Begin instanced rendering for simple shapes

src/gpu/instanced/InstanceProcessor.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 gr_instanced_InstanceProcessor_DEFINED
+#define gr_instanced_InstanceProcessor_DEFINED
+
+#include "GrBufferAccess.h"
+#include "GrGeometryProcessor.h"
+#include "instanced/InstancedRenderingTypes.h"
+
+namespace gr_instanced {
+
+/**
+ * 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 InstanceProcessor : public GrGeometryProcessor {
+public:
+    static bool IsSupported(const GrGLSLCaps&, const GrCaps&, AntialiasMode* lastSupportedAAMode);
+
+    InstanceProcessor(BatchInfo, GrBuffer* paramsBuffer);
+
+    const char* name() const override { return "Instance Processor"; }
+    BatchInfo batchInfo() const { return fBatchInfo; }
+
+    void getGLSLProcessorKey(const GrGLSLCaps&, GrProcessorKeyBuilder* b) const override {
+        b->add32(fBatchInfo.fData);
+    }
+    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 IndexRange GetIndexRangeForRect(AntialiasMode);
+    static IndexRange GetIndexRangeForOval(AntialiasMode, const SkRect& devBounds);
+    static IndexRange GetIndexRangeForRRect(AntialiasMode);
+
+    static const char* GetNameOfIndexRange(IndexRange);
+
+private:
+    const BatchInfo   fBatchInfo;
+    GrBufferAccess    fParamsAccess;
+
+    typedef GrGeometryProcessor INHERITED;
+};
+
+}
+
+#endif