[whatwg] [canvas] imageRenderingQuality property

Oliver Hunt oliver at apple.com
Tue Jul 1 01:37:06 PDT 2008

Yeah, Philip has been slowly convincing me that something like  
imageRenderingQuality with high and auto values* would be useful,  
basically for reasons similar to what you just gave.  I still don't  
believe there should be a "low" option, because (as i have said  
before) the author is not in a position to be able to determine what  
performance tradeoffs are involved in the users system.


* This property was suggested by Philip Taylor in an earlier email

On Jul 1, 2008, at 1:18 AM, Kristof Zelechovski wrote:

> The image rendering quality property is indeed unable to hit the  
> tradeoff
> between beauty of presentation and rendering speed.  However, it is
> perfectly all right to say 'this content is some fancy GUI can be  
> rendered
> downscaled without degrading the content - but that content contains
> engineering drawings that must be rendered as accurately as can  
> be.'  This
> is semantic information the browser has no way of inferring.
> Cheers,
> Chris
> -----Original Message-----
> From: whatwg-bounces at lists.whatwg.org
> [mailto:whatwg-bounces at lists.whatwg.org] On Behalf Of Oliver Hunt
> Sent: Tuesday, July 01, 2008 2:18 AM
> To: Mark Finkle
> Cc: Vladimir Vukicevic; Robert O'Callahan; WHATWG; David Hyatt;  
> Jerason
> Banes; Ian Hickson; Robert O'Callahan
> Subject: Re: [whatwg] [canvas] imageRenderingQuality property
>> So now we need to define levels of graphic burden? and at what level
>> of burden does the quality suffer? Seems just as hard to define.
>> Having the author explicit say "this has to be as high quality as
>> possible" or "less can be low quality" seems better and we have
>> examples of other specs offering the same kind of control.
> No.  The whole point is that the UA is in the best position to
> identify what the tradeoffs are, not the author -- if you want a flag
> to specify the quality to be used then that would require you to
> determine what the tradeoffs were yourself, with no substantial
> knowledge of what combination any given user was actually using.  You
> need to realise that different UAs and different platforms have
> substantially different performance characteristics.

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