Add support for markdown links in paragraphs

[MartinBspheroid]

Support clickable markdown links within paragraphs.
Use regex to detect markdown link syntax ([text](url)) in paragraph content and render them as HTML tags with appropriate attributes.
Links should be styled to match the classic underline design.

Ideas/Features:

• Detect and render markdown links as clickable elements.
• Ensure accessibility attributes like aria-label are added for screen readers.
• Add test cases to verify proper detection and rendering of links.

[orhun]

The current way that this works is that we set a custom modifier style for the text that we want to render as hyperlink:

ratzilla/src/widgets.rs

Lines 3 to 4 in 46be606

	/// When added as a modifier to a style, the styled element is marked as hyperlink.
	pub(crate) const HYPERLINK: Modifier = Modifier::SLOW_BLINK;

ratzilla/src/widgets.rs

Line 13 in 46be606

line: Span::from(url).style(HYPERLINK),

And then while rendering individual cells, we check this modifier and do some magic to wrap the related spans in an anchor tag (i.e. <a href="..."> </a>)

ratzilla/src/wasm_backend.rs

Lines 76 to 78 in 46be606

	for (i, cell) in line.iter().enumerate() {
	if cell.modifier.contains(HYPERLINK) {
	// Start a new hyperlink

This is an approach that I adopted from webatui and I'm guessing the reason why they did that is there isn't a way to retrieve the widget data/metadata in the draw function of the backend.

This also limits our ability to attach arbitrary data to widgets, so I'm not sure if it would be possible to do custom text apart from url if we follow the same approach.

Maybe @joshka can give us some pointers about this 🙏🏼

[Tarbetu]

Auto-detecting Markdown means searching for Markdown in every text for every rendering loop, as I guess correctly. You mentioned Regex, so I am not sure about that everyone would like to run regex in every loop.

It's comfortable, but it will cost the efficiency of the whole application. I like the current approach, but instead of giving a Hyperlink widget let us using Hyperlink modifier for the spans. It would be more efficient, and it would more fit for general usage of Ratatui, as I believe.

[orhun]

let us using Hyperlink modifier for the spans

Can you elaborate this a bit? You can probably set Modifier::SLOW_BLINK (via .add_modifier) on a span manually if that's what you meant.

[joshka]

Related reading:

• Support styling as a hyperlink ratatui/ratatui#1028
• Support arbitrary ANSI sequences (including hyperlinks / images) by passing them through Style ratatui/ratatui#1227
• Don't swallow ANSI ratatui/ratatui#902

[Tarbetu]

@orhun The problem with that is, you have to search the source code to explore the behaviour of the SLOW_BLINK modifier.