Subject: bug#59802: 30.0.50; Checkbox button not rendered

From: Eli Zaretskii <[email-masked]>
Date: Sun, 11 Dec 2022 17:54:00 +0200

> From: Stephen Berman <[email-masked]>
> Cc: [email-masked],  [email-masked]
> Date: Sun, 11 Dec 2022 14:12:09 +0100
> 
> When I visit the SVG image file the image scales without any display
> problem, so the problem apparently only arises with text scaling.  And
> not just via face-remapping with text-scale-mode: when I evaluate
> (set-face-attribute 'default nil :height 200) and then insert
> emacs/etc/images/checked.svg with insert-image-file, the bottom half of
> the image is truncated like in the "+4" buffer in the screenshot I
> attached to my first post in this thread.  (When the image is displayed
> via put-text-property, explicitly passing `:ascent center' does correct
> the initial alignment, but on increasing the font size with `C-x C-+'
> the image still gets pushed down just like in the screenshot I posted.)

In the Custom buffers, we already use ":ascent center" for images, so
they should scale correctly.  If they don't, the place to look is in
the produce image_glyph function: look at the values of ascent and
descent computed there.  Maybe something goes wrong there when the SVG
images are scaled.