use ClipOp instead of SkRegion for clipping

use ClipOp instead of SkRegion for clipping

BUG=skia:3191
follow on CLs in the works...
https://codereview.chromium.org/771563003/
https://codereview.chromium.org/781373002/

[reed2, 2014-12-06 16:10:01]

The CQ bit was checked by reed@chromium.org

[commit-bot: I haz the power, 2014-12-06 16:10:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/777643003/20001

[commit-bot: I haz the power, 2014-12-06 16:10:41]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2014-12-06 22:10 UTC

[commit-bot: I haz the power, 2014-12-06 16:12:29]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-12-06 16:12:30]

Try jobs failed on following builders:
  Build-Ubuntu13.10-GCC4.8-Arm7-Debug-Android-Trybot on client.skia.compile
(http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu13.10-GC...)
  Build-Ubuntu13.10-GCC4.8-x86_64-Release-Trybot on client.skia.compile
(http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu13.10-GC...)

[reed2, 2014-12-06 16:20:02]

The CQ bit was checked by reed@chromium.org

[commit-bot: I haz the power, 2014-12-06 16:20:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/777643003/40001

[commit-bot: I haz the power, 2014-12-06 16:20:40]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2014-12-06 22:20 UTC

[commit-bot: I haz the power, 2014-12-06 16:23:04]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-12-06 16:23:05]

Try jobs failed on following builders:
  Build-Ubuntu13.10-GCC4.8-Arm7-Debug-Android-Trybot on client.skia.compile
(http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu13.10-GC...)

[reed2, 2014-12-06 17:54:17]

The CQ bit was checked by reed@chromium.org

[commit-bot: I haz the power, 2014-12-06 17:54:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/777643003/60001

[commit-bot: I haz the power, 2014-12-06 17:54:55]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2014-12-06 23:54 UTC

[mikerreed, 2014-12-06 21:35:58]

mike@reedtribe.org changed reviewers:
+ bsalomon@google.com, mike@reedtribe.org, mtklein@google.com,
robertphillips@google.com, scroggo@google.com

[commit-bot: I haz the power, 2014-12-06 23:55:00]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-12-06 23:55:01]

No LGTM from a valid reviewer yet. Please ask for an LGTM from a
full Skia committer from
https://skia.googlesource.com/skia/+/master/CQ_COMMITTERS

[scroggo, 2014-12-07 17:45:53]

scroggo@google.com changed reviewers:
+ djsollen@google.com

[scroggo, 2014-12-07 17:45:54]

We'll need to convince Android that they don't want to support any clip
operations besides intersect and difference.

It might help if HWUI does not support them, but I don't know whether it does.
Derek, any ideas?

[djsollen, 2014-12-08 12:55:35]

The Android Java canvas exposes the following (i.e ALL) Region.Ops in the public
canvas.  So it seems like we will need to support these for a while...

Region.Op 	DIFFERENCE 	 
Region.Op 	INTERSECT 	 
Region.Op 	REPLACE 	 
Region.Op 	REVERSE_DIFFERENCE 	 
Region.Op 	UNION 	 
Region.Op 	XOR

[scroggo, 2014-12-08 15:08:06]

On 2014/12/08 12:55:35, djsollen wrote:
> The Android Java canvas exposes the following (i.e ALL) Region.Ops in the
public
> canvas.  So it seems like we will need to support these for a while...
> 
> Region.Op 	DIFFERENCE 	 
> Region.Op 	INTERSECT 	 
> Region.Op 	REPLACE 	 
> Region.Op 	REVERSE_DIFFERENCE 	 
> Region.Op 	UNION 	 
> Region.Op 	XOR

Does the hardware canvas support them? Looking at
http://developer.android.com/guide/topics/graphics/hardware-accel.html, it looks
like as of API level 18, Android supported XOR, DIFFERENCE, and
REVERSE_DIFFERENCE (which includes some of the ones we want to eliminate). As
for the others (REPLACE, UNION, INTERSECT), I'm guessing they supported it all
along?