All major AST elements now have `__tojson` metamethods that return the
JSON representation of an element. This allows to JSON-encode these
elements with libraries that respect the `__tojson` metamethod,
including dkjson.
Thanks and credit go to Aner Lucero, who laid the groundwork for this
feature in the 2021 GSoC project. He contributed many changes, including
modifications to the readers for HTML, JATS, and LaTeX, and to the HTML
and JATS writers.
Shared (Albert Krewinkel):
- The new function `figureDiv`, exported from `Text.Pandoc.Shared`,
offers a standardized way to convert a figure into a Div element.
Readers (Aner Lucero):
- HTML reader: `<figure>` elements are parsed as figures, with the
caption taken from the respective `<figcaption>` elements.
- JATS reader: The `<fig>` and `<caption>` elements are parsed into
figure elements, even if the contents is more complex.
- LaTeX reader: support for figures with non-image contents and for
subfigures.
- Markdown reader: paragraphs containing just an image are treated as
figures if the `implicit_figures` extension is enabled. The identifier
is used as the figure's identifier and the image description is also
used as figure caption; all other attributes are treated as belonging
to the image.
Writers (Aner Lucero, Albert Krewinkel):
- DokuWiki, Haddock, Jira, Man, MediaWiki, Ms, Muse, PPTX, RTF, TEI,
ZimWiki writers: Figures are rendered like Div elements.
- Asciidoc writer: The figure contents is unwrapped; each image in the
the figure becomes a separate figure.
- Classic custom writers: Figures are passed to the global function
`Figure(caption, contents, attr)`, where `caption` and `contents` are
strings and `attr` is a table of key-value pairs.
- ConTeXt writer: Figures are wrapped in a "placefigure" environment
with `\startplacefigure`/`\endplacefigure`, adding the features
caption and listing title as properties. Subfigures are place in a
single row with the `\startfloatcombination` environment.
- DocBook writer: Uses `mediaobject` elements, unless the figure contains
subfigures or tables, in which case the figure content is unwrapped.
- Docx writer: figures with multiple content blocks are rendered as
tables with style `FigureTable`; like before, single-image figures are
still output as paragraphs with style `Figure` or `Captioned Figure`,
depending on whether a caption is attached.
- DokuWiki writer: Caption and "alt-text" are no longer combined. The
alt text of a figure will now be lost in the conversion.
- FB2 writer: The figure caption is added as alt text to the images in
the figure; pre-existing alt texts are kept.
- ICML writer: Only single-image figures are supported. The contents of
figures with additional elements gets unwrapped.
- HTML writer: the alt text is no longer constructed from the caption,
as was the case with implicit figures. This reduces duplication, but
comes at the risk of images that are missing alt texts. Authors should
take care to provide alt texts for all images.
Some readers, most notably the Markdown reader with the
`implicit_figures` extension, add a caption that's identical to the
image description. The writer checks for this and adds an
`aria-hidden` attribute to the `<figcaption>` element in that case.
- JATS writer: The `<fig>` and `<caption>` elements are used write
figures.
- LaTeX writer: complex figures, e.g. with non-image contents and
subfigures, are supported. The `subfigure` template variable is set if
the document contains subfigures, triggering the conditional loading
of the *subcaption* package. Contants of figures that contain tables
are become unwrapped, as longtable environments are not allowed within
figures.
- Markdown writer: figures are output as implicit figures if possible,
via HTML if the `raw_html` extension is enabled, and as Div elements
otherwise.
- OpenDocument writer: A separate paragraph is generated for each block
element in a figure, each with style `FigureWithCaption`. Behavior for
single-image figures therefore remains unchanged.
- Org writer: Only the first element in a figure is given a caption;
additional block elements in the figure are appended without any
caption being added.
- RST writer: Single-image figures are supported as before; the contents
of more complex images become nested in a container of type `float`.
- Texinfo writer: Figures are rendered as float with type `figure`.
- Textile writer: Figures are rendered with the help of HTML elements.
- XWiki: Figures are placed in a group.
Co-authored-by: Aner Lucero <4rgento@gmail.com>
John MacFarlane