tree 37ca6a645d1c5d60078bb283942634e1632fd0fe
parent e5b65d212bcaeaacbf1cec38e8b7d6c20d9f96c1
author Mike Klein <mtklein@google.com> 1568914928 -0500
committer Skia Commit-Bot <skia-commit-bot@chromium.org> 1568951588 +0000

raster 8888 pow2 samples hack

The gist here is to use saveLayer() to create a buffer to draw each
subframe into, but not actually use it to draw anything at restore()
time, hence, canvas->clear(0).  (SkCanvas sniffs out cleverer approaches
like 0 alpha or SkBlendMode::kDst.)

Instead, we accessTopLayerPixels() and slurp the subframe out into a
16-bit accumulator, then when all subframes have drawn and accumulated
there, one more saveLayer() and accessTopLayerPixels() lets us put them
back, shifting back down to 8-bit.

The hot parts of the profile are drawing the frames themselves, then the
accumulate / repack code in renderToRaster8888Pow2Samples().

  $ time out/skottie_tool -i ~/Downloads/mb/data.json -w bar
  Before: 28.39user 1.14system 0:29.54elapsed
  After:  22.08user 1.12system 0:23.21elapsed

    I'm not proud of it.
    ...
    ...
    ...
    I am a bit!

Now using one layer.

Change-Id: I241529fad4c5b55c6abc55793f2d9c9693a03c18
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/242853
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>