When both filter and opacity attributes are set on a leaf node, the
opacity must be applied as a separate layer so that the results of the
filter are modified by the opacity. Previously in this circumstance we
were incorrectly applying the opacity to the paints only (without a
layer).
To illustrate:
<svg viewBox="0 0 1000 500" version="1.1"
xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink">
<defs>
<filter id="Green" x="0%" y="0%" width="100%" height="100%">
<feFlood flood-color="lime" flood-opacity="1" />
</filter>
</defs>
<rect x="30" y="20" width="400" height="100" fill="red" opacity="0.1"
filter="url(#Green)"/>
<g filter="url(#Green)">
<rect x="30" y="200" width="400" height="100" fill="red" opacity="0.1"/>
</g>
</svg>
The two rects should render differently. In the <g> case, the filter
output (opaque green) overrides the translucent red pixels of the rect.
In the <rect> case, the filter output overrides the translucent red
pixels with opaque green, but then is modified by the opacity on the
<rect>.
Relevant W3C test is filters-blend-01-b (and possibly others).
Change-Id: I165eed36c546f1f99457865cee58ee2b3bffe6f1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/354879
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Tyler Denniston <tdenniston@google.com>
a22d21e447