[webkit-dev] Canvas performance and memory usage

Jakob Petsovits jpetso at gmx.at
Tue Sep 14 14:20:20 PDT 2010

On August 16, 2010, David Hyatt wrote:
> There is a temporary method implemented by all ports called:
> 		bool drawsUsingCopy() const; // If the image buffer has to render 
using a
> copied image, it will return true.
> This method only exists right now because some of the ports are still
> copying.  Once everyone has switched over to drawing the image buffer
> without making copies, then I can remove this method from the interface. 
> HTMLCanvasElement is using it in order to cache a copy of the image for
> repeated drawing of a static canvas, so that the "copying" platforms don't
> suffer a performance degradation from my changes.

The OpenVG backend (should I ever get around to spare some more time 
reorganizing my commits and upstreaming more of it) will always need a copying 
fallback, because the size of the ImageBuffer might exceed the maximum OpenVG 
image size. So there's a fallback code path that uses plain EGL pbuffer 
surfaces instead, for which there is no formal maximum size, unless it's an 
implementation-specific one.


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