Start using GrGpuCommandBuffer in GrDrawTarget.

src/gpu/GrGpuCommandBuffer.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 GrGpuCommandBuffer_DEFINED
 #define GrGpuCommandBuffer_DEFINED
 
 #include "GrColor.h"
 
+class GrGpu;
+class GrMesh;
+class GrPipeline;
+class GrPrimitiveProcessor;
 class GrRenderTarget;
+struct SkIRect;
 
+/**
+ * The GrGpuCommandBuffer is a series of commands (draws, clears, and discards), which all target
+ * the same render target. It is possible that these commands execute immediately (GL), or get
+ * buffered up for later execution (Vulkan). GrBatches will execute their draw commands into a
+ * GrGpuCommandBuffer.
+ */
 class GrGpuCommandBuffer {
 public:
-    enum LoadAndStoreOp {
-        kLoadAndStore_LoadAndStoreOp,
-        kLoadAndDiscard_LoadAndStoreOp,
-        kClearAndStore_LoadAndStoreOp,
-        kClearAndDiscard_LoadAndStoreOp,
-        kDiscardAndStore_LoadAndStoreOp,
-        kDiscardAndDiscard_LoadAndStoreOp,
+    enum class LoadOp {
+        kLoad,
+        kClear,
+        kDiscard,
+    };
+
+    enum class StoreOp {
+        kStore,
+        kDiscard,
+    };
+
+    struct LoadAndStoreInfo {
+        LoadOp  fLoadOp;
+        StoreOp fStoreOp;
+        GrColor fClearColor;
     };
 
     GrGpuCommandBuffer() {}
     virtual ~GrGpuCommandBuffer() {}
 
     // Signals the end of recording to the command buffer and that it can now be submitted.
     virtual void end() = 0;
 
     // Sends the command buffer off to the GPU object to execute the commands built up in the
     // buffer. The gpu object is allowed to defer execution of the commands until it is flushed.
-    virtual void submit() = 0;
+    // The bounds should represent the bounds of all the draws put into the command buffer.
+    void submit(const SkIRect& bounds);
+
+    // We pass in an array of meshCount GrMesh to the draw. The backend should loop over each
+    // GrMesh object and emit a draw for it. Each draw will use the same GrPipeline and
+    // GrPrimitiveProcessor. This may fail if the draw would exceed any resource limits (e.g.
+    // number of vertex attributes is too large).
+    bool draw(const GrPipeline&,
+              const GrPrimitiveProcessor&,
+              const GrMesh*,
+              int meshCount);
+
+    /**
+    * Clear the passed in render target. Ignores the draw state and clip.
+    */
+    void clear(const SkIRect& rect, GrColor color, GrRenderTarget* renderTarget);
+
+    void clearStencilClip(const SkIRect& rect, bool insideClip, GrRenderTarget* renderTarget);
+    /**
+    * Discards the contents render target. nullptr indicates that the current render target should
+    * be discarded.
+    **/
+    // TODO: This should be removed in the future to favor using the load and store ops for discard
+    virtual void discard(GrRenderTarget* = nullptr) = 0;
+
+private:
+    virtual GrGpu* gpu() = 0;
+    virtual void onSubmit(const SkIRect& bounds) = 0;
+
+    // overridden by backend-specific derived class to perform the draw call.
+    virtual void onDraw(const GrPipeline&,
+                        const GrPrimitiveProcessor&,
+                        const GrMesh*,
+                        int meshCount) = 0;
+
+    // overridden by backend-specific derived class to perform the clear.
+    virtual void onClear(GrRenderTarget*, const SkIRect& rect, GrColor color) = 0;
+
+    virtual void onClearStencilClip(GrRenderTarget*, const SkIRect& rect, bool insideClip) = 0;
+
 };
 
 #endif