[whatwg] createImageData
Oliver Hunt
oliver at apple.com
Tue May 13 14:58:31 PDT 2008
On May 13, 2008, at 1:53 PM, Vladimir Vukicevic wrote:
> The first argument to the method must be an ImageData object
> returned by createImageData(), getImageData(), or an object
> constructed with the necessary properties by the user. If the
> object was constructed by the user, its width and height dimensions
> are specified in device pixels (which may not map directly to CSS
> pixels). If null or any other object is given that does not present
> the ImageData interface, then the putImageData() method must raise a
> TYPE_MISMATCH_ERR exception.
If we were to add that we should include a note to indicate that using
a custom object is not recommended -- Any code that uses a custom
created object will never benefit from improvements in ImageData
performance made by the UA. That said I still don't believe custom
objects should be allowed, aside from the resolution (which may or may
not be relevant) and performance issues, a custom object with a
generic JS array, rather than an ImageData object will have different
behaviour -- a proper ImageData will clamp on assignment, and throw in
cases that a custom object won't.
>
> - Vlad
>
--Oliver
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