Canvas: rotation of 'no-repeat' pattern is weird

• Component: WebCore Misc.
• Status: RESOLVED FIXED

[Shinichiro Hamaji]

Visit the URL: http://shinh.skr.jp/t/rotate-pattern.html
The face should rotate without displacement. With Safari4, the face moves randomly. Chrome (i.e., skia glue) and Firefox handles this properly.

I think the reason is the error of floating point in PatternCG.cpp. I'll send a patch for this.

[Shinichiro Hamaji]

Created attachment 31322 [details]
Patch v1

 LayoutTests/ChangeLog                              |   15 ++++++++++
 .../fast/canvas/image-object-in-canvas.html        |   11 ++++++-
 .../image-object-in-canvas-expected.checksum       |    2 +-
 .../canvas/image-object-in-canvas-expected.png     |  Bin 56436 -> 78642 bytes
 .../canvas/image-object-in-canvas-expected.txt     |   30 +++++++++++--------
 WebCore/ChangeLog                                  |   15 ++++++++++
 WebCore/platform/graphics/cg/PatternCG.cpp         |    9 +++--
 7 files changed, 63 insertions(+), 19 deletions(-)

[Shinichiro Hamaji]

Created attachment 31323 [details]
image-object-in-canvas-expected.png

[Oliver Hunt]

Comment on attachment 31322 [details]
Patch v1

For completeness can you replaced float xStep/yStep with CGFloat xStep/yStep, and i think we want the largest number possible so i think (1 << 23 - 1) rather than 1 << 21.

[Shinichiro Hamaji]

Created attachment 31490 [details]
Patch v2

 LayoutTests/ChangeLog                              |   15 ++++++++++
 .../fast/canvas/image-object-in-canvas.html        |   11 ++++++-
 .../image-object-in-canvas-expected.checksum       |    2 +-
 .../canvas/image-object-in-canvas-expected.png     |  Bin 56436 -> 78642 bytes
 .../canvas/image-object-in-canvas-expected.txt     |   30 +++++++++++--------
 WebCore/ChangeLog                                  |   15 ++++++++++
 WebCore/platform/graphics/cg/PatternCG.cpp         |    9 +++--
 7 files changed, 63 insertions(+), 19 deletions(-)

[Shinichiro Hamaji]

Comment on attachment 31490 [details]
Patch v2

Thanks for the review! I've modified the patch as you mentioned.

[Simon Fraser (smfr)]

I think olliej should review this.

[Oliver Hunt]

Comment on attachment 31490 [details]
Patch v2

r=me

[David Levin]

Assigned to levin for landing.

[Oliver Hunt]

Committing to http://svn.webkit.org/repository/webkit/trunk ...
	M	LayoutTests/ChangeLog
	M	LayoutTests/fast/canvas/image-object-in-canvas.html
	M	LayoutTests/platform/mac/fast/canvas/image-object-in-canvas-expected.checksum
	M	LayoutTests/platform/mac/fast/canvas/image-object-in-canvas-expected.txt
	M	WebCore/ChangeLog
	M	WebCore/platform/graphics/cg/PatternCG.cpp
Committed r44850