/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * 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 ForceDiscreteGPUHelperCGL_h_
#define ForceDiscreteGPUHelperCGL_h_

#include <OpenGL/OpenGL.h>

/** This RAII helper guarantees that we're on the discrete GPU during its
 * lifetime.
 *
 * As long as any ForceDiscreteGPUHelperCGL object is alive, we're on the
 * discrete GPU.
 */
class ForceDiscreteGPUHelperCGL {
  CGLPixelFormatObj mPixelFormatObj;

 public:
  ForceDiscreteGPUHelperCGL() : mPixelFormatObj(nullptr) {
    // the code in this function is taken from Chromium,
    // src/ui/gfx/gl/gl_context_cgl.cc, r122013
    // BSD-style license, (c) The Chromium Authors
    CGLPixelFormatAttribute attribs[1];
    attribs[0] = static_cast<CGLPixelFormatAttribute>(0);
    GLint num_pixel_formats = 0;
    CGLChoosePixelFormat(attribs, &mPixelFormatObj, &num_pixel_formats);
  }

  ~ForceDiscreteGPUHelperCGL() { CGLReleasePixelFormat(mPixelFormatObj); }
};

#endif  // ForceDiscreteGPUHelperCGL_h_