[whatwg] Canvas pixel manipulation and performance
kbr at google.com
Sun Nov 29 11:21:27 PST 2009
On Sun, Nov 29, 2009 at 11:05 AM, Philip Taylor <excors+whatwg at gmail.com> wrote:
> On Sun, Nov 29, 2009 at 6:59 PM, Kenneth Russell <kbr at google.com> wrote:
>> On Sat, Nov 28, 2009 at 9:47 PM, Boris Zbarsky <bzbarsky at mit.edu> wrote:
>>> Are they even byte stores, necessarily? I know in Gecko imagedata is just a
>>> JS array at the moment; it stores each of R,G,B,A as a JS Number (with the
>>> usual "if it's an integer store as an integer" optimization arrays do).
>>> That might well change in the future, and I hope it does, but that's the
>>> current code.
>>> I can't speak to what the behavior is in Webkit, and in particular whether
>>> it's even the same when using V8 vs Nitro.
>> In Chromium (WebKit + V8), CanvasPixelArray property stores write
>> individual bytes to memory. WebGLByteArray and WebGLUnsignedByteArray
>> behave similarly but have simpler clamping semantics.
> Would it be helpful (for simplicity or performance or consistency etc)
> to change the specification of CanvasPixelArray to have those "simpler
> clamping semantics"? (I don't expect there would be compatibility
> problems with changing it now, particularly since Firefox doesn't
> implement clamping at all in CPA.)
It would. Vladimir Vukicevic from Mozilla was planning to raise this
issue with the whatwg upon release of the first public draft of the
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