gfx/gl/ForceDiscreteGPUHelperCGL.h

   1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef ForceDiscreteGPUHelperCGL_h_
   7 #define ForceDiscreteGPUHelperCGL_h_
   8
   9 #include <OpenGL/OpenGL.h>
  10
  11 /** This RAII helper guarantees that we're on the discrete GPU during its
  12  * lifetime.
  13  *
  14  * As long as any ForceDiscreteGPUHelperCGL object is alive, we're on the
  15  * discrete GPU.
  16  */
  17 class ForceDiscreteGPUHelperCGL {
  18   CGLPixelFormatObj mPixelFormatObj;
  19
  20  public:
  21   ForceDiscreteGPUHelperCGL() : mPixelFormatObj(nullptr) {
  22     // the code in this function is taken from Chromium,
  23     // src/ui/gfx/gl/gl_context_cgl.cc, r122013
  24     // BSD-style license, (c) The Chromium Authors
  25     CGLPixelFormatAttribute attribs[1];
  26     attribs[0] = static_cast<CGLPixelFormatAttribute>(0);
  27     GLint num_pixel_formats = 0;
  28     CGLChoosePixelFormat(attribs, &mPixelFormatObj, &num_pixel_formats);
  29   }
  30
  31   ~ForceDiscreteGPUHelperCGL() { CGLReleasePixelFormat(mPixelFormatObj); }
  32 };
  33
  34 #endif  // ForceDiscreteGPUHelperCGL_h_