[whatwg] I believe source rectangles for HTML5 Canvas drawImage are specified incorrectly

Jeff Muizelaar jmuizelaar at mozilla.com
Mon Sep 10 15:06:08 PDT 2012


On 2012-09-10, at 5:28 PM, Justin Novosad wrote:

> 
> On Mon, Sep 10, 2012 at 4:49 PM, Jeff Muizelaar <jmuizelaar at mozilla.com> wrote:
> 
> On 2012-09-10, at 3:43 PM, Vladimir Vukicevic wrote:
> 
> 
> FWIW, there are also negative performance implications to clamping samples to the source rect. Many graphics APIs do not support this kind sampling, and supporting this behaviour on top of those apis requires a temporary copy of the subimage to be made.
> 
> 
> You are referring to the fact that clamping modes only apply to texture borders in OpenGL and DirectX?  That is not that big of a big deal, you can implement the clamp in a shader.

No, I was referring to CoreGraphics, Cairo and Direct2D.

-Jeff


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