New subclasses for both Gr and GrGL gradient effect classes.

New subclasses for both Gr and GrGL gradient effect classes. 

This replaces GrSingleTextureEffect as the base for gradient effects (so we'll be able to do gradient effects without textures), and adds a base class to the GL gradient custom stage implementations (which will soon handle generating the appropriate code to pass colors in and lerp instead of using a cached texture for simpler gradient cases).

Also added a custom stage for linear gradients.
Committed: https://code.google.com/p/skia/source/detail?r=4674

[rileya, 2012-07-19 14:58:44]

https://codereview.appspot.com/6426049/diff/1/src/gpu/SkGpuDevice.cpp
File src/gpu/SkGpuDevice.cpp (right):

https://codereview.appspot.com/6426049/diff/1/src/gpu/SkGpuDevice.cpp#newcode613
src/gpu/SkGpuDevice.cpp:613: if (skPaint.isFilterBitmap()) {
Originally linear gradients would fall into the default case and not be forced
to do bilinear filtering, this is temporarily set up to mimic that behavior so
we don't have to rebaseline for this CL.

[bsalomon, 2012-07-19 15:07:31]

On 2012/07/19 14:58:44, rileya wrote:
> https://codereview.appspot.com/6426049/diff/1/src/gpu/SkGpuDevice.cpp
> File src/gpu/SkGpuDevice.cpp (right):
> 
>
https://codereview.appspot.com/6426049/diff/1/src/gpu/SkGpuDevice.cpp#newcode613
> src/gpu/SkGpuDevice.cpp:613: if (skPaint.isFilterBitmap()) {
> Originally linear gradients would fall into the default case and not be forced
> to do bilinear filtering, this is temporarily set up to mimic that behavior so
> we don't have to rebaseline for this CL.

This is a nicely isolated building block towards your larger goal. LGTM!

[TomH, 2012-07-19 15:55:57]

After-the-fact LG, but wanted to get my two nits in:

https://codereview.appspot.com/6426049/diff/1/src/gpu/effects/GrGradientEffec...
File src/gpu/effects/GrGradientEffects.cpp (right):

https://codereview.appspot.com/6426049/diff/1/src/gpu/effects/GrGradientEffec...
src/gpu/effects/GrGradientEffects.cpp:54: if (fTexture) {
SkSafeUnref() is all about not having to have this if() explicit in your code.

https://codereview.appspot.com/6426049/diff/1/src/gpu/effects/GrGradientEffec...
src/gpu/effects/GrGradientEffects.cpp:117: return INHERITED::isEqual(sBase);
This function is completely unnecessary? Or are you just putting in scaffolding
for later use?

[rileya, 2012-07-19 16:23:48]

https://codereview.appspot.com/6426049/diff/1/src/gpu/effects/GrGradientEffec...
File src/gpu/effects/GrGradientEffects.cpp (right):

https://codereview.appspot.com/6426049/diff/1/src/gpu/effects/GrGradientEffec...
src/gpu/effects/GrGradientEffects.cpp:54: if (fTexture) {
On 2012/07/19 15:55:57, TomH wrote:
> SkSafeUnref() is all about not having to have this if() explicit in your code.

Ah, I had thought that might be the case, but forget to check... I'll get rid of
the if in a future CL.

https://codereview.appspot.com/6426049/diff/1/src/gpu/effects/GrGradientEffec...
src/gpu/effects/GrGradientEffects.cpp:117: return INHERITED::isEqual(sBase);
On 2012/07/19 15:55:57, TomH wrote:
> This function is completely unnecessary? Or are you just putting in
scaffolding
> for later use?

I think I carelessly pasted this from GrRadialGradient below, but this override
will possibly be necessary soon, I'll remove it (and the GrRadialGradient one
too) in a future CL if that turns out not to be the case.