Add SK_SUPPORT_GPU macro to allow building a gpu-less skia

Adds a GPU-less build. It is controlled by config macro SK_SUPPORT_GPU. It defaults to 1. If it is set to 0 we build without any gpu support. Users of the gyp build system can do a GPU-less build via:

GYP_DEFINES=skia_gpu=0

[bsalomon, 2012-07-30 21:30:01]

This isn't finished yet. The idea is to add a new build macro SK_BUILD_GPU. It
defaults to 1. But if it is set to 0 by the build system or in a custom
SkUserConfig.h file then we will not compile any code that depends on the GPU
backend.

I want to make it work with our gyp build system so that we can have a commit
bot that verifies that we haven't broken the GPUless build. I also want to make
as many of our tools (bench, gm, SampleApp, ..) as possible build and work
GPUless.

[justinlin, 2012-07-30 21:47:50]

http://codereview.appspot.com/6452064/diff/1/src/effects/gradients/SkRadialGr...
File src/effects/gradients/SkRadialGradient.cpp (right):

http://codereview.appspot.com/6452064/diff/1/src/effects/gradients/SkRadialGr...
src/effects/gradients/SkRadialGradient.cpp:250: #if SK_BUILD_GPU
Out of curiosity: are you supposed to be able to call this function in non-gpu
mode? Maybe it should throw an assert or just not exist?

[bsalomon, 2012-08-01 13:22:37]

On 2012/07/30 21:47:50, justinlin wrote:
>
http://codereview.appspot.com/6452064/diff/1/src/effects/gradients/SkRadialGr...
> File src/effects/gradients/SkRadialGradient.cpp (right):
> 
>
http://codereview.appspot.com/6452064/diff/1/src/effects/gradients/SkRadialGr...
> src/effects/gradients/SkRadialGradient.cpp:250: #if SK_BUILD_GPU
> Out of curiosity: are you supposed to be able to call this function in non-gpu
> mode? Maybe it should throw an assert or just not exist?

It shouldn't be called in the GPU-less build. Pulling the function declaration
out would have required sprinkling even more SK_SUPPORT_GPU in more headers. So,
I added asserts in the GPU-less overrides that return NULL.

[bsalomon, 2012-08-01 19:26:24]

ping

[TomH, 2012-08-01 20:05:46]

LGTM, if uglier than one would hope.

http://codereview.appspot.com/6452064/diff/10017/src/effects/SkLightingImageF...
File src/effects/SkLightingImageFilter.cpp (right):

http://codereview.appspot.com/6452064/diff/10017/src/effects/SkLightingImageF...
src/effects/SkLightingImageFilter.cpp:509: return SkNEW(GrGLDistantLight);
nit: over-indented

http://codereview.appspot.com/6452064/diff/10017/src/views/mac/SkNSView.mm
File src/views/mac/SkNSView.mm (right):

http://codereview.appspot.com/6452064/diff/10017/src/views/mac/SkNSView.mm#ne...
src/views/mac/SkNSView.mm:158: { SK_MacEndKey,        kEnd_SkKey        },
nit: }-alignment brkoen

http://codereview.appspot.com/6452064/diff/10017/tests/WritePixelsTest.cpp
File tests/WritePixelsTest.cpp (right):

http://codereview.appspot.com/6452064/diff/10017/tests/WritePixelsTest.cpp#ne...
tests/WritePixelsTest.cpp:12: #include "SkDevice.h"
We needed to add new headers?

[bsalomon, 2012-08-02 14:06:29]

Landed at r4912.

http://codereview.appspot.com/6452064/diff/10017/src/effects/SkLightingImageF...
File src/effects/SkLightingImageFilter.cpp (right):

http://codereview.appspot.com/6452064/diff/10017/src/effects/SkLightingImageF...
src/effects/SkLightingImageFilter.cpp:509: return SkNEW(GrGLDistantLight);
On 2012/08/01 20:05:46, TomH wrote:
> nit: over-indented

Done.

http://codereview.appspot.com/6452064/diff/10017/src/views/mac/SkNSView.mm
File src/views/mac/SkNSView.mm (right):

http://codereview.appspot.com/6452064/diff/10017/src/views/mac/SkNSView.mm#ne...
src/views/mac/SkNSView.mm:158: { SK_MacEndKey,        kEnd_SkKey        },
On 2012/08/01 20:05:46, TomH wrote:
> nit: }-alignment brkoen

Done.

http://codereview.appspot.com/6452064/diff/10017/tests/WritePixelsTest.cpp
File tests/WritePixelsTest.cpp (right):

http://codereview.appspot.com/6452064/diff/10017/tests/WritePixelsTest.cpp#ne...
tests/WritePixelsTest.cpp:12: #include "SkDevice.h"
On 2012/08/01 20:05:46, TomH wrote:
> We needed to add new headers?

We were relying on SkGpuDevice.h to bring these in.