Add "sample locations" feature to GrProcessor

src/gpu/glsl/GrGLSLProgramBuilder.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLSLProgramBuilder_DEFINED
 #define GrGLSLProgramBuilder_DEFINED
 
 #include "GrGeometryProcessor.h"
 #include "GrGpu.h"
+#include "GrPipeline.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
 #include "glsl/GrGLSLGeometryShaderBuilder.h"
 #include "glsl/GrGLSLPrimitiveProcessor.h"
 #include "glsl/GrGLSLProgramDataManager.h"
 #include "glsl/GrGLSLUniformHandler.h"
 #include "glsl/GrGLSLTextureSampler.h"
 #include "glsl/GrGLSLVertexShaderBuilder.h"
 #include "glsl/GrGLSLXferProcessor.h"
 
 class GrGLSLCaps;
 class GrGLSLShaderVar;
 class GrGLSLVaryingHandler;
 
 typedef SkSTArray<8, GrGLSLFragmentProcessor*, true> GrGLSLFragProcs;
 
 class GrGLSLProgramBuilder {
 public:
     typedef GrGpu::DrawArgs DrawArgs;
     typedef GrGLSLUniformHandler::UniformHandle UniformHandle;
 
     virtual ~GrGLSLProgramBuilder() {}
 
     virtual const GrCaps* caps() const = 0;
     virtual const GrGLSLCaps* glslCaps() const = 0;
 
     const GrPrimitiveProcessor& primitiveProcessor() const { return *fArgs.fPrimitiveProcessor; }
     const GrPipeline& pipeline() const { return *fArgs.fPipeline; }
     const GrProgramDesc& desc() const { return *fArgs.fDesc; }
     const GrProgramDesc::KeyHeader& header() const { return fArgs.fDesc->header(); }
+    bool canReadFragmentPosition() const { return this->header().fFragPosKey; }
+    bool canUseSampleLocations() const {
+        SkASSERT(!this->header().fSamplePatternKey || this->pipeline().isHWAntialiasState());
+        return this->header().fSamplePatternKey;
+    }
 
     void appendUniformDecls(GrShaderFlags visibility, SkString*) const;
 
     // Handles for program uniforms (other than per-effect uniforms)
     struct BuiltinUniformHandles {
         UniformHandle       fRTAdjustmentUni;
 
         // We use the render target height to provide a y-down frag coord when specifying
         // origin_upper_left is not supported.
         UniformHandle       fRTHeightUni;
@@ skipping 96 matching lines @@
 #endif
 
     virtual void emitSamplers(const GrProcessor& processor,
                               GrGLSLTextureSampler::TextureSamplerArray* outSamplers) = 0;
 
     GrGLSLPrimitiveProcessor::TransformsIn  fCoordTransforms;
     GrGLSLPrimitiveProcessor::TransformsOut fOutCoords;
 };
 
 #endif