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
