307021 - globalCompositeOperation option darker renders incorrectly

Status: RESOLVED WONTFIX

(Core :: Graphics: Canvas2D, defect, P2)

Description

[Kamiel Martinet]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b4) Gecko/20050903 Firefox/1.0+
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b4) Gecko/20050903 Firefox/1.0+

Currently in the trunk builds source-over and darker don't render correctly.
According to the specification this should render the source on top of the
destination image. In my testcase this renders just as copy does. As far is I
can tell from the source 'over' is currently the default (which renders
correctly) but should be 'source-over'.

The option darker seems to do nothing at the moment

Reproducible: Always

Steps to Reproduce:
1. See testcase
2.
3.

Actual Results:  
'source-over' : Only one blue circle is drawn.
'darker' : Same as default

Expected Results:  
'source-over' : two circles one blue on top of red
'darker' : Two circles one blue and one red. The overlapping sections should be
rendered darker

Comment 1

[Kamiel Martinet]

Attachment: Testcase

My testcase (Note all options for globalCompositeOperation are included)

Comment 2

[Kamiel Martinet]

Attachment: My result

My results in the 1.6a firefox trunk build

Comment 3

[Joe Drew (not getting mail)]

Darker, lighter, and copy all seem broken right now.

Comment 4

[Takeshi Kurosawa :takenspc]

(In reply to comment #3)
> Darker, lighter, and copy all seem broken right now.
> 

Lighter seems ok.
http://mxr.mozilla.org/seamonkey/source/content/canvas/src/nsCanvasRenderingContext2D.cpp#2048 says
> // XXX "darker" isn't really correct

And darker was removed from the spec.
http://www.whatwg.org/specs/web-apps/current-work/multipage/section-the-canvas.html#globalcompositeoperation
http://www.w3.org/TR/2008/WD-html5-20080122/#compositing

Comment 5

[Takeshi Kurosawa :takenspc]

Attachment: Updated testcase

Updated testcase taking into some canvas path spec changes.

Comment 6

[Takeshi Kurosawa :takenspc]

Anyway |source-over| works fine.
-> Remove |source-over| from the summary

Comment 7

[Kamiel Martinet]

Attachment: Testcase

fixed a script error

Comment 8

[Kamiel Martinet]

Attachment: Firefox 3 (windows xp) test results

Results for Firefox 3: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9) Gecko/2008052906 Firefox/3.0

Comment 9

[Alan Thomas]

Per comment 4, "darker" seems to have been well and truly removed from the (draft) HTML5 specification. I can see no reason why development work should be put into supporting something not on the spec. 

For the record, Opera does not implement this (or has dropped it); WebKit may still implement it; IE9 does not even support globalCompositeOperation.

Closing as WONTFIX; feel free to re-open if you have a good reason.