ui/gfx/skia_utils_gtk.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ui/gfx/skia_utils_gtk.h"
   6
   7 #include <gdk/gdk.h>
   8
   9 namespace gfx {
  10
  11 const int kSkiaToGDKMultiplier = 257;
  12
  13 // GDK_COLOR_RGB multiplies by 257 (= 0x10001) to distribute the bits evenly
  14 // See: http://www.mindcontrol.org/~hplus/graphics/expand-bits.html
  15 // To get back, we can just right shift by eight
  16 // (or, formulated differently, i == (i*257)/256 for all i < 256).
  17
  18 SkColor GdkColorToSkColor(GdkColor color) {
  19   return SkColorSetRGB(color.red >> 8, color.green >> 8, color.blue >> 8);
  20 }
  21
  22 GdkColor SkColorToGdkColor(SkColor color) {
  23   GdkColor gdk_color = {
  24       0,
  25       static_cast<guint16>(SkColorGetR(color) * kSkiaToGDKMultiplier),
  26       static_cast<guint16>(SkColorGetG(color) * kSkiaToGDKMultiplier),
  27       static_cast<guint16>(SkColorGetB(color) * kSkiaToGDKMultiplier)
  28   };
  29   return gdk_color;
  30 }
  31
  32 }  // namespace gfx