Add ability to view info about a message

[VAWVAW]

This adds a a command :message to open an info screen that shows:

• the message with image previews
• the full user id of the sender
• send timestamp including date
• list of mentioned users
• list of :openable links
• list of reactions (including username of sender)
• read receipts

hacks

I am using a readonly modalkit TextBox for the display and added a hacky workaround to update the content without loosing cursor position and to add styling to the textbox.

iamb/src/windows/room/message.rs

Lines 419 to 494 in 179648a

	fn render(mut self, area: Rect, buf: &mut Buffer, state: &mut Self::State) {
	let lines = state.render(&mut self, area.width as usize);
	// update text
	let buffer = state.tbox.buffer();
	let mut locked = buffer.write().unwrap();
	let mut text = EditRope::default();
	for (line, _) in lines.iter() {
	for span in line {
	text += span.content.as_ref().into();
	}
	text += '\n'.into();
	}
	locked.text = text;
	std::mem::drop(locked);
	// only store style info
	let lines: Vec<_> = lines
	.into_iter()
	.map(|(line, preview)| {
	let styles: Vec<(_, u16)> = line
	.iter()
	.map(|span| {
	let width = UnicodeSegmentation::graphemes(span.content.as_ref(), true)
	.filter(|symbol| !symbol.contains(|char: char| char.is_control()))
	.map(|symbol| symbol.width() as u16)
	.sum();
	(span.style, width)
	})
	.collect();
	(line.style, styles, preview)
	})
	.collect();
	// draw text
	state.draw(area, buf, self.focused, self.store);
	// set highlighting
	let mut image_previews = vec![];
	let mut draw_lines = lines.into_iter().fuse().skip(state.tbox.viewctx.corner.y);
	let draw_area = area.intersection(buf.area);
	for y in draw_area.top()..draw_area.top() + draw_area.height {
	let mut x = draw_area.left();
	if let Some((line_style, styles, line_preview)) = draw_lines.next() {
	if let Some((backend, msg_x)) = line_preview {
	image_previews.push((x + msg_x, y, backend));
	}
	for (style, width) in styles {
	let remaining_width = draw_area.right().saturating_sub(x);
	for i in 0..remaining_width.min(width) {
	let old_style = buf[(x + i, y)].style();
	let new_style = old_style.patch(line_style).patch(style);
	buf[(x + i, y)].set_style(new_style);
	}
	x += width;
	}
	}
	}
	// Render image previews after all text lines have been drawn, as the render might draw below the current
	// line.
	for (x, y, backend) in image_previews {
	let image_widget = Image::new(&backend);
	let mut rect = backend.area();
	rect.x = x;
	rect.y = y;
	// Don't render outside of scrollback area
	if rect.bottom() <= area.bottom() && rect.right() <= area.right() {
	image_widget.render(rect, buf);
	}
	}
	}

To implement this I had to use VAWVAW/modalkit@6bbe8a4 which sets a few struct member to pub.

I'm not sure whether it is worth to upstream this to modalkit completely or add a few wrappers to allow safe access to these members.