Add GrPaint::*StageEnabled() and GrDrawState::stageEnabled() functions

We now consider a stage to be active if it has a GrTexture *OR* a GrCustomStage/GrGLProgramStage.

This change prepares us for http://codereview.appspot.com/6306097/, which moves the GrTexture *onto* the GrCustomStage; that in turn sets us up for zero- and multi-texture effects.

DEPENDS (probably) on robertphillips@'s change to reset textures + some follow-on work to get rid of half of the vertex layout bits: a stage should default to using positions as texture coordinates.

[TomH, 2012-06-20 18:18:22]

Now with more complete coverage *and* notes about why we can't commit it. Yet.

[TomH, 2012-06-22 20:19:45]

OK, resetting textures & stages landed in r4313, and we didn't note *why* we
care about vertex layout bits. Can we land, or can we be explicit about why this
depends on the vert layout fix?

(If you really think 2-year-olds let you have more sleep than infants, you may
be in for many rude awakenings.)

[TomH, 2012-06-22 20:30:32]

Answer: there are a few call sites which are currently:
  enabled if non-NULL texture AND vert layout bits
Vert layout fix means letting Position-as-Texcoords become a default.
We could then shift those call sites to
  enabled if non-NULL texture
whence it's an easy step to
  enabled if non-NULL texture OR non-NULL custom stage

[TomH, 2012-06-25 15:41:14]

Vert layout fix landed.
This should be clean now? Or am I still missing something?

[bsalomon, 2012-06-25 15:48:09]

Mostly LGTM. 

Let's choose either "active" or "enabled" and stick with it. I don't care which.
Also I'd prefer we had "is" in the name (isStageEnabled or isStageActive).

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrContext.cpp
File src/gpu/GrContext.cpp (right):

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrContext.cpp#newcod...
src/gpu/GrContext.cpp:1595: if (paint.textureStageActive(i)) {
Can/should we move the setTexture() function into the "if"?

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrContext.cpp#newcod...
src/gpu/GrContext.cpp:1606: if (paint.maskStageActive(i)) {
ditto

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrDrawState.h
File src/gpu/GrDrawState.h (right):

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrDrawState.h#newcod...
src/gpu/GrDrawState.h:781: if (stageActive(i) &&
this->

[TomH, 2012-06-25 17:20:18]

This should be fairly consistent with is*Enabled().

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrContext.cpp
File src/gpu/GrContext.cpp (right):

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrContext.cpp#newcod...
src/gpu/GrContext.cpp:1595: if (paint.textureStageActive(i)) {
On 2012/06/25 15:48:09, bsalomon wrote:
> Can/should we move the setTexture() function into the "if"?

Done.

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrContext.cpp#newcod...
src/gpu/GrContext.cpp:1606: if (paint.maskStageActive(i)) {
On 2012/06/25 15:48:09, bsalomon wrote:
> ditto

Done.

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrDrawState.h
File src/gpu/GrDrawState.h (right):

http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrDrawState.h#newcod...
src/gpu/GrDrawState.h:781: if (stageActive(i) &&
On 2012/06/25 15:48:09, bsalomon wrote:
> this->

Done.

[bsalomon, 2012-06-25 17:24:34]

On 2012/06/25 17:20:18, TomH wrote:
> This should be fairly consistent with is*Enabled().
> 
> http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrContext.cpp
> File src/gpu/GrContext.cpp (right):
> 
>
http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrContext.cpp#newcod...
> src/gpu/GrContext.cpp:1595: if (paint.textureStageActive(i)) {
> On 2012/06/25 15:48:09, bsalomon wrote:
> > Can/should we move the setTexture() function into the "if"?
> 
> Done.
> 
>
http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrContext.cpp#newcod...
> src/gpu/GrContext.cpp:1606: if (paint.maskStageActive(i)) {
> On 2012/06/25 15:48:09, bsalomon wrote:
> > ditto
> 
> Done.
> 
> http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrDrawState.h
> File src/gpu/GrDrawState.h (right):
> 
>
http://codereview.appspot.com/6306104/diff/15001/src/gpu/GrDrawState.h#newcod...
> src/gpu/GrDrawState.h:781: if (stageActive(i) &&
> On 2012/06/25 15:48:09, bsalomon wrote:
> > this->
> 
> Done.

LGTM

[TomH, 2012-06-25 17:28:24]

Closed with r4325.