- From: Oliver Hunt <oliver@apple.com>
- Date: Sat, 10 May 2008 19:38:00 -0700
On May 10, 2008, at 7:13 PM, Vladimir Vukicevic wrote:
>
> On May 10, 2008, at 5:44 PM, Oliver Hunt wrote:
>>
>> On May 10, 2008, at 4:53 PM, Vladimir Vukicevic wrote:
>>
>>> Another approach would be to not try to solve this in canvas at
>>> all, and instead specify that by default, all canvas elements are
>>> 96dpi, and provide authors a way to explicitly override this --
>>> then using a combination of CSS Media Queries and other CSS, the
>>> exact dpi desired could be specified. (You can sort of do this
>>> today, given that the canvas width/height attributes are in CSS
>>> pixels, and that if CSS dimensions are present a canvas is scaled
>>> like an image... so canvas { width: 100px; height: 100px; } ...
>>> <canvas width="200" height="200"/> would give a 192dpi canvas
>>> today, no?)
>>
>> Canvas was designed with the intent of allowing resolution
>> independent, removing that intent in the name of a feature that is
>> not used in the general case seems to be a fairly substantial step
>> back from that goal. Unfortunately the "solution" of using a
>> larger canvas scaled to fit a smaller region isn't a real
>> solution. For lower resolution displays it results in higher
>> memory usage and greater computational cost than is otherwise
>> necessary, and for high dpi displays it results either the same
>> issues as the low dpi case (if the canvas resolution is still too
>> high) or it results in a lower resolution display than the display
>> is capable of.
>
> Eh? The resolution used should be whatever the appropriate
> resolution should be; I'm certainly not suggesting that everyone
> unilaterally create canvases with 2x pixel resolution, I'm saying
> that the features exist to allow authors to (dynamically) create a
> canvas at whatever the appropriate resolution is relative to CSS
> resolution.
Ah, sorry for my misunderstanding. :-(
This still isn't ideal as it requires offloading such logic onto web
developers.
> Canvas was designed to allow for programmatic 2D rendering for web
> content; resolution independence would certainly be nice, but it was
> never a goal of the canvas spec. In fact, the spec explicitly
> states that the "canvas element represents a resolution-dependent
> bitmap canvas".
Yes, in that once you draw to a canvas you can't just scale the canvas
up and expect everything to remain crisp -- the only API's for which
this is a problem are the ImageData ones.
>
>
> - Vlad
>
Received on Saturday, 10 May 2008 19:38:00 UTC