Implement instanced rendering for simple shapes

src/gpu/effects/GrInstanceProcessor.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrInstanceProcessor_DEFINED
+#define GrInstanceProcessor_DEFINED
+
+#include "GrBufferAccess.h"
+#include "GrGeometryProcessor.h"
+#include "GrInstancedRenderingTypes.h"
+
+/**
+ * This class provides a GP implementation that uses instanced rendering. Is sends geometry in as
+ * basic, pre-baked canonical shapes, and uses instanced vertex attribs to control how these shapes
+ * are transformed and drawn. MSAA is accomplished with the sample mask rather than finely
+ * tesselated geometry.
+ */
+class GrInstanceProcessor : public GrGeometryProcessor, private GrInstancedRenderingTypes {
+public:
+    static uint32_t GetSupportedAAModes(const GrGLSLCaps&, const GrCaps&);
+
+    GrInstanceProcessor(BatchTracker, GrBuffer* paramsBuffer, AntialiasMode, bool canDiscard);
+
+    const char* name() const override { return "Instance Processor"; }
+    BatchTracker tracker() const { return fTracker; }
+    AntialiasMode antialiasMode() const { return fAntialiasMode; }
+    bool canDiscard() const { return fCanDiscard; }
+
+    void getGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;
+    GrGLSLPrimitiveProcessor* createGLSLInstance(const GrGLSLCaps&) const override;
+
+    /**
+     * Returns a buffer of ShapeVertex that defines the canonical instanced geometry.
+     */
+    static const GrBuffer* SK_WARN_UNUSED_RESULT FindOrCreateVertexBuffer(GrGpu*);
+
+    /**
+     * Returns a buffer of 8-bit indices for the canonical instanced geometry. The client can call
+     * GetIndexRangeForXXX to know which indices to use for a specific shape.
+     */
+    static const GrBuffer* SK_WARN_UNUSED_RESULT FindOrCreateIndex8Buffer(GrGpu*);
+
+    static void GetIndexRangeForRect(AntialiasMode, uint32_t* firstIndex, uint32_t* count);
+    static void GetIndexRangeForOval(AntialiasMode, const SkRect& devBounds, uint32_t* firstIndex,
+                                     uint32_t* count);
+    static void GetIndexRangeForRRect(AntialiasMode, uint32_t* firstIndex, uint32_t* count);
+
+private:
+    const BatchTracker    fTracker;
+    const AntialiasMode   fAntialiasMode;
+    const bool            fCanDiscard;
+    GrBufferAccess        fParamsAccess;
+
+    typedef GrGeometryProcessor INHERITED;
+};
+
+#endif