precompilation when creating previews or LaTeX exports.
+
+***** New option ~org-latex-preview-cache~ to enable preview image caching
+
+When set to =persist=, images produced using ~org-latex-preview~ will
+be cached and persisted across Emacs sessions using
+~org-persist~. Temporary or custom directories can also be used.
+
+***** New option ~org-latex-preview-persist-expiry~ to set persistence period
+
+This is the number of days for which LaTeX preview images will be
+cached, assuming persistence is turned on with
+~org-latex-preview-cache~.
+
+***** New option ~org-latex-preview-process-active-indicator~ to indicate preview processing for LaTeX fragments
+
+This option controls the style of visual indicator for LaTeX fragments
+currently being processed.
+
+***** New option ~org-latex-preview-numbered~ to automatically renumber previewed LaTeX environments
+
+When non-nil, previewed LaTeX environments in the buffer are
+renumbered automatically as required.
+
+***** New option =:page-width= in ~org-latex-preview-appearance-options~ to control the text width for LaTeX fragment previews
+
+This option controls the width of text in preview images.  This is
+relevant for displaymath-type LaTeX environments, and can be specified
+in multiple ways.
+
+***** New option ~org-latex-preview-process-precompiled~ to control LaTeX precompilation
+
+This option controls whether LaTeX headers for buffers are precompiled
+when generating the first preview for the buffer.  Precompilation can
+speed up preview generation by a moderate to large amount depending on
+the complexity of the header.
+
+***** New option ~org-latex-preview-auto-track-inserts~ to auto-generate LaTeX previews when typing
+
+When using ~org-latex-preview-auto-mode~ (which see), setting this option to a non-nil value will cause LaTeX previews to be rendered as you type LaTeX fragments.  This works however new text is added to the buffer, for example by yanking.  When this option is nil and ~org-latex-preview-auto-mode~ is on, existing previews for LaTeX fragments will still be auto-regenerated when edited but no new ones will be auto-generated.
+
+**** Removed or renamed functions and variables
+
+***** Mark ~org-format-latex-options~ obsolete
+
+Use ~org-latex-preview-appearance-options~ instead.  The replacement acts in the
+same way, except that
+- the preview image render size and display size can be independently
+  controlled with the =:scale= and =:zoom= plist keys, and
+- the HTML export-specific parameters =:html-scale=,
+  =:html-foreground= and =:html-background= have been moved to
+  ~org-html-latex-image-options~, which see.
+- the new option =:page-width= (mentioned earlier)
+
+***** Mark ~org-format-latex-header~ obsolete
+
+Use ~org-latex-preview-header~ instead.  The replacement variable
+behaves the exact same way and is renamed for consistency.
+
+***** Mark ~org-preview-latex-default-process~ obsolete
+
+Use ~org-latex-preview-process-default~ instead.  The replacement
+variable behaves the exact same way and is renamed for consistency.
+
+***** Mark ~org-preview-latex-process-alist~ obsolete
+
+Use ~org-latex-preview-process-alist~ instead.  The replacement
+variable acts in the same way, except that =:latex-compiler= must now
+be a single command or a list containing a single command.  The
+placeholder ="%S"= in the format string for =:latex-compiler= is
+ignored.
+
+***** Mark ~org-clear-latex-preview~ obsolete
+
+Use ~org-latex-preview-clear-overlays~ instead.  The replacement
+function acts in the exact same way and is renamed for consistency.
+
+***** Mark ~org-place-formula-image~ obsolete
+
+This functionality is replaced with ~org-latex-preview-place-image~
+(for images) and ~org-latex-preview-place-image-link~ (for links).
+
+***** Mark ~org-latex-color-format~ obsolete
+
+Use ~org-latex-preview--format-color~ instead.  The replacement
+function acts in the exact same way and is renamed for consistency.
+
+***** Mark ~org-latex-color~ obsolete
+
+Use ~org-latex-preview--attr-color~ instead.  The replacement function
+acts in the exact same way and is renamed for consistency.
+
+***** Mark ~org-normalize-color~ obsolete
+
+Use ~org-latex-preview--normalize-color~ instead.  The replacement
+function acts in the exact same way and is renamed for consistency.
+
+***** Mark ~org-latex-to-mathml-jar-file~ obsolete
+
+Use ~org-mathml-converter-jar-file~ instead.  The replacement variable
+acts in the exact same way and is renamed for consistency.
+
+***** Mark ~org-latex-to-mathml-convert-command~ obsolete
+
+Use ~org-mathml-convert-command~ instead.  The replacement variable
+acts in the exact same way and is renamed for consistency.
+
+***** Mark ~org-format-latex-mathml-available-p~ obsolete
+
+Use ~org-mathml-converter-available-p~ instead.  The replacement
+function acts in the exact same way and is renamed for consistency.
+
+***** Mark ~org-create-math-formula~ obsolete
+
+Use ~org-mathml-convert-latex~ instead.  The replacement function acts
+in the exact same way and is renamed for consistency.
+
+
 
 *** =ox-icalendar.el= line ending fix may affect downstream packages
 

lisp/ob-latex.el

@@ -37,7 +37,7 @@
 (require 'ob)
 (require 'org-macs)
 
-(declare-function org-create-formula-image "org" (string tofile options buffer &optional type))
+(declare-function org-latex-preview-create-image "org-latex-preview" (string tofile options buffer &optional type))
 (declare-function org-latex-compile "ox-latex" (texfile &optional snippet))
 (declare-function org-latex-guess-inputenc "ox-latex" (header))
 (declare-function org-splice-latex-header "org" (tpl def-pkg pkg snippets-p &optional extra))
@@ -48,10 +48,10 @@
 (defvar org-babel-tangle-lang-exts)
 (add-to-list 'org-babel-tangle-lang-exts '("latex" . "tex"))
 
-(defvar org-format-latex-header)	  ; From org.el
-(defvar org-format-latex-options)	  ; From org.el
-(defvar org-latex-default-packages-alist) ; From org.el
-(defvar org-latex-packages-alist)	  ; From org.el
+(defvar org-latex-preview-header)             ; From org-latex-preview.el
+(defvar org-latex-preview-appearance-options) ; From org-latex-preview.el
+(defvar org-latex-default-packages-alist)     ; From org-latex-preview.el
+(defvar org-latex-packages-alist)             ; From org-latex-preview.el
 
 (defvar org-babel-default-header-args:latex
   '((:results . "latex") (:exports . "results"))
@@ -167,11 +167,11 @@ This function is called by `org-babel-execute-src-block'."
 	      (append (cdr (assq :packages params)) org-latex-packages-alist)))
         (cond
          ((and (string-suffix-p ".png" out-file) (not imagemagick))
-          (let ((org-format-latex-header
-		 (concat org-format-latex-header "\n"
+          (let ((org-latex-preview-header
+		 (concat org-latex-preview-header "\n"
 			 (mapconcat #'identity headers "\n"))))
-	    (org-create-formula-image
-             body out-file org-format-latex-options in-buffer)))
+	    (org-latex-preview-create-image
+             body out-file org-latex-preview-appearance-options in-buffer)))
 	 ((string= "svg" extension)
 	  (with-temp-file tex-file
 	    (insert (concat (funcall org-babel-latex-preamble params)
@@ -238,7 +238,7 @@ This function is called by `org-babel-execute-src-block'."
 	    (insert
 	     (org-latex-guess-inputenc
 	      (org-splice-latex-header
-	       org-format-latex-header
+	       org-latex-preview-header
 	       (delq
 		nil
 		(mapcar

lisp/oc-biblatex.el

@@ -376,61 +376,47 @@ INFO is the export state, as a property list."
        (other
         (user-error "Invalid entry %S in `org-cite-biblatex-styles'" other))))))
 
-(defun org-cite-biblatex-prepare-preamble (output _keys files style &rest _)
-  "Prepare document preamble for \"biblatex\" usage.
+(defun org-cite-biblatex--generate-latex-usepackage (info)
+  "Ensure that the biblatex package is loaded.
+This is performed by extracting relevant information from the
+INFO export plist, and modifying any existing
+\\usepackage{biblatex} statement in the LaTeX header."
+  (let ((style (org-cite-bibliography-style info))
+        (usepackage-rx (rx "\\usepackage"
+                           (opt (group "[" (*? anything) "]"))
+                           "{biblatex}")))
+    (concat
+     (if (string-match usepackage-rx (plist-get info :latex-full-header))
+         ;; "biblatex" package loaded, but with none (or different) options.
+         ;; Replace with style-including command.
+         (plist-put info :latex-full-header
+                    (replace-match
+                     (format "\\usepackage%s{biblatex}"
+                             (save-match-data
+                               (org-cite-biblatex--package-options nil style)))
+                     t t
+                     (plist-get info :latex-full-header)))
+       ;; No "biblatex" package loaded.  Insert "usepackage" command
+       ;; with appropriate options, including style.
+       (format "\\usepackage%s{biblatex}\n"
+               (org-cite-biblatex--package-options
+                org-cite-biblatex-options style))))))
 
-OUTPUT is the final output of the export process.  FILES is the list of file
-names used as the bibliography.
-
-This function ensures \"biblatex\" package is required.  It also adds resources
-to the document, and set styles."
-  (with-temp-buffer
-    (save-excursion (insert output))
-    (when (search-forward "\\begin{document}" nil t)
-      ;; Ensure there is a \usepackage{biblatex} somewhere or add one.
-      ;; Then set options.
-      (goto-char (match-beginning 0))
-      (let ((re (rx "\\usepackage"
-                    (opt (group "[" (*? anything) "]"))
-                    "{biblatex}")))
-        (cond
-         ;; No "biblatex" package loaded.  Insert "usepackage" command
-         ;; with appropriate options, including style.
-         ((not (re-search-backward re nil t))
-          (save-excursion
-            (insert
-             (format "\\usepackage%s{biblatex}\n"
-                     (org-cite-biblatex--package-options
-                      org-cite-biblatex-options style)))))
-         ;; "biblatex" package loaded, but without any option.
-         ;; Include style only.
-         ((not (match-beginning 1))
-          (search-forward "{" nil t)
-          (insert (org-cite-biblatex--package-options nil style)))
-         ;; "biblatex" package loaded with some options set.  Override
-         ;; style-related options with ours.
-         (t
-          (replace-match
-           (save-match-data
-             (org-cite-biblatex--package-options (match-string 1) style))
-           nil nil nil 1))))
-      ;; Insert resources below.
-      (forward-line)
-      (insert (mapconcat (lambda (f)
-                           (format "\\addbibresource%s{%s}"
-                                   (if (org-url-p f) "[location=remote]" "")
-                                   f))
-                         files
-                         "\n")
-              "\n"))
-    (buffer-string)))
+(defun org-cite-biblatex--generate-latex-bibresources (info)
+  "From INFO generate LaTeX that loads the relevant bibliography resource files."
+  (let ((files (plist-get info :bibliography)))
+    (mapconcat (lambda (f)
+                 (format "\\addbibresource%s{%s}"
+                         (if (org-url-p f) "[location=remote]" "")
+                         f))
+               files
+               "\n")))
 
 
 ;;; Register `biblatex' processor
 (org-cite-register-processor 'biblatex
   :export-bibliography #'org-cite-biblatex-export-bibliography
   :export-citation #'org-cite-biblatex-export-citation
-  :export-finalizer #'org-cite-biblatex-prepare-preamble
   :cite-styles #'org-cite-biblatex-list-styles)
 
 (provide 'oc-biblatex)

lisp/oc-csl.el

@@ -847,27 +847,11 @@ INFO is the export state, as a property list."
        ;; process.
        (org-cite-parse-elements output)))))
 
-(defun org-cite-csl-finalizer (output _keys _files _style _backend info)
-  "Add \"hanging\" package if missing from LaTeX output.
-OUTPUT is the export document, as a string.  INFO is the export state, as a
-property list."
-  (org-cite-csl--barf-without-citeproc)
-  (if (not (eq 'org-latex (org-cite-csl--output-format info)))
-      output
-    (with-temp-buffer
-      (save-excursion (insert output))
-      (when (search-forward "\\begin{document}" nil t)
-	(goto-char (match-beginning 0))
-	;; Insert the CSL-specific parts of the LaTeX preamble.
-	(insert (org-cite-csl--generate-latex-preamble info)))
-      (buffer-string))))
-
 
 ;;; Register `csl' processor
 (org-cite-register-processor 'csl
   :export-citation #'org-cite-csl-render-citation
   :export-bibliography #'org-cite-csl-render-bibliography
-  :export-finalizer #'org-cite-csl-finalizer
   :cite-styles
   '((("author" "a") ("bare" "b") ("caps" "c") ("full" "f") ("bare-caps" "bc") ("caps-full" "cf") ("bare-caps-full" "bcf"))
     (("noauthor" "na") ("bare" "b") ("caps" "c") ("bare-caps" "bc"))

lisp/oc-natbib.el

@@ -168,32 +168,25 @@ state, as a property list."
           (org-cite-natbib--build-optional-arguments citation info)
           (org-cite-natbib--build-arguments citation)))
 
-(defun org-cite-natbib-use-package (output &rest _)
-  "Ensure output requires \"natbib\" package.
-OUTPUT is the final output of the export process."
-  (with-temp-buffer
-    (save-excursion (insert output))
-    (when (search-forward "\\begin{document}" nil t)
-      ;; Ensure there is a \usepackage{natbib} somewhere or add one.
-      (goto-char (match-beginning 0))
-      (let ((re (rx "\\usepackage" (opt "[" (*? nonl) "]") "{natbib}")))
-        (unless (re-search-backward re nil t)
-          (insert
-           (format "\\usepackage%s{natbib}\n"
-                   (if (null org-cite-natbib-options)
-                       ""
-                     (format "[%s]"
-                             (mapconcat #'symbol-name
-                                        org-cite-natbib-options
-                                        ","))))))))
-    (buffer-string)))
+(defun org-cite-natbib--generate-latex-preamble (info)
+  "Ensure that the \"natbib\" package is loaded.
+INFO is a plist used as a communication channel."
+  (and (not (string-match
+             (rx "\\usepackage" (opt "[" (*? nonl) "]") "{natbib}")
+             (plist-get info :latex-full-header)))
+       (format "\\usepackage%s{natbib}\n"
+               (if (null org-cite-natbib-options)
+                   ""
+                 (format "[%s]"
+                         (mapconcat #'symbol-name
+                                    org-cite-natbib-options
+                                    ","))))))
 
 
 ;;; Register `natbib' processor
 (org-cite-register-processor 'natbib
   :export-bibliography #'org-cite-natbib-export-bibliography
   :export-citation #'org-cite-natbib-export-citation
-  :export-finalizer #'org-cite-natbib-use-package
   :cite-styles
   '((("author" "a") ("caps" "a") ("full" "f"))
     (("noauthor" "na") ("bare" "b"))

lisp/ol.el

@@ -1156,6 +1156,9 @@ and then used in capture templates."
 	   if store-func
 	   collect store-func))
 
+(defvar org-link--abbrev-functions nil
+  "Alist of abbrev link expressions and functions.")
+
 (defun org-link-expand-abbrev (link)
   "Replace link abbreviations in LINK string.
 Abbreviations are defined in `org-link-abbrev-alist'."
@@ -1170,14 +1173,27 @@ Abbreviations are defined in `org-link-abbrev-alist'."
 	(setq rpl (cdr as))
 	(cond
 	 ((symbolp rpl) (funcall rpl tag))
-	 ((string-match "%(\\([^)]+\\))" rpl)
+	 ((string-match "%(\\([^) ]+\\))" rpl) ; %(function)
 	  (replace-match
 	   (save-match-data
 	     (funcall (intern-soft (match-string 1 rpl)) tag))
 	   t t rpl))
-	 ((string-match "%s" rpl) (replace-match (or tag "") t t rpl))
-	 ((string-match "%h" rpl)
-	  (replace-match (url-hexify-string (or tag "")) t t rpl))
+         ((string-match "%(\\(.+\\))" rpl) ; %(sexpr using tag)
+          (replace-match
+           (save-match-data
+             (funcall (or (cdr (assoc (match-string 1 rpl)
+                                      org-link--abbrev-functions))
+                          (cdar (push (cons (match-string 1 rpl)
+                                            (eval (read (format
+                                                         "(lambda (tag) (%s))"
+                                                         (match-string 1 rpl)))))
+                                      org-link--abbrev-functions)))
+                      tag))
+           t t rpl))
+	 ((string-match-p "%[0-<>^_]?[0-9]*\\(?:\\.[0-9]+\\)?s" rpl)
+          (format-spec rpl `((?s . ,(or tag "")))))
+	 ((string-match-p "%[0-<>^_]?[0-9]*\\(?:\\.[0-9]+\\)?h" rpl)
+          (format-spec rpl `((?h . ,(url-hexify-string (or tag ""))))))
 	 (t (concat rpl tag)))))))
 
 (defun org-link-open (link &optional arg)

lisp/org-compat.el

@@ -251,6 +251,18 @@ removed."
                     default)))
      ": ")))
 
+(if (fboundp 'ensure-list)
+    (defalias 'org-ensure-list #'ensure-list)
+  (defun org-ensure-list (object)
+    "Return OBJECT as a list.
+If OBJECT is already a list, return OBJECT itself.  If it's
+not a list, return a one-element list containing OBJECT.
+
+Compatability substitute for `ensure-list' in Emacs 28."
+    (if (listp object)
+        object
+      (list object))))
+
 
 ;;; Emacs < 27.1 compatibility
 
@@ -674,6 +686,393 @@ This constant, for example, makes the below code not err:
                "use `org-element' library"
                "9.0")
 
+(define-obsolete-variable-alias
+  'org-format-latex-options 'org-latex-preview-appearance-options "9.7")
+(make-obsolete-variable
+ 'org-format-latex-signal-error "no longer used" "9.7")
+(define-obsolete-variable-alias
+  'org-format-latex-header 'org-latex-preview-preamble "9.7")
+(define-obsolete-variable-alias
+  'org-preview-latex-default-process 'org-latex-preview-process-default "9.7")
+(define-obsolete-variable-alias
+  'org-preview-latex-process-alist 'org-latex-preview-process-alist "9.7")
+(define-obsolete-function-alias
+  'org-clear-latex-preview 'org-latex-preview-clear-overlays "9.7")
+(make-obsolete
+ 'org-place-formula-image "no longer used" "9.7")
+(define-obsolete-function-alias
+  'org-latex-color-format 'org-latex-preview--format-color "9.7")
+(define-obsolete-function-alias
+  'org-latex-color 'org-latex-preview--attr-color "9.7")
+;; MathML related functions from org-latex-preview.el
+(define-obsolete-variable-alias
+  'org-latex-to-mathml-jar-file 'org-mathml-converter-jar-file "9.7")
+(define-obsolete-variable-alias
+  'org-latex-to-mathml-convert-command 'org-mathml-convert-command "9.7")
+(define-obsolete-function-alias
+  'org-format-latex-mathml-available-p 'org-mathml-converter-available-p "9.7")
+(define-obsolete-function-alias
+  'org-create-math-formula 'org-mathml-convert-latex "9.7")
+
+;; FIXME: Unused; obsoleted; to be removed.
+(defun org-format-latex-as-mathml (latex-frag latex-frag-type
+                                              prefix &optional dir)
+  (let* ((absprefix (expand-file-name prefix dir))
+         (print-length nil) (print-level nil)
+         (formula-id (concat
+                      "formula-"
+                      (sha1
+                       (prin1-to-string
+                        (list latex-frag
+                              org-latex-to-mathml-convert-command)))))
+         (formula-cache (format "%s-%s.mathml" absprefix formula-id))
+         (formula-cache-dir (file-name-directory formula-cache)))
+    (unless (file-directory-p formula-cache-dir)
+      (make-directory formula-cache-dir t))
+    (unless (file-exists-p formula-cache)
+      (org-mathml-convert-latex latex-frag formula-cache))
+    (if (file-exists-p formula-cache)
+        ;; Successful conversion.  Return the link to MathML file.
+        (org-add-props
+            (format  "[[file:%s]]" (file-relative-name formula-cache dir))
+            (list 'org-latex-src (replace-regexp-in-string "\"" "" latex-frag)
+                  'org-latex-src-embed-type (if latex-frag-type
+                                                'paragraph 'character)))
+      ;; Failed conversion.  Return the LaTeX fragment verbatim
+      latex-frag)))
+(make-obsolete #'org-format-latex-as-mathml "to be removed" "9.7")
+
+;; FIXME: Unused; obsoleted; to be removed.
+(defun org-dvipng-color (attr)
+  "Return a RGB color specification for dvipng."
+  (org-dvipng-color-format (face-attribute 'default attr nil)))
+
+;; FIXME: Unused; obsoleted; to be removed.
+(defun org-dvipng-color-format (color-name)
+  "Convert COLOR-NAME to a RGB color value for dvipng."
+  (apply #'format "rgb %s %s %s"
+         (mapcar 'org-latex-preview--normalize-color
+                 (color-values color-name))))
+(make-obsolete
+ 'org-dvipng-color "to be removed" "9.7")
+(make-obsolete
+ 'org-dvipng-color-format "to be removed" "9.7")
+
+;; FIXME: Unused; obsoleted; to be removed.
+(defun org-normalize-color (value)
+  "Return string to be used as color value for an RGB component."
+  (format "%g" (/ value 65535.0)))
+(make-obsolete 'org-normalize-color "to be removed" "9.7")
+
+;; FIXME: Unused; obsoleted; to be removed.
+(defcustom org-preview-latex-image-directory "ltximg/"
+  "Path to store latex preview images.
+A relative path here creates many directories relative to the
+processed Org files paths.  An absolute path puts all preview
+images at the same place."
+  :group 'org-latex
+  :version "26.1"
+  :package-version '(Org . "9.0")
+  :type 'string)
+
+(make-obsolete-variable
+ 'org-preview-latex-image-directory "replaced with org-persist" "9.7")
+
+;; FIXME: Unused; obsoleted; to be removed.
+(defun org-format-latex
+    (prefix &optional beg end dir overlays msg forbuffer processing-type)
+  "Replace LaTeX fragments with links to an image.
+
+The function takes care of creating the replacement image.
+
+Only consider fragments between BEG and END when those are
+provided.
+
+When optional argument OVERLAYS is non-nil, display the image on
+top of the fragment instead of replacing it.
+
+PROCESSING-TYPE is the conversion method to use, as a symbol.
+
+Some of the options can be changed using the variable
+`org-format-latex-options', which see."
+  (when (and overlays (fboundp 'clear-image-cache)) (clear-image-cache))
+  (unless (eq processing-type 'verbatim)
+    (let* ((math-regexp "\\$\\|\\\\[([]\\|^[ \t]*\\\\begin{[A-Za-z0-9*]+}")
+	   (cnt 0)
+	   checkdir-flag)
+      (goto-char (or beg (point-min)))
+      ;; Optimize overlay creation: (info "(elisp) Managing Overlays").
+      (when (and overlays (memq processing-type '(dvipng imagemagick)))
+	(overlay-recenter (or end (point-max))))
+      (while (re-search-forward math-regexp end t)
+	(unless (and overlays
+		     (eq (get-char-property (point) 'org-overlay-type)
+			 'org-latex-overlay))
+	  (let* ((context (org-element-context))
+		 (type (org-element-type context)))
+	    (when (memq type '(latex-environment latex-fragment))
+	      (let ((block-type (eq type 'latex-environment))
+		    (value (org-element-property :value context))
+		    (beg (org-element-property :begin context))
+		    (end (save-excursion
+			   (goto-char (org-element-property :end context))
+			   (skip-chars-backward " \r\t\n")
+			   (point))))
+		(cond
+		 ((eq processing-type 'mathjax)
+		  ;; Prepare for MathJax processing.
+		  (if (not (string-match "\\`\\$\\$?" value))
+		      (goto-char end)
+		    (delete-region beg end)
+		    (if (string= (match-string 0 value) "$$")
+			(insert "\\[" (substring value 2 -2) "\\]")
+		      (insert "\\(" (substring value 1 -1) "\\)"))))
+		 ((eq processing-type 'html)
+		  (goto-char beg)
+		  (delete-region beg end)
+		  (insert (org-format-latex-as-html value)))
+		 ((assq processing-type org-preview-latex-process-alist)
+		  ;; Process to an image.
+		  (cl-incf cnt)
+		  (goto-char beg)
+		  (let* ((processing-info
+			  (cdr (assq processing-type org-preview-latex-process-alist)))
+			 (face (face-at-point))
+			 ;; Get the colors from the face at point.
+			 (fg
+			  (let ((color (plist-get org-format-latex-options
+						  :foreground)))
+                            (if forbuffer
+                                (cond
+                                 ((eq color 'auto)
+                                  (face-attribute face :foreground nil 'default))
+                                 ((eq color 'default)
+                                  (face-attribute 'default :foreground nil))
+                                 (t color))
+                              color)))
+			 (bg
+			  (let ((color (plist-get org-format-latex-options
+						  :background)))
+                            (if forbuffer
+                                (cond
+                                 ((eq color 'auto)
+                                  (face-attribute face :background nil 'default))
+                                 ((eq color 'default)
+                                  (face-attribute 'default :background nil))
+                                 (t color))
+                              color)))
+			 (hash (sha1 (prin1-to-string
+				      (list org-format-latex-header
+					    org-latex-default-packages-alist
+					    org-latex-packages-alist
+					    org-format-latex-options
+					    forbuffer value fg bg))))
+			 (imagetype (or (plist-get processing-info :image-output-type) "png"))
+			 (absprefix (expand-file-name prefix dir))
+			 (linkfile (format "%s_%s.%s" prefix hash imagetype))
+			 (movefile (format "%s_%s.%s" absprefix hash imagetype))
+			 (sep (and block-type "\n\n"))
+			 (link (concat sep "[[file:" linkfile "]]" sep))
+			 (options
+			  (org-combine-plists
+			   org-format-latex-options
+			   `(:foreground ,fg :background ,bg))))
+		    (when msg (message msg cnt))
+		    (unless checkdir-flag ; Ensure the directory exists.
+		      (setq checkdir-flag t)
+		      (let ((todir (file-name-directory absprefix)))
+			(unless (file-directory-p todir)
+			  (make-directory todir t))))
+		    (unless (file-exists-p movefile)
+		      (org-create-formula-image
+		       value movefile options forbuffer processing-type))
+                    (org-place-formula-image link block-type beg end value overlays movefile imagetype)))
+		 ((eq processing-type 'mathml)
+		  ;; Process to MathML.
+		  (unless (org-format-latex-mathml-available-p)
+		    (user-error "LaTeX to MathML converter not configured"))
+		  (cl-incf cnt)
+		  (when msg (message msg cnt))
+		  (goto-char beg)
+		  (delete-region beg end)
+		  (insert (org-format-latex-as-mathml
+			   value block-type prefix dir)))
+		 (t
+		  (error "Unknown conversion process %s for LaTeX fragments"
+			 processing-type)))))))))))
+
+;; FIXME: Unused; obsoleted; to be removed.
+(defun org-place-formula-image (link block-type beg end value overlays movefile imagetype)
+  "Place an overlay from BEG to END showing MOVEFILE.
+The overlay will be above BEG if OVERLAYS is non-nil."
+  (if overlays
+      (progn
+        (dolist (o (overlays-in beg end))
+          (when (eq (overlay-get o 'org-overlay-type)
+                    'org-latex-overlay)
+            (delete-overlay o)))
+        (let ((ov (make-overlay beg end))
+              (imagetype (or (intern imagetype) 'png)))
+          (overlay-put ov 'org-overlay-type 'org-latex-overlay)
+          (overlay-put ov 'evaporate t)
+          (overlay-put ov
+                       'modification-hooks
+                       (list (lambda (o _flag _beg _end &optional _l)
+                               (delete-overlay o))))
+          (overlay-put ov
+                       'display
+                       (list 'image :type imagetype :file movefile :ascent 'center)))
+        (goto-char end))
+    (delete-region beg end)
+    (insert
+     (org-add-props link
+         (list 'org-latex-src
+               (replace-regexp-in-string "\"" "" value)
+               'org-latex-src-embed-type
+               (if block-type 'paragraph 'character))))))
+
+
+;; FIXME: Unused; obsoleted; to be removed.
+(defun org-create-formula-image
+    (string tofile options buffer &optional processing-type)
+  "Create an image from LaTeX source using external processes.
+
+The LaTeX STRING is saved to a temporary LaTeX file, then
+converted to an image file by process PROCESSING-TYPE defined in
+`org-preview-latex-process-alist'.  A nil value defaults to
+`org-preview-latex-default-process'.
+
+The generated image file is eventually moved to TOFILE.
+
+The OPTIONS argument controls the size, foreground color and
+background color of the generated image.
+
+When BUFFER non-nil, this function is used for LaTeX previewing.
+Otherwise, it is used to deal with LaTeX snippets showed in
+a HTML file."
+  (let* ((processing-type (or processing-type
+			      org-preview-latex-default-process))
+	 (processing-info
+	  (cdr (assq processing-type org-preview-latex-process-alist)))
+	 (programs (plist-get processing-info :programs))
+	 (error-message (or (plist-get processing-info :message) ""))
+	 (image-input-type (plist-get processing-info :image-input-type))
+	 (image-output-type (plist-get processing-info :image-output-type))
+	 (post-clean (or (plist-get processing-info :post-clean)
+			 '(".dvi" ".xdv" ".pdf" ".tex" ".aux" ".log"
+			   ".svg" ".png" ".jpg" ".jpeg" ".out")))
+	 (latex-header
+	  (or (plist-get processing-info :latex-header)
+	      (org-latex-make-preamble
+	       (org-export-get-environment (org-export-get-backend 'latex))
+	       org-format-latex-header
+	       'snippet)))
+	 (latex-compiler (plist-get processing-info :latex-compiler))
+	 (tmpdir temporary-file-directory)
+	 (texfilebase (make-temp-name
+		       (expand-file-name "orgtex" tmpdir)))
+	 (texfile (concat texfilebase ".tex"))
+	 (image-size-adjust (or (plist-get processing-info :image-size-adjust)
+				'(1.0 . 1.0)))
+	 (scale (* (if buffer (car image-size-adjust) (cdr image-size-adjust))
+		   (or (plist-get options (if buffer :scale :html-scale)) 1.0)))
+	 (dpi (* scale (if (and buffer (display-graphic-p)) (org--get-display-dpi) 140.0)))
+	 (fg (or (plist-get options (if buffer :foreground :html-foreground))
+		 "Black"))
+	 (bg (or (plist-get options (if buffer :background :html-background))
+		 "Transparent"))
+	 (image-converter
+          (or (and (string= bg "Transparent")
+                   (plist-get processing-info :transparent-image-converter))
+              (plist-get processing-info :image-converter)))
+         (log-buf (get-buffer-create "*Org Preview LaTeX Output*"))
+	 (resize-mini-windows nil)) ;Fix Emacs flicker when creating image.
+    (dolist (program programs)
+      (org-check-external-command program error-message))
+    (if (eq fg 'default)
+	(setq fg (org-latex-color :foreground))
+      (setq fg (org-latex-color-format fg)))
+    (setq bg (cond
+	      ((eq bg 'default) (org-latex-color :background))
+	      ((string= bg "Transparent") nil)
+	      (t (org-latex-color-format bg))))
+    ;; Remove TeX \par at end of snippet to avoid trailing space.
+    (if (string-suffix-p string "\n")
+        (aset string (1- (length string)) ?%)
+      (setq string (concat string "%")))
+    (with-temp-file texfile
+      (insert latex-header)
+      (insert "\n\\begin{document}\n"
+	      "\\definecolor{fg}{rgb}{" fg "}%\n"
+	      (if bg
+		  (concat "\\definecolor{bg}{rgb}{" bg "}%\n"
+			  "\n\\pagecolor{bg}%\n")
+		"")
+	      "\n{\\color{fg}\n"
+	      string
+	      "\n}\n"
+	      "\n\\end{document}\n"))
+    (let* ((err-msg (format "Please adjust `%s' part of \
+`org-preview-latex-process-alist'."
+			    processing-type))
+	   (image-input-file
+	    (org-compile-file
+	     texfile latex-compiler image-input-type err-msg log-buf))
+	   (image-output-file
+	    (org-compile-file
+	     image-input-file image-converter image-output-type err-msg log-buf
+	     `((?D . ,(shell-quote-argument (format "%s" dpi)))
+	       (?S . ,(shell-quote-argument (format "%s" (/ dpi 140.0))))))))
+      (copy-file image-output-file tofile 'replace)
+      (dolist (e post-clean)
+	(when (file-exists-p (concat texfilebase e))
+	  (delete-file (concat texfilebase e))))
+      image-output-file)))
+
+;; FIXME: Unused; obsoleted; to be removed.
+(defun org-html-format-latex (latex-frag processing-type info)
+  "Format a LaTeX fragment LATEX-FRAG into HTML.
+PROCESSING-TYPE designates the tool used for conversion.  It can
+be `mathjax', `verbatim', `html', nil, t or symbols in
+`org-preview-latex-process-alist', e.g., `dvipng', `dvisvgm' or
+`imagemagick'.  See `org-html-with-latex' for more information.
+INFO is a plist containing export properties."
+  (let ((cache-relpath "") (cache-dir ""))
+    (unless (or (eq processing-type 'mathjax)
+                (eq processing-type 'html))
+      (let ((bfn (or (buffer-file-name)
+		     (make-temp-name
+		      (expand-file-name "latex" temporary-file-directory))))
+	    (latex-header
+	     (let ((header (plist-get info :latex-header)))
+	       (and header
+		    (concat (mapconcat
+			     (lambda (line) (concat "#+LATEX_HEADER: " line))
+			     (org-split-string header "\n")
+			     "\n")
+			    "\n")))))
+	(setq cache-relpath
+	      (concat (file-name-as-directory org-preview-latex-image-directory)
+		      (file-name-sans-extension
+		       (file-name-nondirectory bfn)))
+	      cache-dir (file-name-directory bfn))
+	;; Re-create LaTeX environment from original buffer in
+	;; temporary buffer so that dvipng/imagemagick can properly
+	;; turn the fragment into an image.
+	(setq latex-frag (concat latex-header latex-frag))))
+    (org-export-with-buffer-copy
+     :to-buffer (get-buffer-create " *Org HTML Export LaTeX*")
+     :drop-visibility t :drop-narrowing t :drop-contents t
+     (erase-buffer)
+     (insert latex-frag)
+     (org-format-latex cache-relpath nil nil cache-dir nil
+		       "Creating LaTeX Image..." nil processing-type)
+     (buffer-string))))
+
+(make-obsolete #'org-format-latex "to be removed" "9.7")
+(make-obsolete #'org-create-formula-image "to be removed" "9.7")
+(make-obsolete #'org-html-format-latex "to be removed" "9.7")
+
 ;; FIXME: Unused; obsoleted; to be removed.
 (defun org-let (list &rest body) ;FIXME: So many kittens are suffering here.
   (declare (indent 1) (obsolete cl-progv "2021"))

lisp/org-macs.el

@@ -368,6 +368,278 @@ If EXCLUDE-TMP is non-nil, ignore temporary buffers."
 	       nil))
 	   (buffer-list)))))
 
+
+;;; Async stack
+
+(defvar org-async--stack nil
+  "List of async currently running task forms.
+Each running task is represented by a list with the following structure:
+  (%PROCESS :success %FUN :failure %FUN
+            :filter %FUN :buffer %BUFFER
+            :timeout %FLOAT :start-time %FLOAT
+            :info %SEXP)")
+
+(defvar org-async--wait-queue nil
+   "List of async queued task forms.
+Each queued task is represented by a list with the following structure:
+  (%PROCESS :success %FUN :failure %FUN
+            :filter %FUN :buffer %BUFFER
+            :info %SEXP :dir %STRING
+            :timeout %FLOAT :coding %SYMBOL)")
+
+(defvar org-async-process-limit 4
+  "Maximum number of processes to run at once.")
+
+(defvar org-async-timeout 120
+  "Default timeout for a process started via `org-async-queue'.")
+
+(defvar org-async-check-timeout-interval 1
+  "Check for processes which have exceeded their timeout every this many seconds.")
+
+(defvar org-async--counter 0)
+
+(cl-defun org-async-call (proc &key success failure filter buffer info timeout now process-variables
+                               (dir default-directory) (coding 'utf-8))
+  "Start PROC and register it with callbacks SUCCESS and FAILURE.
+
+PROC can be a process, string, or list.  A string will be run as
+a shell command, with `start-process-shell-command' and a list
+run using `start-process' with the car as the command and the cdr
+as the arguments.  The process will be executed in DIR (if set)
+or `default-directory'.
+
+There is also a \"special form\" of PROC, namely a list where the
+first item is the symbol org-async-task, and the rest constitutes
+an argument list for `org-async-call'.  This form allows for easy
+specification of callbacks that are themselves async tasks, e.g.
+  (org-async-call \\='(\"sleep 1\")
+                   :success \\='(org-async-task (\"notify-send\" \"done\")))
+When using this form, all other arguments are ignored.
+
+When BUFFER is provided, the output of PROC will be directed to it.
+Shoud BUFFER be t, then a temp buffer will be created and removed
+during `org-async--cleanup-process'.
+
+SUCCESS and FAILURE can be any form accepted by `org-async--execute-callback',
+namely:
+- A string, which is used a `message' string with the exit-code,
+  process-buffer, and INFO as arguments.
+- A function, which is called with exit-code, process-buffer,
+  and INFO as arguments.
+- A list, which is used as an argument list for a new `org-async-call' call.
+- nil, which does nothing.
+
+When PROC succeeds by exiting with an exit code of zero, the SUCCESS
+callback will be run.  Should PROC fail, or be killed, or the process
+runs for more than TIMEOUT seconds, the FAILURE callback will be run.
+
+A function FILTER can be provided, in which case it will be
+called in the same manner as a normal procecss filter, however
+the function FILTER will be called with INFO as a third argument.
+i.e. the call signature is (content new-content-string INFO)
+When BUFFER is non-nil, there are two other major differences:
+- The new content is silently inserted before FILTER is called
+  - Note that `point' is left alone and is not moved by this.
+- The process buffer is the current buffer when FILTER is called.
+
+When CODING is non-nil, both the process encode and decode system
+will be set to CODING.  If unset, UTF-8 is used.
+
+When NOW is non-nil, the PROC is started immediately, regardless
+of `org-async-process-limit'.
+
+For improved performance, PROCESS-VARIABLES is a list of
+let-style bindings that should be applied to the process.
+Variables are supported on an individual basis (i.e. only certain
+variables can be set), with the default value being equivalent to:
+
+  :process-variables ((process-adaptive-read-buffering nil)
+                      (process-connection-type nil)
+                      (read-process-output-max 65536))"
+  (cond
+   ;; Called with a task (as can be used with callbacks), so re-call
+   ;; with expanded arguments.
+   ((and (consp proc)
+         (eq (car proc) 'org-async-task))
+    (apply #'org-async-call (cdr proc)))
+   ;; Start the async process now.
+   ((or now (< (length org-async--stack) org-async-process-limit))
+    (let ((proc
+           (let ((default-directory (or dir default-directory))
+                 (process-adaptive-read-buffering ; No by default
+                  (cadr (or (assoc 'process-adaptive-read-buffering process-variables) nil)))
+                 (process-connection-type ; Use a pipe by default
+                  (cadr (or (assoc 'process-connection-type process-variables) nil)))
+                 (read-process-output-max ; Can be worth changing depending on the process
+                  (or (assq 'read-process-output-max process-variables) read-process-output-max)))
+             (cond ((processp proc) proc)
+                   ((stringp proc)
+                    (start-process-shell-command
+                     (format "org-async-%d" (cl-incf org-async--counter))
+                     buffer proc))
+                   ((consp proc)
+                    (apply #'start-process
+                           (format "org-async-%s-%d"
+                                   (car proc) (cl-incf org-async--counter))
+                           buffer proc))
+                   (t (error "Async process input %S not a recognised format"
+                             proc)))))
+          (timeout (or timeout org-async-timeout)))
+      (set-process-sentinel proc #'org-async--sentinel)
+      (when filter
+        (set-process-filter proc #'org-async--filter))
+      (when coding
+        (set-process-coding-system proc coding coding))
+      (push (list proc
+                  :success success
+                  :failure failure
+                  :filter filter
+                  :buffer (if (eq buffer t)
+                              (cons :temp (generate-new-buffer " *temp*" t))
+                            buffer)
+                  :info info
+                  :timeout timeout
+                  :start-time (float-time))
+            org-async--stack)
+      (org-async--monitor t)
+      (car org-async--stack)))
+   ;; Queue the task to be run later.
+   (t
+    (setq org-async--wait-queue
+          (append org-async--wait-queue
+                  (list (list proc
+                              :success success
+                              :failure failure
+                              :filter filter
+                              :buffer buffer
+                              :info info
+                              :dir dir
+                              :timeout timeout
+                              :coding coding))))
+    (last org-async--wait-queue))))
+
+(defvar org-async--blocking-tasks nil
+  "List of async tasks currently being waited on.")
+
+(defun org-async-wait-for (&rest tasks)
+  "Block until every task of TASKS has finished (including callback tasks)."
+  (setq org-async--blocking-tasks tasks)
+  (while org-async--blocking-tasks
+    (dolist (task org-async--blocking-tasks)
+      (accept-process-output (car task)))))
+
+(defun org-async--filter (process string)
+  "After PROCESS recieves STRING, call the async filter.
+This is implementated to satisfy the filter function documentation in
+`org-async-call'."
+  (when-let ((proc-info (alist-get process org-async--stack)))
+    (let ((filter (plist-get proc-info :filter))
+          (buffer (plist-get proc-info :buffer)))
+      (if buffer
+          (with-current-buffer buffer
+            (save-excursion
+              (goto-char (point-max))
+              (insert string))
+            (funcall filter process string (plist-get proc-info :info)))
+        (funcall filter process string (plist-get proc-info :info))))))
+
+(defun org-async--sentinel (process _signal)
+  "Watch PROCESS for death, and cleanup accordingly.
+When a signal is recieved, the status of PROCESS is checked.
+Should the it have an exit status, with status code 0,
+`org-async--cleanup-process' is run with the \"failed\" argument
+unset.  Should the process have finished in any other manner,
+`org-async--cleanup-process' is run with the \"failed\" argument."
+  (pcase (process-status process)
+    ((and 'exit (guard (= 0 (process-exit-status process))))
+     (org-async--cleanup-process process))
+    ((or 'exit 'signal 'failed)
+     (org-async--cleanup-process process 'failed))))
+
+(defun org-async--cleanup-process (process &optional failed)
+  "Remove PROCESS from the async stack, and run its callback.
+If the exit code of PROCESS is zero and FAILED is non-nil, then
+the success callback is run (via `org-async--execute-callback').
+Otherwise, the failure callback is run."
+  (when (assq process org-async--stack)
+    (let* ((proc-info (cdr (assq process org-async--stack)))
+           (buffer-val (plist-get proc-info :buffer))
+           (proc-buf (if (consp buffer-val) (cdr buffer-val) buffer-val))
+           (blocking-p (cl-member process org-async--blocking-tasks :key #'car)))
+      (setq org-async--stack
+            (delq (assq process org-async--stack) org-async--stack))
+      ;; Ensure that any filter is called on the final output
+      ;; prior to the callbacks.
+      (while (accept-process-output process))
+      (org-async--execute-callback
+       (plist-get
+        proc-info
+        (if (and (not failed)
+                 (= 0 (process-exit-status process)))
+            :success :failure))
+       (process-exit-status process)
+       proc-buf
+       (plist-get proc-info :info)
+       blocking-p)
+      (when blocking-p
+        (setq org-async--blocking-tasks
+              (cl-delete process org-async--blocking-tasks :key #'car)))
+      (when (and (consp buffer-val) (eq :temp (car buffer-val)))
+        (kill-buffer proc-buf)))
+    (when (and org-async--wait-queue
+               (< org-async-process-limit (length org-async--stack)))
+      (apply #'org-async-call (pop org-async--wait-queue)))))
+
+(defun org-async--execute-callback (callback exit-code process-buffer info &optional blocking)
+  "Run CALLBACK with EXIT-CODE, PROCESS-BUFFER, and INFO.
+CALLBACK can take one of four forms:
+- A string, which is used a `message' string with EXIT-CODE,
+  PROCESS-BUFFER, and INFO as arguments.
+- A function, which is called with EXIT-CODE, PROCESS-BUFFER,
+  and INFO as arguments.
+- A list, which is either:
+  - An (org-async-task ...) structure, which passed to an
+    `org-async-call' invocation.
+  - A list of callbacks, which are individually evaluated.
+- nil, which does nothing.
+
+When BLOCKING is set, all callback tasks are made blocking."
+  (cond
+   ((stringp callback)
+    (message callback exit-code process-buffer info))
+   ((functionp callback)
+    (funcall callback exit-code process-buffer info))
+   ((consp callback)
+    (if (eq (car callback) 'org-async-task)
+        (if blocking
+            (push (org-async-call callback) org-async--blocking-tasks)
+          (org-async-call callback))
+      (dolist (clbk callback)
+        (org-async--execute-callback clbk exit-code process-buffer info blocking))))
+   ((null callback)) ; Do nothing.
+   (t (message "Ignoring invalid `org-async-call' callback: %S" callback))))
+
+(defvar org-async--monitor-scheduled nil)
+(defun org-async--monitor (&optional force)
+  "Check each process against their timeouts, and kill any overdue.
+The only runs when `org-async--monitor-scheduled' is nil, unless FORCE is set.
+Should any processes still be alive after checking the stack, this will run
+itself using a timer in `org-async-check-timeout-interval' seconds."
+  (when (or force (null org-async--monitor-scheduled))
+    (dolist (stack-proc org-async--stack)
+      (if (process-live-p (car stack-proc))
+          (let ((timeout (plist-get (cdr stack-proc) :timeout)))
+            (when (and (numberp timeout)
+                       (< 0 timeout
+                          (- (float-time)
+                             (plist-get (cdr stack-proc) :start-time))))
+              (kill-process (car stack-proc))))
+        (org-async--cleanup-process (car stack-proc))))
+    (if org-async--stack
+        (setq org-async--monitor-scheduled
+              (run-at-time org-async-check-timeout-interval
+                           nil #'org-async--monitor t))
+      (setq org-async--monitor-scheduled nil))))
 
 
 ;;; File

lisp/org-persist.el

@@ -602,22 +602,27 @@ MISC, if non-nil will be appended to the collection.  It must be a plist."
 
 ;;;; Reading container data.
 
+(defvar org-persist--inhibit-container-normalization nil
+  "Prevent `org-persist--normalize-container' from doing anything.")
+
 (defun org-persist--normalize-container (container &optional inner)
   "Normalize CONTAINER representation into (type . settings).
 
 When INNER is non-nil, do not try to match as list of containers."
-  (pcase container
-    ((or `elisp `elisp-data `version `file `index `url)
-     `(,container nil))
-    ((or (pred keywordp) (pred stringp) `(quote . ,_))
-     `(elisp-data ,container))
-    ((pred symbolp)
-     `(elisp ,container))
-    (`(,(or `elisp `elisp-data `version `file `index `url) . ,_)
-     container)
-    ((and (pred listp) (guard (not inner)))
-     (mapcar (lambda (c) (org-persist--normalize-container c 'inner)) container))
-    (_ (error "org-persist: Unknown container type: %S" container))))
+  (if org-persist--inhibit-container-normalization
+      container
+    (pcase container
+      ((or `elisp `elisp-data `version `file `index `url)
+       `(,container nil))
+      ((or (pred keywordp) (pred stringp) `(quote . ,_))
+       `(elisp-data ,container))
+      ((pred symbolp)
+       `(elisp ,container))
+      (`(,(or `elisp `elisp-data `version `file `index `url) . ,_)
+       container)
+      ((and (pred listp) (guard (not inner)))
+       (mapcar (lambda (c) (org-persist--normalize-container c 'inner)) container))
+      (_ (error "org-persist: Unknown container type: %S" container)))))
 
 (defvar org-persist--associated-buffer-cache (make-hash-table :weakness 'key)
   "Buffer hash cache.")
@@ -823,20 +828,23 @@ COLLECTION is the plist holding data collection."
 (defun org-persist-write:file (c collection)
   "Write file container C according to COLLECTION."
   (org-persist-collection-let collection
-    (when (or (and path (file-exists-p path))
-              (and (stringp (cadr c)) (file-exists-p (cadr c))))
-      (when (and (stringp (cadr c)) (file-exists-p (cadr c)))
-        (setq path (cadr c)))
-      (let* ((persist-file (plist-get collection :persist-file))
-             (ext (file-name-extension path))
-             (file-copy (org-file-name-concat
-                         org-persist-directory
-                         (format "%s-%s.%s" persist-file (md5 path) ext))))
-        (unless (file-exists-p file-copy)
-          (unless (file-exists-p (file-name-directory file-copy))
-            (make-directory (file-name-directory file-copy) t))
-          (copy-file path file-copy 'overwrite))
-        (format "%s-%s.%s" persist-file (md5 path) ext)))))
+    (if (or (and path (file-exists-p path))
+            (and (stringp (cadr c)) (file-exists-p (cadr c))))
+        (progn
+          (when (and (stringp (cadr c)) (file-exists-p (cadr c)))
+            (setq path (cadr c)))
+          (let* ((persist-file (plist-get collection :persist-file))
+                 (ext (file-name-extension path))
+                 (file-copy (org-file-name-concat
+                             org-persist-directory
+                             (format "%s-%s.%s" persist-file (md5 path) ext))))
+            (unless (file-exists-p file-copy)
+              (unless (file-exists-p (file-name-directory file-copy))
+                (make-directory (file-name-directory file-copy) t))
+              (copy-file path file-copy 'overwrite))
+            (format "%s-%s.%s" persist-file (md5 path) ext)))
+      (when-let ((file-copy (org-persist-read c associated)))
+        (file-relative-name file-copy org-persist-directory)))))
 
 (defun org-persist-write:url (c collection)
   "Write url container C according to COLLECTION."
@@ -950,26 +958,27 @@ VALUE pairs.
 When WRITE-IMMEDIATELY is non-nil, the return value will be the same
 with `org-persist-write'."
   (unless org-persist--index (org-persist--load-index))
-  (setq container (org-persist--normalize-container container))
-  (when inherit
-    (setq inherit (org-persist--normalize-container inherit))
-    (let ((inherited-collection (org-persist--get-collection inherit associated))
-          new-collection)
-      (unless (member container (plist-get inherited-collection :container))
-        (setq new-collection
-              (plist-put (copy-sequence inherited-collection) :container
-                         (cons container (plist-get inherited-collection :container))))
-        (org-persist--remove-from-index inherited-collection)
-        (org-persist--add-to-index new-collection))))
-  (let ((collection (org-persist--get-collection container associated misc)))
-    (when (and expiry (not inherit))
-      (when expiry (plist-put collection :expiry expiry))))
-  (when (or (bufferp associated) (bufferp (plist-get associated :buffer)))
-    (with-current-buffer (if (bufferp associated)
-                             associated
-                           (plist-get associated :buffer))
-      (add-hook 'kill-buffer-hook #'org-persist-write-all-buffer nil 'local)))
-  (when write-immediately (org-persist-write container associated)))
+  (let ((container (org-persist--normalize-container container))
+        (inherit (and inherit (org-persist--normalize-container inherit)))
+        (org-persist--inhibit-container-normalization t))
+    (when inherit
+      (let ((inherited-collection (org-persist--get-collection inherit associated))
+            new-collection)
+        (unless (member container (plist-get inherited-collection :container))
+          (setq new-collection
+                (plist-put (copy-sequence inherited-collection) :container
+                           (cons container (plist-get inherited-collection :container))))
+          (org-persist--remove-from-index inherited-collection)
+          (org-persist--add-to-index new-collection))))
+    (let ((collection (org-persist--get-collection container associated misc)))
+      (when (and expiry (not inherit))
+        (when expiry (plist-put collection :expiry expiry))))
+    (when (or (bufferp associated) (bufferp (plist-get associated :buffer)))
+      (with-current-buffer (if (bufferp associated)
+                               associated
+                             (plist-get associated :buffer))
+        (add-hook 'kill-buffer-hook #'org-persist-write-all-buffer nil 'local)))
+    (when write-immediately (org-persist-write container associated))))
 
 (cl-defun org-persist-unregister (container &optional associated &key remove-related)
   "Unregister CONTAINER in ASSOCIATED to be persistent.
@@ -1084,6 +1093,9 @@ have the same meaning as in `org-persist-read'."
   "Call `org-persist-load-all' in current buffer."
   (org-persist-load-all (current-buffer)))
 
+(defvar org-persist--inhibit-write nil
+  "Whether `org-persist-write' should be inhibited.")
+
 (defun org-persist-write (container &optional associated ignore-return)
   "Save CONTAINER according to ASSOCIATED.
 ASSOCIATED can be a plist, a buffer, or a string.
@@ -1093,31 +1105,33 @@ The return value is nil when writing fails and the written value (as
 returned by `org-persist-read') on success.
 When IGNORE-RETURN is non-nil, just return t on success without calling
 `org-persist-read'."
-  (setq associated (org-persist--normalize-associated associated))
-  ;; Update hash
-  (when (and (plist-get associated :file)
-             (plist-get associated :hash)
-             (get-file-buffer (plist-get associated :file)))
-    (setq associated (org-persist--normalize-associated (get-file-buffer (plist-get associated :file)))))
-  (let ((collection (org-persist--get-collection container associated)))
-    (setf collection (plist-put collection :associated associated))
-    (unless (or
-             ;; Prevent data leakage from encrypted files.
-             ;; We do it in somewhat paranoid manner and do not
-             ;; allow anything related to encrypted files to be
-             ;; written.
-             (and (plist-get associated :file)
-                  (string-match-p epa-file-name-regexp (plist-get associated :file)))
-             (seq-find (lambda (v)
-                         (run-hook-with-args-until-success 'org-persist-before-write-hook v associated))
-                       (plist-get collection :container)))
-      (when (or (file-exists-p org-persist-directory) (org-persist--save-index))
-        (let ((file (org-file-name-concat org-persist-directory (plist-get collection :persist-file)))
-              (data (mapcar (lambda (c) (cons c (org-persist-write:generic c collection)))
-                            (plist-get collection :container))))
-          (puthash file data org-persist--write-cache)
-          (org-persist--write-elisp-file file data)
-          (or ignore-return (org-persist-read container associated)))))))
+  (unless org-persist--inhibit-write
+    (setq associated (org-persist--normalize-associated associated))
+    ;; Update hash
+    (when (and (plist-get associated :file)
+               (plist-get associated :hash)
+               (get-file-buffer (plist-get associated :file)))
+      (setq associated (org-persist--normalize-associated (get-file-buffer (plist-get associated :file)))))
+    (let ((collection (org-persist--get-collection container associated))
+          (org-persist--inhibit-write t))
+      (setf collection (plist-put collection :associated associated))
+      (unless (or
+               ;; Prevent data leakage from encrypted files.
+               ;; We do it in somewhat paranoid manner and do not
+               ;; allow anything related to encrypted files to be
+               ;; written.
+               (and (plist-get associated :file)
+                    (string-match-p epa-file-name-regexp (plist-get associated :file)))
+               (cl-some (lambda (v)
+                          (run-hook-with-args-until-success 'org-persist-before-write-hook v associated))
+                        (plist-get collection :container)))
+        (when (or (file-exists-p org-persist-directory) (org-persist--save-index))
+          (let ((file (org-file-name-concat org-persist-directory (plist-get collection :persist-file)))
+                (data (mapcar (lambda (c) (cons c (org-persist-write:generic c collection)))
+                              (plist-get collection :container))))
+            (puthash file data org-persist--write-cache)
+            (org-persist--write-elisp-file file data)
+            (or ignore-return (org-persist-read container associated))))))))
 
 (defun org-persist-write-all (&optional associated)
   "Save all the persistent data.

lisp/org-src.el

@@ -805,9 +805,42 @@ as `org-src-fontify-natively' is non-nil."
                 (font-lock-append-text-property
                  (1+ pt) (1- (point)) 'face 'org-inline-src-block)))
             (add-face-text-property (1- (point)) (point) '(org-inline-src-block shadow))
-            (setq pt (point)))))
+            (setq pt (point)))
+          (when (and org-inline-src-prettify-results
+                     (re-search-forward "\\= {{{results(" limit t))
+            (font-lock-append-text-property pt (1+ pt) 'face 'org-inline-src-block)
+            (goto-char pt))))
       t)))
 
+(defun org-fontify-inline-src-results (limit)
+  "Apply prettify-symbols modifications to inline results blocks.
+Performed according to `org-inline-src-prettify-results'."
+  (when (and org-inline-src-prettify-results
+             (re-search-forward "{{{results(\\(.+?\\))}}}" limit t))
+    (remove-list-of-text-properties (match-beginning 0) (point)
+                                    '(composition
+                                      prettify-symbols-start
+                                      prettify-symbols-end))
+    (font-lock-append-text-property (match-beginning 0) (match-end 0)
+                                    'face 'org-block)
+    (let ((start (match-beginning 0)) (end (match-beginning 1)))
+      (with-silent-modifications
+        (compose-region start end (if (eq org-inline-src-prettify-results t)
+                                      "(" (car org-inline-src-prettify-results)))
+        (add-text-properties start end `(prettify-symbols-start ,start prettify-symbols-end ,end))))
+    (let ((start (match-end 1)) (end (point)))
+      (with-silent-modifications
+        (compose-region start end (if (eq org-inline-src-prettify-results t)
+                                      ")" (cdr org-inline-src-prettify-results)))
+        (add-text-properties start end `(prettify-symbols-start ,start prettify-symbols-end ,end))))
+    t))
+
+(defun org-toggle-inline-results-display ()
+  "Toggle the literal or contracted display of inline src blocks results."
+  (interactive)
+  (setq org-inline-src-prettify-results (not org-inline-src-prettify-results))
+  (org-restart-font-lock))
+
 
 ;;; Escape contents
 

lisp/org.el

@@ -3209,244 +3209,6 @@ A nil value means to remove them, after a query, from the list."
   :group 'org-agenda
   :type 'boolean)
 
-(defgroup org-latex nil
-  "Options for embedding LaTeX code into Org mode."
-  :tag "Org LaTeX"
-  :group 'org)
-
-(defcustom org-format-latex-options
-  '(:foreground default :background default :scale 1.0
-		:html-foreground "Black" :html-background "Transparent"
-		:html-scale 1.0 :matchers ("begin" "$1" "$" "$$" "\\(" "\\["))
-  "Options for creating images from LaTeX fragments.
-This is a property list with the following properties:
-:foreground  the foreground color for images embedded in Emacs, e.g. \"Black\".
-             `default' means use the foreground of the default face.
-             `auto' means use the foreground from the text face.
-:background  the background color, or \"Transparent\".
-             `default' means use the background of the default face.
-             `auto' means use the background from the text face.
-:scale       a scaling factor for the size of the images, to get more pixels
-:html-foreground, :html-background, :html-scale
-             the same numbers for HTML export.
-:matchers    a list indicating which matchers should be used to
-             find LaTeX fragments.  Valid members of this list are:
-             \"begin\" find environments
-             \"$1\"    find single characters surrounded by $.$
-             \"$\"     find math expressions surrounded by $...$
-             \"$$\"    find math expressions surrounded by $$....$$
-             \"\\(\"    find math expressions surrounded by \\(...\\)
-             \"\\=\\[\"    find math expressions surrounded by \\=\\[...\\]"
-  :group 'org-latex
-  :type 'plist)
-
-(defcustom org-format-latex-signal-error t
-  "Non-nil means signal an error when image creation of LaTeX snippets fails.
-When nil, just push out a message."
-  :group 'org-latex
-  :version "24.1"
-  :type 'boolean)
-
-(defcustom org-latex-to-mathml-jar-file nil
-  "Value of\"%j\" in `org-latex-to-mathml-convert-command'.
-Use this to specify additional executable file say a jar file.
-
-When using MathToWeb as the converter, specify the full-path to
-your mathtoweb.jar file."
-  :group 'org-latex
-  :version "24.1"
-  :type '(choice
-	  (const :tag "None" nil)
-	  (file :tag "JAR file" :must-match t)))
-
-(defcustom org-latex-to-mathml-convert-command nil
-  "Command to convert LaTeX fragments to MathML.
-Replace format-specifiers in the command as noted below and use
-`shell-command' to convert LaTeX to MathML.
-%j:     Executable file in fully expanded form as specified by
-        `org-latex-to-mathml-jar-file'.
-%I:     Input LaTeX file in fully expanded form.
-%i:     Shell-escaped LaTeX fragment to be converted.
-        It must not be used inside a quoted argument, the result of %i
-        expansion inside a quoted argument is undefined.
-%o:     Output MathML file.
-
-This command is used by `org-create-math-formula'.
-
-When using MathToWeb as the converter, set this option to
-\"java -jar %j -unicode -force -df %o %I\".
-
-When using LaTeXML set this option to
-\"latexmlmath %i --presentationmathml=%o\"."
-  :group 'org-latex
-  :version "24.1"
-  :type '(choice
-	  (const :tag "None" nil)
-	  (string :tag "\nShell command")))
-
-(defcustom org-latex-to-html-convert-command nil
-  "Shell command to convert LaTeX fragments to HTML.
-This command is very open-ended: the output of the command will
-directly replace the LaTeX fragment in the resulting HTML.
-Replace format-specifiers in the command as noted below and use
-`shell-command' to convert LaTeX to HTML.
-%i:     The LaTeX fragment to be converted (shell-escaped).
-        It must not be used inside a quoted argument, the result of %i
-        expansion inside a quoted argument is undefined.
-
-For example, this could be used with LaTeXML as
-\"latexmlc literal:%i --profile=math --preload=siunitx.sty 2>/dev/null\"."
-  :group 'org-latex
-  :package-version '(Org . "9.4")
-  :type '(choice
-	  (const :tag "None" nil)
-	  (string :tag "Shell command")))
-
-(defcustom org-preview-latex-default-process 'dvipng
-  "The default process to convert LaTeX fragments to image files.
-All available processes and theirs documents can be found in
-`org-preview-latex-process-alist', which see."
-  :group 'org-latex
-  :version "26.1"
-  :package-version '(Org . "9.0")
-  :type 'symbol)
-
-(defcustom org-preview-latex-process-alist
-  '((dvipng
-     :programs ("latex" "dvipng")
-     :description "dvi > png"
-     :message "you need to install the programs: latex and dvipng."
-     :image-input-type "dvi"
-     :image-output-type "png"
-     :image-size-adjust (1.0 . 1.0)
-     :latex-compiler ("latex -interaction nonstopmode -output-directory %o %f")
-     :image-converter ("dvipng -D %D -T tight -o %O %f")
-     :transparent-image-converter
-     ("dvipng -D %D -T tight -bg Transparent -o %O %f"))
-    (dvisvgm
-     :programs ("latex" "dvisvgm")
-     :description "dvi > svg"
-     :message "you need to install the programs: latex and dvisvgm."
-     :image-input-type "dvi"
-     :image-output-type "svg"
-     :image-size-adjust (1.7 . 1.5)
-     :latex-compiler ("latex -interaction nonstopmode -output-directory %o %f")
-     :image-converter ("dvisvgm %f --no-fonts --exact-bbox --scale=%S --output=%O"))
-    (imagemagick
-     :programs ("latex" "convert")
-     :description "pdf > png"
-     :message "you need to install the programs: latex and imagemagick."
-     :image-input-type "pdf"
-     :image-output-type "png"
-     :image-size-adjust (1.0 . 1.0)
-     :latex-compiler ("pdflatex -interaction nonstopmode -output-directory %o %f")
-     :image-converter
-     ("convert -density %D -trim -antialias %f -quality 100 %O")))
-  "Definitions of external processes for LaTeX previewing.
-Org mode can use some external commands to generate TeX snippet's images for
-previewing or inserting into HTML files, e.g., \"dvipng\".  This variable tells
-`org-create-formula-image' how to call them.
-
-The value is an alist with the pattern (NAME . PROPERTIES).  NAME is a symbol.
-PROPERTIES accepts the following attributes:
-
-  :programs           list of strings, required programs.
-  :description        string, describe the process.
-  :message            string, message it when required programs cannot be found.
-  :image-input-type   string, input file type of image converter (e.g., \"dvi\").
-  :image-output-type  string, output file type of image converter (e.g., \"png\").
-  :image-size-adjust  cons of numbers, the car element is used to adjust LaTeX
-                      image size showed in buffer and the cdr element is for
-                      HTML file.  This option is only useful for process
-                      developers, users should use variable
-                      `org-format-latex-options' instead.
-  :post-clean         list of strings, files matched are to be cleaned up once
-                      the image is generated.  When nil, the files with \".dvi\",
-                      \".xdv\", \".pdf\", \".tex\", \".aux\", \".log\", \".svg\",
-                      \".png\", \".jpg\", \".jpeg\" or \".out\" extension will
-                      be cleaned up.
-  :latex-header       list of strings, the LaTeX header of the snippet file.
-                      When nil, the fallback value is used instead, which is
-                      controlled by `org-format-latex-header',
-                      `org-latex-default-packages-alist' and
-                      `org-latex-packages-alist', which see.
-  :latex-compiler     list of LaTeX commands, as strings.  Each of them is given
-                      to the shell.  Place-holders \"%t\", \"%b\" and \"%o\" are
-                      replaced with values defined below.
-  :image-converter    list of image converter commands strings.  Each of them is
-                      given to the shell and supports any of the following
-                      place-holders defined below.
-
-If set, :transparent-image-converter is used instead of :image-converter to
-convert an image when the background color is nil or \"Transparent\".
-
-Place-holders used by `:image-converter' and `:latex-compiler':
-
-  %f    input file name
-  %b    base name of input file
-  %o    base directory of input file
-  %O    absolute output file name
-
-Place-holders only used by `:image-converter':
-
-  %D    dpi, which is used to adjust image size by some processing commands.
-  %S    the image size scale ratio, which is used to adjust image size by some
-        processing commands."
-  :group 'org-latex
-  :package-version '(Org . "9.6")
-  :type '(alist :tag "LaTeX to image backends"
-		:value-type (plist)))
-
-(defcustom org-preview-latex-image-directory "ltximg/"
-  "Path to store latex preview images.
-A relative path here creates many directories relative to the
-processed Org files paths.  An absolute path puts all preview
-images at the same place."
-  :group 'org-latex
-  :version "26.1"
-  :package-version '(Org . "9.0")
-  :type 'string)
-
-(defun org-format-latex-mathml-available-p ()
-  "Return t if `org-latex-to-mathml-convert-command' is usable."
-  (save-match-data
-    (when (and (boundp 'org-latex-to-mathml-convert-command)
-	       org-latex-to-mathml-convert-command)
-      (let ((executable (car (split-string
-			      org-latex-to-mathml-convert-command))))
-	(when (executable-find executable)
-	  (if (string-match
-	       "%j" org-latex-to-mathml-convert-command)
-	      (file-readable-p org-latex-to-mathml-jar-file)
-	    t))))))
-
-(defcustom org-format-latex-header "\\documentclass{article}
-\\usepackage[usenames]{color}
-\[DEFAULT-PACKAGES]
-\[PACKAGES]
-\\pagestyle{empty}             % do not remove
-% The settings below are copied from fullpage.sty
-\\setlength{\\textwidth}{\\paperwidth}
-\\addtolength{\\textwidth}{-3cm}
-\\setlength{\\oddsidemargin}{1.5cm}
-\\addtolength{\\oddsidemargin}{-2.54cm}
-\\setlength{\\evensidemargin}{\\oddsidemargin}
-\\setlength{\\textheight}{\\paperheight}
-\\addtolength{\\textheight}{-\\headheight}
-\\addtolength{\\textheight}{-\\headsep}
-\\addtolength{\\textheight}{-\\footskip}
-\\addtolength{\\textheight}{-3cm}
-\\setlength{\\topmargin}{1.5cm}
-\\addtolength{\\topmargin}{-2.54cm}"
-  "The document header used for processing LaTeX fragments.
-It is imperative that this header make sure that no page number
-appears on the page.  The package defined in the variables
-`org-latex-default-packages-alist' and `org-latex-packages-alist'
-will either replace the placeholder \"[PACKAGES]\" in this
-header, or they will be appended."
-  :group 'org-latex
-  :type 'string)
-
 (defun org-set-packages-alist (var val)
   "Set the packages alist and make sure it has 3 elements per entry."
   (set-default-toplevel-value var (mapcar (lambda (x)
@@ -3471,15 +3233,6 @@ header, or they will be appended."
     ;; inputenc and fontenc are for pdflatex only
     ("AUTO" "inputenc"  t ("pdflatex"))
     ("T1"   "fontenc"   t ("pdflatex"))
-    (""     "graphicx"  t)
-    (""     "longtable" nil)
-    (""     "wrapfig"   nil)
-    (""     "rotating"  nil)
-    ("normalem" "ulem"  t)
-    ;; amsmath and amssymb after inputenc/fontenc for pdflatex
-    (""     "amsmath"   t ("pdflatex"))
-    (""     "amssymb"   t ("pdflatex"))
-    (""     "capt-of"   nil)
     (""     "hyperref"  nil))
   "Alist of default packages to be inserted in the header.
 
@@ -3489,18 +3242,12 @@ incompatibility with another package you are using.
 The packages in this list are needed by one part or another of
 Org mode to function properly:
 
+- amsmath: for subscript and superscript and math environments
+  (automatically added when needed with pdflatex).
 - fontspec: for font and character selection in lualatex and xetex
 - inputenc, fontenc:  for basic font and character selection
-  in pdflatex
-- graphicx: for including images
-- longtable: For multipage tables
 - wrapfig: for figure placement
 - rotating: for sideways figures and tables
-- ulem: for underline and strike-through
-- amsmath: for subscript and superscript and math environments
-- amssymb: for various symbols used for interpreting the entities
-  in `org-entities'.  You can skip some of this package if you don't
-  use any of the symbols.
 - capt-of: for captions outside of floats
 - hyperref: for cross references
 
@@ -3565,7 +3312,7 @@ A string will be inserted as-is in the header of the document.
 Make sure that you only list packages here which:
 
   - you want in every file;
-  - do not conflict with the setup in `org-format-latex-header';
+  - do not conflict with the setup in `org-latex-preview-header';
   - do not conflict with the default packages in
     `org-latex-default-packages-alist'."
   :group 'org-latex
@@ -5055,7 +4802,7 @@ The following commands are available:
     (org-unmodified
      (when org-startup-with-beamer-mode (org-beamer-mode))
      (when org-startup-with-inline-images (org-display-inline-images))
-     (when org-startup-with-latex-preview (org-latex-preview '(16)))
+     (when org-startup-with-latex-preview (org-latex-preview 'buffer))
      (unless org-inhibit-startup-visibility-stuff (org-cycle-set-startup-visibility))
      (when org-startup-truncated (setq truncate-lines t))
      (when org-startup-numerated (require 'org-num) (org-num-mode 1))
@@ -5496,6 +5243,15 @@ by a #."
   :version "24.1"
   :group 'org-appearance)
 
+(defcustom org-inline-src-prettify-results t
+  "Whether to use (ab)use prettify-symbols-mode on {{{results(...)}}}.
+Either t or a cons cell of strings which are used as substitutions
+for the start and end of inline results, respectively."
+  :type '(choice boolean (cons string string))
+  :package-version '(Org . "9.5")
+  :group 'org-appearance
+  :group 'org-babel)
+
 (defun org-fontify-meta-lines-and-blocks (limit)
   (condition-case-unless-debug nil
       (org-fontify-meta-lines-and-blocks-1 limit)
@@ -5768,7 +5524,7 @@ Result depends on variable `org-highlight-latex-and-related'."
 	(re-latex
 	 (when (or (memq 'latex org-highlight-latex-and-related)
 		   (memq 'native org-highlight-latex-and-related))
-	   (let ((matchers (plist-get org-format-latex-options :matchers)))
+	   (let ((matchers (plist-get org-latex-preview-appearance-options :matchers)))
 	     (delq nil
 		   (mapcar (lambda (x)
 			     (and (member (car x) matchers) (nth 1 x)))
@@ -5782,6 +5538,9 @@ Result depends on variable `org-highlight-latex-and-related'."
 			   (append re-latex re-entities re-sub)
 			   "\\|"))))
 
+(defvar org-latex-preview-appearance-options) ; Defined in org-latex-preview.el.
+(declare-function org-latex-preview--face-around "org-latex-preview" (start end))
+
 (defun org-do-latex-and-related (limit)
   "Highlight LaTeX snippets and environments, entities and sub/superscript.
 Stop at first highlighted object, if any.  Return t if some
@@ -5822,6 +5581,17 @@ highlighting was done, nil otherwise."
 						 'face 'org-latex-and-related))
 	      (add-text-properties (+ offset (match-beginning 0)) (match-end 0)
 				   '(font-lock-multiline t))
+              ;; Refresh the face of LaTeX previews (when applicable).
+              (when (eq (plist-get org-latex-preview-appearance-options :foreground)
+                        'auto)
+                (dolist (ov (overlays-at start))
+                  (when (and (eq (overlay-get ov 'org-overlay-type)
+                                 'org-latex-overlay)
+                             (overlay-get ov 'face)
+                             (not (eq (overlay-get ov 'face) 'error)))
+                    (overlay-put ov 'face
+                                 (org-latex-preview--face-around
+                                  (overlay-start ov) (overlay-end ov))))))
 	      (throw 'found t)))))
 	nil))))
 
@@ -6009,6 +5779,10 @@ needs to be inserted at a specific position in the font-lock sequence.")
 	  ;; Emphasis
           ;; `org-do-emphasis-faces' prepends faces
 	  (when org-fontify-emphasized-text '(org-do-emphasis-faces))
+          ;; Semantic seperator
+          (when org-fontify-semantic-seperator
+            `("\u200b"
+              (0 '(face shadow display ,org-semantic-seperator-displayed))))
 	  ;; Checkboxes
 	  `(,org-list-full-item-re 3 'org-checkbox prepend lax)
 	  (when (cdr (assq 'checkbox org-list-automatic-rules))
@@ -6138,6 +5912,23 @@ needs to be inserted at a specific position in the font-lock sequence.")
 	      (throw 'match t))))
 	nil))))
 
+(defcustom org-fontify-semantic-seperator t
+  "Whether to prettify the semantic seperator.
+When non-nil, `org-semantic-seperator-displayed' will be displayed in place of the semantic seperator."
+  :type 'boolean)
+
+(defcustom org-semantic-seperator-displayed
+  #("┃" 0 1 (display ((raise -0.3) (height 0.3))))
+  "String that should be displayed in place of the semantic seperator.
+This is only relevant when `org-fontify-semantic-seperator' is non-nil."
+  :type 'string)
+
+(defun org-toggle-semantic-seperator-display ()
+  "Toggle display of the semantic seperator."
+  (interactive)
+  (cl-callf not org-fontify-semantic-seperator)
+  (user-error "TODO make this work better"))
+
 (defun org-fontify-like-in-org-mode (s &optional odd-levels)
   "Fontify string S like in Org mode."
   (with-temp-buffer
@@ -16076,466 +15867,6 @@ at point."
     (org-in-regexp
      "\\\\[a-zA-Z]+\\*?\\(\\(\\[[^][\n{}]*\\]\\)\\|\\({[^{}\n]*}\\)\\)*")))
 
-(defun org--make-preview-overlay (beg end image &optional imagetype)
-  "Build an overlay between BEG and END using IMAGE file.
-Argument IMAGETYPE is the extension of the displayed image,
-as a string.  It defaults to \"png\"."
-  (let ((ov (make-overlay beg end))
-	(imagetype (or (intern imagetype) 'png)))
-    (overlay-put ov 'org-overlay-type 'org-latex-overlay)
-    (overlay-put ov 'evaporate t)
-    (overlay-put ov
-		 'modification-hooks
-		 (list (lambda (o _flag _beg _end &optional _l)
-			 (delete-overlay o))))
-    (overlay-put ov
-		 'display
-		 (list 'image :type imagetype :file image :ascent 'center))))
-
-(defun org-clear-latex-preview (&optional beg end)
-  "Remove all overlays with LaTeX fragment images in current buffer.
-When optional arguments BEG and END are non-nil, remove all
-overlays between them instead.  Return a non-nil value when some
-overlays were removed, nil otherwise."
-  (let ((overlays
-	 (cl-remove-if-not
-	  (lambda (o) (eq (overlay-get o 'org-overlay-type) 'org-latex-overlay))
-	  (overlays-in (or beg (point-min)) (or end (point-max))))))
-    (mapc #'delete-overlay overlays)
-    overlays))
-
-(defun org--latex-preview-region (beg end)
-  "Preview LaTeX fragments between BEG and END.
-BEG and END are buffer positions."
-  (let ((file (buffer-file-name (buffer-base-buffer))))
-    (save-excursion
-      (org-format-latex
-       (concat org-preview-latex-image-directory "org-ltximg")
-       beg end
-       ;; Emacs cannot overlay images from remote hosts.  Create it in
-       ;; `temporary-file-directory' instead.
-       (if (or (not file) (file-remote-p file))
-	   temporary-file-directory
-	 default-directory)
-       'overlays nil 'forbuffer org-preview-latex-default-process))))
-
-(defun org-latex-preview (&optional arg)
-  "Toggle preview of the LaTeX fragment at point.
-
-If the cursor is on a LaTeX fragment, create the image and
-overlay it over the source code, if there is none.  Remove it
-otherwise.  If there is no fragment at point, display images for
-all fragments in the current section.  With an active region,
-display images for all fragments in the region.
-
-With a `\\[universal-argument]' prefix argument ARG, clear images \
-for all fragments
-in the current section.
-
-With a `\\[universal-argument] \\[universal-argument]' prefix \
-argument ARG, display image for all
-fragments in the buffer.
-
-With a `\\[universal-argument] \\[universal-argument] \
-\\[universal-argument]' prefix argument ARG, clear image for all
-fragments in the buffer."
-  (interactive "P")
-  (cond
-   ((not (display-graphic-p)) nil)
-   ((and untrusted-content (not org--latex-preview-when-risky)) nil)
-   ;; Clear whole buffer.
-   ((equal arg '(64))
-    (org-clear-latex-preview (point-min) (point-max))
-    (message "LaTeX previews removed from buffer"))
-   ;; Preview whole buffer.
-   ((equal arg '(16))
-    (message "Creating LaTeX previews in buffer...")
-    (org--latex-preview-region (point-min) (point-max))
-    (message "Creating LaTeX previews in buffer... done."))
-   ;; Clear current section.
-   ((equal arg '(4))
-    (org-clear-latex-preview
-     (if (use-region-p)
-         (region-beginning)
-       (if (org-before-first-heading-p) (point-min)
-         (save-excursion
-	   (org-with-limited-levels (org-back-to-heading t) (point)))))
-     (if (use-region-p)
-         (region-end)
-       (org-with-limited-levels (org-entry-end-position)))))
-   ((use-region-p)
-    (message "Creating LaTeX previews in region...")
-    (org--latex-preview-region (region-beginning) (region-end))
-    (message "Creating LaTeX previews in region... done."))
-   ;; Toggle preview on LaTeX code at point.
-   ((let ((datum (org-element-context)))
-      (and (org-element-type-p datum '(latex-environment latex-fragment))
-	   (let ((beg (org-element-begin datum))
-		 (end (org-element-end datum)))
-	     (if (org-clear-latex-preview beg end)
-		 (message "LaTeX preview removed")
-	       (message "Creating LaTeX preview...")
-	       (org--latex-preview-region beg end)
-	       (message "Creating LaTeX preview... done."))
-	     t))))
-   ;; Preview current section.
-   (t
-    (let ((beg (if (org-before-first-heading-p) (point-min)
-		 (save-excursion
-		   (org-with-limited-levels (org-back-to-heading t) (point)))))
-	  (end (org-with-limited-levels (org-entry-end-position))))
-      (message "Creating LaTeX previews in section...")
-      (org--latex-preview-region beg end)
-      (message "Creating LaTeX previews in section... done.")))))
-
-(defun org-format-latex
-    (prefix &optional beg end dir overlays msg forbuffer processing-type)
-  "Replace LaTeX fragments with links to an image.
-
-The function takes care of creating the replacement image.
-
-Only consider fragments between BEG and END when those are
-provided.
-
-When optional argument OVERLAYS is non-nil, display the image on
-top of the fragment instead of replacing it.
-
-PROCESSING-TYPE is the conversion method to use, as a symbol.
-
-Some of the options can be changed using the variable
-`org-format-latex-options', which see."
-  (when (and overlays (fboundp 'clear-image-cache)) (clear-image-cache))
-  (unless (eq processing-type 'verbatim)
-    (let* ((math-regexp "\\$\\|\\\\[([]\\|^[ \t]*\\\\begin{[A-Za-z0-9*]+}")
-	   (cnt 0)
-	   checkdir-flag)
-      (goto-char (or beg (point-min)))
-      ;; FIXME: `overlay-recenter' is not needed (and has no effect)
-      ;; since Emacs 29.
-      ;; Optimize overlay creation: (info "(elisp) Managing Overlays").
-      (when (and overlays (memq processing-type '(dvipng imagemagick)))
-	(overlay-recenter (or end (point-max))))
-      (while (re-search-forward math-regexp end t)
-	(unless (and overlays
-		     (eq (get-char-property (point) 'org-overlay-type)
-			 'org-latex-overlay))
-	  (let* ((context (org-element-context))
-		 (type (org-element-type context)))
-	    (when (memq type '(latex-environment latex-fragment))
-	      (let ((block-type (eq type 'latex-environment))
-		    (value (org-element-property :value context))
-		    (beg (org-element-begin context))
-		    (end (save-excursion
-			   (goto-char (org-element-end context))
-			   (skip-chars-backward " \r\t\n")
-			   (point))))
-		(cond
-		 ((eq processing-type 'mathjax)
-		  ;; Prepare for MathJax processing.
-		  (if (not (string-match "\\`\\$\\$?" value))
-		      (goto-char end)
-		    (delete-region beg end)
-		    (if (string= (match-string 0 value) "$$")
-			(insert "\\[" (substring value 2 -2) "\\]")
-		      (insert "\\(" (substring value 1 -1) "\\)"))))
-		 ((eq processing-type 'html)
-		  (goto-char beg)
-		  (delete-region beg end)
-		  (insert (org-format-latex-as-html value)))
-		 ((assq processing-type org-preview-latex-process-alist)
-		  ;; Process to an image.
-		  (cl-incf cnt)
-		  (goto-char beg)
-		  (let* ((processing-info
-			  (cdr (assq processing-type org-preview-latex-process-alist)))
-			 (face (face-at-point))
-			 ;; Get the colors from the face at point.
-			 (fg
-			  (let ((color (plist-get org-format-latex-options
-						  :foreground)))
-                            (if forbuffer
-                                (cond
-                                 ((eq color 'auto)
-                                  (face-attribute face :foreground nil 'default))
-                                 ((eq color 'default)
-                                  (face-attribute 'default :foreground nil))
-                                 (t color))
-                              color)))
-			 (bg
-			  (let ((color (plist-get org-format-latex-options
-						  :background)))
-                            (if forbuffer
-                                (cond
-                                 ((eq color 'auto)
-                                  (face-attribute face :background nil 'default))
-                                 ((eq color 'default)
-                                  (face-attribute 'default :background nil))
-                                 (t color))
-                              color)))
-			 (hash (sha1 (prin1-to-string
-				      (list org-format-latex-header
-					    org-latex-default-packages-alist
-					    org-latex-packages-alist
-					    org-format-latex-options
-					    forbuffer value fg bg))))
-			 (imagetype (or (plist-get processing-info :image-output-type) "png"))
-			 (absprefix (expand-file-name prefix dir))
-			 (linkfile (format "%s_%s.%s" prefix hash imagetype))
-			 (movefile (format "%s_%s.%s" absprefix hash imagetype))
-			 (sep (and block-type "\n\n"))
-			 (link (concat sep "[[file:" linkfile "]]" sep))
-			 (options
-			  (org-combine-plists
-			   org-format-latex-options
-			   `(:foreground ,fg :background ,bg))))
-		    (when msg (message msg cnt))
-		    (unless checkdir-flag ; Ensure the directory exists.
-		      (setq checkdir-flag t)
-		      (let ((todir (file-name-directory absprefix)))
-			(unless (file-directory-p todir)
-			  (make-directory todir t))))
-		    (unless (file-exists-p movefile)
-		      (org-create-formula-image
-		       value movefile options forbuffer processing-type))
-                    (org-place-formula-image link block-type beg end value overlays movefile imagetype)))
-		 ((eq processing-type 'mathml)
-		  ;; Process to MathML.
-		  (unless (org-format-latex-mathml-available-p)
-		    (user-error "LaTeX to MathML converter not configured"))
-		  (cl-incf cnt)
-		  (when msg (message msg cnt))
-		  (goto-char beg)
-		  (delete-region beg end)
-		  (insert (org-format-latex-as-mathml
-			   value block-type prefix dir)))
-		 (t
-		  (error "Unknown conversion process %s for LaTeX fragments"
-			 processing-type)))))))))))
-
-(defun org-place-formula-image (link block-type beg end value overlays movefile imagetype)
-  "Place an overlay from BEG to END showing MOVEFILE.
-The overlay will be above BEG if OVERLAYS is non-nil."
-  (if overlays
-      (progn
-        (dolist (o (overlays-in beg end))
-          (when (eq (overlay-get o 'org-overlay-type)
-                    'org-latex-overlay)
-            (delete-overlay o)))
-        (org--make-preview-overlay beg end movefile imagetype)
-        (goto-char end))
-    (delete-region beg end)
-    (insert
-     (org-add-props link
-         (list 'org-latex-src
-               (replace-regexp-in-string "\"" "" value)
-               'org-latex-src-embed-type
-               (if block-type 'paragraph 'character))))))
-
-(defun org-create-math-formula (latex-frag &optional mathml-file)
-  "Convert LATEX-FRAG to MathML and store it in MATHML-FILE.
-Use `org-latex-to-mathml-convert-command'.  If the conversion is
-successful, return the portion between \"<math...> </math>\"
-elements otherwise return nil.  When MATHML-FILE is specified,
-write the results in to that file.  When invoked as an
-interactive command, prompt for LATEX-FRAG, with initial value
-set to the current active region and echo the results for user
-inspection."
-  (interactive (list (let ((frag (when (org-region-active-p)
-				   (buffer-substring-no-properties
-				    (region-beginning) (region-end)))))
-		       (read-string "LaTeX Fragment: " frag nil frag))))
-  (unless latex-frag (user-error "Invalid LaTeX fragment"))
-  (let* ((tmp-in-file
-	  (let ((file (file-relative-name
-		       (make-temp-name (expand-file-name "ltxmathml-in")))))
-	    (write-region latex-frag nil file)
-	    file))
-	 (tmp-out-file (file-relative-name
-			(make-temp-name (expand-file-name  "ltxmathml-out"))))
-	 (cmd (format-spec
-	       org-latex-to-mathml-convert-command
-	       `((?j . ,(and org-latex-to-mathml-jar-file
-			     (shell-quote-argument
-			      (expand-file-name
-			       org-latex-to-mathml-jar-file))))
-		 (?I . ,(shell-quote-argument tmp-in-file))
-		 (?i . ,(shell-quote-argument latex-frag))
-		 (?o . ,(shell-quote-argument tmp-out-file)))))
-	 mathml shell-command-output)
-    (when (called-interactively-p 'any)
-      (unless (org-format-latex-mathml-available-p)
-	(user-error "LaTeX to MathML converter not configured")))
-    (message "Running %s" cmd)
-    (setq shell-command-output (shell-command-to-string cmd))
-    (setq mathml
-	  (when (file-readable-p tmp-out-file)
-	    (with-temp-buffer
-              (insert-file-contents tmp-out-file)
-	      (goto-char (point-min))
-	      (when (re-search-forward
-		     (format "<math[^>]*?%s[^>]*?>\\(.\\|\n\\)*</math>"
-			     (regexp-quote
-			      "xmlns=\"http://www.w3.org/1998/Math/MathML\""))
-		     nil t)
-		(match-string 0)))))
-    (cond
-     (mathml
-      (setq mathml
-	    (concat "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" mathml))
-      (when mathml-file
-	(write-region mathml nil mathml-file))
-      (when (called-interactively-p 'any)
-	(message mathml)))
-     ((warn "LaTeX to MathML conversion failed")
-      (message shell-command-output)))
-    (delete-file tmp-in-file)
-    (when (file-exists-p tmp-out-file)
-      (delete-file tmp-out-file))
-    mathml))
-
-(defun org-format-latex-as-mathml (latex-frag latex-frag-type
-					      prefix &optional dir)
-  "Use `org-create-math-formula' but check local cache first."
-  (let* ((absprefix (expand-file-name prefix dir))
-	 (print-length nil) (print-level nil)
-	 (formula-id (concat
-		      "formula-"
-		      (sha1
-		       (prin1-to-string
-			(list latex-frag
-			      org-latex-to-mathml-convert-command)))))
-	 (formula-cache (format "%s-%s.mathml" absprefix formula-id))
-	 (formula-cache-dir (file-name-directory formula-cache)))
-
-    (unless (file-directory-p formula-cache-dir)
-      (make-directory formula-cache-dir t))
-
-    (unless (file-exists-p formula-cache)
-      (org-create-math-formula latex-frag formula-cache))
-
-    (if (file-exists-p formula-cache)
-	;; Successful conversion.  Return the link to MathML file.
-	(org-add-props
-	    (format  "[[file:%s]]" (file-relative-name formula-cache dir))
-	    (list 'org-latex-src (replace-regexp-in-string "\"" "" latex-frag)
-		  'org-latex-src-embed-type (if latex-frag-type
-						'paragraph 'character)))
-      ;; Failed conversion.  Return the LaTeX fragment verbatim
-      latex-frag)))
-
-(defun org-format-latex-as-html (latex-fragment)
-  "Convert LATEX-FRAGMENT to HTML.
-This uses  `org-latex-to-html-convert-command', which see."
-  (let ((cmd (format-spec org-latex-to-html-convert-command
-			  `((?i . ,(shell-quote-argument latex-fragment))))))
-    (message "Running %s" cmd)
-    (shell-command-to-string cmd)))
-
-(defun org--get-display-dpi ()
-  "Get the DPI of the display.
-The function assumes that the display has the same pixel width in
-the horizontal and vertical directions."
-  (if (display-graphic-p)
-      (round (/ (display-pixel-height)
-		(/ (display-mm-height) 25.4)))
-    (error "Attempt to calculate the dpi of a non-graphic display")))
-
-(defun org-create-formula-image
-    (string tofile options buffer &optional processing-type)
-  "Create an image from LaTeX source using external processes.
-
-The LaTeX STRING is saved to a temporary LaTeX file, then
-converted to an image file by process PROCESSING-TYPE defined in
-`org-preview-latex-process-alist'.  A nil value defaults to
-`org-preview-latex-default-process'.
-
-The generated image file is eventually moved to TOFILE.
-
-The OPTIONS argument controls the size, foreground color and
-background color of the generated image.
-
-When BUFFER non-nil, this function is used for LaTeX previewing.
-Otherwise, it is used to deal with LaTeX snippets showed in
-a HTML file."
-  (let* ((processing-type (or processing-type
-			      org-preview-latex-default-process))
-	 (processing-info
-	  (cdr (assq processing-type org-preview-latex-process-alist)))
-	 (programs (plist-get processing-info :programs))
-	 (error-message (or (plist-get processing-info :message) ""))
-	 (image-input-type (plist-get processing-info :image-input-type))
-	 (image-output-type (plist-get processing-info :image-output-type))
-	 (post-clean (or (plist-get processing-info :post-clean)
-			 '(".dvi" ".xdv" ".pdf" ".tex" ".aux" ".log"
-			   ".svg" ".png" ".jpg" ".jpeg" ".out")))
-	 (latex-header
-	  (or (plist-get processing-info :latex-header)
-	      (org-latex-make-preamble
-	       (org-export-get-environment (org-export-get-backend 'latex))
-	       org-format-latex-header
-	       'snippet)))
-	 (latex-compiler (plist-get processing-info :latex-compiler))
-	 (tmpdir temporary-file-directory)
-	 (texfilebase (make-temp-name
-		       (expand-file-name "orgtex" tmpdir)))
-	 (texfile (concat texfilebase ".tex"))
-	 (image-size-adjust (or (plist-get processing-info :image-size-adjust)
-				'(1.0 . 1.0)))
-	 (scale (* (if buffer (car image-size-adjust) (cdr image-size-adjust))
-		   (or (plist-get options (if buffer :scale :html-scale)) 1.0)))
-	 (dpi (* scale (if (and buffer (display-graphic-p)) (org--get-display-dpi) 140.0)))
-	 (fg (or (plist-get options (if buffer :foreground :html-foreground))
-		 "Black"))
-	 (bg (or (plist-get options (if buffer :background :html-background))
-		 "Transparent"))
-	 (image-converter
-          (or (and (string= bg "Transparent")
-                   (plist-get processing-info :transparent-image-converter))
-              (plist-get processing-info :image-converter)))
-         (log-buf (get-buffer-create "*Org Preview LaTeX Output*"))
-	 (resize-mini-windows nil)) ;Fix Emacs flicker when creating image.
-    (dolist (program programs)
-      (org-check-external-command program error-message))
-    (if (eq fg 'default)
-	(setq fg (org-latex-color :foreground))
-      (setq fg (org-latex-color-format fg)))
-    (setq bg (cond
-	      ((eq bg 'default) (org-latex-color :background))
-	      ((string= bg "Transparent") nil)
-	      (t (org-latex-color-format bg))))
-    ;; Remove TeX \par at end of snippet to avoid trailing space.
-    (if (string-suffix-p string "\n")
-        (aset string (1- (length string)) ?%)
-      (setq string (concat string "%")))
-    (with-temp-file texfile
-      (insert latex-header)
-      (insert "\n\\begin{document}\n"
-	      "\\definecolor{fg}{rgb}{" fg "}%\n"
-	      (if bg
-		  (concat "\\definecolor{bg}{rgb}{" bg "}%\n"
-			  "\n\\pagecolor{bg}%\n")
-		"")
-	      "\n{\\color{fg}\n"
-	      string
-	      "\n}\n"
-	      "\n\\end{document}\n"))
-    (let* ((err-msg (format "Please adjust `%s' part of \
-`org-preview-latex-process-alist'."
-			    processing-type))
-	   (image-input-file
-	    (org-compile-file
-	     texfile latex-compiler image-input-type err-msg log-buf))
-	   (image-output-file
-	    (org-compile-file
-	     image-input-file image-converter image-output-type err-msg log-buf
-	     `((?D . ,(shell-quote-argument (format "%s" dpi)))
-	       (?S . ,(shell-quote-argument (format "%s" (/ dpi 140.0))))))))
-      (copy-file image-output-file tofile 'replace)
-      (dolist (e post-clean)
-	(when (file-exists-p (concat texfilebase e))
-	  (delete-file (concat texfilebase e))))
-      image-output-file)))
-
 (defun org-splice-latex-header (tpl def-pkg pkg snippets-p &optional extra)
   "Fill a LaTeX header template TPL.
 In the template, the following place holders will be recognized:
@@ -16595,30 +15926,6 @@ SNIPPETS-P indicates if this is run to create snippet images for HTML."
 		       "\n"))
   (if newline (concat pkg "\n") pkg))
 
-(defun org-dvipng-color (attr)
-  "Return a RGB color specification for dvipng."
-  (org-dvipng-color-format (face-attribute 'default attr nil)))
-
-(defun org-dvipng-color-format (color-name)
-  "Convert COLOR-NAME to a RGB color value for dvipng."
-  (apply #'format "rgb %s %s %s"
-	 (mapcar 'org-normalize-color
-		 (color-values color-name))))
-
-(defun org-latex-color (attr)
-  "Return a RGB color for the LaTeX color package."
-  (org-latex-color-format (face-attribute 'default attr nil)))
-
-(defun org-latex-color-format (color-name)
-  "Convert COLOR-NAME to a RGB color value."
-  (apply #'format "%s,%s,%s"
-	 (mapcar 'org-normalize-color
-		 (color-values color-name))))
-
-(defun org-normalize-color (value)
-  "Return string to be used as color value for an RGB component."
-  (format "%g" (/ value 65535.0)))
-
 
 ;; Image display
 
@@ -20094,12 +19401,23 @@ a footnote definition, try to fill the first paragraph within."
 	     (save-excursion
 	       (goto-char beg)
 	       (let ((cuts (list beg)))
+                 ;; Cut fill on line breaks.
 		 (while (re-search-forward "\\\\\\\\[ \t]*\n" end t)
 		   (when (org-element-type-p
 			  (save-excursion (backward-char)
 					  (org-element-context))
                           'line-break)
 		     (push (point) cuts)))
+                 ;; Cut fill on displayed equations.
+                 (while (re-search-forward "^[ \t]*\\\\\\[" end t)
+                   (let ((el (org-element-context)))
+                     (when (eq 'latex-fragment (org-element-type el))
+                       (setf cuts (append
+                                   (list (org-element-property :end el)
+                                         (- (org-element-property :end el) 2)
+                                         (+ (org-element-property :begin el) 2)
+                                         (org-element-property :begin el))
+                                   cuts)))))
 		 (dolist (c (delq end cuts))
 		   (fill-region-as-paragraph c end justify)
 		   (setq end c))))

lisp/ox-beamer.el

@@ -860,9 +860,7 @@ holding export options."
      ;; Timestamp.
      (and (plist-get info :time-stamp-file)
 	  (format-time-string "%% Created %Y-%m-%d %a %H:%M\n"))
-     ;; LaTeX compiler
-     (org-latex--insert-compiler info)
-     ;; Document class and packages.
+     ;; Document class, packages, and some configuration.
      (org-latex-make-preamble info)
      ;; Define the alternative frame environment, if needed.
      (when (plist-get info :beamer-define-frame)
@@ -915,12 +913,6 @@ holding export options."
      (let ((template (plist-get info :latex-hyperref-template)))
        (and (stringp template)
 	    (format-spec template (org-latex--format-spec info))))
-     ;; engrave-faces-latex preamble
-     (when (and (eq (plist-get info :latex-src-block-backend) 'engraved)
-                (org-element-map (plist-get info :parse-tree)
-                    '(src-block inline-src-block) #'identity
-                    info t))
-       (org-latex-generate-engraved-preamble info))
      ;; Document start.
      "\\begin{document}\n\n"
      ;; Title command.

lisp/ox-html.el

@@ -39,6 +39,8 @@
 (require 'ox)
 (require 'ox-publish)
 (require 'table)
+(require 'org-latex-preview)
+(require 'ox-mathml)
 
 
 ;;; Function Declarations
@@ -107,7 +109,8 @@
     (verbatim . org-html-verbatim)
     (verse-block . org-html-verse-block))
   :filters-alist '((:filter-options . org-html-infojs-install-script)
-		   (:filter-parse-tree . org-html-image-link-filter)
+		   (:filter-parse-tree org-html-image-link-filter
+                                       org-html-prepare-latex-images)
 		   (:filter-final-output . org-html-final-function))
   :menu-entry
   '(?h "Export to HTML"
@@ -155,6 +158,7 @@
     (:html-infojs-template nil nil org-html-infojs-template)
     (:html-inline-image-rules nil nil org-html-inline-image-rules)
     (:html-link-org-files-as-html nil nil org-html-link-org-files-as-html)
+    (:html-latex-image-options nil nil org-html-latex-image-options)
     (:html-mathjax-options nil nil org-html-mathjax-options)
     (:html-mathjax-template nil nil org-html-mathjax-template)
     (:html-metadata-timestamp-format nil nil org-html-metadata-timestamp-format)
@@ -319,7 +323,7 @@ This affects IDs that are determined from the ID property.")
   pre.src-awk:before { content: 'Awk'; }
   pre.src-authinfo::before { content: 'Authinfo'; }
   pre.src-C:before { content: 'C'; }
-  /* pre.src-C++ doesn't work in CSS */
+  pre.src-C\\+\\+:before { content: 'C++'; }
   pre.src-clojure:before { content: 'Clojure'; }
   pre.src-css:before { content: 'CSS'; }
   pre.src-D:before { content: 'D'; }
@@ -822,7 +826,7 @@ e.g. \"tex:mathjax\".  Allowed values are:
                 be loaded.
   `html'        Use `org-latex-to-html-convert-command' to convert
                 LaTeX fragments to HTML.
-  SYMBOL        Any symbol defined in `org-preview-latex-process-alist',
+  SYMBOL        Any symbol defined in `org-latex-preview-process-alist',
                 e.g., `dvipng'."
   :group 'org-export-html
   :version "24.4"
@@ -1168,6 +1172,27 @@ See `format-time-string' for more information on its components."
   :package-version '(Org . "8.0")
   :type 'string)
 
+(defcustom org-html-latex-image-options
+  '(:foreground "Black" :background "Transparent"
+    :page-width 1.0 :scale 1.0 :image-dir "ltximg" :inline nil)
+  "LaTeX preview options that apply to generated images.
+This is a HTML-specific counterpart to
+`org-latex-preview-appearance-options', which see.
+
+This supports two extra properties,
+:image-dir  an html-export counterpart of `org-latex-preview-cache', and
+:inline     a list of image formats (or single format symbol) that
+            should not be saved according to :image-dir, but instead
+            inlined in the generated HTML.  Valid format symbols are:
+            - png, to inline png images using <img> with a data URI
+            - svg, to inline svg images using <img> with a data URI
+            - svg-embed, to inline svg images using an <svg> element.
+              This is only applied when used along with svg, as in
+              (svg svg-embed)."
+  :group 'org-export-html
+  :package-version '(Org . "9.7")
+  :type 'plist)
+
 ;;;; Template :: Mathjax
 
 (defcustom org-html-mathjax-options
@@ -1653,6 +1678,33 @@ https://developer.mozilla.org/en-US/docs/Mozilla/Mobile/Viewport_meta_tag"
   :package-version '(Org . "9.1")
   :type 'string)
 
+;;;; LaTeX Fragments
+
+(defcustom org-latex-to-html-convert-command nil
+  "Shell command to convert LaTeX fragments to HTML.
+This command is very open-ended: the output of the command will
+directly replace the LaTeX fragment in the resulting HTML.
+Replace format-specifiers in the command as noted below and use
+`shell-command' to convert LaTeX to HTML.
+%i:     The LaTeX fragment to be converted (shell-escaped).
+        It must not be used inside a quoted argument, the result of %i
+        expansion inside a quoted argument is undefined.
+
+For example, this could be used with LaTeXML as
+\"latexmlc literal:%i --profile=math --preload=siunitx.sty 2>/dev/null\"."
+  :group 'org-latex
+  :package-version '(Org . "9.4")
+  :type '(choice
+          (const :tag "None" nil)
+          (string :tag "Shell command")))
+
+(defun org-format-latex-as-html (latex-fragment)
+  "Convert LATEX-FRAGMENT to HTML.
+This uses  `org-latex-to-html-convert-command', which see."
+  (let ((cmd (format-spec org-latex-to-html-convert-command
+                          `((?i . ,latex-fragment)))))
+    (message "Running %s" cmd)
+    (shell-command-to-string cmd)))
 
 ;;;; Todos
 
@@ -1688,6 +1740,7 @@ INFO is the current state of the export process, as a plist."
   "Return close-tag for string TAG.
 ATTR specifies additional attributes.  INFO is a property list
 containing current export state."
+  (declare (indent 1))
   (concat "<" tag
 	  (org-string-nw-p (concat " " attr))
 	  (if (org-html-xhtml-p info) " />" ">")))
@@ -1777,11 +1830,7 @@ a communication channel."
    (org-html--make-attribute-string
     (org-combine-plists
      (list :src source
-           :alt (if (string-match-p
-                     (concat "^" org-preview-latex-image-directory) source)
-                    (org-html-encode-plain-text
-                     (org-find-text-property-in-string 'org-latex-src source))
-                  (file-name-nondirectory source)))
+           :alt (file-name-nondirectory source))
      (if (string= "svg" (file-name-extension source))
          (org-combine-plists '(:class "org-svg") attributes '(:fallback nil))
        attributes)))
@@ -3003,58 +3052,72 @@ CONTENTS is nil.  INFO is a plist holding contextual information."
 
 ;;;; LaTeX Environment
 
-(defun org-html-format-latex (latex-frag processing-type info)
-  "Format a LaTeX fragment LATEX-FRAG into HTML.
-PROCESSING-TYPE designates the tool used for conversion.  It can
-be `mathjax', `verbatim', `html', nil, t or symbols in
-`org-preview-latex-process-alist', e.g., `dvipng', `dvisvgm' or
-`imagemagick'.  See `org-html-with-latex' for more information.
-INFO is a plist containing export properties."
-  (let ((cache-relpath "") (cache-dir ""))
-    (unless (or (eq processing-type 'mathjax)
-                (eq processing-type 'html))
-      (let ((bfn (or (buffer-file-name)
-		     (make-temp-name
-		      (expand-file-name "latex" temporary-file-directory))))
-	    (latex-header
-	     (let ((header (plist-get info :latex-header)))
-	       (and header
-		    (concat (mapconcat
-			     (lambda (line) (concat "#+LATEX_HEADER: " line))
-			     (org-split-string header "\n")
-			     "\n")
-			    "\n")))))
-	(setq cache-relpath
-	      (concat (file-name-as-directory org-preview-latex-image-directory)
-		      (file-name-sans-extension
-		       (file-name-nondirectory bfn)))
-	      cache-dir (file-name-directory bfn))
-	;; Re-create LaTeX environment from original buffer in
-	;; temporary buffer so that dvipng/imagemagick can properly
-	;; turn the fragment into an image.
-	(setq latex-frag (concat latex-header latex-frag))))
-    (org-export-with-buffer-copy
-     :to-buffer (get-buffer-create " *Org HTML Export LaTeX*")
-     :drop-visibility t :drop-narrowing t :drop-contents t
-     (erase-buffer)
-     (insert latex-frag)
-     (org-format-latex cache-relpath nil nil cache-dir nil
-		       "Creating LaTeX Image..." nil processing-type)
-     (buffer-string))))
+(defun org-html-prepare-latex-images (parse-tree _backend info)
+  "Make sure that appropriate preview images exist for all LaTeX.
 
-(defun org-html--wrap-latex-environment (contents _ &optional caption label)
+Create a hash table containing preview images for all LaTeX
+fragments in PARSE-TREE, and add it to INFO.  Filter out
+fragments to be ignored according to INFO (see the INFO argument
+of `org-element-map').
+
+The keys of the hash table are elements and the values are lists
+containing image paths and metadata used for display."
+  (prog1 nil
+    (let ((processing-type (plist-get info :with-latex)))
+      (when (assq processing-type org-latex-preview-process-alist)
+        (let* ((image-options (plist-get info :html-latex-image-options))
+               (inline-condition (org-ensure-list
+                                  (plist-get image-options :inline)))
+               (image-type
+                (thread-first processing-type
+                              (alist-get org-latex-preview-process-alist)
+                              (plist-get :image-output-type)
+                              (intern)))
+               (element-preview-hash-table
+                (apply #'org-latex-preview-cache-images parse-tree info
+                       ;; Do not copy preview images to :image-dir if
+                       ;; inlining of images in html is requested
+                       (org-combine-plists
+                        image-options
+                        (and (memq image-type inline-condition)
+                             (list :image-dir nil))))))
+          (plist-put info :html-latex-preview-hash-table element-preview-hash-table))))))
+
+(defun org-html--as-latex (element info &optional content)
+  (let ((content (or content (org-element-property :value element))))
+    (pcase (plist-get info :with-latex)
+      ('verbatim ; Do nothing.
+       content)
+      ((or 't 'mathjax)
+       (cond ; Prepare for MathJax processing.
+        ((string-match-p "\\`\\$\\$" content)
+         (concat "\\[" (substring content 2 -2) "\\]"))
+        ((string-match-p "\\`\\$" content)
+         (concat "\\(" (substring content 1 -1) "\\)"))
+        (t content)))
+      ('html
+       (org-format-latex-as-html content))
+      ('mathml
+       (if-let ((path (org-mathml-convert-latex-cached content)))
+           (with-temp-buffer
+             (insert-file-contents path)
+             (buffer-string))
+         content))
+      ((and ptype (guard (assq ptype org-latex-preview-process-alist)))
+       (org-html-latex-image element info))
+      (processing-type
+       (warn "LaTeX fragment processor `%s' is unknown" processing-type)
+       content))))
+
+(defun org-html--wrap-latex-environment (contents &optional label)
   "Wrap CONTENTS string within appropriate environment for equations.
 When optional arguments CAPTION and LABEL are given, use them for
 caption and \"id\" attribute."
-  (format "\n<div%s class=\"equation-container\">\n%s%s\n</div>"
+  (format "\n<div%s class=\"equation-container\">\n%s\n</div>"
           ;; ID.
           (if (org-string-nw-p label) (format " id=\"%s\"" label) "")
           ;; Contents.
-          (format "<span class=\"equation\">\n%s\n</span>" contents)
-          ;; Caption.
-          (if (not (org-string-nw-p caption)) ""
-            (format "\n<span class=\"equation-label\">\n%s\n</span>"
-                    caption))))
+          (format "<span class=\"equation\">\n%s\n</span>" contents)))
 
 (defun org-html--math-environment-p (element &optional _)
   "Non-nil when ELEMENT is a LaTeX math environment.
@@ -3086,57 +3149,137 @@ For instance, change an `equation' environment to `equation*'."
   "Transcode a LATEX-ENVIRONMENT element from Org to HTML.
 CONTENTS is nil.  INFO is a plist holding contextual information."
   (let ((processing-type (plist-get info :with-latex))
-	(latex-frag (org-remove-indentation
-		     (org-element-property :value latex-environment)))
-        (attributes (org-export-read-attribute :attr_html latex-environment))
-        (label (org-html--reference latex-environment info t))
-        (caption (and (org-html--latex-environment-numbered-p latex-environment)
-		      (number-to-string
-		       (org-export-get-ordinal
-			latex-environment info nil
-			(lambda (l _)
-			  (and (org-html--math-environment-p l)
-			       (org-html--latex-environment-numbered-p l))))))))
-    (cond
-     ((memq processing-type '(t mathjax))
-      (org-html-format-latex
-       (if (org-string-nw-p label)
-	   (replace-regexp-in-string "\\`.*"
-				     (format "\\&\n\\\\label{%s}" label)
-				     latex-frag)
-	 latex-frag)
-       'mathjax info))
-     ((assq processing-type org-preview-latex-process-alist)
-      (let ((formula-link
-             (org-html-format-latex
-              (org-html--unlabel-latex-environment latex-frag)
-              processing-type info)))
-        (when (and formula-link (string-match "file:\\([^]]*\\)" formula-link))
-          (let ((source (org-export-file-uri (match-string 1 formula-link))))
-	    (org-html--wrap-latex-environment
-	     (org-html--format-image source attributes info)
-	     info caption label)))))
-     (t (org-html--wrap-latex-environment latex-frag info caption label)))))
+        (latex-frag (org-remove-indentation
+                     (org-element-property :value latex-environment)))
+        (label (org-html--reference latex-environment info t)))
+    (if (memq processing-type '(t mathjax))
+        (org-html--as-latex
+         latex-environment info
+         (if (org-string-nw-p label)
+             (replace-regexp-in-string "\\`.*"
+                                       (format "\\&\n\\\\label{%s}" label)
+                                       latex-frag)
+           latex-frag))
+      (org-html--wrap-latex-environment
+       (org-html--as-latex latex-environment info latex-frag)
+       label))))
 
 ;;;; LaTeX Fragment
 
 (defun org-html-latex-fragment (latex-fragment _contents info)
   "Transcode a LATEX-FRAGMENT object from Org to HTML.
 CONTENTS is nil.  INFO is a plist holding contextual information."
-  (let ((latex-frag (org-element-property :value latex-fragment))
-	(processing-type (plist-get info :with-latex)))
-    (cond
-     ((memq processing-type '(t mathjax))
-      (org-html-format-latex latex-frag 'mathjax info))
-     ((memq processing-type '(t html))
-      (org-html-format-latex latex-frag 'html info))
-     ((assq processing-type org-preview-latex-process-alist)
-      (let ((formula-link
-	     (org-html-format-latex latex-frag processing-type info)))
-	(when (and formula-link (string-match "file:\\([^]]*\\)" formula-link))
-	  (let ((source (org-export-file-uri (match-string 1 formula-link))))
-	    (org-html--format-image source nil info)))))
-     (t latex-frag))))
+  (org-html--as-latex latex-fragment info))
+
+(defun org-html-latex-image (element info)
+  "Transcode the LaTeX fragment or environment ELEMENT from Org to HTML.
+INFO is a plist holding contextual information, and it is assumed
+that an image for ELEMENT already exists within it."
+  (let* ((path-info
+          (or (gethash element (plist-get info :html-latex-preview-hash-table))
+              (prog1 nil
+                (org-display-warning
+                 (format "Expected LaTeX preview image to exist for element, but none found: %s"
+                         (string-replace "\n" " " (org-element-property :value element)))))))
+         (image-options (org-ensure-list (plist-get info :html-latex-image-options)))
+         (block-p (memq (aref (org-element-property :value element) 1) '(?$ ?\[)))
+         (image-source (if path-info (org-html-latex-image--data path-info info block-p) "")))
+    (if (and (eq (plist-get (cdr path-info) :image-type) 'svg)
+             (memq 'svg-embed (plist-get image-options :inline)))
+        image-source
+      (let ((scaling
+             (if (and (plist-get (cdr path-info) :height)
+                      (plist-get (cdr path-info) :depth))
+                 (org-html-latex-image--scaling path-info info)
+               (prog1 nil
+                 (org-display-warning
+                  (format "Missing geometry information for LaTeX preview image for element: %s"
+                          (string-replace "\n" " " (org-element-property :value element))))))))
+        (org-html-close-tag "img"
+          (org-html--make-attribute-string
+           (nconc
+            (list :src image-source
+                  :alt (org-html-encode-plain-text (org-element-property :value element))
+                  :style
+                  (if path-info
+                      (if scaling
+                          (if block-p
+                              (format "height: %.4fem; display: block" (plist-get scaling :height))
+                            (format "height: %.4fem; vertical-align: -%.4fem; display: inline-block"
+                                    (plist-get scaling :height) (plist-get scaling :depth)))
+                        (if block-p "display: block" "display: inline-block"))
+                    "color: red")
+                  :class (format "org-latex org-latex-%s" (if block-p "block" "inline")))
+            (unless path-info (list :title "LaTeX preview image not generated."))))
+          info)))))
+
+(defun org-html-latex-image--scaling (image-path-info info)
+  "Determine the appropriate (<height> . <depth>) of IMAGE-PATH-INFO given INFO."
+  (let* ((image-options (plist-get info :html-latex-image-options))
+         (rescale-factor (if (eq (plist-get (cdr image-path-info) :image-type) 'svg)
+                             (plist-get image-options :scale)
+                           1)))
+    (list :height (* rescale-factor (plist-get (cdr image-path-info) :height))
+          :depth (* rescale-factor (plist-get (cdr image-path-info) :depth)))))
+
+(defun org-html-latex-image--data (image-path-info info &optional block-p)
+  "Obtaine the image source for IMAGE-PATH-INFO as a string.
+This can take the form of a path, data URI, or <svg> element
+depending on HASH and INFO.  BLOCK-P signals that the image
+should be a block element."
+  (let* ((image-options (plist-get info :html-latex-image-options))
+         (inline-condition (org-ensure-list (plist-get image-options :inline)))
+         (image-format (plist-get (cdr image-path-info) :image-type))
+         (source-file (car image-path-info)))
+    (if (memq image-format inline-condition)
+     (let ((coding-system-for-read 'utf-8)
+           (file-name-handler-alist nil))
+       (with-temp-buffer
+         (insert-file-contents-literally source-file)
+         (cond
+          ((and (memq 'svg-embed inline-condition)
+                (eq image-format 'svg))
+           (goto-char (point-min))
+           (let ((svg-closing-tag (and (search-forward "<svg" nil t)
+                                       (search-forward ">" nil t))))
+
+             (dolist (search '("<!-- This file was generated by dvisvgm [^\n]+ -->"
+                               " height=['\"][^\"']+[\"']"
+                               " width=['\"][^\"']+[\"']"))
+               (goto-char (point-min))
+               (when (re-search-forward search svg-closing-tag t)
+                 (replace-match "")))
+             (goto-char (point-min))
+             (when (re-search-forward "viewBox=['\"][^\"']+[\"']" svg-closing-tag t)
+               (insert
+                " style=\""
+                (let ((scaling (org-html-latex-image--scaling image-path-info info)))
+                  (if block-p
+                      (format "height: %.4fem; display: block" (plist-get scaling :height))
+                    (format "height: %.4fem; vertical-align: -%.4fem; display: inline-block"
+                            (plist-get scaling :height) (plist-get scaling :depth))))
+                "\" class=\"org-latex org-latex-"
+                (if block-p "block" "inline")
+                "\"")))
+           (buffer-string))
+          ((eq image-format 'svg)
+           ;; Modelled after <https://codepen.io/tigt/post/optimizing-svgs-in-data-uris>.
+           (concat "data:image/svg+xml,"
+                   (url-hexify-string
+                    (subst-char-in-string ?\" ?\' (buffer-string))
+                    '(?a ?b ?c ?d ?e ?f ?g ?h ?i ?j ?k ?l ?m ?n
+                      ?o ?p ?q ?r ?s ?t ?u ?v ?w ?x ?y ?z ?A ?B
+                      ?C ?D ?E ?F ?G ?H ?I ?J ?K ?L ?M ?N ?O ?P
+                      ?Q ?R ?S ?T ?U ?V ?W ?X ?Y ?Z ?0 ?1 ?2 ?3
+                      ?4 ?5 ?6 ?7 ?8 ?9 ?- ?_ ?. ?~
+                      ;;Special additions
+                      ?\s ?= ?: ?/))))
+          (t
+           (base64-encode-region (point-min) (point-max))
+           (goto-char (point-min))
+           (insert "data:image/" (symbol-name image-format) ";base64,")
+           (buffer-string)))))
+     source-file)))
 
 ;;;; Line Break
 

lisp/ox-latex.el

@@ -48,6 +48,7 @@
 (defvar engrave-faces-latex-output-style)
 (defvar engrave-faces-current-preset-style)
 (defvar engrave-faces-latex-mathescape)
+(defvar engrave-faces-latex-colorbox-strut)
 
 
 ;;; Define Backend
@@ -110,9 +111,9 @@
 	(?l "As LaTeX file" org-latex-export-to-latex)
 	(?p "As PDF file" org-latex-export-to-pdf)
 	(?o "As PDF file and open"
-	    (lambda (a s v b)
-	      (if a (org-latex-export-to-pdf t s v b)
-		(org-open-file (org-latex-export-to-pdf nil s v b)))))))
+	    (lambda (async subtreep visable-only body-only)
+	      (if async (org-latex-export-to-pdf t subtreep visable-only body-only)
+		(org-latex-export-to-pdf-and-open nil subtreep visable-only body-only))))))
   :filters-alist '((:filter-options . org-latex-math-block-options-filter)
 		   (:filter-paragraph . org-latex-clean-invalid-line-breaks)
 		   (:filter-parse-tree org-latex-math-block-tree-filter
@@ -170,7 +171,83 @@
     (:latex-toc-command nil nil org-latex-toc-command)
     (:latex-compiler "LATEX_COMPILER" nil org-latex-compiler)
     ;; Redefine regular options.
-    (:date "DATE" nil "\\today" parse)))
+    (:date "DATE" nil "\\today" parse))
+  :feature-conditions-alist
+  `((t !announce-start !announce-end
+     !guess-pollyglossia !guess-babel !guess-inputenc)
+    (,(lambda (info)
+        ;; Since amsmath is added unconditionally when using
+        ;; xelatex/lualatex (see `org-latex-default-packages-alist'),
+        ;; and amssymb is not needed, we need not bother when using
+        ;; thoese compilers.
+        (and (not (member (plist-get info :latex-compiler) '("xelatex" "lualatex")))
+             (org-element-map (plist-get info :parse-tree)
+                 '(latex-fragment latex-environment) #'identity info t)))
+     maths)
+    (,(lambda (info)
+        (org-element-map (plist-get info :parse-tree)
+            'underline #'identity info t))
+     underline)
+    ("\\\\uu?line\\|\\\\uwave\\|\\\\sout\\|\\\\xout\\|\\\\dashuline\\|\\dotuline\\|\\markoverwith"
+     underline)
+    (,(lambda (info)
+        (org-element-map (plist-get info :parse-tree)
+            'link
+          (lambda (link)
+            (and (member (org-element-property :type link)
+                         '("http" "https" "ftp" "file"))
+                 (file-name-extension (org-element-property :path link))
+                 (equal (downcase (file-name-extension
+                                   (org-element-property :path link)))
+                        "svg")))
+          info t))
+     svg)
+    (org-latex-tables-booktabs booktabs)
+    (,(lambda (info)
+        (equal (plist-get info :latex-default-table-environment)
+               "longtable"))
+     longtable)
+    ("^[ \t]*\\+attr_latex: .*:environment +longtable"
+     longtable)
+    (,(lambda (info)
+        (eq (plist-get info :latex-src-block-backend) 'engraved))
+     engraved-code)
+    ("^[ \t]*#\\+attr_latex: .*:float +wrap"
+     float-wrap)
+    ("^[ \t]*#\\+attr_latex: .*:float +sideways"
+     rotate)
+    ("^[ \t]*#\\+caption\\(?:\\[.*\\]\\)?:\\|\\\\caption{" caption))
+  :feature-implementations-alist
+  `((!announce-start
+     :snippet ,(lambda (info)
+                 (with-temp-buffer
+                   (setq-local left-margin 2)
+                   (insert (string-join
+                            (mapcar #'symbol-name
+                                    (plist-get info :features))
+                            ", ")
+                           ".")
+                   (fill-region-as-paragraph (point-min) (point-max))
+                   (goto-char (point-min))
+                   (insert "%% ox-latex features:\n% ")
+                   (while (search-forward "\n" nil t)
+                     (insert "%"))
+                   (buffer-string)))
+     :order -100)
+    (maths :snippet "\\usepackage{amsmath}\n\\usepackage{amssymb}" :order 0.2)
+    (underline :snippet "\\usepackage[normalem]{ulem}" :order 0.5)
+    (image :snippet "\\usepackage{graphicx}" :order 2)
+    (svg :snippet "\\usepackage[inkscapelatex=false]{svg}" :order 2 :when image)
+    (longtable :snippet "\\usepackage{longtable}" :when table :order 2)
+    (booktabs :snippet "\\usepackage{booktabs}" :when table :order 2)
+    (float-wrap :snippet "\\usepackage{wrapfig}" :order 2)
+    (rotate :snippet "\\usepackage{rotating}" :order 2)
+    (caption :snippet "\\usepackage{capt-of}")
+    (engraved-code :when code :snippet org-latex-generate-engraved-preamble)
+    (!guess-pollyglossia :snippet org-latex-guess-polyglossia-language)
+    (!guess-babel :snippet org-latex-guess-babel-language)
+    (!guess-inputenc :snippet org-latex-guess-inputenc)
+    (!announce-end :snippet "%% end ox-latex features\n" :order 100)))
 
 
 
@@ -1200,9 +1277,10 @@ will produce
 
 % Define a Code environment to prettily wrap the fontified code.
 \\usepackage[breakable,xparse]{tcolorbox}
+\\providecommand{\\codefont}{\\footnotesize}
 \\DeclareTColorBox[]{Code}{o}%
 {colback=EfD!98!EFD, colframe=EfD!95!EFD,
-  fontupper=\\footnotesize\\setlength{\\fboxsep}{0pt},
+  fontupper=\\setlength{\\fboxsep}{0pt}\\codefont,
   colupper=EFD,
   IfNoValueTF={#1}%
   {boxsep=2pt, arc=2.5pt, outer arc=2.5pt,
@@ -1226,7 +1304,9 @@ as long as it:
 In the default value the colors \"EFD\" and \"EfD\" are provided
 as they are respectively the foreground and background colors,
 just in case they aren't provided by the generated preamble, so
-we can assume they are always set.
+we can assume they are always set.  The command \"\\codefont\" is
+also provided (defaulting to \"\\footnotesize\"), to allow the
+font used in \"Code\" environments to be easily tweaked.
 
 Within this preamble there are two recognized macro-like placeholders:
 
@@ -1323,7 +1403,19 @@ default values of which are given by `org-latex-engraved-preamble' and
                (alist-get 'default
                           (if theme
                               (engrave-faces-get-theme (intern theme))
-                            engrave-faces-current-preset-style)))))))
+                            engrave-faces-current-preset-style))))))
+         (gen-theme-command
+          (lambda (theme)
+            (format "\n\\newcommand{\\engravedtheme%s}{%%\n%s\n}"
+                    (replace-regexp-in-string
+                     "[^A-Za-z]" "" (symbol-name theme))
+                    (replace-regexp-in-string
+                     "\\\\newcommand\\\\efstrut[^\n]*\n" ""
+                     (replace-regexp-in-string
+                      "\\\\newcommand{\\(.+?\\)}\\[1\\]" "\\\\long\\\\def\\1##1"
+                      (replace-regexp-in-string
+                       "#1" "##1"
+                       (funcall gen-theme-spec theme))))))))
     (when (stringp engraved-theme)
       (setq engraved-theme (intern engraved-theme)))
     (when (string-match "^[ \t]*\\[FVEXTRA-SETUP\\][ \t]*\n?" engraved-preamble)
@@ -1353,37 +1445,57 @@ default values of which are given by `org-latex-engraved-preamble' and
              t t
              engraved-preamble)))
     (concat
-     "\n% Setup for code blocks [1/2]\n\n"
+     "% Setup for code blocks [1/2]\n\n"
      engraved-preamble
      "\n\n% Setup for code blocks [2/2]: syntax highlighting colors\n\n"
      (if (require 'engrave-faces-latex nil t)
          (if engraved-themes
              (concat
+              ;; We don't want to re-define the efstrut, so we now need to
+              ;; define it seperately.
+              (format "\\newcommand\\efstrut{%s}\n\n"
+                      engrave-faces-latex-colorbox-strut)
+              ;; Define default theme
+              (funcall gen-theme-command engraved-theme)
+              "\n"
+              ;; Define other themes
               (mapconcat
-               (lambda (theme)
-                 (format
-                  "\n\\newcommand{\\engravedtheme%s}{%%\n%s\n}"
-                  (replace-regexp-in-string "[^A-Za-z]" "" (symbol-name theme))
-                  (replace-regexp-in-string
-                   "newcommand" "renewcommand"
-                   (replace-regexp-in-string
-                    "#" "##"
-                    (funcall gen-theme-spec theme)))))
-               engraved-themes
+               gen-theme-command
+               (cl-remove-if (lambda (theme) (string= theme (symbol-name engraved-theme)))
+                             engraved-themes)
                "\n")
-              "\n\n"
-              (cond
-               ((memq engraved-theme engraved-themes)
-                (concat "\\engravedtheme"
-                        (replace-regexp-in-string
-                         "[^A-Za-z]" "" engraved-theme)
-                        "\n"))
-               (t (funcall gen-theme-spec engraved-theme))))
+              ;; Load the default theme
+              "\n\n\\engravedtheme"
+              (replace-regexp-in-string
+               "[^A-Za-z]" "" (symbol-name engraved-theme))
+              "\n")
            (funcall gen-theme-spec engraved-theme))
        (warn "Cannot engrave source blocks. Consider installing `engrave-faces'.")
        "% WARNING syntax highlighting unavailable as engrave-faces-latex was missing.\n")
      "\n")))
 
+;; Citation features
+
+(org-export-update-features 'latex
+  (bibliography-csl
+   :condition (eq (org-cite-processor info) 'csl)
+   :when bibliography
+   :snippet org-cite-csl--generate-latex-preamble)
+  (bibliography-biblatex
+   :condition (eq (org-cite-processor info) 'biblatex)
+   :when bibliography
+   :snippet org-cite-biblatex--generate-latex-usepackage)
+  (bibliography-biblatex-resources
+   :condition (eq (org-cite-processor info) 'biblatex)
+   :when bibliography
+   :snippet org-cite-biblatex--generate-latex-bibresources
+   :no-precompile t
+   :order 90)
+  (bibliography-natbib
+   :condition (eq (org-cite-processor info) 'natbib)
+   :when bibliography
+   :snippet org-cite-natbib--generate-latex-preamble))
+
 ;;;; Compilation
 
 (defcustom org-latex-compiler-file-string "%% Intended LaTeX compiler: %s\n"
@@ -1632,29 +1744,29 @@ For non-floats, see `org-latex--wrap-label'."
 	      (org-trim label)
 	      (org-export-data main info))))))
 
-(defun org-latex-guess-inputenc (header)
+(defun org-latex-guess-inputenc (info)
   "Set the coding system in inputenc to what the buffer is.
 
-HEADER is the LaTeX header string.  This function only applies
-when specified inputenc option is \"AUTO\".
+INFO is the plist used as a communication channel.
+This function only applies when specified inputenc option is \"AUTO\".
 
 Return the new header, as a string."
-  (let* ((cs (or (ignore-errors
-		   (latexenc-coding-system-to-inputenc
-		    (or org-export-coding-system buffer-file-coding-system)))
-		 "utf8")))
-    (if (not cs) header
+  (let ((header (plist-get info :latex-full-header))
+        (cs (or (ignore-errors
+                  (latexenc-coding-system-to-inputenc
+                   (or org-export-coding-system buffer-file-coding-system)))
+                "utf8")))
+    (when (and cs (string-match "\\\\usepackage\\[\\(AUTO\\)\\]{inputenc}" header))
       ;; First translate if that is requested.
       (setq cs (or (cdr (assoc cs org-latex-inputenc-alist)) cs))
-      ;; Then find the \usepackage statement and replace the option.
-      (replace-regexp-in-string "\\\\usepackage\\[\\(AUTO\\)\\]{inputenc}"
-				cs header t nil 1))))
+      (plist-put info :latex-full-header
+                 (replace-match cs t t header 1))))
+  nil)
 
-(defun org-latex-guess-babel-language (header info)
+(defun org-latex-guess-babel-language (info)
   "Set Babel's language according to LANGUAGE keyword.
 
-HEADER is the LaTeX header string.  INFO is the plist used as
-a communication channel.
+INFO is the plist used as a communication channel.
 
 Insertion of guessed language only happens when Babel package has
 explicitly been loaded.  Then it is added to the rest of
@@ -1668,52 +1780,48 @@ already loaded.
 
 Return the new header."
   (let* ((language-code (plist-get info :language))
-	 (plist (cdr
-		 (assoc language-code org-latex-language-alist)))
-	 (language (plist-get plist :babel))
-	 (language-ini-only (plist-get plist :babel-ini-only))
+         (plist (cdr (assoc language-code org-latex-language-alist)))
+         (language (plist-get plist :babel))
+         (header (plist-get info :latex-full-header))
+         (language-ini-only (plist-get plist :babel-ini-only))
          (language-ini-alt (plist-get plist :babel-ini-alt))
-	 ;; If no language is set, or Babel package is not loaded, or
-	 ;; LANGUAGE keyword value is a language served by Babel
-	 ;; exclusively through ini files, return HEADER as-is.
-	 (header (if (or language-ini-only
-			 (not (stringp language-code))
-			 (not (string-match "\\\\usepackage\\[\\(.*\\)\\]{babel}" header)))
-		     header
-		   (let ((options (save-match-data
-				    (org-split-string (match-string 1 header) ",[ \t]*"))))
-		     ;; If LANGUAGE is already loaded, return header
-		     ;; without AUTO.  Otherwise, replace AUTO with language or
-		     ;; append language if AUTO is not present.  Languages that are
-		     ;; served in Babel exclusively through ini files are not added
-		     ;; to the babel argument, and must be loaded using
-		     ;; `\babelprovide'.
-		     (replace-match
-		      (mapconcat (lambda (option) (if (equal "AUTO" option) language option))
-				 (cond ((member language options) (delete "AUTO" options))
-				       ((member "AUTO" options) options)
-				       (t (append options (list language))))
-				 ", ")
-		      t nil header 1)))))
+         (babel-header-options
+          ;; If no language is set, or Babel package is not loaded, or
+          ;; LANGUAGE keyword value is a language served by Babel
+          ;; exclusively through ini files, return HEADER as-is.
+          (and (not language-ini-only)
+               (stringp language-code)
+               (string-match "\\\\usepackage\\[\\(.*\\)\\]{babel}" header)
+               (let ((options (save-match-data
+                                (org-split-string (match-string 1 header) ",[ \t]*"))))
+                 (cond ((member language options) (delete "AUTO" options))
+                       ((member "AUTO" options) options)
+                       (t (append options (list language))))))))
+    (when babel-header-options
+      ;; If AUTO is present in the header options, replace it with `language'.
+      (setq header
+            (replace-match
+             (mapconcat (lambda (option) (if (equal "AUTO" option) language option))
+                        babel-header-options
+                        ", ")
+             t nil header 1)))
     ;; If `\babelprovide[args]{AUTO}' is present, AUTO is
     ;; replaced by LANGUAGE.
-    (if (not (string-match "\\\\babelprovide\\[.*\\]{\\(.+\\)}" header))
-	header
-      (let ((prov (match-string 1 header)))
-	(if (equal "AUTO" prov)
-	    (replace-regexp-in-string (format
-				       "\\(\\\\babelprovide\\[.*\\]\\)\\({\\)%s}" prov)
-				      (format "\\1\\2%s}"
-					      (if language-ini-alt language-ini-alt
-                                                (or language language-ini-only)))
-				      header t)
-	  header)))))
+    (when (string-match "\\\\babelprovide\\[.*\\]{AUTO}" header)
+      (setq header
+            (replace-regexp-in-string
+             (format
+              "\\(\\\\babelprovide\\[.*\\]\\)\\({\\)%s}" babel-header-options)
+             (format "\\1\\2%s}" (if language-ini-alt language-ini-alt
+                                   (or language language-ini-only)))
+             header t)))
+    (plist-put info :latex-full-header header))
+  nil)
 
-(defun org-latex-guess-polyglossia-language (header info)
+(defun org-latex-guess-polyglossia-language (info)
   "Set the Polyglossia language according to the LANGUAGE keyword.
 
-HEADER is the LaTeX header string.  INFO is the plist used as
-a communication channel.
+INFO is the plist used as a communication channel.
 
 Insertion of guessed language only happens when the Polyglossia
 package has been explicitly loaded.
@@ -1724,48 +1832,50 @@ replaced with the language of the document or
 using \setdefaultlanguage and not as an option to the package.
 
 Return the new header."
-  (let* ((language (plist-get info :language)))
+  (let ((header (plist-get info :latex-full-header))
+        (language (plist-get info :language)))
     ;; If no language is set or Polyglossia is not loaded, return
     ;; HEADER as-is.
-    (if (or (not (stringp language))
-	    (not (string-match
-		  "\\\\usepackage\\(?:\\[\\([^]]+?\\)\\]\\){polyglossia}\n"
-		  header)))
-	header
+    (when (and (stringp language)
+               (string-match
+                "\\\\usepackage\\(?:\\[\\([^]]+?\\)\\]\\){polyglossia}\n"
+                header))
       (let* ((options (org-string-nw-p (match-string 1 header)))
-	     (languages (and options
-			     ;; Reverse as the last loaded language is
-			     ;; the main language.
-			     (nreverse
-			      (delete-dups
-			       (save-match-data
-				 (org-split-string
-				  (replace-regexp-in-string
-				   "AUTO" language options t)
-				  ",[ \t]*"))))))
-	     (main-language-set
-	      (string-match-p "\\\\setmainlanguage{.*?}" header)))
-	(replace-match
-	 (concat "\\usepackage{polyglossia}\n"
-		 (mapconcat
-		  (lambda (l)
-		    (let* ((plist (cdr
-				   (assoc language org-latex-language-alist)))
-			   (polyglossia-variant (plist-get plist :polyglossia-variant))
-			   (polyglossia-lang (plist-get plist :polyglossia))
-			   (l (if (equal l language)
-				  polyglossia-lang
-				l)))
-		      (format (if main-language-set (format "\\setotherlanguage{%s}\n" l)
-				(setq main-language-set t)
-				"\\setmainlanguage%s{%s}\n")
-			      (if polyglossia-variant
-				  (format "[variant=%s]" polyglossia-variant)
-				"")
-			      l)))
-		  languages
-		  ""))
-	 t t header 0)))))
+             (languages (and options
+                             ;; Reverse as the last loaded language is
+                             ;; the main language.
+                             (nreverse
+                              (delete-dups
+                               (save-match-data
+                                 (org-split-string
+                                  (replace-regexp-in-string
+                                   "AUTO" language options t)
+                                  ",[ \t]*"))))))
+             (main-language-set
+              (string-match-p "\\\\setmainlanguage{.*?}" header))
+             (polyglossia-modified-header
+              (replace-match
+               (concat "\\usepackage{polyglossia}\n"
+                       (mapconcat
+                        (lambda (l)
+                          (let* ((plist (cdr (assoc language org-latex-language-alist)))
+                                 (polyglossia-variant (plist-get plist :polyglossia-variant))
+                                 (polyglossia-lang (plist-get plist :polyglossia))
+                                 (l (if (equal l language)
+                                        polyglossia-lang
+                                      l)))
+                            (format (if main-language-set (format "\\setotherlanguage{%s}\n" l)
+                                      (setq main-language-set t)
+                                      "\\setmainlanguage%s{%s}\n")
+                                    (if polyglossia-variant
+                                        (format "[variant=%s]" polyglossia-variant)
+                                      "")
+                                    l)))
+                        languages
+                        ""))
+               t t header 0)))
+        (plist-put info :latex-full-header polyglossia-modified-header))))
+  nil)
 
 (defun org-latex--remove-packages (pkg-alist info)
   "Remove packages based on the current LaTeX compiler.
@@ -1970,32 +2080,103 @@ non-nil, only includes packages relevant to image generation, as
 specified in `org-latex-default-packages-alist' or
 `org-latex-packages-alist'."
   (let* ((class (plist-get info :latex-class))
-	 (class-template
-	  (or template
-	      (let* ((class-options (plist-get info :latex-class-options))
-		     (header (nth 1 (assoc class (plist-get info :latex-classes)))))
-		(and (stringp header)
-		     (if (not class-options) header
-		       (replace-regexp-in-string
-			"^[ \t]*\\\\documentclass\\(\\(\\[[^]]*\\]\\)?\\)"
-			class-options header t nil 1))))
-	      (user-error "Unknown LaTeX class `%s'" class))))
-    (org-latex-guess-polyglossia-language
-     (org-latex-guess-babel-language
-      (org-latex-guess-inputenc
-       (org-element-normalize-string
-	(org-splice-latex-header
-	 class-template
-	 (org-latex--remove-packages org-latex-default-packages-alist info)
-	 (org-latex--remove-packages org-latex-packages-alist info)
-	 snippet?
-	 (mapconcat #'org-element-normalize-string
-		    (list (plist-get info :latex-header)
-			  (and (not snippet?)
-			       (plist-get info :latex-header-extra)))
-		    ""))))
-      info)
-     info)))
+         (class-template
+          (or template
+              (let* ((class-options (plist-get info :latex-class-options))
+                     (header (nth 1 (assoc class (plist-get info :latex-classes)))))
+                (and (stringp header)
+                     (if (not class-options) header
+                       (replace-regexp-in-string
+                        "^[ \t]*\\\\documentclass\\(\\(\\[[^]]*\\]\\)?\\)"
+                        class-options header t nil 1))))
+              (user-error "Unknown LaTeX class `%s'" class)))
+         (header-split (format "\n%%--org-latex-header-temp-split-%d--\n" (random 10000)))
+         (header (concat (org-element-normalize-string (plist-get info :latex-header))
+                         header-split
+                         (and (not snippet?)
+                              (org-element-normalize-string
+                               (plist-get info :latex-header-extra)))))
+         generated-preamble preamble-nonprecompilable)
+    (plist-put info :latex-full-header
+               (org-element-normalize-string
+                (org-splice-latex-header
+                 class-template
+                 (org-latex--remove-packages org-latex-default-packages-alist info)
+                 (org-latex--remove-packages org-latex-packages-alist info)
+                 snippet?
+                 header)))
+    (if snippet?
+        (setq generated-preamble
+              (progn
+                (org-latex-guess-inputenc info)
+                (org-latex-guess-babel-language info)
+                (org-latex-guess-polyglossia-language info)
+                "\n% Generated preamble omitted for snippets."))
+      (let (impl-precomp impl-noprecomp)
+        (dolist (impl (plist-get info :feature-implementations))
+          (message "LaTeX feature: %s" (car impl))
+          (if (or impl-noprecomp (plist-get (cdr impl) :no-precompile))
+              (push impl impl-noprecomp)
+            (push impl impl-precomp)))
+        (message "Precomp feats: %S" (reverse (mapcar #'car impl-precomp)))
+        (message "No precomp feats: %S" (reverse (mapcar #'car impl-noprecomp)))
+        (setq generated-preamble
+              (string-join
+               (org-export-expand-feature-snippets
+                info (nreverse impl-precomp))
+               "\n\n")
+              preamble-nonprecompilable
+              (string-join
+               (org-export-expand-feature-snippets
+                info (nreverse impl-noprecomp))
+               "\n\n"))))
+    (let* ((header-parts
+            (split-string (plist-get info :latex-full-header)
+                          (regexp-quote header-split)))
+           (header-main (car header-parts))
+           (header-extra (cadr header-parts))
+           (preamble
+            (concat
+             (org-latex--insert-compiler info)
+             header-main
+             "\n"
+             generated-preamble
+             "\n"))
+           (format-file
+            (and org-latex-precompile
+                 ;; Precompilation is disabled for xelatex/lualatex for now.
+                 (if (member (plist-get info :latex-compiler)
+                             '("xelatex" "lualatex"))
+                     (progn
+                       (display-warning
+                        '(org latex-export disable-local-precompile)
+                        (format "%s does not support precompilation, disabling LaTeX precompile in this buffer.\n To re-enable, run `(setq-local org-latex-precompile t)' or reopen this buffer."
+                                (plist-get info :latex-compiler)))
+                       (setf (buffer-local-value
+                              'org-latex-precompile (get-buffer (plist-get info :input-buffer)))
+                             nil))
+                   (org-latex--precompile
+                    info preamble
+                    (string-match-p "\\(?:\\\\input{\\|\\\\include{\\)[^/]" preamble))))))
+      (when (and format-file (not snippet?))
+        (let ((preamble-parts (split-string preamble (regexp-quote header-split))))
+          (setq preamble (car preamble-parts)
+                preamble-nonprecompilable
+                (concat preamble-nonprecompilable
+                        (cadr preamble-parts)))))
+      (concat (and format-file
+                   (concat "%& " (file-name-sans-extension format-file) "\n"))
+              (and (plist-get info :time-stamp-file)
+                   (format-time-string "%% Created %Y-%m-%d %a %H:%M\n"))
+              preamble
+              (and format-file
+                   "\n% end precompiled preamble\n\\ifcsname endofdump\\endcsname\\endofdump\\fi\n")
+              "\n"
+              preamble-nonprecompilable
+              (and preamble-nonprecompilable
+                   (not (string-empty-p preamble-nonprecompilable))
+                   "\n")
+              header-extra))))
 
 (defun org-latex-template (contents info)
   "Return complete document string after LaTeX conversion.
@@ -2004,12 +2185,7 @@ holding export options."
   (let ((title (org-export-data (plist-get info :title) info))
 	(spec (org-latex--format-spec info)))
     (concat
-     ;; Timestamp.
-     (and (plist-get info :time-stamp-file)
-	  (format-time-string "%% Created %Y-%m-%d %a %H:%M\n"))
-     ;; LaTeX compiler.
-     (org-latex--insert-compiler info)
-     ;; Document class and packages.
+     ;; Timestamp, compiler statement, document class and packages.
      (org-latex-make-preamble info)
      ;; Possibly limit depth for headline numbering.
      (let ((sec-num (plist-get info :section-numbers)))
@@ -2046,12 +2222,6 @@ holding export options."
      (let ((template (plist-get info :latex-hyperref-template)))
        (and (stringp template)
             (format-spec template spec)))
-     ;; engrave-faces-latex preamble
-     (when (and (eq (plist-get info :latex-src-block-backend) 'engraved)
-                (org-element-map (plist-get info :parse-tree)
-                    '(src-block inline-src-block) #'identity
-                    info t))
-       (org-latex-generate-engraved-preamble info))
      ;; Document start.
      "\\begin{document}\n\n"
      ;; Title command.
@@ -2079,6 +2249,118 @@ holding export options."
      ;; Document end.
      "\\end{document}")))
 
+(defvar org-latex-precompile t
+  "Precompile the preamble during export.
+This requires the LaTeX package \"mylatexformat\" to be installed.")
+
+(defconst org-latex--precompile-log "*Org LaTeX Precompilation*")
+
+(defvar org-latex-precompile-command
+  "%l -output-directory %o -ini -jobname=%b \"&%L\" mylatexformat.ltx %f")
+
+(defvar org-latex-precompile-compiler-map
+  '(("pdflatex" . "latex")
+    ("xelatex" . "xelatex -no-pdf")
+    ("lualatex" . "dvilualatex")))
+
+(defun org-latex--precompile (info preamble &optional tempfile-p)
+  "Precompile/dump LaTeX PREAMBLE text.
+
+The path to the format file (.fmt) is returned.  If the format
+file could not be found in the persist cache, it is generated
+according to PROCESSING-INFO and stored.  INFO is a plist used as
+a communication channel.
+
+If TEMPFILE-P is non-nil, then it is assumed the preamble does
+not contain any relative references to other files.
+
+This is intended to speed up Org's LaTeX preview generation
+process."
+  (let ((preamble-hash
+         (thread-first
+           preamble
+           (concat
+            (plist-get info :latex-compiler)
+            (if tempfile-p "-temp"
+              default-directory))
+           (sha1)))
+        (default-directory
+          (if tempfile-p temporary-file-directory default-directory)))
+    (or (cadr
+         (org-persist-read "LaTeX format file cache"
+                           (list :key preamble-hash)
+                           nil nil :read-related t))
+        (when-let ((dump-file
+                    (org-latex--precompile-preamble
+                     info preamble (expand-file-name preamble-hash temporary-file-directory))))
+          (cadr
+           (org-persist-register `(,"LaTeX format file cache"
+                                   (file ,dump-file))
+                                 (list :key preamble-hash)
+                                 :write-immediately t))))))
+
+(defun org-latex--remove-cached-preamble (latex-compiler preamble &optional tempfile-p)
+  "Remove the cached preamble file for PREAMBLE compiled with LATEX-COMPILER.
+TEMPFILE-P should be set to mirror the caching `org-latex--precompile' call
+which is intended to be evicted from the cache."
+  (let ((preamble-hash
+         (thread-first
+           preamble
+           (concat
+            latex-compiler
+            (if tempfile-p "-temp"
+              default-directory))
+           (sha1))))
+    (org-persist-unregister "LaTeX format file cache"
+                            (list :key preamble-hash)
+                            :remove-related t)))
+
+(defun org-latex--precompile-preamble (info preamble basepath)
+  "Precompile PREAMBLE with \"mylatexformat\".
+The PREAMBLE string is placed in BASEPATH.tex and compiled
+according to PROCESSING-INFO. If compilation and dumping
+succeeded, BASEPATH.fmt will be returned.
+
+Should any errors occur during compilation, nil will be returned,
+and appropriate warnings may be emitted."
+  (let ((dump-file (concat basepath ".fmt"))
+        (preamble-file (concat basepath ".tex"))
+        (precompile-buffer
+         (with-current-buffer
+             (get-buffer-create org-latex--precompile-log)
+           (erase-buffer)
+           (current-buffer))))
+    (with-temp-file preamble-file
+      (insert preamble "\n\\endofdump\n"))
+    (message "Precompiling Org LaTeX preamble...")
+    (condition-case nil
+        (org-compile-file
+         preamble-file (list org-latex-precompile-command)
+         "fmt" nil precompile-buffer
+         (or (plist-get info :precompile-format-spec)
+             `((?l . ,(plist-get info :latex-compiler))
+               (?L . ,(plist-get info :latex-compiler)))))
+      (:success
+       (kill-buffer precompile-buffer)
+       (delete-file preamble-file)
+       dump-file)
+      (error
+       (unless (= 0 (call-process "kpsewhich" nil nil nil "mylatexformat.ltx"))
+         (display-warning
+          '(org latex-preview preamble-precompilation)
+          "The LaTeX package \"mylatexformat\" is required for precompilation, but could not be found")
+         :warning)
+       (unless (= 0 (call-process "kpsewhich" nil nil nil "preview.sty"))
+         (display-warning
+          '(org latex-preview preamble-precompilation)
+          "The LaTeX package \"preview\" is required for precompilation, but could not be found")
+         :warning)
+       (display-warning
+        '(org latex-preview preamble-precompilation)
+        (format "Failed to precompile preamble (%s), see the \"%s\" buffer."
+                preamble-file precompile-buffer)
+        :warning)
+       nil))))
 
 
 ;;; Transcode Functions
@@ -2483,8 +2765,12 @@ INFO, CODE, and LANG are provided by `org-latex-inline-src-block'."
 (defun org-latex-inline-src-block--engraved (info code lang)
   "Transcode an inline src block's content from Org to LaTeX, using engrave-faces.
 INFO, CODE, and LANG are provided by `org-latex-inline-src-block'."
-  (org-latex-src--engrave-code
-   code lang nil (plist-get info :latex-engraved-options) t))
+  (let ((engraved-theme (plist-get info :latex-engraved-theme)))
+    (when (stringp engraved-theme)
+      (setq engraved-theme (intern engraved-theme)))
+    (org-latex-src--engrave-code
+     code lang engraved-theme nil
+     (plist-get info :latex-engraved-options) t)))
 
 (defun org-latex-inline-src-block--listings (info code lang)
   "Transcode an inline src block's content from Org to LaTeX, using lstlistings.
@@ -3535,7 +3821,7 @@ and FLOAT are extracted from SRC-BLOCK and INFO in `org-latex-src-block'."
       (when (eq mathescape 'yes)
         (or engrave-faces-latex-mathescape t)))))
 
-(defun org-latex-src--engrave-code (content lang &optional theme options inline)
+(defun org-latex-src--engrave-code (content lang &optional theme explicit-theme-p options inline)
   "Engrave CONTENT to LaTeX in a LANG-mode buffer, and give the result.
 When the THEME symbol is non-nil, that theme will be used.
 
@@ -3576,12 +3862,12 @@ to the Verbatim environment or Verb command."
                 (concat "\\begin{Code}\n\\begin{Verbatim}" engraved-options "\n"
                         engraved-code "\n\\end{Verbatim}\n\\end{Code}"))))
         (kill-buffer engraved-buffer)
-        (if theme
-            (concat "{\\engravedtheme"
+        (if (and theme explicit-theme-p)
+            (concat "\\begingroup\\engravedtheme"
                     (replace-regexp-in-string "[^A-Za-z]" ""
                                               (symbol-name theme))
                     engraved-wrapped
-                    "}")
+                    "\\endgroup")
           engraved-wrapped))
     (user-error "Cannot engrave code as `engrave-faces-latex' is unavailable.")))
 
@@ -3615,7 +3901,16 @@ and FLOAT are extracted from SRC-BLOCK and INFO in `org-latex-src-block'."
                `(("linenos")
                  ("firstnumber" ,(number-to-string (1+ num-start)))))
              (and local-options `((,local-options))))))
-         (engraved-theme (plist-get attributes :engraved-theme))
+         (intern-safe
+          (lambda (name)
+            (if (stringp name)
+                (intern name)
+              name)))
+         (engraved-doc-theme
+          (funcall intern-safe (plist-get info :latex-engraved-theme)))
+         (engraved-theme
+          (or (funcall intern-safe (plist-get attributes :engraved-theme))
+              engraved-doc-theme))
          (content
           (let* ((code-info (org-export-unravel-code src-block))
                  (max-width
@@ -3641,7 +3936,8 @@ and FLOAT are extracted from SRC-BLOCK and INFO in `org-latex-src-block'."
                  (org-latex-src--engrave-mathescape-p info options)))
             (org-latex-src--engrave-code
              content lang
-             (when engraved-theme (intern engraved-theme))
+             engraved-theme
+             (not (eq engraved-theme engraved-doc-theme))
              options))))
     (concat (car float-env) body (cdr float-env))))
 
@@ -4355,13 +4651,21 @@ Return PDF file's name."
       async subtreep visible-only body-only ext-plist
       #'org-latex-compile)))
 
-(defun org-latex-compile (texfile &optional snippet)
+(defun org-latex-export-to-pdf-and-open (&optional async subtreep visible-only body-only ext-plist)
+  (let ((outfile (org-export-output-file-name ".tex" subtreep)))
+    (org-export-to-file 'latex outfile
+      async subtreep visible-only body-only ext-plist
+      (lambda (f) (org-latex-compile f nil t)))))
+
+(defun org-latex-compile (texfile &optional snippet open-pdf)
   "Compile a TeX file.
 
 TEXFILE is the name of the file being compiled.  Processing is
 done through the command specified in `org-latex-pdf-process',
 which see.  Output is redirected to \"*Org PDF LaTeX Output*\"
-buffer.
+buffer.  When the process is a shell command (and not a
+function), it will be run asyncronously via `org-async-call',
+unless the current session is `noninteractive'.
 
 When optional argument SNIPPET is non-nil, TEXFILE is a temporary
 file used to preview a LaTeX snippet.  In this case, do not
@@ -4396,16 +4700,34 @@ produced."
                  (?L . ,(shell-quote-argument compiler))))
 	 (log-buf-name "*Org PDF LaTeX Output*")
          (log-buf (and (not snippet) (get-buffer-create log-buf-name)))
-         outfile)
-    ;; Erase compile buffer at the start.
+         (outfile (expand-file-name (concat (file-name-base texfile) ".pdf")
+                                    (file-name-directory texfile))))
     (with-current-buffer log-buf
       (erase-buffer))
-    (setq outfile
-          (org-compile-file
-           texfile process "pdf"
-	   (format "See %S for details" log-buf-name)
-	   log-buf spec))
-    (org-latex-compile--postprocess outfile log-buf snippet)
+    (if (or noninteractive (functionp process))
+        (progn
+          (org-compile-file texfile process "pdf"
+                            (format "See %S for details" log-buf-name)
+                            log-buf spec)
+          (and open-pdf (org-open-file outfile))
+          (org-latex-compile--postprocess outfile log-buf snippet))
+      (let ((failure-msg (format "File %S wasn't produced (exit code %%d).  See %%s for details."
+                                 outfile))
+            async-call-spec)
+        (dolist (cmd (reverse (org-compile-file-commands
+                               texfile process "pdf" spec)))
+          (setq async-call-spec
+                (list cmd
+                      :buffer log-buf
+                      :success
+                      (or async-call-spec
+                          (list (and open-pdf (lambda (_ _ _) (org-open-file outfile)))
+                                (lambda (_ buf _)
+                                  (org-latex-compile--postprocess outfile buf snippet))))
+                      :failure
+                      failure-msg)))
+        (message "Compiling %s..." texfile)
+        (apply #'org-async-call async-call-spec)))
     ;; Return output file name.
     outfile))
 

lisp/ox-mathml.el

@@ -0,0 +1,157 @@
+;;; ox-mathml.el --- Support for MathML exports -*- lexical-binding: t; -*-
+;;
+;; Copyright (C) 2023 TEC
+;;
+;; Author: TEC <contact@tecosaur.net>
+;; Maintainer: TEC <contact@tecosaur.net>
+;; Created: February 27, 2023
+;; Modified: February 27, 2023
+;; Version: 0.0.1
+;; Keywords: abbrev bib c calendar comm convenience data docs emulations extensions faces files frames games hardware help hypermedia i18n internal languages lisp local maint mail matching mouse multimedia news outlines processes terminals tex tools unix vc wp
+;; Homepage: https://github.com/tecosaur/ox-mathml
+;; Package-Requires: ((emacs "24.3"))
+;;
+;; This file is not part of GNU Emacs.
+;;
+;;; Commentary:
+;;
+;;  Support for MathML exports
+;;
+;;; Code:
+
+(defgroup org-mathml nil
+  "Options for generation of MathML representations of LaTeX math."
+  :tag "Org MathML export"
+  :group 'org-export)
+
+(defcustom org-mathml-converter-jar-file nil
+  "Value of\"%j\" in `org-mathml-convert-command'.
+Use this to specify additional executable file say a jar file.
+
+When using MathToWeb as the converter, specify the full-path to
+your mathtoweb.jar file."
+  :group 'org-mathml
+  :version "24.1"
+  :type '(choice
+          (const :tag "None" nil)
+          (file :tag "JAR file" :must-match t)))
+
+(defcustom org-mathml-convert-command nil
+  "Command to convert LaTeX fragments to MathML.
+Replace format-specifiers in the command as noted below and use
+`shell-command' to convert LaTeX to MathML.
+%j:     Executable file in fully expanded form as specified by
+        `org-latex-to-mathml-jar-file'.
+%I:     Input LaTeX file in fully expanded form.
+%i:     Shell-escaped LaTeX fragment to be converted.
+        It must not be used inside a quoted argument, the result of %i
+        expansion inside a quoted argument is undefined.
+%o:     Output MathML file.
+
+This command is used by `org-mathml-convert-latex'.
+
+When using MathToWeb as the converter, set this option to
+\"java -jar %j -unicode -force -df %o %I\".
+
+When using LaTeXML set this option to
+\"latexmlmath %i --preload=amsmath.sty --preload=amssymb.sty --presentationmathml=%o\"."
+  :group 'org-mathml
+  :version "24.1"
+  :type '(choice
+          (const :tag "None" nil)
+          (string :tag "\nShell command")))
+
+(defun org-mathml-converter-available-p ()
+  "Return t if `org-mathml-convert-command' is usable."
+  (save-match-data
+    (when (and (boundp 'org-mathml-convert-command)
+               org-mathml-convert-command)
+      (let ((executable (car (split-string
+                              org-mathml-convert-command))))
+        (when (executable-find executable)
+          (if (string-match
+               "%j" org-mathml-convert-command)
+              (file-readable-p org-mathml-converter-jar-file)
+            t))))))
+
+(defun org-mathml-convert-latex (latex-frag &optional mathml-file)
+  "Convert LATEX-FRAG to MathML and store it in MATHML-FILE.
+Use `org-latex-to-mathml-convert-command'.  If the conversion is
+successful, return the portion between \"<math...> </math>\"
+elements otherwise return nil.  When MATHML-FILE is specified,
+write the results in to that file.  When invoked as an
+interactive command, prompt for LATEX-FRAG, with initial value
+set to the current active region and echo the results for user
+inspection."
+  (interactive (list (let ((frag (when (org-region-active-p)
+                                   (buffer-substring-no-properties
+                                    (region-beginning) (region-end)))))
+                       (read-string "LaTeX Fragment: " frag nil frag))))
+  (unless latex-frag (user-error "Invalid LaTeX fragment"))
+  (let* ((tmp-in-file
+          (let ((file (file-relative-name
+                       (make-temp-name (expand-file-name "ltxmathml-in")))))
+            (write-region latex-frag nil file)
+            file))
+         (tmp-out-file (file-relative-name
+                        (make-temp-name (expand-file-name  "ltxmathml-out"))))
+         (cmd (format-spec
+               org-mathml-convert-command
+               `((?j . ,(and org-mathml-converter-jar-file
+                             (shell-quote-argument
+                              (expand-file-name
+                               org-mathml-converter-jar-file))))
+                 (?I . ,(shell-quote-argument tmp-in-file))
+                 (?i . ,latex-frag)
+                 (?o . ,(shell-quote-argument tmp-out-file)))))
+         mathml shell-command-output)
+    (when (called-interactively-p 'any)
+      (unless (org-mathml-converter-available-p)
+        (user-error "LaTeX to MathML converter not configured")))
+    (message "Running %s" cmd)
+    (setq shell-command-output (shell-command-to-string cmd))
+    (setq mathml
+          (when (file-readable-p tmp-out-file)
+            (with-current-buffer (find-file-noselect tmp-out-file t)
+              (goto-char (point-min))
+              (when (re-search-forward
+                     (format "<math[^>]*?%s[^>]*?>\\(.\\|\n\\)*</math>"
+                             (regexp-quote
+                              "xmlns=\"http://www.w3.org/1998/Math/MathML\""))
+                     nil t)
+                (prog1 (match-string 0) (kill-buffer))))))
+    (cond
+     (mathml
+      (setq mathml
+            (concat "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" mathml))
+      (when mathml-file
+        (write-region mathml nil mathml-file))
+      (when (called-interactively-p 'any)
+        (message mathml)))
+     ((warn "LaTeX to MathML conversion failed")
+      (message shell-command-output)))
+    (delete-file tmp-in-file)
+    (when (file-exists-p tmp-out-file)
+      (delete-file tmp-out-file))
+    mathml))
+
+(defun org-mathml-convert-latex-cached (latex-frag)
+  "Use `org-mathml-convert-latex' but check local cache first."
+  (let ((latex-hash-path
+         (expand-file-name
+          (concat
+           "org-mathml-formula-"
+           (sha1
+            (prin1-to-string
+             (list latex-frag
+                   org-mathml-convert-command)))
+           ".mathml")
+          temporary-file-directory))
+        print-length print-level)
+    (unless (file-exists-p latex-hash-path)
+      (org-mathml-convert-latex latex-frag latex-hash-path))
+    (and (file-exists-p latex-hash-path)
+         latex-hash-path)))
+
+(provide 'ox-mathml)
+;;; ox-mathml.el ends here

lisp/ox-odt.el

@@ -34,6 +34,8 @@
 (require 'org-macs)
 (require 'ox)
 (require 'table nil 'noerror)
+(require 'ox-mathml)
+(require 'org-latex-preview)
 
 (declare-function org-at-heading-p "org" (&optional _))
 (declare-function org-back-to-heading "org" (&optional invisible-ok))
@@ -119,6 +121,7 @@
     (:odt-pixels-per-inch nil nil org-odt-pixels-per-inch)
     (:odt-table-styles nil nil org-odt-table-styles)
     (:odt-use-date-fields nil nil org-odt-use-date-fields)
+    (:odt-latex-image-options nil nil org-odt-latex-image-options)
     ;; Redefine regular option.
     (:with-latex nil "tex" org-odt-with-latex)
     ;; Retrieve LaTeX header for fragments.
@@ -720,6 +723,15 @@ Any other symbol is a synonym for `mathjax'."
 	  (const :tag "Use imagemagick to make images" imagemagick)
 	  (other :tag "Use MathJax to display math" mathjax)))
 
+(defcustom org-odt-latex-image-options
+  '(:foreground "Black" :background "Transparent"
+    :page-width 1.0 :scale 1.0 :inline nil)
+  "LaTeX preview options that apply to generated images.
+This is a ODT-specific counterpart to
+`org-latex-preview-appearance-options', which see."
+  :group 'org-export-odt
+  :package-version '(Org . "9.7")
+  :type 'plist)
 
 ;;;; Links
 
@@ -2284,12 +2296,24 @@ used as a communication channel."
 	 ;;
 	 ;; Handle `:width', `:height' and `:scale' properties.  Read
 	 ;; them as numbers since we need them for computations.
-	 (size (org-odt--image-size
-		src-expanded info
-		(let ((width (plist-get attr-plist :width)))
-		  (and width (read width)))
-		(let ((length (plist-get attr-plist :length)))
-		  (and length (read length)))
+	 (--em-to-cm
+          ;; FIXME: Hardcoded default font-size to 12 according to the
+          ;; default value of styles.xml in org-odt-styles-dir.  I
+          ;; don't know how how to determine this dynamically.
+          (lambda (size) (and size (* 12 0.0352778 size))))
+         (em-geometry
+          (cdr-safe
+           (gethash element (plist-get info :odt-latex-preview-hash-table))))
+         (width (or (funcall --em-to-cm (plist-get em-geometry :width)) ;latex image size
+                    (and-let* ((w (plist-get attr-plist :width)) ;ATTR_ODT specified size
+                               ((stringp w)))
+                      (read w))))
+         (height (or (funcall --em-to-cm (plist-get em-geometry :height)) ;latex image size
+                     (and-let* ((l (plist-get attr-plist :length)) ;ATTR_ODT specified size
+                                ((stringp l)))
+                       (read l))))
+         (size (org-odt--image-size
+		src-expanded info width height
 		(let ((scale (plist-get attr-plist :scale)))
 		  (and scale (read scale)))
 		nil			; embed-as
@@ -3729,115 +3753,135 @@ contextual information."
 
 (defun org-odt--translate-latex-fragments (tree _backend info)
   (let ((processing-type (plist-get info :with-latex))
-	(count 0)
+        (count 0)
         (warning nil))
-    ;; Normalize processing-type to one of dvipng, mathml or verbatim.
-    ;; If the desired converter is not available, force verbatim
-    ;; processing.
-    (cl-case processing-type
-      ((t mathml)
-       (if (and (fboundp 'org-format-latex-mathml-available-p)
-		(org-format-latex-mathml-available-p))
-	   (setq processing-type 'mathml)
-         (setq warning "`org-odt-with-latex': LaTeX to MathML converter not available.  Falling back to verbatim.")
-	 (setq processing-type 'verbatim)))
-      ((dvipng imagemagick)
-       (unless (and (org-check-external-command "latex" "" t)
-		    (org-check-external-command
-		     (if (eq processing-type 'dvipng) "dvipng" "convert") "" t))
-	 (setq warning "`org-odt-with-latex': LaTeX to PNG converter not available.  Falling back to verbatim.")
-	 (setq processing-type 'verbatim)))
-      (verbatim) ;; nothing to do
-      (otherwise
-       (setq warning "`org-odt-with-latex': Unknown LaTeX option.  Forcing verbatim.")
-       (setq processing-type 'verbatim)))
-
-    ;; Display warning if the selected PROCESSING-TYPE is not
-    ;; available, but there are fragments to be converted.
-    (when warning
-      (org-element-map tree '(latex-fragment latex-environment)
-        (lambda (_) (warn warning))
-        info 'first-match nil t))
-
-    ;; Store normalized value for later use.
-    (when (plist-get info :with-latex)
-      (plist-put info :with-latex processing-type))
-    (message "Formatting LaTeX using %s" processing-type)
-
-    ;; Convert `latex-fragment's and `latex-environment's.
-    (when (memq processing-type '(mathml dvipng imagemagick))
-      (org-element-map tree '(latex-fragment latex-environment)
-	(lambda (latex-*)
-	  (cl-incf count)
-	  (let* ((latex-frag (org-element-property :value latex-*))
-		 (input-file (plist-get info :input-file))
-		 (cache-dir (file-name-directory input-file))
-		 (cache-subdir (concat
-				(cl-case processing-type
-				  ((dvipng imagemagick)
-				   org-preview-latex-image-directory)
-				  (mathml "ltxmathml/"))
-				(file-name-sans-extension
-				 (file-name-nondirectory input-file))))
-		 (display-msg
-		  (cl-case processing-type
-		    ((dvipng imagemagick)
-		     (format "Creating LaTeX Image %d..." count))
-		    (mathml (format "Creating MathML snippet %d..." count))))
-		 ;; Get an Org-style link to PNG image or the MathML
-		 ;; file.
-		 (link
-		  (with-temp-buffer
-		    (insert latex-frag)
-                    (delay-mode-hooks (let ((org-inhibit-startup t)) (org-mode)))
-		    ;; When converting to a PNG image, make sure to
-		    ;; copy all LaTeX header specifications from the
-		    ;; Org source.
-		    (unless (eq processing-type 'mathml)
-		      (let ((h (plist-get info :latex-header)))
-			(when h
-			  (insert "\n"
-				  (replace-regexp-in-string
-				   "^" "#+LATEX_HEADER: " h)))))
-		    (org-format-latex cache-subdir nil nil cache-dir
-				      nil display-msg nil
-				      processing-type)
-		    (goto-char (point-min))
-		    (skip-chars-forward " \t\n")
-		    (org-element-link-parser))))
-	    (if (not (org-element-type-p link 'link))
-		(message "LaTeX Conversion failed.")
-	      ;; Conversion succeeded.  Parse above Org-style link to
-	      ;; a `link' object.
-	      (let ((replacement
-		     (cl-case (org-element-type latex-*)
-		       ;;LaTeX environment.  Mimic a "standalone image
-		       ;; or formula" by enclosing the `link' in
-		       ;; a `paragraph'.  Copy over original
-		       ;; attributes, captions to the enclosing
-		       ;; paragraph.
-		       (latex-environment
-			(org-element-adopt
-			    (list 'paragraph
-			          (list :style "OrgFormula"
-				        :name
-				        (org-element-property :name latex-*)
-				        :caption
-				        (org-element-property :caption latex-*)))
-			  link))
-		       ;; LaTeX fragment.  No special action.
-		       (latex-fragment link))))
-		;; Note down the object that link replaces.
-		(org-element-put-property replacement :replaces
-					  (list (org-element-type latex-*)
-						(list :value latex-frag)))
-		;; Restore blank after initial element or object.
-		(org-element-put-property
-		 replacement :post-blank
-		 (org-element-property :post-blank latex-*))
-		;; Replace now.
-		(org-element-set latex-* replacement)))))
-	info nil nil t)))
+    ;; MathML will be handled seperately.
+    (if (and (memq processing-type '(t mathml))
+             (fboundp 'org-mathml-converter-available-p)
+             (org-mathml-converter-available-p)
+             (plist-put info :with-latex 'mathml))
+        (org-element-map tree '(latex-fragment latex-environment)
+          (lambda (latex)
+            (cl-incf count)
+            (if-let ((latex-frag (org-element-property :value latex))
+                     (path (org-mathml-convert-latex-cached latex-frag))
+                     (link (list 'link
+                                 (list :type "file"
+                                       :path path
+                                       :format 'bracket
+                                       :raw-link (format "file:%s" path))))
+                     (replacement
+                      (if (eq (org-element-type latex) 'latex-environment)
+                          ;;LaTeX environment.  Mimic a "standalone image
+                          ;; or formula" by enclosing the `link' in
+                          ;; a `paragraph'.  Copy over original
+                          ;; attributes, captions to the enclosing
+                          ;; paragraph.
+                          (org-element-adopt-elements
+                              (list 'paragraph
+                                    (list :style "OrgFormula"
+                                          :name
+                                          (org-element-property :name latex)
+                                          :caption
+                                          (org-element-property :caption latex)))
+                            link)
+                        link)))
+                (progn
+                  ;; Note down the object that link replaces.
+                  (org-element-put-property replacement :replaces
+                                            (list (org-element-type latex)
+                                                  (list :value latex-frag)))
+                  ;; Restore blank after initial element or object.
+                  (org-element-put-property
+                   replacement :post-blank
+                   (org-element-property :post-blank latex))
+                  ;; Replace now.
+                  (org-element-set-element latex replacement))
+              (setq warning "Conversion of LaTeX to MathML failed.  Falling back to verbatim.")))
+          info nil nil)
+      ;; Normalize processing-type to one of dvipng or verbatim.
+      ;; If the desired converter is not available, force verbatim
+      ;; processing.
+      (cl-case processing-type
+        ((t mathml)
+         (setq warning "LaTeX to MathML converter not available.  Falling back to verbatim."
+               processing-type 'verbatim))
+        ((dvipng imagemagick dvisvgm)
+         (let ((programs
+                (thread-first processing-type
+                              (alist-get org-latex-preview-process-alist)
+                              (plist-get :programs))))
+           (unless (cl-every (lambda (p) (org-check-external-command p "" 'no-error)) programs)
+             (setq warning "LaTeX or image converter not available.  Falling back to verbatim."
+                   processing-type 'verbatim))))
+        (otherwise
+         (setq warning "Unknown LaTeX option.  Forcing verbatim."
+               processing-type 'verbatim)))
+      ;; Display warning if the selected PROCESSING-TYPE is not
+      ;; available, but there are fragments to be converted.
+      (when warning
+        (org-element-map tree '(latex-fragment latex-environment)
+          (lambda (_) (org-display-warning warning))
+          info 'first-match nil t))
+      ;; Store normalized value for later use.
+      (when (plist-get info :with-latex)
+        (plist-put info :with-latex processing-type))
+      (message "Formatting LaTeX using %s" processing-type)
+      ;; Convert `latex-fragment's and `latex-environment's.
+      (when (memq processing-type '(dvipng imagemagick dvisvgm))
+        ;; Prepare hash table with image file data
+        (plist-put info :odt-latex-preview-hash-table
+                   (apply #'org-latex-preview-cache-images tree info
+                          org-odt-latex-image-options))
+        ;; Map over the parse tree again and replace LaTeX
+        ;; fragments with links.  If an image doesn't exist for the
+        ;; fragment, leave it in verbatim.
+        (org-element-map tree '(latex-fragment latex-environment)
+          (lambda (latex-*)
+            (when-let*
+                ((latex-preview-hash-table (plist-get info :odt-latex-preview-hash-table))
+                 (latex-frag (org-element-property :value latex-*))
+                 (path-info
+                  (or (gethash latex-* latex-preview-hash-table)
+                      (prog1 nil (org-display-warning
+                                  (format "Failed to generate preview image for element: %s" latex-frag)))))
+                 (source-file (car path-info))
+                 (link (list 'link (list :type "file"
+                                         :path source-file
+                                         :format 'bracket
+                                         :raw-link (format "file:%s" source-file)))))
+              (let ((replacement
+                     (cl-case (org-element-type latex-*)
+                       ;;LaTeX environment.  Mimic a "standalone image
+                       ;; or formula" by enclosing the `link' in
+                       ;; a `paragraph'.  Copy over original
+                       ;; attributes, captions to the enclosing
+                       ;; paragraph.
+                       (latex-environment
+                        (org-element-adopt-elements
+                            (list 'paragraph
+                                  (list :style "OrgFormula"
+                                        :name
+                                        (org-element-property :name latex-*)
+                                        :caption
+                                        (org-element-property :caption latex-*)))
+                          link))
+                       ;; LaTeX fragment.  No special action.
+                       (latex-fragment link))))
+                ;; Note down the object that link replaces.
+                (org-element-put-property replacement :replaces
+                                          (list (org-element-type latex-*)
+                                                (list :value latex-frag)))
+                ;; Restore blank after initial element or object.
+                (org-element-put-property
+                 replacement :post-blank
+                 (org-element-property :post-blank latex-*))
+                ;; Replace now.
+                (org-element-set-element latex-* replacement)
+                ;; Also replace in the latex preview table
+                (puthash replacement (gethash latex-* latex-preview-hash-table)
+                         latex-preview-hash-table))))
+          info))))
   tree)
 
 
@@ -4164,7 +4208,7 @@ MathML source to kill ring depending on the value of
 	    (save-buffer-coding-system 'utf-8))
        (set-buffer buffer)
        (set-buffer-file-coding-system coding-system-for-write)
-       (let ((mathml (org-create-math-formula latex-frag)))
+       (let ((mathml (org-mathml-convert-latex-cached latex-frag)))
 	 (unless mathml (error "No Math formula created"))
 	 (insert mathml)
 	 ;; Add MathML to kill ring, if needed.

lisp/ox.el

@@ -1060,7 +1060,7 @@ mode."
 
 (cl-defstruct (org-export-backend (:constructor org-export-create-backend)
 				  (:copier nil))
-  name parent transcoders options filters blocks menu)
+  name parent transcoders options filters blocks menu feature-conditions feature-implementations)
 
 ;;;###autoload
 (defun org-export-get-backend (name)
@@ -1166,6 +1166,62 @@ returns filters inherited from parent backends, if any."
 	(setq filters (append filters (org-export-backend-filters backend))))
       filters)))
 
+(defvar org-export-conditional-features)
+
+(defun org-export-get-all-feature-conditions (backend)
+  "Return full feature condition alist for BACKEND.
+
+BACKEND is an export back-end, as return by, e.g,,
+`org-export-create-backend'.  Return value is an alist where keys
+are feature conditions, and values are feature symbols.
+
+Unlike `org-export-backend-feature-conditions', this function
+also returns conditions inherited from parent back-ends, if any."
+  (when (symbolp backend) (setq backend (org-export-get-backend backend)))
+  (and backend
+       (let ((conditions (org-export-backend-feature-conditions backend))
+             parent)
+         (while (setq parent (org-export-backend-parent backend))
+           (setq backend (org-export-get-backend parent))
+           (dolist (condition (org-export-backend-feature-conditions backend))
+             (push condition conditions)))
+         (dolist (condition org-export-conditional-features)
+           (unless (assq (car condition) conditions)
+             (push condition conditions)))
+         conditions)))
+
+(defun org-export-get-all-feature-implementations (backend)
+  "Return full feature implementation alist for BACKEND.
+
+BACKEND is an export back-end, as return by, e.g,,
+`org-export-create-backend'.  Return value is an alist where keys
+are feature symbols, and values are an implementation
+specification plist.
+
+Unlike `org-export-backend-feature-implementations', this function
+also returns implementations inherited from parent back-ends, if any."
+  (when (symbolp backend) (setq backend (org-export-get-backend backend)))
+  (and backend
+       (let ((implementations (org-export-backend-feature-implementations backend))
+             parent)
+         (while (setq parent (org-export-backend-parent backend))
+           (setq backend (org-export-get-backend parent))
+           (dolist (implementation (org-export-backend-feature-implementations backend))
+             (unless (assq (car implementation) implementations)
+               (push implementation implementations))))
+         implementations)))
+
+(defun org-export-install-features (info)
+  "Install feature conditions and implementations in the communication channel.
+INFO is a plist containing the current communication channel.
+Return the updated communication channel."
+  (plist-put info :feature-conditions
+             (org-export-get-all-feature-conditions
+              (plist-get info :back-end)))
+  (plist-put info :feature-implementations
+             (org-export-get-all-feature-implementations
+              (plist-get info :back-end))))
+
 (defun org-export-define-backend (backend transcoders &rest body)
   "Define a new backend BACKEND.
 
@@ -1277,20 +1333,24 @@ keywords are understood:
     `org-export-options-alist' for more information about
     structure of the values."
   (declare (indent 1))
-  (let (filters menu-entry options)
+  (let (filters menu-entry options feature-conditions feature-implementations)
     (while (keywordp (car body))
       (let ((keyword (pop body)))
 	(pcase keyword
 	  (:filters-alist (setq filters (pop body)))
 	  (:menu-entry (setq menu-entry (pop body)))
 	  (:options-alist (setq options (pop body)))
+	  (:feature-conditions-alist (setq feature-conditions (pop body)))
+	  (:feature-implementations-alist (setq feature-implementations (pop body)))
 	  (_ (error "Unknown keyword: %s" keyword)))))
     (org-export-register-backend
      (org-export-create-backend :name backend
 				:transcoders transcoders
 				:options options
 				:filters filters
-				:menu menu-entry))))
+				:menu menu-entry
+                                :feature-conditions feature-conditions
+                                :feature-implementations feature-implementations))))
 
 (defun org-export-define-derived-backend (child parent &rest body)
   "Create a new backend as a variant of an existing one.
@@ -1337,7 +1397,7 @@ The backend could then be called with, for example:
 
   (org-export-to-buffer \\='my-latex \"*Test my-latex*\")"
   (declare (indent 2))
-  (let (filters menu-entry options transcoders)
+  (let (filters menu-entry options transcoders feature-conditions feature-implementations)
     (while (keywordp (car body))
       (let ((keyword (pop body)))
 	(pcase keyword
@@ -1345,6 +1405,8 @@ The backend could then be called with, for example:
 	  (:menu-entry (setq menu-entry (pop body)))
 	  (:options-alist (setq options (pop body)))
 	  (:translate-alist (setq transcoders (pop body)))
+	  (:feature-conditions-alist (setq feature-conditions (pop body)))
+	  (:feature-implementations-alist (setq feature-implementations (pop body)))
 	  (_ (error "Unknown keyword: %s" keyword)))))
     (org-export-register-backend
      (org-export-create-backend :name child
@@ -1352,7 +1414,9 @@ The backend could then be called with, for example:
 				:transcoders transcoders
 				:options options
 				:filters filters
-				:menu menu-entry))))
+				:menu menu-entry
+                                :feature-conditions feature-conditions
+                                :feature-implementations feature-implementations))))
 
 
 
@@ -2055,6 +2119,550 @@ keywords before output."
 	    (funcall (intern (format "org-element-%s-interpreter" type))
 		     blob contents))))
 
+
+;;; Conditional/Generated Features
+;;
+;; Many formats have some version of a preamble, whether it be HTML's
+;; <head>...</head> or the content before LaTeX's \begin{document}.
+;; Depending on the particular features in the Org document being
+;; exported, different setup snippets will be needed.  There's the
+;; "everything and the kitchen sink" approach of adding absolutely
+;; everything that might be needed, and the post-translation editing
+;; with filters approach, but neither really solve this problem nicely.
+;;
+;; The conditional/generated preamble defines mechanisms of detecting
+;; which "export features" are used in a document, handles
+;; interactions between features, and provides/generates content to
+;; support the features.
+;;
+;; Each export feature condition takes the form of a
+;; (CONDITION . FEATURES) cons cell (see `org-export-detect-features'),
+;; and each implementation takes the form of a (FEATURE . (:KEY VALUE ...))
+;; associated plist (see `org-export-resolve-feature-implementations'
+;; and `org-export-expand-feature-snippets').
+;;
+;; This functionality is applied during export as follows:
+;; 1. The export feature conditions and implementations are installed
+;;    into the INFO plist with `org-export-install-features'.
+;;    This simply applies `org-export-get-all-feature-conditions' and
+;;    `org-export-get-all-feature-implementations', which merges the
+;;    backend's conditions/implementations with all of it's parents and
+;;    finally the global condition list
+;;    `org-export-conditional-features'.
+;; 2. The "export features" used in a document are detected with
+;;    `org-export-detect-features'.
+;; 3. The interaction between different feature implementations is
+;;    resolved with `org-export-resolve-feature-implementations',
+;;    producing an ordered list of implementations to be actually used
+;;    in an export.
+;; 4. The feature implementation's snippets are transformed into strings
+;;    to be inserted with `org-export-expand-feature-snippets'.
+
+(defcustom org-export-conditional-features
+  `(("^[ \t]*#\\+print_bibliography:" bibliography)
+    (,(lambda (info)
+       (org-element-map (plist-get info :parse-tree)
+           'link
+         (lambda (link)
+           (and (member (org-element-property :type link)
+                        '("http" "https" "ftp" "file"))
+                (file-name-extension (org-element-property :path link))
+                (member (downcase (file-name-extension
+                                   (org-element-property :path link)))
+                        image-file-name-extensions)))
+         info t))
+     image)
+    (,(lambda (info)
+       (org-element-map (plist-get info :parse-tree)
+           'table #'identity info t))
+     table)
+    (,(lambda (info)
+       (org-element-map (plist-get info :parse-tree)
+           '(src-block inline-src-block) #'identity info t))
+     code))
+  "Org feature tests and associated feature flags.
+
+Alist where the car is a test for the presense of the feature,
+and the CDR is either a single feature symbol or a list of
+feature symbols.
+
+See `org-export-detect-features' for how this is processed."
+  :group 'org-export-general
+  :type '(alist :key-type
+                (choice (regexp :tag "Feature test regexp")
+                        (variable :tag "Feature variable")
+                        (function :tag "Feature test function"))
+                :value-type
+                (repeat symbol :tag "Feature symbols")))
+
+(defun org-export-detect-features (info)
+  "Detect features from `org-export-conditional-features' in INFO.
+
+More specifically, for each (CONDITION . FEATURES) cons cell of
+the :feature-conditions list in INFO, the CONDITION is evaluated
+in two phases.
+
+In phase one, CONDITION is transformed like so:
+- If a variable symbol, the value is fetched
+- If a function symbol, the function is called with INFO as the
+  sole argument
+- If a string, passed on unmodified
+
+In phase two, if the CONDITION result is a string, it is used as
+a case-sensitive regexp search in the buffer.  The regexp
+matching is taken as confirmation of the existance of FEATURES.
+Any other non-nil value indicates the existance of FEATURES.
+
+A list of all detected feature symbols is returned.
+
+This function should be run in the processed export Org buffer,
+after includes have been expanded and commented trees removed."
+  (delete-dups
+   (cl-loop
+    for (condition . features) in (plist-get info :feature-conditions)
+    for matcher =
+    (cond
+     ((stringp condition) condition)
+     ((functionp condition) (funcall condition info))
+     ((symbolp condition) (symbol-value condition))
+     (t (error "org-export: Feature condition %s (for %s) unable to be used"
+               condition features)))
+    for active-features =
+    (and (if (stringp matcher)
+             (save-excursion
+               (goto-char (point-min))
+               (re-search-forward matcher nil t))
+           matcher)
+         (copy-sequence features))
+    when active-features
+    nconc active-features)))
+
+(define-error 'org-missing-feature-dependency
+  "A feature was asked for, but is not availible")
+
+(define-error 'org-circular-feature-dependency
+  "There was a circular dependency between some features")
+
+(defun org-export-resolve-feature-implementations (info &optional features implementations)
+  "Resolve the IMPLEMENTATIONS of FEATURES, of INFO.
+
+FEATURES should be a list of all feature symbols to be resolved,
+and defaults to (plist-get info :features).  IMPLEMENTATIONS
+should be an alist of feature symbols and specification plists,
+and defaults to (plist-get info :feature-implementations).
+
+The following keys of the each implementation plist are recognised:
+- :snippet, which is either,
+  - A string, which should be included in the preamble verbatim.
+  - A variable, the value of which should be included in the preamble.
+  - A function, which is called with two arguments — the export info,
+    and the list of feature flags.  The returned value is included in
+    the preamble.
+- :requires, a feature or list of features this feature will enable.
+- :when, a feature or list of features which are required for this
+  feature to be active.
+- :prevents, a feature or list of features that should be masked.
+- :order, for when inclusion order matters.  Feature implementations
+  with a lower order appear first.  The default is 0.
+- :after, a feature or list of features that must be preceding.
+- :before, a feature or list of features that must be succeeding.
+
+This function processes :requires, :when, and :prevents in turn,
+sorting according by :order both before processing :requires and
+after processing :prevents.  The final implementation list is
+returned."
+  (let* ((explicit-features (or features (plist-get info :features)))
+         (implementations (or implementations
+                              (plist-get info :feature-implementations)))
+         (current-implementations
+          (sort (cl-loop for feat in explicit-features
+                         collect (assq feat implementations))
+                (lambda (a b)
+                  (< (or (plist-get (cdr a) :order) 0)
+                     (or (plist-get (cdr b) :order) 0)))))
+         ;; require-records serves to record /why/ a particular implementation
+         ;; is used.  It takes the form of an alist with feature symbols as the
+         ;; keys, and a list of features that ask for that feature as values.
+         ;; A t value is used to indicate the feature has been explicitly
+         ;; required.
+         (require-records
+          (cl-loop for feat in explicit-features
+                   collect (list feat t))))
+    ;; * Process ~:requires~
+    ;; Here we temporarily treat current-implementations as a queue of
+    ;; unproceesed implementations, and for each implemention move
+    ;; it to processed-implementations if not already present.
+    ;; :requires are processed by being added to the current-implementations
+    ;; stack as they are seen.  Along the way require-records is built for
+    ;; the sake of the subsequent :prevents processing.
+    (let ((impl-queue-last (last current-implementations))
+          processed-implementations impl)
+      (while current-implementations
+        (setq impl (pop current-implementations))
+        (unless (memq impl processed-implementations)
+          (push impl processed-implementations)
+          (dolist (req (org-ensure-list
+                        (plist-get (cdar processed-implementations) :requires)))
+            (unless (assq req processed-implementations)
+              (let ((required-impl (assq req implementations)))
+                (unless required-impl
+                  (signal 'org-missing-feature-dependency
+                          (format "The feature `%s' was asked for but could not be found"
+                                  req)))
+                (setq impl-queue-last
+                      (if current-implementations
+                          (setcdr impl-queue-last (list required-impl))
+                        (setq current-implementations (list required-impl))))
+                (push (car impl) (alist-get req require-records)))))))
+      (setq current-implementations
+            (nreverse (delq nil processed-implementations))))
+    ;; * Process ~:when~
+    ;; More specifically, remove features with unfulfilled :when conditions.
+    ;; To correctly resolve all the various :when conditions,
+    ;; do not make any assumptions about which features are active.
+    ;; Initially only consider non-:when implementations to be
+    ;; active, then run through the list of unconfirmed :when
+    ;; implementations and check their conditions against the list
+    ;; of confirmed features.  Continue doing this until no more
+    ;; features are confirmed.
+    (let ((processing t)
+          (confirmed-features
+           (cl-remove-if ; Count unimplemented features as present.
+            (lambda (feat) (assq feat current-implementations))
+            explicit-features))
+          conditional-implementations when)
+      ;; Sort all features by the presense of :when.
+      (dolist (impl current-implementations)
+        (if (plist-get (cdr impl) :when)
+            (push impl conditional-implementations)
+          (push (car impl) confirmed-features)))
+      (while processing
+        (setq processing nil)
+        ;; Check for implementations which have satisfied :when
+        ;; contions.
+        (dolist (impl conditional-implementations)
+          (setq when (plist-get (cdr impl) :when))
+          (when (cond
+                 ((symbolp when)
+                  (memq when confirmed-features))
+                 ((consp when)
+                  (not (cl-set-difference when confirmed-features))))
+            (push (car impl) confirmed-features)
+            (setq conditional-implementations
+                  (delq impl conditional-implementations)
+                  processing t))))
+      ;; Now all that remains is implementations with unsatisfiable
+      ;; :when conditions.
+      (dolist (impl conditional-implementations)
+        (setq current-implementations
+              (delq impl current-implementations))))
+    ;; * Process ~:prevents~
+    ;; Go through every implementation and for prevented features
+    ;; 1. Remove them from current-implementations
+    ;; 2. Go through require-records and remove them from the cdrs.
+    ;; By modifying require-records in this way, features that are
+    ;; only present due to a now-prevented feature will have a
+    ;; nil cdr.  We can then (recursively) check for these features
+    ;; with `rassq' and remove them.
+    ;; Since we used a queue rather than a stack when processing
+    ;; :requires, we know that second order requires (i.e. :requires
+    ;; of :requires) will come after after first order requires.
+    ;; This means that should a n-th order require be prevented by
+    ;; (n-1)-th order require, it will be removed before being
+    ;; processed, and hence handled correctly.
+    (let (feats-to-remove removed null-require)
+      (dolist (impl current-implementations)
+        (setq feats-to-remove (org-ensure-list (plist-get (cdr impl) :prevents)))
+        (while feats-to-remove
+          ;; Remove each of feats-to-remove.
+          (dolist (feat feats-to-remove)
+            (unless (memq feat removed)
+              (push feat removed)
+              (setq current-implementations
+                    (delq (assq feat current-implementations)
+                          current-implementations))
+              (when (assq feat require-records)
+                (setq require-records
+                      (delq (assq feat require-records) require-records)))))
+          (dolist (rec require-records)
+            (setcdr rec (cl-set-difference (cdr rec) feats-to-remove)))
+          ;; The features have now been removed.
+          (setq feats-to-remove nil)
+          ;; Look for orphan requires.
+          (when (setq null-require (rassq nil require-records))
+            (push (car null-require) feats-to-remove)))))
+    ;; Re-sort by ~:order~, to position reqirued features correctly.
+    (setq current-implementations
+          (sort current-implementations
+                (lambda (a b)
+                  (< (or (plist-get (cdr a) :order) 0)
+                     (or (plist-get (cdr b) :order) 0)))))
+    ;; * Processing ~:before~ and ~:after~
+    ;; To resolve dependency order, we will now perform a stable topological
+    ;; sort on any DAGs that exist within current-implementations.
+    (org-export--feature-implementation-toposort
+     current-implementations)))
+
+(defun org-export--feature-implementation-toposort (implementations)
+  "Perform a stable topological sort of IMPLEMENTATIONS.
+The sort is performed based on the :before and :after properties.
+
+See <https://en.wikipedia.org/wiki/Topological_sorting> for more information
+on what this entails."
+  (let ((feature-indicies
+         (cl-loop
+          for elt in implementations
+          and index from 0
+          collect (cons (car elt) index)))
+        resolved-implementations
+        adj-list node-stack)
+    ;; Build an adjacency list from :before and :after.
+    (dolist (impl implementations)
+      (push (list (car impl)) adj-list))
+    (dolist (impl implementations)
+      (let ((before (org-ensure-list (plist-get (cdr impl) :before)))
+            (after (org-ensure-list (plist-get (cdr impl) :after))))
+        (dolist (child before)
+          (push (car impl) (cdr (assq child adj-list))))
+        (when after
+          (setcdr (assq (car impl) adj-list)
+                  (nconc (cdr (assq (car impl) adj-list))
+                         after)))))
+    ;; Initialise the node stack with the first implementation.
+    (setq node-stack (list (car implementations))
+          ;; Make the order of adj-list match implementations.
+          adj-list
+          (mapcar
+           (lambda (entry)
+             (cons (car entry)
+                   ;; Sort edges according to feature order, to do
+                   ;; the DFS in order and make the result stable.
+                   (sort (cdr entry)
+                         (lambda (a b)
+                           (< (or (alist-get a feature-indicies)
+                                  most-positive-fixnum)
+                              (or (alist-get b feature-indicies)
+                                  most-positive-fixnum))))))
+           (nreverse adj-list)))
+    (while adj-list
+      (let ((deps (alist-get (caar node-stack) adj-list))
+            new-dep-found)
+        ;; Look for any unresolved dependencies.
+        (while (and deps (not new-dep-found))
+          (if (not (assq (car deps) adj-list))
+              (setq deps (cdr deps))
+            ;; Check the unresolved dependency is not part of a cycle.
+            (when (assq (car deps) node-stack)
+              (signal 'org-circular-feature-dependency
+                      (format "Found a cycle in the feature dependency graph: %S"
+                              (cons (car deps)
+                                    (nreverse (memq (car deps)
+                                                    (nreverse
+                                                     (mapcar #'car node-stack))))))))
+            ;; Push the unresolved dependency to the top of the stack.
+            (push (assq (car deps) implementations)
+                  node-stack)
+            (setq new-dep-found t)))
+        (unless new-dep-found
+          ;; The top item of the stack has no unresolved dependencies.
+          ;; Move it to the resolved list, and remove its entry from
+          ;; adj-list to both mark it as such and ensure that
+          ;; node-stack will not be incremented to it when/if the
+          ;; stack is emptied.
+          (push (car node-stack) resolved-implementations)
+          (setq adj-list
+                (delq (assq (caar node-stack) adj-list) adj-list)
+                node-stack
+                (or (cdr node-stack)
+                    (list (assq (caar adj-list) implementations)))))))
+    (nreverse resolved-implementations)))
+
+(defun org-export-expand-feature-snippets (info &rest feature-implementations)
+  "Expand each of the feature :snippet keys in FEATURE-IMPLEMENTATIONS.
+FEATURE-IMPLEMENTATIONS is expected to be a list of implementation
+plists, if not provided explicitly it is extracted from the
+:feature-implementations key of INFO.  Note that an explicitly
+provided nil FEATURE-IMPLEMENTATIONS is interpreted as no features.
+
+Each implementation plist's :snippet value is expanded in order, in
+the following manner:
+- nil values are ignored
+- functions are called with INFO, and must produce a string or nil
+- variable symbols use the value, which must be a string or nil
+- strings are included verbatim
+- all other values throw an `error'.
+
+\(fn INFO &optional FEATURE-IMPLEMENTATIONS)"
+  (let ((feat-impls
+         (cond
+          ((not feature-implementations)
+           (plist-get info :feature-implementations))
+          ((= (length feature-implementations) 1)
+           (car feature-implementations))
+          (t (signal 'wrong-number-of-arguments
+                     `(org-export-expand-feature-snippets
+                       ,(1+ (length feature-implementations)))))))
+        expanded-snippets snippet value)
+    (dolist (impl feat-impls)
+      (setq snippet (plist-get (cdr impl) :snippet)
+            value (cond
+                   ((null snippet) nil)
+                   ((functionp snippet) (funcall snippet info))
+                   ((symbolp snippet) (symbol-value snippet))
+                   ((stringp snippet) snippet)
+                   (t (error "org-export: The %s feature snippet %S is invalid (must be either nil, a function/variable symbol, or a string)"
+                             (car impl) snippet))))
+      (cond
+       ((stringp value)
+        (push value expanded-snippets))
+       (value ; Non-string value, could come from function or variable.
+        (error "org-export: The %s feature snippet %s must give nil or a string, but instead gave %S"
+               (car impl)
+               (cond
+                ((and (functionp snippet) (symbolp snippet))
+                 (format "function (`%s')" snippet))
+                ((functionp snippet) "anonymous function")
+                (t (format "variable (`%s')" snippet)))
+               value))))
+    (nreverse expanded-snippets)))
+
+(defun org-export-process-features (info)
+  "Install feature conditions/implementations in INFO, and resolve them.
+See `org-export-detect-features' and `org-export-resolve-feature-implementations' for
+more information on what this entails."
+  (org-export-install-features info)
+  (let* ((exp-features (org-export-detect-features info))
+         (resolved-implementations
+          (org-export-resolve-feature-implementations info exp-features)))
+    (plist-put info :feature-implementations resolved-implementations)
+    (plist-put info :features (mapcar #'car resolved-implementations))))
+
+;;;###autoload
+(defmacro org-export-update-features (backend &rest feature-property-value-lists)
+  "For BACKEND's export spec, set each FEATURE's :PROPERTY to VALUE.
+
+The behaviour of this macro is best behaved with an example.
+For instance, to add some preamble content from the variable
+\"my-org-beamer-metropolis-tweaks\" when using the metropolis theme
+with beamer export:
+
+  (org-export-update-features \\='beamer
+    (beamer-metropolis
+     :condition (string-match-p \"metropolis$\" (plist-get info :beamer-theme))
+     :snippet my-org-beamer-metropolis-tweaks
+     :order 3))
+
+The modifies the beamer backend, either creating or updating the
+\"beamer-metropolis\" feature.  The :condition property adds a
+condition which detects the feature, and all other properties are
+applied to the feature's implementation plist.  Setting
+:condition to t means the feature will always be enabled, and
+conversely setting :condition to nil means the feature will never
+be enabled.
+
+When setting the :condition and :snippet properties, any sexp is
+is implicitly converted to,
+  (lambda (info) SEXPR)
+
+Each (FEATURE . (:PROPERTY VALUE)) form that is processed is
+taken from the single &rest argument
+FEATURE-PROPERTY-VALUE-LISTS.
+
+\(fn BACKEND &rest (FEATURE . (:PROPERTY VALUE)...)...)"
+  (declare (indent 1))
+  (org-with-gensyms (backend-struct the-entry the-condition the-feat-impl cond-feat)
+    (let ((backend-expr
+           (if (and (eq (car-safe backend) 'quote)
+                    (symbolp (cadr backend))
+                    (not (cddr backend)))
+               `(org-export-get-backend ',(cadr backend))
+             `(if (symbolp ,backend)
+                  (org-export-get-backend ,backend)
+                backend)))
+          (backend-impls
+           (list 'aref backend-struct
+                 (cl-struct-slot-offset 'org-export-backend 'feature-implementations)))
+          (backend-conds
+           (list 'aref backend-struct
+                 (cl-struct-slot-offset 'org-export-backend 'feature-conditions)))
+          body condition-set-p implementation-set-p)
+      (dolist (feature-property-value-set feature-property-value-lists)
+        (when (eq (car feature-property-value-set) 'quote)
+          (pop feature-property-value-set))
+        (let ((features (car feature-property-value-set))
+              (property-value-pairs (cdr feature-property-value-set))
+              let-body property value)
+          (while property-value-pairs
+            (setq property (pop property-value-pairs)
+                  value (pop property-value-pairs))
+            (cond
+             ((consp value)
+              (unless (memq (car value) '(function quote))
+                (if (and (memq property '(:condition :snippet))
+                         (not (functionp value)))
+                    (setq value `(lambda (info) ,value))
+                  (setq value (list 'quote value)))))
+             ((memq value '(nil t))) ; Leave unmodified.
+             ((symbolp value)
+              (setq value (list 'quote value))))
+            (if (eq property :condition)
+                (progn
+                  (unless condition-set-p
+                    (setq condition-set-p t))
+                  (push
+                   (if value
+                       (let ((the-features (org-ensure-list features)))
+                         `(let* ((,the-condition ,value)
+                                 (,the-entry (assoc ,the-condition ,backend-conds)))
+                            (if ,the-entry
+                                (setcdr ,the-entry
+                                        (append ',the-features (cdr ,the-entry)))
+                              (push (cons ,the-condition ',the-features)
+                                    ,backend-conds))))
+                     (let ((single-feature
+                            (if (consp features)
+                                (intern (string-join (mapcar #'symbol-name features)
+                                                     "-and-"))
+                              features)))
+                       `(dolist (,cond-feat ,backend-conds)
+                          (cond
+                           ((equal (cdr ,cond-feat) (list ',single-feature))
+                            (setf ,backend-conds (delq ,cond-feat ,backend-conds)))
+                           ((memq ',single-feature (cdr ,cond-feat))
+                            (setcdr ,cond-feat
+                                    (delq ',single-feature (cdr ,cond-feat))))))))
+                   body))
+              (unless implementation-set-p
+                (setq implementation-set-p t))
+              (push
+               (if let-body
+                   `(plist-put (cdr ,the-feat-impl) ,property ,value)
+                 `(setcdr ,the-feat-impl
+                   (plist-put (cdr ,the-feat-impl) ,property ,value)))
+               let-body)))
+          (when let-body
+            (let ((the-feature
+                   (if (consp features)
+                       (intern (string-join (mapcar #'symbol-name features)
+                                            "-and-"))
+                     features)))
+              (when (consp features)
+                (push
+                 `(plist-put (cdr ,the-feat-impl) :when ',features)
+                 let-body))
+              (push
+               `(let ((,the-feat-impl
+                       (or (assoc ',the-feature ,backend-impls)
+                           (car (push (list ',the-feature ,property nil)
+                                      ,backend-impls)))))
+                  ,@(nreverse let-body))
+               body)))))
+      `(let ((,backend-struct ,backend-expr))
+         ,@(and (not (org-export-backend-p backend-expr))
+                `((unless (org-export-backend-p ,backend-struct)
+                    (error "`%s' is not a loaded export backend" ,backend))))
+         ,@(nreverse body)
+         nil))))
 
 
 ;;; The Filter System
@@ -3129,6 +3737,8 @@ still inferior to file-local settings."
     (when (plist-get info :with-cite-processors)
       (org-cite-process-citations info)
       (org-cite-process-bibliography info))
+    ;; Install all the feature conditions and implementations.
+    (org-export-process-features info)
     info))
 
 ;;;###autoload

testing/examples/org-latex-preview-test.org

@@ -0,0 +1,30 @@
+#+latex_header: \usepackage{amsmath}
+#+latex_header: \usepackage{amssymb}
+
+* Inline fragments and LaTeX environments
+:PROPERTIES:
+:ID:       0b3807b3-69af-40cb-a27a-b380d54879cc
+:END:
+
+The LQR problem for a time-periodic system of the form
+\begin{align}
+\dot{x} = A(t) x + B(t) u, \quad  t \in [0, \infty), \quad x(0) = x_i \label{eq:time-varying-system}\\
+A(t+T) = A(t),\ B(t + T) = B(t) \nonumber
+\end{align}
+is as follows. With a quadratic form defined on \( (x,u) \) pairs
+\begin{align}
+\label{eq:quadratic-form}
+\mathbf{q}(x, u) := \lim_{t_f \to \infty} \int_{0}^{t_f} \begin{bmatrix} x \\ u \end{bmatrix}^{\star} \begin{bmatrix}
+Q & 0 \\
+0 & r
+ \end{bmatrix} \begin{bmatrix} x \\ u \end{bmatrix} =: \lim_{t_f \to \infty} \int_{0}^{t_f} q(x,u) dt
+\end{align}
+with \( q \ge 0 \) and \( r \ge 0 \), find the infimum of the quadratic form \( \mathbf{q} \) subject to the dynamics:
+\[
+\inf_{x,u} \mathbf{q}(x,u).
+\]
+\begin{align}
+\label{eq:lqr-inf-via-duality}
+\inf_{x, u} \mathbf{q}(x, u) = x_i^{\star} \bar{\lambda}(0) x_i,
+\end{align}
+where \( \bar{\lambda} \) is the maximal solution of the differential linear matrix inequality over \( [0, t] \).

testing/lisp/test-org-latex-preview.el

@@ -0,0 +1,344 @@
+;;; test-org-latex-preview.el --- tests for org-latex-preview.el  -*- lexical-binding: t; -*-
+
+;; Copyright (c) 2023 Karthik Chikmagalur
+;; Authors: Karthik Chikmagalur
+
+;; This file is not part of GNU Emacs.
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Code:
+(unless (featurep 'org-latex-preview)
+  (signal 'missing-test-dependency "Support for LaTeX previews"))
+(require 'org-latex-preview)
+(require 'cl-lib)
+
+(ert-deftest test-org-latex-preview/assert ()
+  (should t))
+
+
+;; Test for executables required for preview generation
+(org-test-for-executable "latex")
+(org-test-for-executable "dvisvgm")
+(org-test-for-executable "dvipng")
+;; Should we test imagemagick?
+;; (org-test-for-executable "convert")
+
+
+;; fragment pre-processing tests
+
+;;; Collect fragments
+(ert-deftest test-org-latex-preview/collect-fragments-inline ()
+  "Test LaTeX fragment collection"
+  (let ((elements
+         '((latex-fragment
+            (:value "\\( q \\ge 0 \\)" :begin 770 :end 784 :post-blank 1 :parent
+             (paragraph
+              (:begin 765 :end 918 :contents-begin 765 :contents-end 918 :post-blank 0 :post-affiliated 765 :mode nil :granularity element :parent
+               (section
+                (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+                 (headline
+                  (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))))
+           (latex-fragment
+            (:value "\\( r \\ge 0 \\)" :begin 788 :end 801 :post-blank 0 :parent
+             (paragraph
+              (:begin 765 :end 918 :contents-begin 765 :contents-end 918 :post-blank 0 :post-affiliated 765 :mode nil :granularity element :parent
+               (section
+                (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+                 (headline
+                  (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments")))))))))))
+    (org-test-at-id
+        "0b3807b3-69af-40cb-a27a-b380d54879cc"
+      (should
+       (equal (org-latex-preview-collect-fragments 765 807) elements))
+      (should
+       (equal (org-latex-preview--construct-entries elements)
+              '(((770 783 "\\( q \\ge 0 \\)")
+                (788 801 "\\( r \\ge 0 \\)"))
+                nil)))
+      (should
+       (equal (org-latex-preview--construct-entries elements)
+              (org-latex-preview--construct-entries elements 'with-numbering))))))
+
+(ert-deftest test-org-latex-preview/collect-fragments-environment ()
+  "Test LaTeX fragment collection"
+  (let ((elements
+         '((latex-environment
+            (:begin 241 :end 412 :value "\\begin{align}\n\\dot{x} = A(t) x + B(t) u, \\quad  t \\in [0, \\infty), \\quad x(0) = x_i \\label{eq:time-varying-system}\\\\\nA(t+T) = A(t),\\ B(t + T) = B(t) \\nonumber\n\\end{align}\n" :post-blank 0 :post-affiliated 241 :mode nil :granularity element :parent
+             (section
+              (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+               (headline
+                (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments")))))))))
+    (org-test-at-id
+        "0b3807b3-69af-40cb-a27a-b380d54879cc"
+      (should
+       (equal (org-latex-preview-collect-fragments 186 426) elements))
+      (should
+       (equal (org-latex-preview--construct-entries elements)
+              '(((241 411 "\\begin{align}\n\\dot{x} = A(t) x + B(t) u, \\quad  t \\in [0, \\infty), \\quad x(0) = x_i \\label{eq:time-varying-system}\\\\\nA(t+T) = A(t),\\ B(t + T) = B(t) \\nonumber\n\\end{align}\n"))
+                nil)))
+      (should
+       (equal (org-latex-preview--construct-entries elements 'with-numbering)
+              '(((241 411 "\\begin{align}\n\\dot{x} = A(t) x + B(t) u, \\quad  t \\in [0, \\infty), \\quad x(0) = x_i \\label{eq:time-varying-system}\\\\\nA(t+T) = A(t),\\ B(t + T) = B(t) \\nonumber\n\\end{align}\n"))
+                (1)))))))
+
+(ert-deftest test-org-latex-preview/collect-fragments-all ()
+  "Test LaTeX fragment collection"
+  (let ((elements
+         '((latex-environment
+            (:begin 241 :end 412 :value "\\begin{align}\n\\dot{x} = A(t) x + B(t) u, \\quad  t \\in [0, \\infty), \\quad x(0) = x_i \\label{eq:time-varying-system}\\\\\nA(t+T) = A(t),\\ B(t + T) = B(t) \\nonumber\n\\end{align}\n" :post-blank 0 :post-affiliated 241 :mode nil :granularity element :parent
+             (section
+              (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+               (headline
+                (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))
+           (latex-fragment
+            (:value "\\( (x,u) \\)" :begin 460 :end 472 :post-blank 1 :parent
+             (paragraph
+              (:begin 412 :end 478 :contents-begin 412 :contents-end 478 :post-blank 0 :post-affiliated 412 :mode nil :granularity element :parent
+               (section
+                (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+                 (headline
+                  (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))))
+           (latex-environment
+            (:begin 478 :end 765 :value "\\begin{align}\n\\label{eq:quadratic-form}\n\\mathbf{q}(x, u) := \\lim_{t_f \\to \\infty} \\int_{0}^{t_f} \\begin{bmatrix} x \\\\ u \\end{bmatrix}^{\\star} \\begin{bmatrix}\nQ & 0 \\\\\n0 & r\n \\end{bmatrix} \\begin{bmatrix} x \\\\ u \\end{bmatrix} =: \\lim_{t_f \\to \\infty} \\int_{0}^{t_f} q(x,u) dt\n\\end{align}\n" :post-blank 0 :post-affiliated 478 :mode nil :granularity element :parent
+             (section
+              (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+               (headline
+                (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))
+           (latex-fragment
+            (:value "\\( q \\ge 0 \\)" :begin 770 :end 784 :post-blank 1 :parent
+             (paragraph
+              (:begin 765 :end 918 :contents-begin 765 :contents-end 918 :post-blank 0 :post-affiliated 765 :mode nil :granularity element :parent
+               (section
+                (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+                 (headline
+                  (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))))
+           (latex-fragment
+            (:value "\\( r \\ge 0 \\)" :begin 788 :end 801 :post-blank 0 :parent
+             (paragraph
+              (:begin 765 :end 918 :contents-begin 765 :contents-end 918 :post-blank 0 :post-affiliated 765 :mode nil :granularity element :parent
+               (section
+                (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+                 (headline
+                  (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))))
+           (latex-fragment
+            (:value "\\( \\mathbf{q} \\)" :begin 842 :end 859 :post-blank 1 :parent
+             (paragraph
+              (:begin 765 :end 918 :contents-begin 765 :contents-end 918 :post-blank 0 :post-affiliated 765 :mode nil :granularity element :parent
+               (section
+                (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+                 (headline
+                  (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))))
+           (latex-fragment
+            (:value "\\[\n\\inf_{x,u} \\mathbf{q}(x,u).\n\\]" :begin 884 :end 917 :post-blank 0 :parent
+             (paragraph
+              (:begin 765 :end 918 :contents-begin 765 :contents-end 918 :post-blank 0 :post-affiliated 765 :mode nil :granularity element :parent
+               (section
+                (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+                 (headline
+                  (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))))
+           (latex-environment
+            (:begin 918 :end 1040 :value "\\begin{align}\n\\label{eq:lqr-inf-via-duality}\n\\inf_{x, u} \\mathbf{q}(x, u) = x_i^{\\star} \\bar{\\lambda}(0) x_i,\n\\end{align}\n" :post-blank 0 :post-affiliated 918 :mode nil :granularity element :parent
+             (section
+              (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+               (headline
+                (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))
+           (latex-fragment
+            (:value "\\( \\bar{\\lambda} \\)" :begin 1046 :end 1066 :post-blank 1 :parent
+             (paragraph
+              (:begin 1040 :end 1154 :contents-begin 1040 :contents-end 1154 :post-blank 0 :post-affiliated 1040 :mode nil :granularity element :parent
+               (section
+                (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+                 (headline
+                  (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments"))))))))
+           (latex-fragment
+            (:value "\\( [0, t] \\)" :begin 1140 :end 1152 :post-blank 0 :parent
+             (paragraph
+              (:begin 1040 :end 1154 :contents-begin 1040 :contents-end 1154 :post-blank 0 :post-affiliated 1040 :mode nil :granularity element :parent
+               (section
+                (:begin 118 :end 1154 :contents-begin 118 :contents-end 1154 :robust-begin 118 :robust-end 1152 :post-blank 0 :post-affiliated 118 :mode section :granularity element :parent
+                 (headline
+                  (:raw-value "Inline fragments and LaTeX environments" :begin 76 :end 1154 :pre-blank 0 :contents-begin 118 :contents-end 1154 :robust-begin 184 :robust-end 1152 :level 1 :priority nil :tags nil :todo-keyword nil :todo-type nil :post-blank 0 :footnote-section-p nil :archivedp nil :commentedp nil :post-affiliated 76 :ID "0b3807b3-69af-40cb-a27a-b380d54879cc" :title "Inline fragments and LaTeX environments")))))))))))
+    (org-test-at-id
+        "0b3807b3-69af-40cb-a27a-b380d54879cc"
+      (should
+       (equal (org-latex-preview-collect-fragments) elements))
+      (should (equal (org-latex-preview--construct-entries elements)
+                     '(((241 411 "\\begin{align}\n\\dot{x} = A(t) x + B(t) u, \\quad  t \\in [0, \\infty), \\quad x(0) = x_i \\label{eq:time-varying-system}\\\\\nA(t+T) = A(t),\\ B(t + T) = B(t) \\nonumber\n\\end{align}\n")
+                        (460 471 "\\( (x,u) \\)")
+                        (478 764 "\\begin{align}\n\\label{eq:quadratic-form}\n\\mathbf{q}(x, u) := \\lim_{t_f \\to \\infty} \\int_{0}^{t_f} \\begin{bmatrix} x \\\\ u \\end{bmatrix}^{\\star} \\begin{bmatrix}\nQ & 0 \\\\\n0 & r\n \\end{bmatrix} \\begin{bmatrix} x \\\\ u \\end{bmatrix} =: \\lim_{t_f \\to \\infty} \\int_{0}^{t_f} q(x,u) dt\n\\end{align}\n")
+                        (770 783 "\\( q \\ge 0 \\)")
+                        (788 801 "\\( r \\ge 0 \\)")
+                        (842 858 "\\( \\mathbf{q} \\)")
+                        (884 917 "\\[\n\\inf_{x,u} \\mathbf{q}(x,u).\n\\]")
+                        (918 1039 "\\begin{align}\n\\label{eq:lqr-inf-via-duality}\n\\inf_{x, u} \\mathbf{q}(x, u) = x_i^{\\star} \\bar{\\lambda}(0) x_i,\n\\end{align}\n")
+                        (1046 1065 "\\( \\bar{\\lambda} \\)")
+                        (1140 1152 "\\( [0, t] \\)"))
+                       nil)))
+      (should (equal (org-latex-preview--construct-entries elements 'with-numbering)
+                     '(((241 411 "\\begin{align}\n\\dot{x} = A(t) x + B(t) u, \\quad  t \\in [0, \\infty), \\quad x(0) = x_i \\label{eq:time-varying-system}\\\\\nA(t+T) = A(t),\\ B(t + T) = B(t) \\nonumber\n\\end{align}\n")
+                        (460 471 "\\( (x,u) \\)")
+                        (478 764 "\\begin{align}\n\\label{eq:quadratic-form}\n\\mathbf{q}(x, u) := \\lim_{t_f \\to \\infty} \\int_{0}^{t_f} \\begin{bmatrix} x \\\\ u \\end{bmatrix}^{\\star} \\begin{bmatrix}\nQ & 0 \\\\\n0 & r\n \\end{bmatrix} \\begin{bmatrix} x \\\\ u \\end{bmatrix} =: \\lim_{t_f \\to \\infty} \\int_{0}^{t_f} q(x,u) dt\n\\end{align}\n")
+                        (770 783 "\\( q \\ge 0 \\)")
+                        (788 801 "\\( r \\ge 0 \\)")
+                        (842 858 "\\( \\mathbf{q} \\)")
+                        (884 917 "\\[\n\\inf_{x,u} \\mathbf{q}(x,u).\n\\]")
+                        (918 1039 "\\begin{align}\n\\label{eq:lqr-inf-via-duality}\n\\inf_{x, u} \\mathbf{q}(x, u) = x_i^{\\star} \\bar{\\lambda}(0) x_i,\n\\end{align}\n")
+                        (1046 1065 "\\( \\bar{\\lambda} \\)")
+                        (1140 1152 "\\( [0, t] \\)"))
+                       (1 nil 2 nil nil nil nil 4 nil nil)))))))
+
+;;; Set up overlays
+(ert-deftest test-org-latex-preview/ensure-overlay ()
+  (org-test-at-id "0b3807b3-69af-40cb-a27a-b380d54879cc"
+    (org-latex-preview-clear-overlays (point-min) (point-max))
+    (let* ((elements (org-latex-preview-collect-fragments))
+           (entries (car (org-latex-preview--construct-entries elements)))
+           (ov) (all-ovs))
+      (pcase-dolist(`(,beg ,end ,value) entries)
+        (setq ov (org-latex-preview--ensure-overlay beg end))
+        (push ov all-ovs)
+        (should (eq (get-char-property beg 'org-overlay-type) 'org-latex-overlay))
+        (should (eq (overlay-get ov 'org-overlay-type) 'org-latex-overlay))
+        (should (eq (overlay-get ov 'evaporate) t))
+        (should (eq (overlay-get ov 'priority) org-latex-preview--overlay-priority))
+        (should (equal (overlay-get ov 'modification-hooks)
+                    (list #'org-latex-preview-auto--mark-overlay-modified)))
+        (should (equal (overlay-get ov 'insert-in-front-hooks)
+                    (list #'org-latex-preview-auto--insert-front-handler)))
+        (should (equal (overlay-get ov 'insert-behind-hooks)
+                    (list #'org-latex-preview-auto--insert-behind-handler))))
+      (should (eq (length all-ovs) (length elements))))
+    (org-latex-preview-clear-overlays (point-min) (point-max))))
+
+
+;; Precompilation test
+;; TODO
+
+
+;; Process fragments
+
+;;; No precompilation, no caching
+(ert-deftest test-org-latex-preview/place-previews-1 ()
+  (org-test-at-id "0b3807b3-69af-40cb-a27a-b380d54879cc"
+    (let ((org-latex-preview-process-precompiled nil)
+          (org-latex-preview-cache 'temp)
+          (org-latex-preview-process-default 'dvisvgm))
+      (org-latex-preview-auto-mode -1)
+      (goto-char 255)
+      (let ((element (org-element-context)))
+        (should (eq (org-element-type element) 'latex-environment))
+        (org-latex-preview-clear-cache (org-element-property :begin element)
+                                       (org-element-property :end element))
+        (apply #'org-async-wait-for
+               (org-latex-preview--place-from-elements
+                org-latex-preview-process-default
+                (list element)))
+        (let ((ov (cl-some (lambda (o) (and (eq (overlay-get o 'org-overlay-type)
+                                           'org-latex-overlay)
+                                       o))
+                           (overlays-at (point)))))
+          (should (overlayp ov))
+          (let ((display (overlay-get ov 'display))
+                (face    (overlay-get ov 'face))
+                (hidden-face (overlay-get ov 'hidden-face))
+                (preview-image (overlay-get ov 'preview-image)))
+            ;; Image properties
+            (should (consp display))
+            (should (eq (car display) 'image))
+            (should (eq (plist-get (cdr display) :type) 'svg))
+            (should (stringp (plist-get (cdr display) :file)))
+            (should (string-suffix-p ".svg" (plist-get (cdr display) :file)))
+            (should (eq preview-image display))
+            ;; Face properties
+            (should (eq face 'default))
+            (should (eq hidden-face face))))))))
+
+(ert-deftest test-org-latex-preview/place-previews-all ()
+  (org-test-at-id "0b3807b3-69af-40cb-a27a-b380d54879cc"
+    (let ((org-latex-preview-process-precompiled nil)
+          (org-latex-preview-cache 'temp)
+          (org-latex-preview-process-default 'dvisvgm))
+      (org-latex-preview-auto-mode -1)
+      (org-latex-preview-clear-cache (point-min) (point-max))
+      (let ((elements (org-latex-preview-collect-fragments)))
+        (apply #'org-async-wait-for
+               (org-latex-preview--place-from-elements
+                org-latex-preview-process-default
+                elements))
+        (dolist (element elements)
+          (let ((ov (cl-some (lambda (o) (and (eq (overlay-get o 'org-overlay-type)
+                                             'org-latex-overlay)
+                                         o))
+                             (overlays-at (org-element-property :begin element)))))
+            (should (overlayp ov))
+            (let ((display (overlay-get ov 'display))
+                  (face    (overlay-get ov 'face))
+                  (hidden-face (overlay-get ov 'hidden-face))
+                  (preview-image (overlay-get ov 'preview-image)))
+              ;; Image properties
+              (should (consp display))
+              (should (eq (car display) 'image))
+              (should (eq (plist-get (cdr display) :type) 'svg))
+              (should (stringp (plist-get (cdr display) :file)))
+              (should (string-suffix-p ".svg" (plist-get (cdr display) :file)))
+              (should (eq preview-image display))
+              ;; Face properties
+              (should (eq face 'default))
+              (should (eq hidden-face face)))))
+        (org-latex-preview-clear-cache (point-min) (point-max))))))
+
+;; TODO: Test with precompilation
+;; TODO: Test with caching
+
+
+;; dvisvgm filter+callback test
+;; dvipng filter+callback test
+;; imagemagick filter+callback test
+;; TODO
+
+
+;; Color extraction
+;; TODO
+
+
+;; Scaling
+;; TODO
+
+
+;; Caching
+;; TODO
+
+;;; clear-cache test
+
+
+;; Numbering
+;; TODO
+
+
+;; org-latex-preview-auto-mode
+;; TODO
+
+
+;; live previews
+;; TODO
+
+
+;; lualatex-specific tests
+
+
+;; xelatex-specific tests
+
+(provide 'test-org-latex-preview)
+;;; test-org-latex-preview.el ends here

testing/lisp/test-ox.el

@@ -2140,6 +2140,120 @@ Footnotes[fn:2], foot[fn:test] and [fn:inline:inline footnote]
 	(bold . (lambda (bold contents info) (concat contents "!")))))
      '(:with-emphasize t)))))
 
+
+;;; Export features
+
+(ert-deftest test-org-export/feature-resolution ()
+  "Test the behaviour of `org-export-resolve-feature-implementations'"
+  ;; Check implementations for listed features are given.
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a) (b) (c)))
+          '((a) (b) (c))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a)))
+          '((a))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a) '((a) (b) (c)))
+          '((a))))
+  ;; Check depencency resolution.
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a) '((a :requires b) (b) (c)))
+          '((a :requires b) (b))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a) '((a :requires (b c)) (b) (c)))
+          '((a :requires (b c)) (b) (c))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a) '((a :requires b) (b :requires c) (c)))
+          '((a :requires b) (b :requires c) (c))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a :prevents b) (b) (c)))
+          '((a :prevents b) (c))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a :prevents (b c)) (b) (c)))
+          '((a :prevents (b c)))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c d) '((a :requires (b c)) (b) (c) (d :prevents b)))
+          '((a :requires (b c)) (c) (d :prevents b))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c d) '((a :requires (b c)) (b) (c :prevents b)))
+          '((a :requires (b c)) (c :prevents b))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a d) '((a :requires b) (b :requires c) (c) (d :prevents a)))
+          '((d :prevents a))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c d) '((a :requires b) (b :requires c) (c) (d :prevents a)))
+          '((b :requires c) (c) (d :prevents a))))
+  (should-error
+   (org-export-resolve-feature-implementations
+    nil '(a) '((a :requires b)))
+   :type 'org-missing-feature-dependency)
+  ;; Check application of the :when condition.
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a :when b) (b)))
+          '((a :when b) (b))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a :when (b c)) (b) (c)))
+          '((a :when (b c)) (b) (c))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a) (b) (c :when (a b))))
+          '((a) (b) (c :when (a b)))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a :when b) (b :when c) (c)))
+          '((a :when b) (b :when c) (c))))
+  ;; Check simple ordering.
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a :order 3) (b :order 1) (c :order 2)))
+          '((b :order 1) (c :order 2) (a :order 3))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a :order 1) (b) (c :order -1)))
+          '((c :order -1) (b) (a :order 1))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a) '((a :order 1 :requires b) (b :requires c) (c :order -1)))
+          '((c :order -1) (b :requires c) (a :order 1 :requires b))))
+  ;; Check before/after ordering.
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a :after (b c)) (b) (c)))
+          '((b) (c) (a :after (b c)))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a :after b) (b :after c) (c)))
+          '((c) (b :after c) (a :after b))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a) (b) (c :before (a b))))
+          '((c :before (a b)) (a) (b))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a) (b :before a) (c :before b)))
+          '((c :before b) (b :before a) (a))))
+  (should
+   (equal (org-export-resolve-feature-implementations
+           nil '(a b c) '((a) (b :after c :before a) (c)))
+          '((c) (b :after c :before a) (a))))
+  (should-error ; Circular dependency
+   (org-export-resolve-feature-implementations
+    nil '(a b) '((a :after b) (b :after a)))
+   :type 'org-circular-feature-dependency))
 
 
 ;;; Comments