bug#67533: SVG images confound position pixel measurements

[JD Smith]

> On Dec 3, 2023, at 11:33 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: JD Smith <jdtsmith@gmail.com>
>> Date: Sun, 3 Dec 2023 10:49:37 -0500
>> 
>> BTW, in case anyone is wondering where window-text-pixel-size with a 
>> negative pixel FROM offset is needed, Po Lu's pixel-scroll-precision-up-page 
>> is using precisely this approach to measure the content above window-start 
>> (so as to smoothly scroll up with high performance):
>> 
>>        (let* ((start (window-start))
>>               (dims (window-text-pixel-size nil (cons start (- delta))
>>                                             start nil nil nil t))
>> 
> 
> I know very well why that feature was added.  My questions was not
> about negative offsets in general, but about negative offsets when
> FROM is in the first line of the buffer, i.e. when there's no text at
> all above that line.

Thanks, all set on this end.  Just mentioning the use-case for the casual 
reader who may wonder what real world impact it has.