are failing on GTK bots since added.
I can not build Cairo graphics port. In the past, beginTransparencyLayer created a new paint mask for GraphicsContextCairo. This was basically doing what CG does: creating a new layer that is composited with an alpha value afterwards. I wonder why this would not work anymore. Could you send screenshots of https://developer.mozilla.org/samples/canvas-tutorial/6_1_canvas_composite.html please?
Created attachment 228811 [details]
Stroke compositing test
Sorry, please upload an image for the attached test.
Created attachment 228816 [details]
WebKitGTK stroke compositing test
This is the screenshot of stroke compositing test that ran on MiniBrowser of WebKitGTK+.
(In reply to comment #3)
> Created an attachment (id=228816) [details]
> WebKitGTK stroke compositing test
> This is the screenshot of stroke compositing test that ran on MiniBrowser of WebKitGTK+.
It looks like destination-atop and source-out improved by the patch. Source-in and destination-in are incorrect. Since the other cases work, it seems more like a bug in Cairo graphics.
fixed by the dependent bug.