bug#38109: Updated Emacs to HEAD, consistently not scaling now

[Unknown <unknown@unknown.invalid>]

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Eli writes:

>> However the png-image is still not scaled, and still shown in the larger
>> canvas.

> What do you mean by "shown in the larger canvas"?

I mean that the original 16x16 pixel image is shown in the corner of a
320x320 pixel white box.

As can be seen in the screenshot here:

 · https://debbugs.gnu.org/cgi/bugreport.cgi?att=1;filename=emacs27-image-scaling.png;bug=38109;msg=5

> Can you post a screenshot of how you see those PNG images with and
> without scaling, after applying that patch?

The patch doesn't make any difference on the scaling of the PNG images.

--with-cairo does.

Here is a screenshot of the attached .png with and without scaling,
without the patch and without Cairo (i.e. with Xrender):


[-- Attachment #2: without-patch.png --]
[-- Type: image/png, Size: 47567 bytes --]

[-- Attachment #3: Type: text/plain, Size: 104 bytes --]


Here is a screenshot of the attached .png with and without scaling, with
the patch and without Cairo:


[-- Attachment #4: with-patch.png --]
[-- Type: image/png, Size: 46954 bytes --]

[-- Attachment #5: Type: text/plain, Size: 81 bytes --]


Here is what happens when I also apply Alan's patch for
image_set_transform():


[-- Attachment #6: with-two-patches.png --]
[-- Type: image/png, Size: 50907 bytes --]

[-- Attachment #7: Type: text/plain, Size: 89 bytes --]


And finally what I see with no patches and --with-cairo (this is the
expected result):


[-- Attachment #8: with-cairo.png --]
[-- Type: image/png, Size: 88525 bytes --]

[-- Attachment #9: Type: text/plain, Size: 119 bytes --]


Here is the image I'm using for testing:

  medium-wry.png: PNG image data, 16 x 16, 4-bit colormap, non-interlaced:


[-- Attachment #10: medium-wry.png --]
[-- Type: image/png, Size: 404 bytes --]