"FAB per tab" missing frames when animating FAB

[sethladd]

Open the gallery app, open Demos, and select "floating action buttons". Swipe between tabs, and watch the FAB animate in.

Tested on a Nexus 5, running Android 6.0

[abarth]

I've seen this anecdotally as well. /me will investigate.

[abarth]

Also, the ink response in the FAB is janky.

[abarth]

Note: This screenshot is from slow mode, but I think I've see it in production mode as well.

[sethladd]

Yeah, sorry about leaving Slow Mode on by accident :(

[chinmaygarde]

Checked mode should not affect rasterizer time. Besides, I observed the same on precompiled mode on iOS. Took a capture in the OpenGLES frame debugger. A large chunk was being rendered offscreen with most of the being spent in two fragment shaders.

[abarth]

Something pathological is going on in the rasterization phase:

[abarth]

The problem is that Skia is creating new blur kernels on every frame because we're scaling with a matrix that's novel each time due to floating point precision. The blur kernels are n^2 to create.

[abarth]

Filed https://bugs.chromium.org/p/skia/issues/detail?id=5224 for the Skia issue.

[sethladd]

Thanks for tracking it down!