Re: Drawing UI elements behind text

[Eli Zaretskii]

> Date: Wed, 27 Nov 2024 00:19:43 +0100
> Cc: emacs-devel <emacs-devel@gnu.org>
> From: Cecilio Pardo <cpardo@imayhem.com>
> 
> I haven't found a way to draw behind the text that is not too 
> complicated or affects redisplay too much. So now the idea is drawing 
> over the text. For the applications I have in mind this works equally well.
> 
> The starting drawing elements are going to be vertical and horizontal 
> segments, with color (maybe with alpha), width and different patterns. 
> They can be placed on pixel positions or character positions when using 
> fixed size fonts, using floating point numbers so you can put, for 
> example, indent lines in the middle of characters.
> 
> They are associated with a buffer, and have a 'source' marker so the 
> facility can be shared by several programs.

How/whether are these drawing elements connected to the glyph
matrices?

If they are completely disconnected, how does this work when the
window is scrolled several lines?