Add methods to SkLayerDrawLooper to allow adding layers on top

Add methods to SkLayerDrawLooper to allow adding layers on top
as well as on the bottom.

This is more convenient for some callers who generate layers
from a data structure in bottom-to-top, rather than top-to-bottom,
order.

BUG=242529
Committed: http://code.google.com/p/skia/source/detail?r=9233

[Tom Hudson, 2013-05-22 09:46:04]

Thanks for adding a unit test.

LGTM modulo nit

https://codereview.chromium.org/15314003/diff/8001/include/effects/SkLayerDra...
File include/effects/SkLayerDrawLooper.h (right):

https://codereview.chromium.org/15314003/diff/8001/include/effects/SkLayerDra...
include/effects/SkLayerDrawLooper.h:102: // Similar to addLayer, but adds a
layer to the top.
Nit: please use doxygen (javadoc)-style comments: /// or /**

https://codereview.chromium.org/15314003/diff/8001/src/effects/SkLayerDrawLoo...
File src/effects/SkLayerDrawLooper.cpp (left):

https://codereview.chromium.org/15314003/diff/8001/src/effects/SkLayerDrawLoo...
src/effects/SkLayerDrawLooper.cpp:173: SkLayerDrawLooper::Rec*
SkLayerDrawLooper::Rec::Reverse(Rec* head) {
Getting rid of this looks like a win to me!

https://codereview.chromium.org/15314003/diff/8001/tests/LayerDrawLooperTest.cpp
File tests/LayerDrawLooperTest.cpp (right):

https://codereview.chromium.org/15314003/diff/8001/tests/LayerDrawLooperTest....
tests/LayerDrawLooperTest.cpp:38: SkAutoUnref aur(looper);
Probably slightly more idiomatic to use SkAutoUnref<>() here, but this ought to
be OK.

[jbroman, 2013-05-22 12:18:48]

https://codereview.chromium.org/15314003/diff/8001/include/effects/SkLayerDra...
File include/effects/SkLayerDrawLooper.h (right):

https://codereview.chromium.org/15314003/diff/8001/include/effects/SkLayerDra...
include/effects/SkLayerDrawLooper.h:102: // Similar to addLayer, but adds a
layer to the top.
On 2013/05/22 09:46:04, Tom Hudson wrote:
> Nit: please use doxygen (javadoc)-style comments: /// or /**

Done.

https://codereview.chromium.org/15314003/diff/8001/tests/LayerDrawLooperTest.cpp
File tests/LayerDrawLooperTest.cpp (right):

https://codereview.chromium.org/15314003/diff/8001/tests/LayerDrawLooperTest....
tests/LayerDrawLooperTest.cpp:38: SkAutoUnref aur(looper);
On 2013/05/22 09:46:04, Tom Hudson wrote:
> Probably slightly more idiomatic to use SkAutoUnref<>() here, but this ought
to
> be OK.

Changed to SkAutoTUnref<SkLayerDrawLooper>, here and below.

[commit-bot: I haz the power, 2013-05-22 12:21:47]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/jbroman@chromium.org/15314003/13001

[commit-bot: I haz the power, 2013-05-22 12:35:53]

Change committed as 9233

[reed1, 2013-05-22 13:46:41]

nice change