Allow GrGLEffects to produce variable length keys.

src/gpu/gl/GrGLProgramDesc.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLProgramDesc_DEFINED
 #define GrGLProgramDesc_DEFINED
 
 #include "GrGLEffect.h"
 #include "GrDrawState.h"
 #include "GrGpu.h"
 
 class GrGpuGL;
 
 #ifdef SK_DEBUG
   // Optionally compile the experimental GS code. Set to SK_DEBUG so that debug build bots will
   // execute the code.
   #define GR_GL_EXPERIMENTAL_GS 1
 #else
   #define GR_GL_EXPERIMENTAL_GS 0
 #endif
 
 
 /** This class describes a program to generate. It also serves as a program cache key. Very little
-    of this is GL-specific. There is the generation of GrGLEffect::EffectKeys and the dst-read part
-    of the key set by GrGLShaderBuilder. If the interfaces that set those portions were abstracted
-    to be API-neutral then so could this class. */
+    of this is GL-specific. The GL-specific parts could be factored out into a subclass. */
 class GrGLProgramDesc {
 public:
     GrGLProgramDesc() {}
     GrGLProgramDesc(const GrGLProgramDesc& desc) { *this = desc; }
 
     // Returns this as a uint32_t array to be used as a key in the program cache.
     const uint32_t* asKey() const {
         return reinterpret_cast<const uint32_t*>(fKey.begin());
     }
 
@@ skipping 149 matching lines @@
     };
 
     template<typename T, size_t OFFSET> T* atOffset() {
         return reinterpret_cast<T*>(reinterpret_cast<intptr_t>(fKey.begin()) + OFFSET);
     }
 
     template<typename T, size_t OFFSET> const T* atOffset() const {
         return reinterpret_cast<const T*>(reinterpret_cast<intptr_t>(fKey.begin()) + OFFSET);
     }
 
-    typedef GrBackendEffectFactory::EffectKey EffectKey;
-
     KeyHeader* header() { return this->atOffset<KeyHeader, kHeaderOffset>(); }
 
     // Shared code between setRandom() and Build().
     static bool GetEffectKeyAndUpdateStats(const GrEffectStage& stage,
                                            const GrGLCaps& caps,
                                            bool useExplicitLocalCoords,
                                            GrEffectKeyBuilder* b,
                                            uint16_t* effectKeySize,
                                            bool* setTrueIfReadsDst,
                                            bool* setTrueIfReadsPos,
                                            bool* setTrueIfHasVertexCode);
 
     void finalize();
 
     const KeyHeader& getHeader() const { return *this->atOffset<KeyHeader, kHeaderOffset>(); }
 
     /** Used to provide effects' keys to their emitCode() function. */
     class EffectKeyProvider {
     public:
         enum EffectType {
             kColor_EffectType,
             kCoverage_EffectType,
         };
 
         EffectKeyProvider(const GrGLProgramDesc* desc, EffectType type) : fDesc(desc) {
             // Coverage effect key offsets begin immediately after those of the color effects.
             fBaseIndex = kColor_EffectType == type ? 0 : desc->numColorEffects();
         }
 
-        EffectKey get(int index) const {
-            const uint16_t* offsets = reinterpret_cast<const uint16_t*>(
+        GrEffectKey get(int index) const {
+            const uint16_t* offsetsAndLengths = reinterpret_cast<const uint16_t*>(
                 fDesc->fKey.begin() + kEffectKeyOffsetsAndLengthOffset);
             // We store two uint16_ts per effect, one for the offset to the effect's key and one for
             // its length. Here we just need the offset.
-            uint16_t offset = offsets[2 * (fBaseIndex + index)];
-            return *reinterpret_cast<const EffectKey*>(fDesc->fKey.begin() + offset);
+            uint16_t offset = offsetsAndLengths[2 * (fBaseIndex + index) + 0];
+            uint16_t length = offsetsAndLengths[2 * (fBaseIndex + index) + 1];
+            // Currently effects must add to the key in units of uint32_t.
+            SkASSERT(0 == (length % sizeof(uint32_t)));
+            return GrEffectKey(reinterpret_cast<const uint32_t*>(fDesc->fKey.begin() + offset),
+                               length / sizeof(uint32_t));
         }
     private:
         const GrGLProgramDesc*  fDesc;
         int                     fBaseIndex;
     };
 
     enum {
         kMaxPreallocEffects = 8,
         kIntsPerEffect      = 4,    // This is an overestimate of the average effect key size.
         kPreAllocSize = kEffectKeyOffsetsAndLengthOffset +
                         kMaxPreallocEffects * sizeof(uint32_t) * kIntsPerEffect,
     };
 
     SkSTArray<kPreAllocSize, uint8_t, true> fKey;
 
     // GrGLProgram and GrGLShaderBuilder read the private fields to generate code. TODO: Split out
     // part of GrGLShaderBuilder that is used by effects so that this header doesn't need to be
     // visible to GrGLEffects. Then make public accessors as necessary and remove friends.
     friend class GrGLProgram;
     friend class GrGLShaderBuilder;
     friend class GrGLFullShaderBuilder;
     friend class GrGLFragmentOnlyShaderBuilder;
 };
 
 #endif