/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef GLBLITTEXTUREIMAGEHELPER_H_
#define GLBLITTEXTUREIMAGEHELPER_H_

#include "mozilla/Attributes.h"
#include "GLContextTypes.h"
#include "GLConsts.h"
#include "mozilla/gfx/Rect.h"

namespace mozilla {
namespace gl {
class GLContext;
class TextureImage;
}  // namespace gl
namespace layers {

class CompositorOGL;

class GLBlitTextureImageHelper final {
  // The GLContext is the sole owner of the GLBlitTextureImageHelper.
  CompositorOGL* mCompositor;

  // lazy-initialized things
  GLuint mBlitProgram, mBlitFramebuffer;
  void UseBlitProgram();
  void SetBlitFramebufferForDestTexture(GLuint aTexture);

 public:
  explicit GLBlitTextureImageHelper(CompositorOGL* gl);
  ~GLBlitTextureImageHelper();

  /**
   * Copy a rectangle from one TextureImage into another.  The
   * source and destination are given in integer coordinates, and
   * will be converted to texture coordinates.
   *
   * For the source texture, the wrap modes DO apply -- it's valid
   * to use REPEAT or PAD and expect appropriate behaviour if the source
   * rectangle extends beyond its bounds.
   *
   * For the destination texture, the wrap modes DO NOT apply -- the
   * destination will be clipped by the bounds of the texture.
   *
   * Note: calling this function will cause the following OpenGL state
   * to be changed:
   *
   *   - current program
   *   - framebuffer binding
   *   - viewport
   *   - blend state (will be enabled at end)
   *   - scissor state (will be enabled at end)
   *   - vertex attrib 0 and 1 (pointer and enable state [enable state will
   *     be disabled at exit])
   *   - array buffer binding (will be 0)
   *   - active texture (will be 0)
   *   - texture 0 binding
   */
  void BlitTextureImage(gl::TextureImage* aSrc, const gfx::IntRect& aSrcRect,
                        gl::TextureImage* aDst, const gfx::IntRect& aDstRect);
};

}  // namespace layers
}  // namespace mozilla

#endif  // GLBLITTEXTUREIMAGEHELPER_H_