- From: Oliver Hunt <oliver@apple.com>
- Date: Fri, 25 Jan 2008 15:05:19 -0800
Ah true I had forgotten that, however this still fails for non- integral ratios :-/ --Oliver On Jan 25, 2008, at 3:05 PM, Anne van Kesteren wrote: > On Fri, 25 Jan 2008 23:57:56 +0100, Oliver Hunt <oliver at apple.com> > wrote: >> Another thing that we need is some way to determine what the device >> pixel->css pixel ratio is. Currently there's isn't even a real way >> to tell that it's 1:1 -- you would have do do a fillRect(width-1, >> height-1, 1, 1),; then getImageData(width-1, height-1, 1, 1) and >> see if they match. Conceivably you could do this multiple times to >> estimate the ratio, but it would be non-trivial. > > You can determine this by checking the height and width attributes > on the ImageData object. If you get a 2x2 region and ImageData.width > and .height return 4 you know there's a factor two scaling happening > between canvas pixels and device pixels. What the factor is between > canvas pixels and CSS pixels isn't really relevant (and easy to > determine). > > > -- > Anne van Kesteren > <http://annevankesteren.nl/> > <http://www.opera.com/>
Received on Friday, 25 January 2008 15:05:19 UTC