== Subpixel Layout == Started by Google 2 years ago * to do better space distribution in the short term * sub pixel layout * support hiDPI displays by painting on odd device pixels in the long term * sub pixel painting Subpixel Layout works right now has some directional rounding errors for non-horizontal-tb flows Subpixel painting/rendering work in progress === how does it work? === ==== what is a layout unit ==== * made integer based to support fractional values without the burden of float arithmetic * 1 layout unit == 1/64 CSS pixels * Layout units are not rounded/etc during layout except in some cases, like in RenderLayer * value is snapped during painting time ==== how does snapping work? ==== * float value gets snapped to device pixel boundary, still a float after being snapped * this mostly happens in paint() in RenderObject classes * can't do in GraphicsContext since sometimes you need to do floor or ceil instead of rounding * border types like groove, ridge, double require floor/ceil to keep the spacing ==== Testing ==== * prefix test case with 'hidpi-' * that will cause the test framework to switch to hidpi mode