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[whatwg] "canvas" tag and animations ?

From: Ian Hickson <ian@hixie.ch>
Date: Tue, 8 May 2007 04:57:35 +0000 (UTC)
Message-ID: <Pine.LNX.4.62.0705080455530.15437@dhalsim.dreamhost.com>
On Tue, 16 May 2006, Andrew Fedoniouk wrote:
> > > |
> > > | Canvases are automatically double-buffered.
> > > 
> > > Why? Is this a requirement?
> > 
> > Not in theory, but in practice it is. Early Opera implementations 
> > didn't do this and the performance was too slow for practical use.
> 
> This does not mean that acceptable implementation without 
> double-buffering is not possible or does not make sense.
> 
> For simple cases like custom bullet for the list it makes sense to have 
> one of these (or combination of these):
>
> 1) non-buffered draw, small area to draw and simple image. If
>    buffered draw needed - use Image;
>
> 2) or to have getGraphics defined as
>    getGraphics("what",x,y,width, height, backgroundColor = transparent) or
>
> 3) or to be able to say for example
>    element.style.listStyleImage = new Image();
>
> 4) or in <style> to define
>    li {  list-style-image: url("script: nameOfVariableHoldingImage;");  }
> 
> (assumption was made that getGraphics/Canvas will be available for any 
> element)

I don't really understand. For bullets, <canvas> isn't really the right 
answer anyway. The expected use case for <canvas> is graphs, games, that 
kind of thing. I also don't see why double buffering would be bad even for 
bullets.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Monday, 7 May 2007 21:57:35 UTC

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