[whatwg] [canvas] imageRenderingQuality property
David Hyatt
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. :)
dave
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
>> cannot be almost directly attributed to JavaScript itself rather
>> than the canvas.
>>
>> --Oliver
>>
>> 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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