text: // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef CHROME_COMMON_GFX_COLOR_UTILS_H__
  #define CHROME_COMMON_GFX_COLOR_UTILS_H__
  
  #include "SkColor.h"
  
  class SkBitmap;
  
  namespace color_utils {
  
  // Represents set of CIE XYZ tristimulus values.
  struct CIE_XYZ {
    double X;
    double Y; // luminance
    double Z;
  };
  
  // Represents a L*a*b* color value
  struct LabColor {
    int L;
    int a;
    int b;
  };
  
  // Note: these transformations assume sRGB as the source color space
  
  // Convert between different color spaces
  void SkColorToCIEXYZ(SkColor c, CIE_XYZ* xyz);
  void CIEXYZToLabColor(const CIE_XYZ& xyz, LabColor* lab);
  
  SkColor CIEXYZToSkColor(SkAlpha alpha, const CIE_XYZ& xyz);
  void LabColorToCIEXYZ(const LabColor& lab, CIE_XYZ* xyz);
  
  void SkColorToLabColor(SkColor c, LabColor* lab);
  SkColor LabColorToSkColor(const LabColor& lab, SkAlpha alpha);
  
  // Determine if a given alpha value is nearly completely transparent.
  bool IsColorCloseToTransparent(SkAlpha alpha);
  
  // Determine if a color is near grey.
  bool IsColorCloseToGrey(int r, int g, int b);
  
  // Gets a color representing a bitmap. The definition of "representing" is the
  // average color in the bitmap. The color returned is modified to have the
  // specified alpha.
  SkColor GetAverageColorOfFavicon(SkBitmap* bitmap, SkAlpha alpha);
  
  // Builds a histogram based on the Y' of the Y'UV representation of
  // this image.
  void BuildLumaHistogram(SkBitmap* bitmap, int histogram[256]);
  
  // Create a color from a base color and a specific alpha value.
  SkColor SetColorAlpha(SkColor c, SkAlpha alpha);
  
  // Gets a Windows system color as a SkColor
  SkColor GetSysSkColor(int which);
  
  } // namespace color_utils
  
  #endif  // #ifndef CHROME_COMMON_GFX_COLOR_UTILS_H__
  