[whatwg] Proposal: ImageData constructor or factory method with preexisting data
ian at hixie.ch
Fri Aug 9 14:34:35 PDT 2013
On Fri, 9 Aug 2013, Rik Cabanier wrote:
> On Fri, Aug 9, 2013 at 1:32 PM, Ian Hickson <ian at hixie.ch> wrote:
> > On Mon, 11 Mar 2013, Kenneth Russell wrote:
> > >
> > > It would be useful to be able to create an ImageData  object with
> > > preexisting data. The main use case is to display arbitrary data in
> > > the 2D canvas context with no data copies.
> > Doesn't ImageBitmap support this already? I'm not sure I understand
> > the use case here. Where are you getting the image data from, that
> > it's already in raw RGBA form rather than compressed e.g. as a PNG?
> > (Presumably this isn't coming over the network, since I would imagine
> > the time to compress and decompress an image is far smaller than the
> > time to send uncompressed data. But maybe I'm wrong about that.)
> From re-reading the thread, it seems that this data comes from the
> server (or a web worker?) as uncompressed data. The http protocol likely
> did compression on the packets so the size difference is probably not
> that great.
> I think the use-case is to avoid having to copy over the data pixel by
> pixel from the arraybuffer.
Could you elaborate on the use case?
I'm happy to believe that there are times that a server or worker is
generating lots of pixel data, but having never run into such a case
myself, I would very much like to understand it better. It may be that
there are better solutions to the real underlying problem.
Ian Hickson U+1047E )\._.,--....,'``. fL
http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,.
Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
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