[whatwg] Still more comments and questions on Web Apps 1.0

[Ian Hickson]

On Sun, 10 Jun 2007, Maciej Stachowiak wrote:
> On Jun 8, 2007, at 6:05 PM, Ian Hickson wrote:
> > 
> > > I am not an expert here, but IIRC, the underlying PDF/Quartz imaging 
> > > model does not allow general xoring. I think it is important to 
> > > ensure that canvas can be implemented on top a Quartz 2D drawing 
> > > context on OS X without breaking hardware acceleration or PDF 
> > > output.
> > 
> > I can drop 'xor', I guess...
> 
> PDF can't actually do the other porter-duff operators either (except 
> SrcOver). Instead it has a different concept of "blend modes" which are 
> supposedly more general but can't actually synthesize the porter-duff 
> operators. However, on OS X the 'xor' operator will be supported at 
> least as well on any given graphics context as, say, SrcAtop or 
> DestAtop. In practice what happens on graphics contexts that can't 
> natively support the operator is that a bitmap is generated.
> 
> I would recommend against dropping XOR.

Ok, 'xor' remains.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'