Preserve affine transforms when rendering feImage

[Cees-Kettenis]

feImage discards rotation, skew, and reflection from the filter transform, so referenced artwork is painted with the wrong geometry.

Apply the complete transform to the image at the primitive origin and clip skewed or rotated output to the transformed primitive rectangle, because extracting positive scale components loses both orientation and the correct clipping shape. The regression compares filtered artwork with an ordinary use at 1x and 2x scale and fails on main; two existing golden images are updated after Chrome comparisons, and the full workspace tests, formatting, copyright check, and no-default-feature checks pass.

Download the SVG reproducer

[LaurenzV]

Pretty sure #1155 should fix this more generally, could you please check? If so, i think this PR can be closed in favor of #1155.

[Cees-Kettenis]

Thanks, I tested #1155 against my reproducer and agree that it addresses the problem more generally.

For this particular SVG rendered at 2×, using Chrome as the reference, I measured:
My patch: 0.216% differing pixels.
#1155: 0.476% differing pixels.

Both restore the correct geometry, though my narrower patch produces fewer pixel differences in this example.

That doesn’t establish that it renders better overall.
I’d be happy to contribute the reproducer and investigate whether the remaining differences can be reduced within #1155’s approach.

[LaurenzV]

0.4% seems small enough, probably just some anti-aliasing? I've merged the other PR so will close this one, thanks though! And feel free to open another issue/PR if you notice anything else.

[Cees-Kettenis]

0.4% seems small enough, probably just some anti-aliasing? I've merged the other PR so will close this one, thanks though! And feel free to open another issue/PR if you notice anything else.

I will check the newly merged code and see if i can improve it. I do have other PR open to fix other issues. Feel free to have a look. Happy to help!