.\"	$Id: lowdown.3,v 1.56 2021/02/19 21:50:39 kristaps Exp $
.\"
.\" Copyright (c) 2017, 2020 Kristaps Dzonsons <kristaps@bsd.lv>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: February 19 2021 $
.Dt LOWDOWN 3
.Os
.Sh NAME
.Nm lowdown
.Nd simple markdown translator library
.Sh LIBRARY
.Lb liblowdown
.Sh SYNOPSIS
.In sys/queue.h
.In stdio.h
.In lowdown.h
.Vt "struct lowdown_metadata"
.Vt "struct lowdown_node"
.Vt "struct lowdown_opts"
.Sh DESCRIPTION
This library parses
.Xr lowdown 5
into various output formats.
.Pp
The library consists first of a high-level interface consisting of
.Xr lowdown_buf 3 ,
.Xr lowdown_buf_diff 3 ,
.Xr lowdown_file 3 ,
and
.Xr lowdown_file_diff 3 .
.Pp
The high-level functions interface with low-level functions that perform
parsing and formatting.
These consist of
.Xr lowdown_doc_new 3 ,
.Xr lowdown_doc_parse 3 ,
and
.Xr lowdown_doc_free 3
for parsing
.Xr lowdown 5
documents into an abstract syntax tree.
.Pp
The front-end functions for freeing, allocation, and rendering are as
follows.
.Bl -bullet
.It
HTML5:
.Bl -item -compact
.It
.Xr lowdown_html_free 3
.It
.Xr lowdown_html_new 3
.It
.Xr lowdown_html_rndr 3
.El
.It
gemini:
.Bl -item -compact
.It
.Xr lowdown_gemini_free 3
.It
.Xr lowdown_gemini_new 3
.It
.Xr lowdown_gemini_rndr 3
.El
.It
LaTeX:
.Bl -item -compact
.It
.Xr lowdown_latex_free 3
.It
.Xr lowdown_latex_new 3
.It
.Xr lowdown_latex_rndr 3
.El
.It
roff:
.Bl -item -compact
.It
.Xr lowdown_nroff_free 3
.It
.Xr lowdown_nroff_new 3
.It
.Xr lowdown_nroff_rndr 3
.El
.It
UTF-8 ANSI terminal:
.Bl -item -compact
.It
.Xr lowdown_term_free 3
.It
.Xr lowdown_term_new 3
.It
.Xr lowdown_term_rndr 3
.El
.It
debugging:
.Bl -item -compact
.It
.Xr lowdown_tree_rndr 3
.El
.El
.Pp
To compile and link, use
.Xr pkg-config 1 :
.Bd -literal
% cc `pkg-config --cflags lowdown` -c -o sample.o sample.c
% cc -o sample sample.o `pkg-config --libs lowdown`
.Ed
.Ss Pledge Promises
The
.Nm lowdown
library is built to operate in security-sensitive environments, such as
those using
.Xr pledge 2
on
.Ox .
The only promise required is
.Va stdio
for
.Xr lowdown_file_diff 3
and
.Xr lowdown_file 3 :
both require access to the stream for reading input.
.Ss Types
All
.Nm lowdown
functions use one or more of the following structures.
.Pp
The
.Vt struct lowdown_opts
structure manage features.
It has the following fields:
.Bl -tag -width Ds -offset indent
.It Va unsigned int feat
Features used during the parse.
This bit-field may have the following bits OR'd:
.Pp
.Bl -tag -width Ds -compact
.It Dv LOWDOWN_AUTOLINK
Parse
.Li http ,
.Li https ,
.Li ftp ,
.Li mailto ,
and relative links or link fragments.
.It Dv LOWDOWN_COMMONMARK
Tighten input parsing to the CommonMark specification.
This also uses the first ordered list value instead of starting all
lists at one.
This feature is
.Em experimental
and
.Em incomplete .
.It Dv LOWDOWN_DEFLIST
Parse PHP extra definition lists.
This is currently constrained to single-key lists.
.It Dv LOWDOWN_FENCED
Parse GFM fenced (language-specific) code blocks.
.It Dv LOWDOWN_FOOTNOTES
Parse MMD style footnotes.
This only supports the referenced footnote style, not the
.Qq inline
style.
.It Dv LOWDOWN_HILITE
Parse highlit sequences.
This are disabled by default because it may be erroneously interpreted
as section headers.
.It Dv LOWDOWN_IMG_EXT
Parse PHP image extended attributes.
.It Dv LOWDOWN_MATH
Parse mathematics equations.
.It Dv LOWDOWN_METADATA
Parse in-document MMD metadata.
For the first paragraph to count as meta-data, the first line must have
a colon in it.
.It Dv LOWDOWN_NOCODEIND
Do not parse indented content as code blocks.
.It Dv LOWDOWN_NOINTEM
Do not parse emphasis within words.
.It Dv LOWDOWN_STRIKE
Parse strikethrough sequences.
.It Dv LOWDOWN_SUPER
Parse super-scripts.
This accepts foo^bar, which puts the parts following the caret until
whitespace in superscripts; or foo^(bar), which puts only the parts in
parenthesis.
.It Dv LOWDOWN_TABLES
Parse GFM tables.
.El
.Pp
The default value is zero (none).
.It Va unsigned int oflags
Features used by the output generators.
This bit-field may have the following enabled.
Note that bits are by definition specific to an output
.Va type .
.Pp
For
.Dv LOWDOWN_HTML :
.Pp
.Bl -tag -width Ds -compact
.It Dv LOWDOWN_HTML_ESCAPE
If
.Dv LOWDOWN_HTML_SKIP_HTML
has not been set, escapes in-document HTML so that it is rendered as
opaque text.
.It Dv LOWDOWN_HTML_HARD_WRAP
Retain line-breaks within paragraphs.
.It Dv LOWDOWN_HTML_HEAD_IDS
Have an identifier written with each header element consisting of an
HTML-escaped version of the header contents.
.It Dv LOWDOWN_HTML_OWASP
When escaping text, be extra paranoid in following the OWASP suggestions
for which characters to escape.
.It Dv LOWDOWN_HTML_NUM_ENT
Convert, when possible, HTML entities to their numeric form.
If not set, the entities are used as given in the input.
.It Dv LOWDOWN_HTML_SKIP_HTML
Do not render in-document HTML at all.
.El
.Pp
For
.Dv LOWDOWN_GEMINI ,
there are several flags for controlling link placement.
By default, links (images, autolinks, and links) are queued when
specified in-line then emitted in a block sequence after the nearest
block element.
.Pp
.Bl -tag -width Ds -compact
.It Dv LOWDOWN_GEMINI_LINK_END
Emit the queue of links at the end of the document instead of after the
nearest block element.
.It Dv LOWDOWN_GEMINI_LINK_IN
Render all links within the flow of text.
This will cause breakage when nested links, such as images within links,
links in blockquotes, etc.
It should not be used unless in carefully crafted documents.
.It Dv LOWDOWN_GEMINI_LINK_NOREF
Do not format link labels.
Takes precedence over
.Dv LOWDOWN_GEMINI_LINK_ROMAN .
.It Dv LOWDOWN_GEMINI_LINK_ROMAN
When formatting link labels, use lower-case Roman numerals instead of
the default lowercase hexavigesimal (i.e.,
.Dq a ,
.Dq b ,
\&...,
.Dq aa ,
.Dq ab ,
\&...).
.It Dv LOWDOWN_GEMINI_METADATA
Print metadata as the canonicalised key followed by a colon then the
value, each on one line (newlines replaced by spaces).
The metadata block is terminated by a double newline.
If there is no metadata, this does nothing.
.El
.Pp
There may only be one of
.Dv LOWDOWN_GEMINI_LINK_END
or
.Dv LOWDOWN_GEMINI_LINK_IN .
If both are specified, the latter is unset.
.Pp
For
.Dv LOWDOWN_LATEX :
.Pp
.Bl -tag -width Ds -compact
.It Dv LOWDOWN_LATEX_NUMBERED
Use the default numbering scheme for sections, subsections, etc.
If not specified, these are inhibited.
.It Dv LOWDOWN_LATEX_SKIP_HTML
Do not render in-document HTML at all.
Text within HTML elements remains.
.El
.Pp
And for
.Dv LOWDOWN_MAN
and
.Dv LOWDOWN_NROFF :
.Pp
.Bl -tag -width Ds -compact
.It Dv LOWDOWN_NROFF_GROFF
Use GNU extensions (i.e., for
.Xr groff 1 )
when rendering output.
You'll need to include
.Fl m Ar pdfmark
when invoking
.Xr groff 1
for formatting links.
Applies to the
.Dv LOWDOWN_MAN
and
.Dv LOWDOWN_NROFF
output types.
.It Dv LOWDOWN_NROFF_NUMBERED
Use numbered sections if
.Dv LOWDOWON_NROFF_GROFF
is not specified.
Only applies to the
.Dv LOWDOWN_NROFF
output type.
.It Dv LOWDOWN_NROFF_SKIP_HTML
Do not render in-document HTML at all.
Text within HTML elements remains.
.It Dv LOWDOWN_NROFF_SHORTLINK
Render link URLs in short form.
Applies to images, autolinks, and regular links.
Only in
.Dv LOWDOWN_MAN
or when
.Dv LOWDOWN_NROFF_GROFF
is not specified.
.It Dv LOWDOWN_NROFF_NOLINK
Don't show links at all if they have embedded text.
Applies to images and regular links.
Only in
.Dv LOWDOWN_MAN
or when
.Dv LOWDOWN_NROFF_GROFF
is not specified.
.El
.Pp
For
.Dv LOWDOWN_TERM :
.Pp
.Bl -tag -width Ds -compact
.It Dv LOWDOWN_TERM_SHORTLINK
Render link URLs in short form.
Applies to images, autolinks, and regular links.
.It Dv LOWDOWN_TERM_NOLINK
Don't show links at all.
Applies to images and regular links.
.El
.Pp
For any mode, you may specify:
.Pp
.Bl -tag -width Ds -compact
.It Dv LOWDOWN_SMARTY
Don't use smart typography formatting.
.It Dv LOWDOWN_STANDALONE
Emit a full document instead of a document fragment.
This envelope is largely populated from metadata if
.Dv LOWDOWN_METADATA
was provided as an option or as given in
.Va meta
or
.Va metaovr .
.El
.It Va size_t maxdepth
The maximum parse depth before the parser exits.
Most documents will have a parse depth in the single digits.
.It Va size_t cols
For
.Dv LOWDOWN_TERM ,
the
.Qq soft limit
for width of terminal output not including margins.
If zero, 80 shall be used.
.It Va size_t hmargin
For
.Dv LOWDOWN_TERM ,
the left margin (space characters).
.It Va size_t vmargin
For
.Dv LOWDOWN_TERM ,
the top/bottom margin (newlines).
.It Va enum lowdown_type type
May be set to
.Dv LOWDOWN_HTML
for HTML5 output,
.Dv LOWDOWN_LATEX
for LaTeX,
.Dv LOWDOWN_MAN
for
.Fl man
macros,
.Dv LOWDOWN_TERM
for ANSI-compatible UTF-8 terminal output,
.Dv LOWDOWN_GEMINI
for the Gemini format, or
.Dv LOWDOWN_NROFF
for
.Fl ms
macros.
The
.Dv LOWDOWN_TREE
type causes a debug tree to be written.
.Pp
Both
.Dv LOWDOWN_MAN
and
.Dv LOWDOWN_MS
will use troff tables, which usually require the
.Xr tbl 1
preprocessor.
.It Va char **meta
An array of metadata key-value pairs or
.Dv NULL .
Each pair must appear as if provided on one line (or multiple lines) of
the input, including the terminating newline character.
If not consisting of a valid pair (e.g., no newline, no colon), then it is
ignored.
When processed, these values are overridden by those in the document (if
.Dv LOWDOWN_METADATA
is specified) or by those in
.Va metaovr .
.It Va size_t metasz
Number of pairs in
.Va metaovr .
.It Va char **metaovr
See
.Va meta .
The difference is that
.Va metaovr
is applied after
.Va meta
and in-document metadata, so it overrides prior values.
.It Va size_t metaovrsz
Number of pairs in
.Va metaovr .
.El
.Pp
Another common structure is
.Vt "struct lowdown_metadata" ,
which is used to hold parsed (and output-formatted) metadata keys and
values if
.Dv LOWDOWN_METADATA
was provided as an input bit.
This structure consists of the following fields:
.Bl -tag -width Ds -offset indent
.It Va char *key
The metadata key in its lowercase, canonical form.
.It Va char *value
The metadata value as rendered in the current output format.
This may be an empty string.
.El
.Pp
The abstract syntax tree is encoded in
.Vt struct lowdown_node ,
which consists of the following.
.Bl -tag -width Ds -offset indent
.It Va enum lowdown_rndrt type
The node type.
.Pq Described below.
.It Va size_t id
An identifier unique within the document.
This can be used as a table index since the number is assigned from a
monotonically increasing point during the parse.
.It Va struct lowdown_node *parent
The parent of the node, or
.Dv NULL
at the root.
.It Va enum lowdown_chng chng
Change tracking: whether this node was inserted
.Pq Dv LOWDOWN_CHNG_INSERT ,
deleted
.Pq Dv LOWDOWN_CHNG_DELETE ,
or neither
.Pq Dv LOWDOWN_CHNG_NONE .
.It Va struct lowdown_nodeq children
A possibly-empty list of child nodes.
.It Va <anon union>
An anonymous union of type-specific structures.
See below for a description of each one.
.El
.Pp
The nodes may be one of the following types, with default rendering in
HTML5 to illustrate functionality.
.Bl -tag -width Ds -offset indent
.It Dv LOWDOWN_ROOT
The root of the document.
This is always the topmost node, and the only node where the
.Va parent
field is
.Dv NULL .
.It Dv LOWDOWN_BLOCKCODE
A block-level (and possibly language-specific) snippet of code.
Described by the
.Li <pre><code>
elements.
.It Dv LOWDOWN_BLOCKHTML
A block-level snippet of HTML.
This is simply opaque HTML content.
(Only if configured during parse.)
.It Dv LOWDOWN_BLOCKQUOTE
A block-level quotation.
Described by the
.Li <blockquote>
element.
.It Dv LOWDOWN_CODESPAN
A snippet of code.
Described by the
.Li <code>
element.
.It Dv LOWDOWN_DOC_FOOTER
Closes out the document opened in
.Dv LOWDOWN_DOC_HEADER .
.It Dv LOWDOWN_DOC_HEADER
A header with data gathered from document metadata (if configured).
Described by the
.Li <head>
element.
(Only if configured during parse.)
.It Dv LOWDOWN_DOUBLE_EMPHASIS
Bold (or otherwise notable) content.
Described by the
.Li <strong>
element.
.It Dv LOWDOWN_EMPHASIS
Italic (or otherwise notable) content.
Described by the
.Li <em>
element.
.It Dv LOWDOWN_ENTITY
An HTML entity, which may either be named or numeric.
.It Dv LOWDOWN_FOOTNOTE_DEF
A footnote within a
.Dv LOWDOWN_FOOTNOTES_BLOCK
node.
Described by the
.Li <li id="fnXX">
element.
(Only if configured during parse.)
.It Dv LOWDOWN_FOOTNOTE_REF
A reference to a
.Dv LOWDOWN_FOOTNOTE_DEF .
Described by the
.Li <sup><a>
elements.
(Only if configured during parse.)
.It Dv LOWDOWN_FOOTNOTES_BLOCK
A block of footnotes.
Described by the
.Li <div class="footnotes"><hr /><ol>
elements.
(Only if configured during parse.)
.It Dv LOWDOWN_HEADER
A block-level header.
Described (in the HTML case) by one of
.Li <h1>
through
.Li <h6> .
.It Dv LOWDOWN_HIGHLIGHT
Marked test.
Described by the
.Li <mark>
element.
(Only if configured during parse.)
.It Dv LOWDOWN_HRULE
A horizontal line.
Described by
.Li <hr> .
.It Dv LOWDOWN_IMAGE
An image.
Described by the
.Li <img>
element.
.It Dv LOWDOWN_LINEBREAK
A hard line-break within a block context.
Described by the
.Li <br>
element.
.It Dv LOWDOWN_LINK
A link to external media.
Described by the
.Li <a>
element.
.It Dv LOWDOWN_LINK_AUTO
Like
.Dv LOWDOWN_LINK ,
except inferred from text content.
Described by the
.Li <a>
element.
(Only if configured during parse.)
.It Dv LOWDOWN_LIST
A block-level list enclosure.
Described by
.Li <ul>
or
.Li <ol> .
.It Dv LOWDOWN_LISTITEM
A block-level list item, always appearing within a
.Dv LOWDOWN_LIST .
Described by
.Li <li> .
.It Dv LOWDOWN_MATH_BLOCK
A block (or inline) of mathematical text in LaTeX format.
Described within
.Li \e[xx\e]
or
.Li \e(xx\e) .
This is usually (in HTML) externally handled by a JavaScript renderer.
(Only if configured during parse.)
.It Dv LOWDOWN_META
Meta-data keys and values.
(Only if configured during parse.)
These are described by elements in the
.Li <head>
element.
.It Dv LOWDOWN_NORMAL_TEXT
Normal text content.
.It Dv LOWDOWN_PARAGRAPH
A block-level paragraph.
Described by the
.Li <p>
element.
.It Dv LOWDOWN_RAW_HTML
An inline of raw HTML.
(Only if configured during parse.)
.It Dv LOWDOWN_STRIKETHROUGH
Content struck through.
Described by the
.Li <del>
element.
(Only if configured during parse.)
.It Dv LOWDOWN_SUPERSCRIPT
A superscript.
Described by the
.Li <sup>
element.
(Only if configured during parse.)
.It Dv LOWDOWN_TABLE_BLOCK
A table block.
Described by
.Li <table> .
(Only if configured during parse.)
.It Dv LOWDOWN_TABLE_BODY
A table body section.
Described by
.Li <tbody> .
Parent is always
.Dv LOWDOWN_TABLE_BLOCK .
(Only if configured during parse.)
.It Dv LOWDOWN_TABLE_CELL
A table cell.
Described by
.Li <td>
or
.Li <th>
if in the header.
Parent is always
.Dv LOWDOWN_TABLE_ROW .
(Only if configured during parse.)
.It Dv LOWDOWN_TABLE_HEADER
A table header section.
Described by
.Li <thead> .
Parent is always
.Dv LOWDOWN_TABLE_BLOCK .
(Only if configured during parse.)
.It Dv LOWDOWN_TABLE_ROW
A table row.
Described by
.Li <tr> .
Parent is always
.Dv LOWDOWN_TABLE_HEADER
or
.Dv LOWDOWN_TABLE_BODY .
(Only if configured during parse.)
.It Dv LOWDOWN_TRIPLE_EMPHASIS
Combination of
.Dv LOWDOWN_EMPHASIS
and
.Dv LOWDOWN_DOUBLE_EMPHASIS .
.El
.Pp
The following anonymous union structures correspond to certain nodes.
Note that all buffers may be zero-length.
.Bl -tag -width Ds -offset indent
.It Va rndr_meta
Each
.Dv LOWDOWN_META
key-value pair is represented.
The keys are lower-case without spaces or non-ASCII characters.
If provided, enclosed nodes may consist only of
.Dv LOWDOWN_NORMAL_TEXT
and
.Dv LOWDOWN_ENTITY .
.It Va rndr_definition
For
.Dv LOWDOWN_DEFINITION ,
containing
.Va flags
that may be
.Dv HLIST_FL_BLOCK
if the definition list should be interpreted as containing block
elements.
.It Va rndr_list
For
.Dv LOWDOWN_LIST ,
consists of a bitfield
.Va flags
that may be set to
.Dv HLIST_FL_ORDERED
for an ordered list and
.Dv HLIST_FL_UNORDERED
for an unordered one.
If
.Dv HLIST_FL_BLOCK
is set, the list should be output as if items were separate blocks.
If
.Va start
is a non-empty string, it is the first list item value.
.It Va rndr_paragraph
For
.Dv LOWDOWN_PARAGRAPH ,
species how many
.Va lines
the paragraph has in the input file and
.Va beoln ,
set to non-zero if the paragraph ends with an empty line instead of a
breaking block element.
.It Va rndr_listitem
For
.Dv LOWDOWN_LISTITEM ,
consists of a bitfield
.Va flags
that may be set to
.Dv HLIST_FL_ORDERED
.Pq an ordered list ,
.Dv HLIST_FL_UNORDERED
.Pq unordered list ,
.Dv HLIST_FL_DEF
.Pq definition list data ,
and/or
.Dv HLIST_FL_BLOCK
.Pq list item output as if containing block elements .
The
.Dv HLIST_FL_BLOCK
should not be used: use the parent list (or definition list) flags for
this.
The
.Va num
is the index in an ordered list.
.It Va rndr_header
For
.Dv LOWDOWN_HEADER ,
the
.Va level
of the header starting at zero
This value is relative to the metadata base header level, defaulting to
one (the top-level header).
.It Va rndr_normal_text
The basic
.Va text
content for
.Dv LOWDOWN_NORMAL_TEXT .
.It Va rndr_entity
For
.Dv LOWDOWN_ENTITY ,
the entity
.Va text .
.It Va rndr_autolink
For
.Dv LOWDOWN_LINK_AUTO ,
the link address as
.Va link ;
the textual component
.Va text ;
and the link type
.Va type ,
which may be one of
.Dv HALINK_EMAIL
for e-mail links and
.Dv HALINK_NORMAL
otherwise.
Any buffer may be empty-sized.
.It Va rndr_raw_html
For
.Dv LOWDOWN_RAW_HTML ,
the opaque HTML
.Va text .
.It Va rndr_link
Like
.Va rndr_autolink .
.It Va rndr_blockcode
For
.Dv LOWDOWN_BLOCKCODE ,
the opaque
.Va text
of the block and the optional
.Va lang
of the code language.
.It Va rndr_codespan
The opaque
.Va text
of the contents.
.It Va rndr_table
For
.Dv LOWDOWN_TABLE_BLOCK ,
the number of
.Va columns
in each row or header row.
The number of columns in
.Va rndr_table ,
.Va rndr_table_header ,
and
.Va rndr_table_cell
are the same.
.It Va rndr_table_header
For
.Dv LOWDOWN_TABLE_HEADER ,
the number of
.Va columns
in each row and the per-column
.Va flags ,
which may be bits of
.Dv HTBL_FL_ALIGN_LEFT ,
.Dv HTBL_FL_ALIGN_RIGHT ,
or
.Dv HTBL_FL_ALIGN_CENTER
when masked with
.Dv HTBL_FL_ALIGNMASK ;
or
.Dv HTBL_FL_HEADER .
The number of columns in
.Va rndr_table ,
.Va rndr_table_header ,
and
.Va rndr_table_cell
are the same.
.It Va rndr_table_cell
For
.Dv LOWDOWN_TABLE_CELL ,
the current
.Va col
column number out of
.Va columns .
See
.Va rndr_table_header
for a description of the bits in
.Va flags .
The number of columns in
.Va rndr_table ,
.Va rndr_table_header ,
and
.Va rndr_table_cell
are the same.
.It Va rndr_footnote_def
For
.Dv LOWDOWN_FOOTNOTE_DEF ,
the footnote number
.Va  num
(starting at zero).
This matches a single
.Dv LOWDOWN_FOOTNOTE_DEF
similarly numbered.
The
.Va key
is its original in-document reference key.
.It Va rndr_footnote_ref
For a
.Dv LOWDOWN_FOOTNOTE_REF
reference to a
.Dv LOWDOWN_FOOTNOTE_DEF ,
the footnote number
.Va num
(starting at zero).
The
.Va def
is the content parsed as children to the matching
.Dv LOWDOWN_FOOTNOTE_DEF .
The
.Va key
is its original in-document reference key.
.It Va rndr_image
For
.Dv LOWDOWN_IMAGE ,
the image address
.Va link ,
the image title
.Va title ,
dimensions NxN (width by height) in
.Va dims ,
and alternate text
.Va alt .
.It Va rndr_math
For
.Dv LOWDOWN_MATH ,
the mode of display
.Va displaymode :
if 1, in-line math; if 2, multi-line.
.It Va rndr_blockhtml
For
.Dv LOWDOWN_BLOCKHTML ,
the opaque HTML
.Va text .
.El
.Sh SEE ALSO
.Xr lowdown 1 ,
.Xr lowdown_buf 3 ,
.Xr lowdown_buf_diff 3 ,
.Xr lowdown_diff 3 ,
.Xr lowdown_doc_free 3 ,
.Xr lowdown_doc_new 3 ,
.Xr lowdown_doc_parse 3 ,
.Xr lowdown_file 3 ,
.Xr lowdown_file_diff 3 ,
.Xr lowdown_gemini_free 3 ,
.Xr lowdown_gemini_new 3 ,
.Xr lowdown_gemini_rndr 3 ,
.Xr lowdown_html_free 3 ,
.Xr lowdown_html_new 3 ,
.Xr lowdown_html_rndr 3 ,
.Xr lowdown_latex_free 3 ,
.Xr lowdown_latex_new 3 ,
.Xr lowdown_latex_rndr 3 ,
.Xr lowdown_metaq_free 3 ,
.Xr lowdown_nroff_free 3 ,
.Xr lowdown_nroff_new 3 ,
.Xr lowdown_nroff_rndr 3 ,
.Xr lowdown_term_free 3 ,
.Xr lowdown_term_new 3 ,
.Xr lowdown_term_rndr 3 ,
.Xr lowdown_tree_rndr 3 ,
.Xr lowdown 5
.Sh AUTHORS
.Nm lowdown
was forked from
.Lk https://github.com/hoedown/hoedown hoedown
by
.An Kristaps Dzonsons ,
.Mt kristaps@bsd.lv .
It has been considerably modified since.