Intent to Implement: DEAA (Antialiasing) for CSS Transformed Layer Edges

[Kearwood "Kip" Gilbert]

Summary:

Edges of layers with rotations and projections applied through CSS
transforms have stair-step, aliased edges. Visiting the attached URL
demonstrates the aliasing effect.

Applying DEAA (Distance to Edge Anti-aliasing) for transformed layers
enables anti-aliasing without requiring viewport multi-sampling and
without performance impact when drawing layers that do not require it.

Bug:

https://bugzilla.mozilla.org/show_bug.cgi?id=1151549

Platform Coverage:

Android, Desktop, Firefox OS, Windows, OSX, Linux

There will be separate implementations for the OpenGL, D3D9, and D3D11
compositors. The OpenGL compositor implementation of DEAA will be
enabled first, enabled by default on desktop platforms. The DirectX
implementation will follow, enabling this for Windows.

Safari, Chrome, and IE have already enabled DEAA by default on Desktop,
so there should be little risk of performance issues.

Mobile platforms can benefit greatly from DEAA; however, we will need to
be selective on which hardware to enable this on to avoid performance
regressions.

Estimated or target release:

Early Q2 2015

Preferences behind which this will be implemented:

layers.opengl.deaa.enabled
layers.d3d9.deaa.enabled
layers.d3d11.deaa.enabled