Bug 93244 – [Cairo] canvas/philip/tests/2d.drawImage.self.2.html test failing on ports using Cairo

• Status: RESOLVED
• Resolution: FIXED
• Component: Canvas

[Sudarsana Nagineni (babu)]

canvas/philip/tests/2d.drawImage.self.2.html test failing on ports using Cairo. The failure looks like this:

--- WebKit/WebKitBuild/Release/layout-test-results/canvas/philip/tests/2d.drawImage.self.2-expected.txt
+++ WebKit/WebKitBuild/Release/layout-test-results/canvas/philip/tests/2d.drawImage.self.2-actual.txt
@@ -1 +1,2 @@
-Passed
+Failed assertion: got pixel [255,0,0,255] at (0,49), expected [0,255,0,255] +/- 2
+Failed assertion: got pixel [255,0,0,255] at (99,49), expected [0,255,0,255] +/- 2

[Dominik Röttsches (drott)]

https://bugs.webkit.org/show_bug.cgi?id=54458#c7 has some insight:
# When drawing canvas into itself, WebCore draws canvas's buffer into the same buffer. This
# results in recursive drawing into cairo surface. We should either use groups when drawing
# with cairo or copy the buffer every time the HTMLCanvasElement gets repainted.
canvas/philip/tests/2d.drawImage.self.2.html

[Dominik Röttsches (drott)]

Created attachment 158040 [details]
Copying buffer when src and dst are identical.

[Kenneth Rohde Christiansen]

Comment on attachment 158040 [details]
Copying buffer when src and dst are identical.

View in context: https://bugs.webkit.org/attachment.cgi?id=158040&action=review

> Source/WebCore/platform/graphics/cairo/ImageBufferCairo.cpp:99
> +void ImageBuffer::draw(GraphicsContext* destContext, ColorSpace styleColorSpace, const FloatRect& destRect, const FloatRect& srcRect,

why not write it out destinationContext or just destination.

[Dominik Röttsches (drott)]

Created attachment 158048 [details]
Copying buffer when src and dst are identical, v2.

[Dominik Röttsches (drott)]

Thanks Kenneth, updated patch with review comment addressed.

[WebKit Review Bot]

Comment on attachment 158048 [details]
Copying buffer when src and dst are identical, v2.

Clearing flags on attachment: 158048

Committed r125432: <http://trac.webkit.org/changeset/125432>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.