error in compositing with globalCompositeOperation copy using drawimage and fillrect




Canvas: 2D
7 years ago
7 years ago


(Reporter: Martin Braun, Unassigned)


Firefox Tracking Flags

(Not tracked)



(4 attachments, 1 obsolete attachment)



7 years ago
User-Agent:       Mozilla/5.0 (Windows NT 6.1; rv:2.0) Gecko/20100101 Firefox/4.0
Build Identifier:

Compositing with globalCompositeOperation="copy" seems to be flawed in FF4.0RC2.

Please see the attached screenshots and code for details.

The behaviour is correct in FF3.6 and Chrome 11. 
InternetExplorer 9.0 and Opera 11 behave the same as FF4.0.

Note: The shown case might be a corner case not explicitly formulated in the HTML5 Specification thus it might be controversial if this is a bug. Also so far i have not found any official test cases checking for this case.
I believe however the behaviour in FF3.6 and Chrome 11 is correct.

Reproducible: Always

Actual Results:  
see attachments

Comment 1

7 years ago
Created attachment 520757 [details]
test case - jquery required

Comment 2

7 years ago
Created attachment 520759 [details]
chrome 11 screenshot

Comment 3

7 years ago
Created attachment 520760 [details]
ff4 rc2 screenshot

Comment 4

7 years ago
Created attachment 520761 [details]
ff 3.6 screenshot

Comment 5

7 years ago
Created attachment 520880 [details]
test case
Attachment #520757 - Attachment is obsolete: true
For that testcase, the behavior change range is:

So presumably this is a result of bug 366283.

If I read that bug correctly, this is a purposeful change to match what the canvas spec says.
Blocks: 366283
Yes, FF4, IE9 and Opera 11 are following the spec, and Chrome and FF3.6 are not.
Last Resolved: 7 years ago
Resolution: --- → INVALID
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