[webkit-reviews] review requested: [Bug 74352] [skia] Track a simple opaque area when painting via PlatformContextSkia and save in LayerTextureUpdater : [Attachment 119329] Patch

[bugzilla-daemon at webkit.org]

Dana Jansens <danakj at chromium.org> has asked  for review:
Bug 74352: [skia] Track a simple opaque area when painting via
PlatformContextSkia and save in LayerTextureUpdater
https://bugs.webkit.org/show_bug.cgi?id=74352

Attachment 119329: Patch
https://bugs.webkit.org/attachment.cgi?id=119329&action=review

------- Additional Comments from Dana Jansens <danakj at chromium.org>
I ran the following test both with PCSkia::setTrackOpaqueRegion enabled and
disabled.

http://www.corp.google.com/~danakj/paint-culling/test-painted-foreground.html

There appears no measurable difference in time to paint, as random noise
dominated the differences in results.

For example, to paint the set of layers in one frame (in milliseconds).

Without tracking for two different frames:
.420		 .472
.174		 .178
.150		 .152
.167		 .151
.170		 .168

With tracking:
.443		 .479		   .490
.167		 .175		   .176
.148		 .165		   .147
.143		 .150		   .153
.165		 .175		   .216

Each frame is drawing the same things, just different colours, so as you can
see the variation between frames with tracking enabled/disabled is as large as
the difference between the two.