path ops : add support for inverse fill

path ops : add support for inverse fill

add inverse fill, reverse diff, and gm tests
cleaned up some interfaces
Committed: https://code.google.com/p/skia/source/detail?r=8798

[caryclark, 2013-04-22 12:51:47]

Brian, this is my first GM -- please take a look to see if I'm doing anything
stupid

[bsalomon, 2013-04-22 13:13:57]

LGTM w/ some inline comments.

https://codereview.chromium.org/14371011/diff/1/gm/pathopsinverse.cpp
File gm/pathopsinverse.cpp (right):

https://codereview.chromium.org/14371011/diff/1/gm/pathopsinverse.cpp#newcode19
gm/pathopsinverse.cpp:19: this->makePaints();
There's a virtual on GM called "onOnceBeforeDraw". For some reason that I can't
recall we sometimes create the GMs without running them (maybe to get their
names?). onOnceBeforeDraw() is called once per GM but only when the draw will be
called.

https://codereview.chromium.org/14371011/diff/1/gm/pathopsinverse.cpp#newcode104
gm/pathopsinverse.cpp:104: SkPaint onePaint;
fOnePaint, etc?

https://codereview.chromium.org/14371011/diff/1/include/pathops/SkPathOps.h
File include/pathops/SkPathOps.h (right):

https://codereview.chromium.org/14371011/diff/1/include/pathops/SkPathOps.h#n...
include/pathops/SkPathOps.h:16: enum SkPathOp {
We have SkRegion::Op which is used in a bunch of places outside of SkRegion.
Perhaps it's time to replace it with a shared enum outside of any particular
class declaration. SkSetOp?

[caryclark, 2013-04-22 14:37:15]

Committed patchset #1 manually as r8798 (presubmit successful).