For reference desktop webkit implementations will automatically increase the canvas backing store resolution as the device:css pixel ratio increases.
--Oliver On Mar 4, 2011, at 1:44 AM, Charles Pritchard wrote: > On 3/4/2011 1:35 AM, Kenneth Rohde Christiansen wrote: >> Hi again, >> >>> I'm trying to keep the canvas bitmap at the same pixel resolution as the >>> device, >>> otherwise it is blurry. >> OK, I see. >> >>> This, for example, works if the pixel ratio is 2. >>> <canvas style="width: 100px; height: 100px;" width="200" >>> height="200"></canvas> >>> >>> Yes, when the user has a zoom level set, I'd like to paint to match the >>> pixel ratio, >>> so that, a zoomed in user still receives crisp output, instead of blurry >>> output. >> -webkit-device-pixel-ratio does not change when the user scaled the >> content; it is a device value. >> >> On old iPhone it is 1.0, on Android it can be 0.5, 1.0 and 1.5 >> depending on it being a low, medium (160) or high dpi (240) device. On >> the iPhone 4 and the new iPod Touch it is 2.0. >> >> On Android devices, with for instance, a device-pixel-ratio of 1.5, >> you can disable the upscaling by adding target-densitydpi=device-dpi >> to the viewport meta tag. >> >> What you can do is to disable user scaling (add user-scaling=no to the >> viewport meta tag) and then handle zooming in your app using the touch >> events. This only works on mobile devices though. > > I haven't debugged with enough tablet devices, such as the color kindle, to > know how many webkit distros it works with. > What should I do about user zoom on the desktop (and possibly, the kindle) ? > > Drawing in high res, just-in-case, makes for a poorer experience for users at > a 1.0 ratio, > and asking users to slide a "sharpen" slider is a little awkward. > > Mozilla, in their implementation, has setup device-pixel-ratio to scale when > the user scales content; > they directly expose window css pixel ratio value to trusted scripts, but not > to web content; requiring > web content to use css device-pixel-ratio. > > Microsoft has exposed the values through window.screen. > > > > -Charles > _______________________________________________ > webkit-dev mailing list > webkit-dev@lists.webkit.org > http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
