bug#16992: feature request: background images

[Cecilio Pardo <cpardo@imayhem.com>]

On 08/11/2024 19:50, Eli Zaretskii wrote:
> So what is the Lisp API for drawing those "dynamic" things?  AFAIU,
> you've only shown the API to set a single static background image.

There is no lisp api yet. In this example the fill-column line is drawn 
always, in the part that iterates through the windows.

> Is the background image scrolled or isn't it?

No. The background image is always fixed at this point.

> Those "dynamic" drawings are the most wanted feature that is currently
> missing.  And the challenge is to implement them in a way that won't
> make redisplay significantly slower, e.g. due to disabled
> optimizations (like scrolling_window).

Then let's drop the image thing for now and focus on this.

The two use cases I have right now imply just a series of vertical lines:

- Lines fixed One to an x coordinate with an infinite height, for 
fill-column.
- Segments distributed through the window for the indent-lines.

We could have buffer local variables to define these lines.

What other features should we consider? Should we open a new bug report 
to discuss this?