bug#71605: 30.0.50; [PATCH] Support variable-width text in 'visual-wrap-prefix-mode'

[Jim Porter]

On 6/17/2024 9:13 AM, Jim Porter wrote:
> Note that I haven't removed any of the old logic though; it's all there 
> as before, since the space characters are useful for terminals (where 
> the pixelwise :width display-spec doesn't do anything for us, if I 
> understand correctly).

Evidently I wasn't understanding this correctly, since further testing 
and consulting the code shows that the :width display-spec works just 
fine on terminals. It does make it harder to get this patch working well 
though...

Maybe :align-to could be made to work. It doesn't seem to work at all 
for me, even in a minimal test case like calling this on a long line of 
text:

  (put-text-property (point-min) (point-max) 'wrap-prefix '(space 
:align-to 4))

Replacing :align-to with :width works just fine though. It's entirely 
possible I'm just doing something wrong, but maybe this is a bug?

(Now what would be great is if :align-to supported a *string* value that 
meant "use the pixel-width of this string". Which actually gives me an 
idea... what if the wrap-prefix is just the original text like "* " and 
we fontify it to be invisible? It's not part of the buffer and you can't 
select it anyway, so it doesn't really matter what the text is so long 
as it's not visible.)