gpu: Compositor management of GpuMemoryBuffer instances.

ui/gfx/gpu_memory_buffer.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_GPU_MEMORY_BUFFER_H_
 #define UI_GFX_GPU_MEMORY_BUFFER_H_
 
 #include "base/memory/shared_memory.h"
 #include "build/build_config.h"
 #include "ui/gfx/gfx_export.h"
 
 #if defined(USE_X11)
 #include "ui/gfx/x/x11_types.h"
 #endif
 
+extern "C" typedef struct _ClientBuffer* ClientBuffer;
+
 namespace gfx {
 
 enum GpuMemoryBufferType {
   EMPTY_BUFFER,
   SHARED_MEMORY_BUFFER,
   IO_SURFACE_BUFFER,
   ANDROID_NATIVE_BUFFER,
   SURFACE_TEXTURE_BUFFER,
   X11_PIXMAP_BUFFER,
   OZONE_NATIVE_BUFFER,
@@ skipping 20 matching lines @@
 #if defined(USE_X11)
   XID pixmap;
 #endif
 };
 
 // This interface typically correspond to a type of shared memory that is also
 // shared with the GPU. A GPU memory buffer can be written to directly by
 // regular CPU code, but can also be read by the GPU.
 class GFX_EXPORT GpuMemoryBuffer {
  public:
-  GpuMemoryBuffer();
-  virtual ~GpuMemoryBuffer();
+  // The format needs to be taken into account when mapping a buffer into the
+  // client's address space.
+  enum Format { RGBA_8888, RGBX_8888, BGRA_8888, FORMAT_LAST = BGRA_8888 };
+
+  // The usage mode affects how a buffer can be used. Only buffers created with
+  // MAP can be mapped into the client's address space and accessed by the CPU.
+  enum Usage { MAP, SCANOUT, USAGE_LAST = SCANOUT };
+
+  virtual ~GpuMemoryBuffer() {}
 
   // Maps the buffer into the client's address space so it can be written to by
   // the CPU. This call may block, for instance if the GPU needs to finish
   // accessing the buffer or if CPU caches need to be synchronized. Returns NULL
   // on failure.
   virtual void* Map() = 0;
 
   // Unmaps the buffer. It's illegal to use the pointer returned by Map() after
   // this has been called.
   virtual void Unmap() = 0;
 
   // Returns true iff the buffer is mapped.
   virtual bool IsMapped() const = 0;
 
+  // Returns the format for the buffer.
+  virtual Format GetFormat() const = 0;
+
   // Returns the stride in bytes for the buffer.
   virtual uint32 GetStride() const = 0;
 
   // Returns a platform specific handle for this buffer.
   virtual GpuMemoryBufferHandle GetHandle() const = 0;
+
+  // Type-checking downcast routine.
+  virtual ClientBuffer AsClientBuffer() = 0;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_GPU_MEMORY_BUFFER_H_