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Re: Canvas in SVG, was: Re: minutes, SVG WG Seattle F2F 2011 day 1

From: Charles Pritchard <chuck@jumis.com>
Date: Fri, 29 Jul 2011 12:17:40 -0700
Message-ID: <4E330754.6080305@jumis.com>
To: Boris Zbarsky <bzbarsky@MIT.EDU>
CC: www-svg@w3.org
On 7/29/2011 8:03 AM, Boris Zbarsky wrote:
> On 7/29/11 9:04 AM, Alex Danilo wrote:
>> *<canvas>  in SVG defaults to retained mode, i.e. we can have an 
>> attribute
>>     or property retain="retain|discard" that controls what happens to 
>> the
>>     drawing commands on the canvas when resize/zoom occurs.
>
> As proposed (using a replay buffer) this can very easily leak to 
> effectively leaking lots of memory for the page lifetime, and would 
> for most canvas uses I've seen, unless browsers implement complicated 
> heuristics to detect when they can drop things from the buffer because 
> the entire area covered by them has since been painted over with 
> opaque colors.
>
> As an implementor I would be very wary of implementing this, assuming 
> I were willing to do it at all...

And it still turns foul when dealing with ImageData-based filters.

I think we may most -easily- be able to get Canvas into SVG by 
restricting it to the defs as other paint servers are.
As for resolution management, I think that's something that the author 
will have to manage.

Canvas, unlike other tags, requires that the viewer have scripting enabled.
Fallback paint servers should be considered.
http://www.w3.org/Graphics/SVG/WG/track/issues/2040


-Charles
Received on Friday, 29 July 2011 19:18:20 GMT

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