HTML tag support tracker

[kevinaboos]

This issue tracks which Html tags are supported (both parsed and displayed fully correctly) in rich Html message content.

For more info, see ~~the list of supported Html tags and attributes in the Matrix spec~~ the newest v1.13 spec's list of supported Html tags and attributes.

• [x] Headers: h1, h2, h3, h4, h5, h6

• [x] b, strong: bold

• [x] i, em: italic/emphasis

• [x] u: underline

• [x] del/strike: strikethrough/cross-out

• [x] p: paragraph

• [x] hr: horizontal rule, separator

• [x] br: line break, new line

• [x] blockquote

• [x] ul

• [x] ol

  • [x] start

• [x] li

• [x] pre: code blocks

  • [ ] class="language-*" for syntax highlighting
    • This is blocked on Makepad's upcoming support for syntax highlighting

• [x] code: inline code

• [x] font

  • [x] color
  • [x] data-mx-color
  • [x] data-mx-bg-color

• [x] span

  • [x] data-mx-bg-color
  • [x] data-mx-color
  • [x] data-mx-spoiler: #274

• [x] a: hyper links

  • [x] href
    • Note: href value must not be relative, must have a scheme matching one of: https, http, ftp, mailto, magnet
    • web clients should add a `rel="noopener"``attribute
  • [x] name — this is explicitly not supported
  • [x] target — this is explicitly not supported

• [x] sup

• [x] sub

  • [ ] <sub> is parsed correctly, but doesn't always display properly

• [ ] div

• [ ] table

  • caption -- a table caption
  • thead -- a table header (the first row, typically column labels)
  • tbody -- a table body (rows that come after the thead table header)
  • tr -- a table row
  • th -- a table column header (the left-most cell in a row)
  • td -- a table data cell

• [x] img: inline images

  • [x] width
  • [x] height
  • [x] alt
  • [x] title
  • [x] src

• [ ] details: an expandable view that shows a summary when closed and the full content when open.

  • [ ] summary: the short content viewable when details is closed.

• [x] mx-reply: see issue https://github.com/project-robius/robrix/issues/82

[kevinaboos]

<span> and <font> are fully supported as of #319