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[whatwg] getImageData/putImageData comments

From: Robert O'Callahan <robert@ocallahan.org>
Date: Mon, 1 Jun 2009 16:08:53 +1200
Message-ID: <11e306600905312108t34eb1879q4ccb583c3195c8a8@mail.gmail.com>
On Mon, Jun 1, 2009 at 3:47 PM, Boris Zbarsky <bzbarsky at mit.edu> wrote:

> Oliver Hunt wrote:
>
>>   Worse yet, the current setup means that a script that tries
>>>   createImageData, fill in the pixels, and then paint it to the
>>>   canvas, needs to fill different numbers of pixels depending on the
>>>   output device.  I fully expect script authors to get this very very
>>>   wrong, since it's such non-intuitive behavior.  It would make more
>>>   sense to just have the script work entirely in CSS pixels; if it
>>>   wishes to create a higher-resolution image it can create a canvas
>>>   with bigger dimensions (and scale its actual display via setting
>>>   its width and height CSS properties).
>>>
>> This has been discussed heavily before.
>>
>
> Pointer, please.


Here are a couple of relevant threads:
http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2007-May/011284.html
http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2008-February/013906.html
Then there was a discussion on #whatwg more recently.
http://krijnhoetmer.nl/irc-logs/whatwg/20090326#l-263

So far it seems the data supports the hypothesis that authors expect
getImageData to return 1 image pixel per CSS pixel and their scripts break
when that's not true. That won't change until authors all have high-dpi
screens.

Actually I thought I'd won Ollie over on this:
http://krijnhoetmer.nl/irc-logs/whatwg/20090326#l-367

Rob
-- 
"He was pierced for our transgressions, he was crushed for our iniquities;
the punishment that brought us peace was upon him, and by his wounds we are
healed. We all, like sheep, have gone astray, each of us has turned to his
own way; and the LORD has laid on him the iniquity of us all." [Isaiah
53:5-6]
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