[webkit-reviews] review requested: [Bug 25417] Skia CompositeCopy should be mapped to kSrc_Mode not kSrcOver_Mode. : [Attachment 30207] Adding layout test

[bugzilla-daemon at webkit.org]

Shinichiro Hamaji <hamaji at google.com> has asked  for review:
Bug 25417: Skia CompositeCopy should be mapped to kSrc_Mode not kSrcOver_Mode.
https://bugs.webkit.org/show_bug.cgi?id=25417

Attachment 30207: Adding layout test
https://bugs.webkit.org/attachment.cgi?id=30207&action=review

------- Additional Comments from Shinichiro Hamaji <hamaji at google.com>
Added test cases except for alpha=0 case. When alpha is zero, some graphic
engine does nothing for optimization but it's not correct behavior for some
composite operations such as copy.
I also updated the function which compares the value of RGB in layout test so
that this compares the actual colors users see (it compares [R*A, G*A, B*A]
instead of [R, G, B]). I did this because Skia's outputs have some errors due
to optimization for the cases alpha is small.