[whatwg] Opera canvas bug?

Ian Hickson ian at hixie.ch
Thu May 10 19:19:54 PDT 2007

On Sun, 1 Oct 2006, Benjamin Joffe wrote:
> I have set up a few pages to demonstrate bugs with Opera's canvas 
> implementation. You can see it here: 
> http://abrahamjoffe.com.au/ben/opera_canvas_bugs/index.htm , I am sure 
> that the first 3 are genuine Opera bugs but the 4th one might not be 
> because I do not think that the WhatWG spec is specific enough with 
> nested clipping paths, none-the-less I feel that the way Firefox handles 
> the script is more correct than how Opera does. Would you agree?

The first test is:


Definitely an Opera bug. I've added a test based on this to my test suite:


The second test:


...is actually a bug in Firefox and Safari:


The third test:


...seems to work everywhere now.

The fourth test:


...is indeed an Opera bug. The spec seems clear, though:

# The clip() method must create a new clipping path by calculating the 
# intersection of the current clipping path and the area described by the 
# current path (after applying the current transformation), using the 
# non-zero winding number rule.

Is that confusing?

I've created this test:


...based on your test.

The fifth and final test:


...seems to work everywhere now.

Thanks for the feedback,
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
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