[whatwg] SVG extensions to <canvas>

Vlad Alexander (xhtml.com) vlad.alexander at xhtml.com
Thu Oct 25 12:35:49 PDT 2007

Anne, on a semi-related topic, can you please help me understand why Opera does not scale the SVG image when loaded via IMG element? Here is a test page:



-------- Original Message --------
From: Anne van Kesteren
Date: 2007-10-25 2:58 PM
> Hi,
> (Please reply to either HTML or WHATWG list.)
> For Opera 9.5 beta we implemented some experimental extensions to 
> <canvas> involving SVGSvgElement. SVGSvgElement is supported as "image" 
> argument to both drawImage and createPattern. (An HTMLImageElement 
> pointing to an SVG element is also supported, but that seems natural if 
> you support SVG from <img>.)
> For drawImage the pixel size of the SVG is determined as follows:
>   1. The image size parameters passed to drawImage
>   2. The intrinsic size of the SVG image
>   3. 300 x 150
> For createPattern it is as follows:
>   1. The intrinsic size of the SVG image
>   2. 300 x 150
> (It would be nice if createPattern was extended to allow height/width 
> arguments as well.)
> The intrinsic size of the SVG image is the specified size with 
> percentages resolved against 300 x 150, and sizes depending on the 
> font-size resolved against the computed font-size of the SVGSvgElement 
> (will be the browser default most of the time).
> The SVG image is always rendered at time 0 for animated images.
> Drawing an SVG image currently marks the canvas context as unsafe so 
> toDataURL() and getImageData() throw. We expect to make this story a bit 
> nicer at some point.
> Cheers,

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