Bug 18821 - Canvas putImageData incorrect when data has alpha
Summary: Canvas putImageData incorrect when data has alpha
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: DOM (show other bugs)
Version: 528+ (Nightly build)
Hardware: PC Windows Vista
: P2 Normal
Assignee: Dave Hyatt
URL: http://philip.html5.org/tests/canvas/...
Keywords:
Depends on:
Blocks:
 
Reported: 2008-04-30 18:31 PDT by Philip Taylor
Modified: 2008-05-05 11:29 PDT (History)
0 users

See Also:

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 an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description Philip Taylor 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.
Comment 1 Dave Hyatt 2008-05-01 11:50:41 PDT 
Created attachment 20914 [details]
Fix bugs in the loops of both get and putImageData
Comment 2 Dave Hyatt 2008-05-01 11:51:57 PDT 
Created attachment 20915 [details]
Fix bugs in the loops of both get and putImageData
Comment 3 Eric Seidel (no email) 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.
Comment 4 Dave Hyatt 2008-05-05 11:19:38 PDT 
Created attachment 20971 [details]
Patch to fix the bug
Comment 5 Eric Seidel (no email) 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.
Comment 6 Dave Hyatt 2008-05-05 11:29:58 PDT 
Fixed in r32878.