[whatwg] Canvas in Workers

Ian Hickson ian at hixie.ch
Tue Dec 11 09:04:05 PST 2012

On Tue, 11 Dec 2012, Gregg Tavares (社ç~T¨) wrote:
> discussion seems to have died down here but I'd like to bring up another
> issue
> In WebGL land we have creation attributes on the drawingbuffer made for a
> canvas. Example
>     gl = canvas.getContext("webgl", { preserveDrawingBuffer: false });
> We're working out the details on how to set those options for the case
> where we have 1 context and multiple canvases.
> The particular option above would apparently be a huge perf win for 
> canvas 2d for mobile. Which suggests that whatever API is decided on it 
> would be nice if it worked for both APIs the same.

What does it do?

In the 2D canvas, whenever you bind to a new canvas, the context is reset 
to its default state, the context's hit region list is reset, and the 
context's bitmap is reset. The next time the context is flushed, the 
canvas itself is always reset (since flushing the context causes the 
bitmap and hit region list to be pushed to the canvas, replacing whatever 
was there before).

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

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