bug#51995: 29.0.50; `string-pixel-width' depends on the current window width

[martin rudalics]

> I meant that a facility should be added to `window-text-pixel-size' so
> that callers like `string-pixel-width' can ask for having no (X) limit
> without specifying a large number themselves.  Basically I want to use:
>
>    (window-text-pixel-size window (point-min) (point) t)
>                                                      ^^^
>     (or some other value that `window-text-pixel-size'
>     should understand as meaning "no limit" for X-LIMIT)
>
> instead of:
>
>    (window-text-pixel-size window (point-min) (point) 123456789)
>
> The default behavior of the function should stay the same.

OK.

>> Any clients of 'window-text-pixel-size' like 'string-pixel-width' can
>> easily set X-LIMIT to some sufficiently large value without affecting
>> the basic functionality of 'window-text-pixel-size'.
>
> Yes, that's the simplest solution, but I find passing a random magic number
> instead of providing a simple interface to say "I don't want to use a limit"
> (like Y-LIMIT already allows, as I previously mentioned) rather inelegant :)

Agreed (also because 'most-positive-fixnum' and anything beyond INT_MAX
as argument don't work at the moment which is confusing).

> Minus one glaring issue:
> `string-pixel-width' is using `buffer-size' as the X-LIMIT, but
> that function returns the amount of characters in the buffer.
> This means that instead of returning the pixel width, it merely
> returns the amount of characters in a string.  If I change that,
> everything else seems to be in good order.

Yes.  This wasn't a very bright idea.  The function will now be

(defun string-pixel-width (string)
  "Return the width of STRING in pixels."
  (with-temp-buffer
    (insert string)
    (car (buffer-text-pixel-size nil nil t))))

as you suggested.  The xdisp.c change is attached.  Apply the
'string-pixel-width' change manually.

Thanks, martin

buffer-text-pixel-size.diff
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