Bug 18821

Summary:

Canvas putImageData incorrect when data has alpha

Product:

WebKit

Reporter:

Philip Taylor <excors>

Component:

DOM

Assignee:

Dave Hyatt <hyatt>

Status:

RESOLVED FIXED

Severity:

Normal

Priority:

Version:

528+ (Nightly build)

Hardware:

OS:

Windows Vista

URL:

http://philip.html5.org/tests/canvas/misc/alpha-putimagedata.html

Attachments:

Description	Flags
Fix bugs in the loops of both get and putImageData	hyatt: review-
Fix bugs in the loops of both get and putImageData	eric: review+
Patch to fix the bug	eric: review+

Philip Taylor

Reported 2008-04-30 18:31:11 PDT

See test case in URL. It draws a very-transparent red column on the left, then fills the rest of the canvas with slightly-transparent green, then calls putImageData(getImageData(...), ...) which should have no effect. Expected output: alert box saying "0,255,0,254" (or maybe 253), alert box saying "0,255,0,254" (or maybe 253), green canvas. Actual output: alert box saying "0,255,0,253", alert box saying "255,0,0,253", red canvas. Tested on Windows r32574.

Attachments
Fix bugs in the loops of both get and putImageData (3.82 KB, patch) 2008-05-01 11:50 PDT, Dave Hyatt	hyatt: review-	Details Formatted Diff Diff
Fix bugs in the loops of both get and putImageData (2.08 KB, patch) 2008-05-01 11:51 PDT, Dave Hyatt	eric: review+	Details Formatted Diff Diff
Patch to fix the bug (5.11 KB, patch) 2008-05-05 11:19 PDT, Dave Hyatt	eric: review+	Details Formatted Diff Diff
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.

Dave Hyatt

Comment 1 2008-05-01 11:50:41 PDT

Created attachment 20914 [details] Fix bugs in the loops of both get and putImageData

Dave Hyatt

Comment 2 2008-05-01 11:51:57 PDT

Created attachment 20915 [details] Fix bugs in the loops of both get and putImageData

Eric Seidel (no email)

Comment 3 2008-05-01 19:41:15 PDT

Comment on attachment 20915 [details] Fix bugs in the loops of both get and putImageData Needs a test case and changelog when you land. Otherwise fine.

Dave Hyatt

Comment 4 2008-05-05 11:19:38 PDT

Created attachment 20971 [details] Patch to fix the bug

Eric Seidel (no email)

Comment 5 2008-05-05 11:27:45 PDT

Comment on attachment 20971 [details] Patch to fix the bug Looks saner. Still needs a ChangeLog when landing.

Dave Hyatt

Comment 6 2008-05-05 11:29:58 PDT

Fixed in r32878.

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