Bug 16859

Summary: Canvas repaints too much
Product: WebKit Reporter: Oliver Hunt <oliver>
Component: Layout and RenderingAssignee: Oliver Hunt <oliver>
Status: RESOLVED FIXED    
Severity: Normal CC: eric, hyatt
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: All   
OS: All   
Attachments:
Description Flags
Very very preliminary patch
none
Real patch oliver: review+

Oliver Hunt
Reported 2008-01-13 01:00:28 PST
whenever the graphics context of a canvas is updated, it marks the entire element as needing an update, regardless of actual need.
Attachments
Very very preliminary patch (1.47 KB, patch)
2008-01-13 01:03 PST, Oliver Hunt 		no flags
DetailsFormatted DiffDiff
Real patch (3.38 KB, patch)
2008-01-13 04:12 PST, Oliver Hunt 		oliver: review+
DetailsFormatted DiffDiff
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.
Oliver Hunt
Comment 1 2008-01-13 01:03:23 PST
Created attachment 18418 [details] Very very preliminary patch This is just a proof of triviality patch, it works correctly afaict, however someone else may want to test. Here are the problems: * i don't have a machine that is slow enough for a full canvas repaint to be more significant than the 10ms minimum timer interval * This is a hack job, and needs to be tidied up and made cross platform (currently it blindly assumes CG is present).
Oliver Hunt
Comment 2 2008-01-13 02:47:14 PST
Okay further investigation has shown a gain when the canvas is very large (eg. 1000x1000), but also when scaled in css, eg. <canvas width="1000" height="1000" style="width:500px; height: 500px" ></canvas> there is a substantial benefit *provided* the painting is spread out suffuciently or over a compact enough region to prevent repaint rect coalescing from effectively repainting the entire canvas
Oliver Hunt
Comment 3 2008-01-13 04:12:24 PST
Created attachment 18421 [details] Real patch Here we go, fresh off the compiler
Oliver Hunt
Comment 4 2008-01-13 05:22:43 PST
Comment on attachment 18421 [details] Real patch REviewed with comments by mark Landed 29448
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