Bug 22026 – [Transforms] Transformed element is clipped when opacity is applied

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Simon Fraser (smfr)]

In the attached testcase, there should be a red box, but it's getting clipped. Remove the opacity to see what it should look like.

I think the transparency clip rect is ignoring transforms.

[Simon Fraser (smfr)]

Created attachment 24831 [details]
Testcase

[Simon Fraser (smfr)]

Created attachment 24859 [details]
Reduced testcase

[Simon Fraser (smfr)]

diff --git a/WebCore/platform/graphics/cg/GraphicsContextCG.cpp b/WebCore/platform/graphics/cg/GraphicsContextCG.cpp
index 3f0e6e7..31fcc2b 100644
--- a/WebCore/platform/graphics/cg/GraphicsContextCG.cpp
+++ b/WebCore/platform/graphics/cg/GraphicsContextCG.cpp
@@ -651,6 +651,12 @@ void GraphicsContext::beginTransparencyLayer(float opacity)
     CGContextSaveGState(context);
     CGContextSetAlpha(context, opacity);
     CGContextBeginTransparencyLayer(context, 0);
+
+    // paint a big rect so we can see how big the layer is
+    float red[] = { 1.0f, 0.0f, 0.0f, 0.1f };
+    CGContextSetFillColor(context, red);
+    CGContextFillRect(context, CGRectMake(-1000.0f, -1000.0f, 2000.0f, 2000.0f));
+
     m_data->beginTransparencyLayer();
     m_data->m_userToDeviceTransformKnownToBeIdentity = false;
 }

[Simon Fraser (smfr)]

That patch in the previous comment is some debugging code that will reveal how big the opacity layer is.

[Simon Fraser (smfr)]

Created attachment 24866 [details]
Patch, testcase, changelog

[Dave Hyatt]

Comment on attachment 24866 [details]
Patch, testcase, changelog

r=me

[Simon Fraser (smfr)]

Committed r38079
	M	WebCore/rendering/RenderLayer.cpp
	M	WebCore/ChangeLog
	A	LayoutTests/platform/mac/fast/layers/opacity-transforms-expected.txt
	A	LayoutTests/platform/mac/fast/layers/opacity-transforms-expected.png
	A	LayoutTests/platform/mac/fast/layers/opacity-transforms-expected.checksum
	M	LayoutTests/ChangeLog
	A	LayoutTests/fast/layers/opacity-transforms.html
r38079 = f9050b37b90e1c8a40699dc2e8c58cdda5dbbfcb (trunk)