// Copyright (c) 2010 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 CHROME_GPU_GPU_BACKING_STORE_GLX_CONTEXT_H_
#define CHROME_GPU_GPU_BACKING_STORE_GLX_CONTEXT_H_

#include "base/basictypes.h"
#include "base/gfx/size.h"
#include "chrome/gpu/x_util.h"

class GpuThread;


class GpuBackingStoreGLXContext {
 public:
  explicit GpuBackingStoreGLXContext(GpuThread* gpu_thread);
  ~GpuBackingStoreGLXContext();

  // Returns the context, creating it if necessary, and binding it to the given
  // display and window identified by the XID. This will avoid duplicate calls
  // to MakeCurrent if the display/XID hasn't changed from the last call.
  // Returns NULL on failure.
  GLXContext BindContext(XID window_id);

  bool BindTextureForScrolling(XID window_id,
                               const gfx::Size& size);

  unsigned int SwapTextureForScrolling(unsigned int old_texture,
                                       const gfx::Size& old_size);

 private:
  GpuThread* gpu_thread_;

  // Set to true when we've tried to create the context. This prevents us from
  // trying to initialize the OpenGL context over and over in the failure case.
  bool tried_to_init_;

  // The OpenGL context. Non-NULL when initialized.
  GLXContext context_;

  // The last window we've bound our context to. This allows us to avoid
  // duplicate "MakeCurrent" calls which are expensive.
  XID previous_window_id_;

  // The frame buffer object we use to render scrolled images into. We'll set
  // is_frame_buffer_bound_ when the FBO is bound so we can perform some checks
  // to make sure we're not forgetting to unbind it.
  unsigned int frame_buffer_for_scrolling_;
  bool is_frame_buffer_bound_;

  // The temporary texture we use for scrolling. The ID will be 0 if it is
  // uninitialized. Otherwise, this will give the ID and size of an existing
  // texture that can be re-used for a temporary buffer for scrolling.
  unsigned int temp_scroll_texture_id_;
  gfx::Size temp_scroll_texture_size_;

  DISALLOW_COPY_AND_ASSIGN(GpuBackingStoreGLXContext);
};

#endif  // CHROME_GPU_GPU_BACKING_STORE_GLX_CONTEXT_H_