Bug 32405

Summary: [Qt] canvas clipping is buggy
Product: WebKit Reporter: Noam Rosenthal <noam>
Component: WebKit QtAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Major CC: ariya.hidayat, benjamin, commit-queue, cshu, hausmann, laszlo.gombos, noam
Priority: P2 Keywords: Qt
Version: 528+ (Nightly build)   
Hardware: PC   
OS: All   
Attachments:
Description Flags
Fix GraphicsContext::roundToDevicePixels in Qt none

Noam Rosenthal
Reported 2009-12-10 20:11:02 PST
test case: http://glimr.rubyforge.org/cake/canvas.html, choose ImageTest in the combo box The image rotates and moves very slowly and with a lot of artifacts and flickers, compared to Safari/Chrome.
Attachments
Fix GraphicsContext::roundToDevicePixels in Qt (3.16 KB, patch)
2010-02-13 19:11 PST, Noam Rosenthal 		no flags
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Benjamin Poulain
Comment 1 2009-12-11 05:21:49 PST
Confirmed. Here is the direct link to the test : http://glimr.rubyforge.org/cake/canvas.html#KeyboardTest The image should not be clipped when transformed.
Noam Rosenthal
Comment 2 2010-02-13 19:11:12 PST
Created attachment 48713 [details] Fix GraphicsContext::roundToDevicePixels in Qt I found the source of the problem - our GraphicsContext::roundToDevicePixels function is wrong, as it doesn't make the right calculation in the case of rotating images. The attached fix makes that function completely equivalent to the CG implementation, and rotating canvas images now look fine!
Simon Hausmann
Comment 3 2010-02-15 07:14:23 PST
Nice! I've seen this bug a few times in the past. Any chance that this is also covered by an existing but currently skipped canvas layout test? Adding Ariya to CC, he's more qualified than me to review this piece :)
Ariya Hidayat
Comment 4 2010-02-16 00:30:31 PST
Comment on attachment 48713 [details] Fix GraphicsContext::roundToDevicePixels in Qt Looks good.
WebKit Commit Bot
Comment 5 2010-02-16 01:17:50 PST
Comment on attachment 48713 [details] Fix GraphicsContext::roundToDevicePixels in Qt Clearing flags on attachment: 48713 Committed r54811: <http://trac.webkit.org/changeset/54811>
WebKit Commit Bot
Comment 6 2010-02-16 01:18:03 PST
All reviewed patches have been landed. Closing bug.
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