Add SkCanvasStack and update the Canvas utilities to use it.

Add SkCanvasStack and update the Canvas utilities to use it.

BUG=
R=reed@google.com

Committed: https://code.google.com/p/skia/source/detail?r=11081

[reed1, 2013-09-04 13:00:56]

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cpp
File src/utils/SkCanvasStack.cpp (right):

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:17: void SkCanvasStack::pushCanvas(SkCanvas* canvas,
SkIPoint origin) {
nit: const SkIPoint& origin

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:23: SkNWayCanvas::addCanvas(canvas);
nit: this->...

perhaps use INHERITED instead of SkNWayCanvas?

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:46: SkNWayCanvas::removeAll();
nit: this->...

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:51: void SkCanvasStack::setMatrix(const SkMatrix&
matrix) {
Perhaps a comment-block nearby explaining why we have to treat setMatrix()
special, but why concat/translate/scale all work "for free"

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:68:
fList[i]->clipRegion(fCanvasData[i].requiredClip, SkRegion::kIntersect_Op);
simple comment explaining why we need this Intersect?

Perhaps a helper function (with a nice declarative name) that can be called by
all of these clipFoo methods?

[djsollen, 2013-09-04 13:34:43]

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cpp
File src/utils/SkCanvasStack.cpp (right):

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:17: void SkCanvasStack::pushCanvas(SkCanvas* canvas,
SkIPoint origin) {
On 2013/09/04 13:00:56, reed1 wrote:
> nit: const SkIPoint& origin

Done.

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:23: SkNWayCanvas::addCanvas(canvas);
On 2013/09/04 13:00:56, reed1 wrote:
> nit: this->...
> 
> perhaps use INHERITED instead of SkNWayCanvas?

Done.

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:46: SkNWayCanvas::removeAll();
On 2013/09/04 13:00:56, reed1 wrote:
> nit: this->...

Done.

https://codereview.chromium.org/23865004/diff/3001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:68:
fList[i]->clipRegion(fCanvasData[i].requiredClip, SkRegion::kIntersect_Op);
On 2013/09/04 13:00:56, reed1 wrote:
> simple comment explaining why we need this Intersect?
> 
> Perhaps a helper function (with a nice declarative name) that can be called by
> all of these clipFoo methods?

Done.

[reed1, 2013-09-04 15:00:00]

lgtm w/ some nits/questions

https://codereview.chromium.org/23865004/diff/9001/src/utils/SkCanvasStack.cpp
File src/utils/SkCanvasStack.cpp (right):

https://codereview.chromium.org/23865004/diff/9001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:82: clipToZOrderedBounds();
nit: this->clipToZOrderedBounds()

https://codereview.chromium.org/23865004/diff/9001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:99: SkASSERT(fList.count() == fCanvasData.count());
perhaps small comment here:

// This loop replaces clipToZOrderedBounds, but differs since it must ...

https://codereview.chromium.org/23865004/diff/9001/src/utils/SkCanvasStack.h
File src/utils/SkCanvasStack.h (right):

https://codereview.chromium.org/23865004/diff/9001/src/utils/SkCanvasStack.h#...
src/utils/SkCanvasStack.h:21: virtual void removeAll() SK_OVERRIDE;
Do we need to expose this guy for Clank, or can we mark it as "hidden" like
addCanvas/removeCanvas?

https://codereview.chromium.org/23865004/diff/9001/src/utils/SkCanvasStack.h#...
src/utils/SkCanvasStack.h:29: virtual void addCanvas(SkCanvas*) SK_OVERRIDE {};
SkASSERT(!"don't call addCanvas on a CanvasStack"); ???

[djsollen, 2013-09-04 17:16:07]

Committed patchset #4 manually as r11081 (presubmit successful).

[bungeman-skia, 2013-12-02 18:34:18]

https://codereview.chromium.org/23865004/diff/9001/src/utils/SkCanvasStack.cpp
File src/utils/SkCanvasStack.cpp (right):

https://codereview.chromium.org/23865004/diff/9001/src/utils/SkCanvasStack.cp...
src/utils/SkCanvasStack.cpp:38:
fList[i-i]->clipRegion(fCanvasData[i-1].requiredClip);
i-i