Remove default implementation of GrEffect::isEqual. Make GrSingleTextureEffect abstract.

Remove default implementation of GrEffect::isEqual. Make GrSingleTextureEffect abstract.
Committed: https://code.google.com/p/skia/source/detail?r=7254

[bsalomon, 2013-01-17 15:17:09]

As I've been working on the GrEffectRef stuff I've noticed two related problems.
It is easy to write a new effect and not properly implement
getConstantColorComponents() and isEqual().

Part of the problem is that many effects subclass GrSingleTextureEffect.
However, they all spawn different GrGLEffect classes that emit shader code that
may not be compatible with the implementation of these functions in
GrSingleTextureEffect. To fix this I made GrSingleTextureEffect abstract,
without these functions implemented, and made a new concrete class,
GrSimpleTextureEffect. GrSimpleTextureEffect's implementation is the old
implementation of GrSingleTextureEffect.

Moreover, GrEffect provides a default implementation of isEqual(). This is
inviting danger. I made isEqual nonvirtual and have it call out out to
pure-virtual onIsEqual. isEqual now encapsulates the "subclass is the same" test
and has some sanity checking asserts.

Several classes were missing or had incomplete implementations of
getConstantColorComponents or isEqual and I fixed those.

Now when someone writes an effect they must implement both onIsEqual and
getConstantColorComponents.

[bsalomon, 2013-01-17 15:18:20]

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffectStage.h
File include/gpu/GrEffectStage.h (right):

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffectStage.h#...
include/gpu/GrEffectStage.h:42: if
(!this->getEffect()->isEqual(*other.getEffect())) {
I don't understand why this if {} is repeated twice in the side-by-side diff. In
my file the isEqual() test is only done once.

[robertphillips, 2013-01-17 16:35:02]

lgtm + nits

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h
File include/gpu/GrEffect.h (right):

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h#newco...
include/gpu/GrEffect.h:107: /** Returns true if this and other effect
conservatively draw identically. It can only return
subclass subclass

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h#newco...
include/gpu/GrEffect.h:113: computed by the GrBackendEffectFactory:
that might be worth wrapping in a helper function

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h#newco...
include/gpu/GrEffect.h:124: for (int i = 0; i < this->numTextures(); ++i) {
[0] -> [i]

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h#newco...
include/gpu/GrEffect.h:180: /** Subclass implements this to support isEqual().
It will only be called if it is known that
subclass subclass

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffectStage.h
File include/gpu/GrEffectStage.h (right):

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffectStage.h#...
include/gpu/GrEffectStage.h:42: if
(!this->getEffect()->isEqual(*other.getEffect())) {
Worrisome

https://codereview.appspot.com/7142049/diff/2001/src/gpu/effects/GrSingleText...
File src/gpu/effects/GrSingleTextureEffect.h (right):

https://codereview.appspot.com/7142049/diff/2001/src/gpu/effects/GrSingleText...
src/gpu/effects/GrSingleTextureEffect.h:16: /**
An -> A

[bsalomon, 2013-01-17 16:50:07]

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h
File include/gpu/GrEffect.h (right):

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h#newco...
include/gpu/GrEffect.h:107: /** Returns true if this and other effect
conservatively draw identically. It can only return
On 2013/01/17 16:35:02, robertphillips wrote:
> subclass subclass

Done.

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h#newco...
include/gpu/GrEffect.h:113: computed by the GrBackendEffectFactory:
On 2013/01/17 16:35:02, robertphillips wrote:
> that might be worth wrapping in a helper function

We don't really do this. We compute a bigger key for the whole program that
includes the stage key and compare that.

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h#newco...
include/gpu/GrEffect.h:124: for (int i = 0; i < this->numTextures(); ++i) {
On 2013/01/17 16:35:02, robertphillips wrote:
> [0] -> [i]
nice catch.

https://codereview.appspot.com/7142049/diff/2001/include/gpu/GrEffect.h#newco...
include/gpu/GrEffect.h:180: /** Subclass implements this to support isEqual().
It will only be called if it is known that
On 2013/01/17 16:35:02, robertphillips wrote:
> subclass subclass

Done.

https://codereview.appspot.com/7142049/diff/2001/src/gpu/effects/GrSingleText...
File src/gpu/effects/GrSingleTextureEffect.h (right):

https://codereview.appspot.com/7142049/diff/2001/src/gpu/effects/GrSingleText...
src/gpu/effects/GrSingleTextureEffect.h:16: /**
On 2013/01/17 16:35:02, robertphillips wrote:
> An -> A

Done.