[Filters] Applying CoreGraphics filters on different tiles may result in white borders around the tiles #50371

shallawa · 2025-09-05T17:29:16Z

`0bd4123`

[Filters] Applying CoreGraphics filters on different tiles may result in white borders around the tiles
https://bugs.webkit.org/show_bug.cgi?id=298453
rdar://159951868

Reviewed by Simon Fraser.

The transparency layer of the CoreGraphics filter should be clipped to the layer
backgroundClipRect without intersecting it with the paintDirtyRect. CoreGraphics
expects the context is set to the coordinates of the target filtered renderer
not only the dirty rectangle only.

Test: css3/filters/effect-graphics-context-blur-tile-boundaries.html
* LayoutTests/css3/filters/effect-graphics-context-blur-tile-boundaries-expected.html: Added.
* LayoutTests/css3/filters/effect-graphics-context-blur-tile-boundaries.html: Added.
* Source/WebCore/rendering/LayerFragment.h:
(WebCore::LayerFragment::Rects::backgroundRect const):
(WebCore::LayerFragment::backgroundRect const):
* Source/WebCore/rendering/RenderLayer.cpp:
(WebCore::RenderLayer::paintLayerContents):

Canonical link: https://commits.webkit.org/300038@main

7dd209d

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	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
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webkit-early-warning-system · 2025-09-05T17:29:23Z

EWS run on previous version of this PR (hash 313760f)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	❌ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

smfr

This needs a test.

smfr · 2025-09-08T16:24:35Z

Source/WebCore/platform/graphics/TransparencyLayerContextSwitcher.cpp

-        destinationContext.clip(intersection(filterStyle.imageRect, clipRect));
+
+        auto maxSide = filterStyle.outsets.maxSide();
+        auto outsets = FloatBoxExtent { maxSide, maxSide, maxSide, maxSide };


Why do we have to take the max of the outsets, rather than just expanding by the appropriate amount on each side?

smfr · 2025-09-08T16:25:52Z

Source/WebCore/platform/graphics/FloatRect.h


+inline FloatBoxExtent operator-(const FloatRect& a, const FloatRect& b)
+{
+    return FloatBoxExtent {


Should this clamp negative to zero, so we don't return negative extents?

If we have

FloatRect a = { 0, 0, 3, 3 }; FloatRect b = { 1, 1, 1, 1 }; FloatBoxExtent c = a - b; // c = { 1, 1, 1, 1 }; FloatBoxExtent c = b - a; // Should d = { -1, -1, -1, -1 }? Or should d = { 0, 0, 0, 0 }?

I think the result should be signed. If the rect edge is positive, this means a - b is expanded in this direction. If the rect edge is negative, this means a -b is shrunk in this direction.

It turned out this part is not needed to fix this bug.

webkit-early-warning-system · 2025-09-13T00:35:58Z

EWS run on previous version of this PR (hash f71edec)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	❌ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	❌ 🧪 ios-wk2-wpt	❌ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	❌ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	❌ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	❌ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	❌ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

webkit-early-warning-system · 2025-09-16T00:56:48Z

EWS run on previous version of this PR (hash df76b85)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	⏳ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	❌ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	❌ 🧪 ios-wk2-wpt	❌ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	❌ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	❌ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	❌ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	❌ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

shallawa · 2025-09-16T01:06:25Z

This needs a test.

The new test case shows this display without this PR:

The expected page shows this display:

webkit-early-warning-system · 2025-09-16T04:45:00Z

EWS run on previous version of this PR (hash 0f60c45)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	❌ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	❌ 🧪 ios-wk2-wpt	❌ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	❌ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

webkit-early-warning-system · 2025-09-16T10:12:29Z

EWS run on current version of this PR (hash 7dd209d)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

… in white borders around the tiles https://bugs.webkit.org/show_bug.cgi?id=298453 rdar://159951868 Reviewed by Simon Fraser. The transparency layer of the CoreGraphics filter should be clipped to the layer backgroundClipRect without intersecting it with the paintDirtyRect. CoreGraphics expects the context is set to the coordinates of the target filtered renderer not only the dirty rectangle only. Test: css3/filters/effect-graphics-context-blur-tile-boundaries.html * LayoutTests/css3/filters/effect-graphics-context-blur-tile-boundaries-expected.html: Added. * LayoutTests/css3/filters/effect-graphics-context-blur-tile-boundaries.html: Added. * Source/WebCore/rendering/LayerFragment.h: (WebCore::LayerFragment::Rects::backgroundRect const): (WebCore::LayerFragment::backgroundRect const): * Source/WebCore/rendering/RenderLayer.cpp: (WebCore::RenderLayer::paintLayerContents): Canonical link: https://commits.webkit.org/300038@main

webkit-commit-queue · 2025-09-16T17:16:43Z

Committed 300038@main (0bd4123): https://commits.webkit.org/300038@main

Reviewed commits have been landed. Closing PR #50371 and removing active labels.

shallawa self-assigned this Sep 5, 2025

shallawa added the Layout and Rendering For bugs with layout and rendering of Web pages. label Sep 5, 2025

shallawa requested a review from smfr September 5, 2025 19:10

webkit-ews-buildbot added the merging-blocked Applied to prevent a change from being merged label Sep 5, 2025

smfr reviewed Sep 8, 2025

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shallawa removed the merging-blocked Applied to prevent a change from being merged label Sep 13, 2025

shallawa force-pushed the eng/Filters-Applying-CoreGraphics-filters-on-different-tiles-may-result-in-white-borders-around-the-tiles branch from 313760f to f71edec Compare September 13, 2025 00:35

webkit-ews-buildbot added the merging-blocked Applied to prevent a change from being merged label Sep 13, 2025

shallawa removed the merging-blocked Applied to prevent a change from being merged label Sep 16, 2025

shallawa force-pushed the eng/Filters-Applying-CoreGraphics-filters-on-different-tiles-may-result-in-white-borders-around-the-tiles branch from f71edec to df76b85 Compare September 16, 2025 00:56

webkit-ews-buildbot added the merging-blocked Applied to prevent a change from being merged label Sep 16, 2025

shallawa removed the merging-blocked Applied to prevent a change from being merged label Sep 16, 2025

shallawa force-pushed the eng/Filters-Applying-CoreGraphics-filters-on-different-tiles-may-result-in-white-borders-around-the-tiles branch from df76b85 to 0f60c45 Compare September 16, 2025 04:44

webkit-ews-buildbot added the merging-blocked Applied to prevent a change from being merged label Sep 16, 2025

shallawa removed the merging-blocked Applied to prevent a change from being merged label Sep 16, 2025

shallawa force-pushed the eng/Filters-Applying-CoreGraphics-filters-on-different-tiles-may-result-in-white-borders-around-the-tiles branch from 0f60c45 to 7dd209d Compare September 16, 2025 10:12

smfr approved these changes Sep 16, 2025

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shallawa added the merge-queue Applied to send a pull request to merge-queue label Sep 16, 2025

webkit-commit-queue force-pushed the eng/Filters-Applying-CoreGraphics-filters-on-different-tiles-may-result-in-white-borders-around-the-tiles branch from 7dd209d to 0bd4123 Compare September 16, 2025 17:16

webkit-commit-queue merged commit 0bd4123 into WebKit:main Sep 16, 2025

webkit-commit-queue removed the merge-queue Applied to send a pull request to merge-queue label Sep 16, 2025

shallawa deleted the eng/Filters-Applying-CoreGraphics-filters-on-different-tiles-may-result-in-white-borders-around-the-tiles branch September 18, 2025 19:12

[Filters] Applying CoreGraphics filters on different tiles may result in white borders around the tiles #50371

[Filters] Applying CoreGraphics filters on different tiles may result in white borders around the tiles #50371

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