Move instanced index buffer creation to flush time

src/gpu/GrResourceProvider.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 GrResourceProvider_DEFINED
 #define GrResourceProvider_DEFINED
 
 #include "GrTextureProvider.h"
 
+class GrIndexBuffer;
+class GrVertexBuffer;
+
 /**
  * An extension of the texture provider for arbitrary resource types. This class is intended for
  * use within the Gr code base, not by clients or extensions (e.g. third party GrProcessor
  * derivatives).
  */
 class GrResourceProvider : public GrTextureProvider {
 public:
 
-    GrResourceProvider(GrGpu* gpu, GrResourceCache* cache) : INHERITED(gpu, cache) {}
+    GrResourceProvider(GrGpu* gpu, GrResourceCache* cache);
+
+    template <typename T> T* findAndRefTByUniqueKey(const GrUniqueKey& key) {
+        return static_cast<T*>(this->findAndRefResourceByUniqueKey(key));
+    }
+
+    /**
+     * Either finds and refs, or creates an index buffer for instanced drawing with a specific
+     * pattern if the index buffer is not found. If the return is non-null, the caller owns
+     * a ref on the returned GrIndexBuffer.
+     *
+     * @param pattern     the pattern of indices to repeat
+     * @param patternSize size in bytes of the pattern
+     * @param reps        number of times to repeat the pattern
+     * @param vertCount   number of vertices the pattern references
+     * @param key         Key to be assigned to the index buffer.
+     *
+     * @return The index buffer if successful, otherwise NULL.
+     */
+    const GrIndexBuffer* refOrCreateInstancedIndexBuffer(const uint16_t* pattern,
+                                                         int patternSize,
+                                                         int reps,
+                                                         int vertCount,
+                                                         const GrUniqueKey& key) {
+        if (GrIndexBuffer* buffer = this->findAndRefTByUniqueKey<GrIndexBuffer>(key)) {
+            return buffer;
+        }
+        return this->createInstancedIndexBuffer(pattern, patternSize, reps, vertCount, key);
+    }
+
+    /**
+     * Returns an index buffer that can be used to render quads.
+     * Six indices per quad: 0, 1, 2, 0, 2, 3, etc.
+     * The max number of quads can be queried using GrIndexBuffer::maxQuads().
+     * Draw with kTriangles_GrPrimitiveType
+     * @ return the quad index buffer
+     */
+    const GrIndexBuffer* refQuadIndexBuffer() {
+        if (GrIndexBuffer* buffer =
+            this->findAndRefTByUniqueKey<GrIndexBuffer>(fQuadIndexBufferKey)) {
+            return buffer;
+        }
+        return this->createQuadIndexBuffer();
+    }
+
 
     using GrTextureProvider::assignUniqueKeyToResource;
     using GrTextureProvider::findAndRefResourceByUniqueKey;
     using GrTextureProvider::abandon;
 
+private:
+    const GrIndexBuffer* createInstancedIndexBuffer(const uint16_t* pattern,
+                                                    int patternSize,
+                                                    int reps,
+                                                    int vertCount,
+                                                    const GrUniqueKey& key);
+
+    const GrIndexBuffer* createQuadIndexBuffer();
+
+    GrUniqueKey fQuadIndexBufferKey;
+
     typedef GrTextureProvider INHERITED;
 };
 
 #endif