[whatwg] SVG extensions to <canvas>

Ian Hickson ian at hixie.ch
Thu Apr 30 12:15:04 PDT 2009

On Thu, 25 Oct 2007, Anne van Kesteren wrote:
> 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.

As far as I can tell this doesn't require any changes to HTML5, since the 
same applies here as applies to a regular <img>, right?

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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