third_party/WebKit/Source/platform/graphics/Color.h

/*
 * Copyright (C) 2003, 2004, 2005, 2006, 2010 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef Color_h
#define Color_h

#include "platform/animation/AnimationUtilities.h"
#include "wtf/Allocator.h"
#include "wtf/Forward.h"
#include "wtf/text/StringView.h"
#include "wtf/text/Unicode.h"

namespace blink {

class Color;

typedef unsigned RGBA32;  // RGBA quadruplet

PLATFORM_EXPORT RGBA32 makeRGB(int r, int g, int b);
PLATFORM_EXPORT RGBA32 makeRGBA(int r, int g, int b, int a);

PLATFORM_EXPORT RGBA32 makeRGBA32FromFloats(float r, float g, float b, float a);
PLATFORM_EXPORT RGBA32 makeRGBAFromHSLA(double h, double s, double l, double a);
PLATFORM_EXPORT RGBA32
makeRGBAFromCMYKA(float c, float m, float y, float k, float a);

PLATFORM_EXPORT int differenceSquared(const Color&, const Color&);

inline int redChannel(RGBA32 color) {
  return (color >> 16) & 0xFF;
}
inline int greenChannel(RGBA32 color) {
  return (color >> 8) & 0xFF;
}
inline int blueChannel(RGBA32 color) {
  return color & 0xFF;
}
inline int alphaChannel(RGBA32 color) {
  return (color >> 24) & 0xFF;
}

struct NamedColor {
  DISALLOW_NEW();
  const char* name;
  unsigned ARGBValue;
};

PLATFORM_EXPORT const NamedColor* findColor(register const char* str,
                                            register unsigned len);

class PLATFORM_EXPORT Color {
  DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();

 public:
  Color() : m_color(Color::transparent) {}
  Color(RGBA32 color) : m_color(color) {}
  Color(int r, int g, int b) : m_color(makeRGB(r, g, b)) {}
  Color(int r, int g, int b, int a) : m_color(makeRGBA(r, g, b, a)) {}
  // Color is currently limited to 32bit RGBA. Perhaps some day we'll support
  // better colors.
  Color(float r, float g, float b, float a)
      : m_color(makeRGBA32FromFloats(r, g, b, a)) {}
  // Creates a new color from the specific CMYK and alpha values.
  Color(float c, float m, float y, float k, float a)
      : m_color(makeRGBAFromCMYKA(c, m, y, k, a)) {}

  static Color createUnchecked(int r, int g, int b) {
    RGBA32 color = 0xFF000000 | r << 16 | g << 8 | b;
    return Color(color);
  }
  static Color createUnchecked(int r, int g, int b, int a) {
    RGBA32 color = a << 24 | r << 16 | g << 8 | b;
    return Color(color);
  }

  // Returns the color serialized according to HTML5:
  // http://www.whatwg.org/specs/web-apps/current-work/#serialization-of-a-color
  String serialized() const;

  // Returns the color serialized according to CSSOM:
  // http://dev.w3.org/csswg/cssom/#serialize-a-css-component-value
  String serializedAsCSSComponentValue() const;

  // Returns the color serialized as either #RRGGBB or #RRGGBBAA. The latter
  // format is not a valid CSS color, and should only be seen in DRT dumps.
  String nameForLayoutTreeAsText() const;

  // Returns whether parsing succeeded. The resulting Color is arbitrary
  // if parsing fails.
  bool setFromString(const String&);
  bool setNamedColor(const String&);

  bool hasAlpha() const { return alpha() < 255; }

  int red() const { return redChannel(m_color); }
  int green() const { return greenChannel(m_color); }
  int blue() const { return blueChannel(m_color); }
  int alpha() const { return alphaChannel(m_color); }

  RGBA32 rgb() const { return m_color; }  // Preserve the alpha.
  void setRGB(int r, int g, int b) { m_color = makeRGB(r, g, b); }
  void setRGB(RGBA32 rgb) { m_color = rgb; }
  void getRGBA(float& r, float& g, float& b, float& a) const;
  void getRGBA(double& r, double& g, double& b, double& a) const;
  void getHSL(double& h, double& s, double& l) const;

  Color light() const;
  Color dark() const;

  Color combineWithAlpha(float otherAlpha) const;

  // This is an implementation of Porter-Duff's "source-over" equation
  Color blend(const Color&) const;
  Color blendWithWhite() const;

  static bool parseHexColor(const StringView&, RGBA32&);
  static bool parseHexColor(const LChar*, unsigned, RGBA32&);
  static bool parseHexColor(const UChar*, unsigned, RGBA32&);

  static const RGBA32 black = 0xFF000000;
  static const RGBA32 white = 0xFFFFFFFF;
  static const RGBA32 darkGray = 0xFF808080;
  static const RGBA32 gray = 0xFFA0A0A0;
  static const RGBA32 lightGray = 0xFFC0C0C0;
  static const RGBA32 transparent = 0x00000000;

 private:
  RGBA32 m_color;
};

inline bool operator==(const Color& a, const Color& b) {
  return a.rgb() == b.rgb();
}

inline bool operator!=(const Color& a, const Color& b) {
  return !(a == b);
}

PLATFORM_EXPORT Color colorFromPremultipliedARGB(RGBA32);
PLATFORM_EXPORT RGBA32 premultipliedARGBFromColor(const Color&);

inline Color blend(const Color& from,
                   const Color& to,
                   double progress,
                   bool blendPremultiplied = true) {
  if (blendPremultiplied) {
    // Contrary to the name, RGBA32 actually stores ARGB, so we can initialize
    // Color directly from premultipliedARGBFromColor(). Also,
    // premultipliedARGBFromColor() bails on zero alpha, so special-case that.
    Color premultFrom = from.alpha() ? premultipliedARGBFromColor(from) : 0;
    Color premultTo = to.alpha() ? premultipliedARGBFromColor(to) : 0;

    Color premultBlended(
        blend(premultFrom.red(), premultTo.red(), progress),
        blend(premultFrom.green(), premultTo.green(), progress),
        blend(premultFrom.blue(), premultTo.blue(), progress),
        blend(premultFrom.alpha(), premultTo.alpha(), progress));

    return Color(colorFromPremultipliedARGB(premultBlended.rgb()));
  }

  return Color(blend(from.red(), to.red(), progress),
               blend(from.green(), to.green(), progress),
               blend(from.blue(), to.blue(), progress),
               blend(from.alpha(), to.alpha(), progress));
}
}  // namespace blink

#endif  // Color_h