gecko-dev/gfx/gl/GLReadTexImageHelper.h

/* -*- 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 GLREADTEXIMAGEHELPER_H_
#define GLREADTEXIMAGEHELPER_H_

#include "GLContextTypes.h"
#include "mozilla/Attributes.h"
#include "nsSize.h"
#include "mozilla/RefPtr.h"
#include "mozilla/gfx/Types.h"

namespace mozilla {

namespace gfx {
class DataSourceSurface;
}  // namespace gfx

namespace gl {

// Returns true if the `dest{Format,Type}` are the same as the
// `read{Format,Type}`.
bool GetActualReadFormats(GLContext* gl, GLenum destFormat, GLenum destType,
                          GLenum* out_readFormat, GLenum* out_readType);

void ReadPixelsIntoDataSurface(GLContext* aGL,
                               gfx::DataSourceSurface* aSurface);

already_AddRefed<gfx::DataSourceSurface> ReadBackSurface(
    GLContext* gl, GLuint aTexture, bool aYInvert, gfx::SurfaceFormat aFormat);

already_AddRefed<gfx::DataSourceSurface> YInvertImageSurface(
    gfx::DataSourceSurface* aSurf, uint32_t aStride);

void SwapRAndBComponents(gfx::DataSourceSurface* surf);

class GLReadTexImageHelper final {
  // The GLContext is the sole owner of the GLBlitHelper.
  GLContext* mGL;

  GLuint mPrograms[4];

  GLuint TextureImageProgramFor(GLenum aTextureTarget, int aShader);

  bool DidGLErrorOccur(const char* str);

 public:
  explicit GLReadTexImageHelper(GLContext* gl);
  ~GLReadTexImageHelper();

  /**
   * Read the image data contained in aTexture, and return it as an
   * ImageSurface. If GL_RGBA is given as the format, a
   * SurfaceFormat::A8R8G8B8_UINT32 surface is returned. Not implemented yet: If
   * GL_RGB is given as the format, a SurfaceFormat::X8R8G8B8_UINT32 surface is
   * returned. If GL_LUMINANCE is given as the format, a SurfaceFormat::A8
   * surface is returned.
   *
   * THIS IS EXPENSIVE.  It is ridiculously expensive.  Only do this
   * if you absolutely positively must, and never in any performance
   * critical path.
   *
   * NOTE: aShaderProgram is really mozilla::layers::ShaderProgramType. It is
   * passed as int to eliminate including LayerManagerOGLProgram.h here.
   */
  already_AddRefed<gfx::DataSourceSurface> ReadTexImage(
      GLuint aTextureId, GLenum aTextureTarget, const gfx::IntSize& aSize,
      /* ShaderProgramType */ int aShaderProgram, bool aYInvert = false);

  bool ReadTexImage(gfx::DataSourceSurface* aDest, GLuint aTextureId,
                    GLenum aTextureTarget, const gfx::IntSize& aSize,
                    int aShaderProgram, bool aYInvert = false);
};

}  // namespace gl
}  // namespace mozilla

#endif