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[whatwg] Canvas context.drawImage clarification

From: Oliver Hunt <oliver@apple.com>
Date: Fri, 10 Jul 2009 20:45:22 -0700
Message-ID: <3B19186D-948E-4358-A6FE-3B90D204B34C@apple.com>

On Jul 10, 2009, at 6:38 PM, Gregg Tavares wrote:

> On Thu, Jul 9, 2009 at 6:25 PM, Oliver Hunt <oliver at apple.com> wrote:
>> Inconsistency doesn't lead to no one depending on a behaviour, it  
>> just means sites only work in one browser.  Your suggesting would  
>> result in sites being broken in all browsers -- the only options  
>> from here on out are either nothing gets drawn (as in gecko and  
>> presto), or the destination is normalised (as in webkit).
>>
>> Or making it consistent when the DOCTYPE is set to something.
> API behaviour is not effected by the DOCTYPE, only parsing.   
> Unfortunately you can't change a DOM API that has existed for years  
> to something contradictory.
>
> I guess I don't understand. I'm new to the list so forgive me but I  
> thought HTML5 was still a working draft and that the canvas tag was  
> part of that draft. How is a draft immutable?

A reasonable amount of HTML5 is also defining existing behaviour --  
Canvas has been shipping in browsers for years now, it was introduced  
in Safari *2*, so there is actually existing content.

> ...
> Consistency and usefulness should win in this case. There is the  
> chance to make the spec unambiguous and more useful before canvas  
> becomes widely used.
I'm not arguing that i should not have specified behaviour, i'm merely  
saying that it needs to specify one of the actually accepted  
behaviour, it can't introduce a new one.

> I can't claim it's a bug if the spec doesn't define what the correct  
> behavior is.
I can't speak for the gecko canvas implementor, but if this were an  
issue in webkit i would want a bug so that the behavioural difference  
was recorded somewhere :D

--Oliver

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