[whatwg] [canvas] imageRenderingQuality property
hyatt at apple.com
Mon Jun 2 14:26:41 PDT 2008
I like the idea of this property. I actually would love to see the
SVG property applied to HTML <img> as well. :)
On Jun 2, 2008, at 4:15 PM, Vladimir Vukicevic wrote:
> Sure; bilinear filtering is slower than nearest neighbour sampling,
> and in many cases the app author would like to be able to decide
> that tradeoff (or, at least, to be able to say "I want this to go as
> fast as possible, regardless of quality"). Some apps might also
> render to a canvas just once, and would prefer to do it at the
> highest quality filtering available even if it's more expensive than
> the default.
> - Vlad
> On Jun 2, 2008, at 12:25 PM, Oliver Hunt wrote:
>> Um, could you actually give some kind of reasoning for these? I am
>> not aware of any significant performance issues in Canvas that
>> than the canvas.
>> On Jun 2, 2008, at 12:19 PM, Vladimir Vukicevic wrote:
>>> 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
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