[whatwg] [canvas] imageRenderingQuality property

[Vladimir Vukicevic]

I'd like to propose adding an imageRenderingQuality property on the  
canvas 2D context to allow authors to choose speed vs. quality when  
rendering images (especially transformed ones).  This is modeled on  
the SVG image-rendering property, at http://www.w3.org/TR/SVG/painting.html#ImageRenderingProperty 
:

   attribute string imageRenderingQuality;

'auto' (default): The user agent shall make appropriate tradeoffs to  
balance speed and quality, but quality shall be given more importance  
than speed.

'optimizeQuality': Emphasize quality over rendering speed.

'optimizeSpeed': Emphasize speed over rendering quality.

No specific image sampling algorithm is specified for any of these  
properties, with the exception that, at a minimum, nearest-neighbour  
resampling should be used.  One alternative is to specify 'best',  
'good', 'fast', with "good" being the default, as opposed to the SVG  
names; I think those names are more descriptive, but there might be  
value in keeping the names consistent with SVG, especially if that  
property bubbles up into general CSS usage.

     - Vlad