Markdown Rendering Support

The MarkdownNode renders GFM (GitHub Flavored Markdown) directly to a Skia Picture using pulldown-cmark's event stream and Skia's textlayout::Paragraph API. No HTML/CSS pipeline is involved — the markdown source is walked and drawn in a single pass.

• Parser: pulldown-cmark 0.13 with ENABLE_STRIKETHROUGH | ENABLE_TABLES | ENABLE_TASKLISTS | ENABLE_MATH
• Renderer: crates/grida/src/painter/markdown.rs
• Node schema: MarkdownNodeRec in crates/grida/src/node/schema.rs
• Theme: GitHub markdown light (hardcoded colors from fixtures/css/github-markdown-light.css)

Block Elements

Element	Status	Notes
Heading h1	✅	32px semi-bold, bottom border
Heading h2	✅	24px semi-bold, bottom border
Heading h3	✅	20px semi-bold
Heading h4	✅	16px semi-bold
Heading h5	✅	14px semi-bold
Heading h6	✅	13.5px semi-bold
Paragraph	✅	Word-wrapped to content width
Code block	✅	Monospace, rounded background rect + border
Code block (lang)	⚠️	Language tag parsed but no syntax highlighting
Blockquote	✅	Left border + indented text
Horizontal rule	✅	2px stroke line
Unordered list	✅	Bullet prefix, nested depth tracked
Ordered list	✅	Numbered prefix, auto-incrementing
Task list	✅	Checkbox character prefix (☐/☑)
Display math $$	⚠️	Rendered as centered monospace italic text (raw LaTeX source)

Inline Elements

Element	Status	Notes
Bold	✅	Font weight BOLD
Italic	✅	Font slant Italic
Strikethrough	✅	LINE_THROUGH decoration
Inline code	✅	Monospace font, 0.85x font size
Link	✅	Blue color + underline decoration
Inline math $	⚠️	Rendered as monospace italic text (raw LaTeX)
Soft break	✅	Collapsed to space
Hard break	✅	Newline character

Tables

Feature	Status	Notes
Basic table	✅	Equal-width columns, cell padding
Header row	✅	Semi-bold text, light background
Column alignment	✅	Left / Center / Right from :--- syntax
Grid borders	✅	Full horizontal + vertical border grid
Multi-line cells	✅	Row height adapts to tallest cell

Images

Feature	Status	Notes
Image placeholder	✅	Rounded rect with alt text label (🖼 prefix)
Image loading	❌	No actual image fetch/display; placeholder only

Known Limitations

Feature	Status	Effort	Notes
LaTeX math rendering	❌	High	Requires TeX math layout engine (e.g. KaTeX/MathJax binding or OpenType MATH table consumer). Current fallback shows raw LaTeX source in monospace italic.
Syntax highlighting	❌	Medium	Code block language tag is parsed but ignored. Would need a tokenizer (e.g. syntect or tree-sitter) to map tokens to colored text styles.
Inline HTML (<sup>, etc)	❌	Medium	pulldown-cmark emits Event::Html for inline HTML. Would need mini HTML parser for supported tags.
<details><summary>	❌	High	Requires interactive expand/collapse state.
Dark theme	❌	Low	Theme colors are hardcoded light. fixtures/css/github-markdown-dark.css exists for reference.
Footnotes	❌	Medium	Parser flag exists (ENABLE_FOOTNOTES) but events not handled.
Nested blockquotes	❌	Low	Only one level of blockquote indentation rendered.
Image loading	❌	Medium	Requires async fetch + resource registration into the renderer.
Picture caching	❌	Low	Currently re-renders every frame. Should cache keyed on (markdown hash, width).