Re: Emacs canvas support

[tomas]

On Wed, Apr 29, 2020 at 10:25:04PM +0300, Eli Zaretskii wrote:

[...]

> The current display engine works by screen lines, so if we want to
> keep it, we must use the existing framework.

Now imagine there's a (graphical) line going from (text) display
line 3 to 7. You are not implying that we have to segment that
into four chunks, one per text line?

>                                               When a portion of a
> window is exposed, we redraw all the glyphs in the exposed area(s),
> and we find the glyphs that need to be redrawn by comparing their
> coordinates with those of the exposed rectangle(s).

... but rather that we intersect the exposed area(s) with each [1]
of the graphical objects and redraw that (be it before or after the
text)?

Cheers

[1] conceptually; in reality we'll need some index structure
   to avoid looking at most of the graphical objects. Quad-
   trees, whatever.

-- t

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