SkRectShaderImageFilter: add a new factory method which takes a CropRect.

SkRectShaderImageFilter: add a new factory method which takes a CropRect.
This will become the preferred API, and the old Create method will be deprecated.

R=reed@google.com, reed
BUG=

Committed: https://code.google.com/p/skia/source/detail?r=11773

[Stephen White, 2013-10-12 17:19:50]

Take two: PTAL. Thanks!

[reed1, 2013-10-14 12:45:57]

https://codereview.chromium.org/26220004/diff/1/include/effects/SkRectShaderI...
File include/effects/SkRectShaderImageFilter.h (right):

https://codereview.chromium.org/26220004/diff/1/include/effects/SkRectShaderI...
include/effects/SkRectShaderImageFilter.h:21: *  The region parameter is used to
specify on which region the shader is applied.
1. "region"?
2. It appears now that the rect/region is optional. Can you update the dox to
clarify what happens in that case?
3. Can you document what this filter does? e.g. why are we passing in a shader?

[Stephen White, 2013-10-15 14:59:36]

On 2013/10/14 12:45:57, reed1 wrote:
>
https://codereview.chromium.org/26220004/diff/1/include/effects/SkRectShaderI...
> File include/effects/SkRectShaderImageFilter.h (right):
> 
>
https://codereview.chromium.org/26220004/diff/1/include/effects/SkRectShaderI...
> include/effects/SkRectShaderImageFilter.h:21: *  The region parameter is used
to
> specify on which region the shader is applied.
> 1. "region"?
> 2. It appears now that the rect/region is optional. Can you update the dox to
> clarify what happens in that case?
> 3. Can you document what this filter does? e.g. why are we passing in a
shader?

I didn't write this, but I've made an attempt to clean it up.

Note that the behaviour with a NULL cropRect may seem surprising in isolation,
but it makes sense as a convenience for a full filter DAG. For example, consider
a filter that displaces its input with noise: it's useful to be able to produce
turbulence of the same size as the input primitive, in order to match the
displacement. You can then draw multiple primitives of different bounds with the
same filter.

Let me know if the first example is helpful, and I can add it to the docs.

[Stephen White, 2013-10-15 15:01:09]

New patch up; PTAL. Thanks!

[reed1, 2013-10-15 15:05:31]

lgtm

[Stephen White, 2013-10-15 15:25:22]

Committed patchset #3 manually as r11773 (presubmit successful).