It's not possible to discover the scaling of CSS pixels to actual device
pixels, with the current standard.
There are three non-standard ways to access them, from what I can see.
Mozilla:
window.QueryInterface(Components.interfaces.nsIInterfaceRequestor).getInterface(Components.interfaces.nsIDOMWindowUtils).screenPixelsPerCSSPixel
Google:
chrome.tabs.getZoomPercentage
window.innerWidth and window.outerWidth are decoupled, one is in CSS pixels,
the other is in screen pixels. So that's a minor work-around.
Microsoft:
window.screen
This is apart from the existing convention on mobile phones of
targetDpiDensity and dpiPixelRatio.
Microsoft's solution, seems to be superior, by exposing everything:
http://msdn.microsoft.com/en-us/library/ms535868(v=VS.85).aspx
systemXDPI, deviceXDPI, logicalXDPI (and YDPI ).
They also have fontSmoothingEnabled and updateInterval;
which are handy, but out of scope for this section.
Moz has animation hooks:
window.mozAnimationStartTime
window.addEventListener("MozBeforePaint")
window.mozRequestAnimationFrame()
I'm pushing Microsoft's solution, of exposing the data through
window.screen.
Can we all get on board with that one? Are there other proposals?
