[whatwg] I believe source rectangles for HTML5 Canvas drawImage are specified incorrectly

Ian Hickson ian at hixie.ch
Wed Dec 12 10:16:20 PST 2012

On Wed, 12 Dec 2012, Rik Cabanier wrote:
> What would be the next step? Should we define a new version of drawImage 
> with the extra parameter?

At the WHATWG, the process, insofar as there is one, is that the spec's 
editor (in this case me) goes through the e-mails on a topic and edits the 
spec based on the feedback and based on how much vendor buy-in an issue has.

On this particular topic, I've only heard interest in implementing this 
from one vendor, Google, so adding support to the spec at this point is 
probably premature. If other vendors are interested in implementing 
something for this (a feature to make drawImage scale subsets with 
clamping at the source rectangle rather than the original image), I 
encourage them to indicate this on this thread.

> If so, we probably want the description of the existing drawImage call 
> to change so it leaves the resampling issue undefined unless WebKit is 
> OK with changing their current behavior.

Leaving the spec undefined is not acceptable. :-)

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

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