WebCore/platform/graphics/Color.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2003, 2004, 2005, 2006 Apple Computer, 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.
  */

 #include "config.h"
 #include "Color.h"

 #include "DeprecatedString.h"
 #include "PlatformString.h"
 #include <math.h>
 #include <wtf/Assertions.h>
 #include <wtf/MathExtras.h>

 #include "ColorData.c"

 using namespace std;

 namespace WebCore {

 const RGBA32 lightenedBlack = 0xFF545454;
 const RGBA32 darkenedWhite = 0xFFABABAB;

 RGBA32 makeRGB(int r, int g, int b)
 {
     return 0xFF000000 | max(0, min(r, 255)) << 16 | max(0, min(g, 255)) << 8 | max(0, min(b, 255));
 }

 RGBA32 makeRGBA(int r, int g, int b, int a)
 {
     return max(0, min(a, 255)) << 24 | max(0, min(r, 255)) << 16 | max(0, min(g, 255)) << 8 | max(0, min(b, 255));
 }

 static double calcHue(double temp1, double temp2, double hueVal)
 {
     if (hueVal < 0.0)
         hueVal++;
     else if (hueVal > 1.0)
         hueVal--;
     if (hueVal * 6.0 < 1.0)
         return temp1 + (temp2 - temp1) * hueVal * 6.0;
     if (hueVal * 2.0 < 1.0)
         return temp2;
     if (hueVal * 3.0 < 2.0)
         return temp1 + (temp2 - temp1) * (2.0 / 3.0 - hueVal) * 6.0;
     return temp1;
 }

 // Explanation of this algorithm can be found in the CSS3 Color Module
 // specification at http://www.w3.org/TR/css3-color/#hsl-color with further
 // explanation available at http://en.wikipedia.org/wiki/HSL_color_space

 // all values are in the range of 0 to 1.0
 RGBA32 makeRGBAFromHSLA(double hue, double saturation, double lightness, double alpha)
 {
     const double scaleFactor = nextafter(256.0, 0.0);

     if (!saturation) {
         int greyValue = static_cast<int>(lightness * scaleFactor);
         return makeRGBA(greyValue, greyValue, greyValue, static_cast<int>(alpha * scaleFactor));
     }

     double temp2 = lightness < 0.5 ? lightness * (1.0 + saturation) : lightness + saturation - lightness * saturation;
     double temp1 = 2.0 * lightness - temp2;

     return makeRGBA(static_cast<int>(calcHue(temp1, temp2, hue + 1.0 / 3.0) * scaleFactor),
                     static_cast<int>(calcHue(temp1, temp2, hue) * scaleFactor),
                     static_cast<int>(calcHue(temp1, temp2, hue - 1.0 / 3.0) * scaleFactor),
                     static_cast<int>(alpha * scaleFactor));
 }

 // originally moved here from the CSS parser
 bool Color::parseHexColor(const String& name, RGBA32& rgb)
 {
     int len = name.length();
     if (len == 3 || len == 6) {
         bool ok;
         int val = name.deprecatedString().toInt(&ok, 16);
         if (ok) {
             if (len == 6) {
                 rgb = 0xFF000000 | val;
                 return true;
             }
             // #abc converts to #aabbcc according to the specs
             rgb = 0xFF000000
                 | (val & 0xF00) << 12 | (val & 0xF00) << 8
                 | (val & 0xF0) << 8 | (val & 0xF0) << 4
                 | (val & 0xF) << 4 | (val & 0xF);
             return true;
         }
     }
     return false;
 }

 int differenceSquared(const Color& c1, const Color& c2)
 {
     int dR = c1.red() - c2.red();
     int dG = c1.green() - c2.green();
     int dB = c1.blue() - c2.blue();
     return dR * dR + dG * dG + dB * dB;
 }

 Color::Color(const String& name)
 {
     if (name.startsWith("#"))
         m_valid = parseHexColor(name.substring(1), m_color);
     else
         setNamedColor(name);
 }

 Color::Color(const char* name)
 {
     if (name[0] == '#')
         m_valid = parseHexColor(&name[1], m_color);
     else {
         const NamedColor* foundColor = findColor(name, strlen(name));
         m_color = foundColor ? foundColor->RGBValue : 0;
         m_color |= 0xFF000000;
         m_valid = foundColor;
     }
 }

 String Color::name() const
 {
     if (alpha() < 0xFF)
         return String::format("#%02X%02X%02X%02X", red(), green(), blue(), alpha());
     return String::format("#%02X%02X%02X", red(), green(), blue());
 }

 void Color::setNamedColor(const String& name)
 {
     DeprecatedString dname = name.deprecatedString();
     const NamedColor* foundColor = dname.isAllASCII() ? findColor(dname.latin1(), dname.length()) : 0;
     m_color = foundColor ? foundColor->RGBValue : 0;
     m_color |= 0xFF000000;
     m_valid = foundColor;
 }

 Color Color::light() const
 {
     // Hardcode this common case for speed.
     if (m_color == black)
         return lightenedBlack;

     const float scaleFactor = nextafterf(256.0f, 0.0f);

     float r, g, b, a;
     getRGBA(r, g, b, a);

     float v = max(r, max(g, b));

     if (v == 0.0f)
         // Lightened black with alpha.
         return Color(0x54, 0x54, 0x54, alpha());

     float multiplier = min(1.0f, v + 0.33f) / v;

     return Color(static_cast<int>(multiplier * r * scaleFactor),
                  static_cast<int>(multiplier * g * scaleFactor),
                  static_cast<int>(multiplier * b * scaleFactor),
                  alpha());
 }

 Color Color::dark() const
 {
     // Hardcode this common case for speed.
     if (m_color == white)
         return darkenedWhite;

     const float scaleFactor = nextafterf(256.0f, 0.0f);

     float r, g, b, a;
     getRGBA(r, g, b, a);

     float v = max(r, max(g, b));
     float multiplier = max(0.0f, (v - 0.33f) / v);

     return Color(static_cast<int>(multiplier * r * scaleFactor),
                  static_cast<int>(multiplier * g * scaleFactor),
                  static_cast<int>(multiplier * b * scaleFactor),
                  alpha());
 }

 static int blendComponent(int c, int a)
 {
     // We use white.
     float alpha = a / 255.0f;
     int whiteBlend = 255 - a;
     c -= whiteBlend;
     return static_cast<int>(c / alpha);
 }

 const int cStartAlpha = 153; // 60%
 const int cEndAlpha = 204; // 80%;
 const int cAlphaIncrement = 17; // Increments in between.

 Color Color::blend(const Color& source) const
 {
     if (!alpha() || !source.hasAlpha())
         return source;

     if (!source.alpha())
         return *this;

     int d = 255 * (alpha() + source.alpha()) - alpha() * source.alpha();
     int a = d / 255;
     int r = (red() * alpha() * (255 - source.alpha()) + 255 * source.alpha() * source.red()) / d;
     int g = (green() * alpha() * (255 - source.alpha()) + 255 * source.alpha() * source.green()) / d;
     int b = (blue() * alpha() * (255 - source.alpha()) + 255 * source.alpha() * source.blue()) / d;
     return Color(r, g, b, a);
 }

 Color Color::blendWithWhite() const
 {
     // If the color contains alpha already, we leave it alone.
     if (hasAlpha())
         return *this;

     Color newColor;
     for (int alpha = cStartAlpha; alpha <= cEndAlpha; alpha += cAlphaIncrement) {
         // We have a solid color.  Convert to an equivalent color that looks the same when blended with white
         // at the current alpha.  Try using less transparency if the numbers end up being negative.
         int r = blendComponent(red(), alpha);
         int g = blendComponent(green(), alpha);
         int b = blendComponent(blue(), alpha);

         newColor = Color(r, g, b, alpha);

         if (r >= 0 && g >= 0 && b >= 0)
             break;
     }
     return newColor;
 }

 void Color::getRGBA(float& r, float& g, float& b, float& a) const
 {
     r = red() / 255.0f;
     g = green() / 255.0f;
     b = blue() / 255.0f;
     a = alpha() / 255.0f;
 }

 void Color::getRGBA(double& r, double& g, double& b, double& a) const
 {
     r = red() / 255.0;
     g = green() / 255.0;
     b = blue() / 255.0;
     a = alpha() / 255.0;
 }

 } // namespace WebCore
	/*
	* Copyright (C) 2003, 2004, 2005, 2006 Apple Computer, 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.
	*/

	#include "config.h"
	#include "Color.h"

	#include "DeprecatedString.h"
	#include "PlatformString.h"
	#include <math.h>
	#include <wtf/Assertions.h>
	#include <wtf/MathExtras.h>

	#include "ColorData.c"

	using namespace std;

	namespace WebCore {

	const RGBA32 lightenedBlack = 0xFF545454;
	const RGBA32 darkenedWhite = 0xFFABABAB;

	RGBA32 makeRGB(int r, int g, int b)
	{
	return 0xFF000000 \| max(0, min(r, 255)) << 16 \| max(0, min(g, 255)) << 8 \| max(0, min(b, 255));
	}

	RGBA32 makeRGBA(int r, int g, int b, int a)
	{
	return max(0, min(a, 255)) << 24 \| max(0, min(r, 255)) << 16 \| max(0, min(g, 255)) << 8 \| max(0, min(b, 255));
	}

	static double calcHue(double temp1, double temp2, double hueVal)
	{
	if (hueVal < 0.0)
	hueVal++;
	else if (hueVal > 1.0)
	hueVal--;
	if (hueVal * 6.0 < 1.0)
	return temp1 + (temp2 - temp1) * hueVal * 6.0;
	if (hueVal * 2.0 < 1.0)
	return temp2;
	if (hueVal * 3.0 < 2.0)
	return temp1 + (temp2 - temp1) * (2.0 / 3.0 - hueVal) * 6.0;
	return temp1;
	}

	// Explanation of this algorithm can be found in the CSS3 Color Module
	// specification at http://www.w3.org/TR/css3-color/#hsl-color with further
	// explanation available at http://en.wikipedia.org/wiki/HSL_color_space

	// all values are in the range of 0 to 1.0
	RGBA32 makeRGBAFromHSLA(double hue, double saturation, double lightness, double alpha)
	{
	const double scaleFactor = nextafter(256.0, 0.0);

	if (!saturation) {
	int greyValue = static_cast<int>(lightness * scaleFactor);
	return makeRGBA(greyValue, greyValue, greyValue, static_cast<int>(alpha * scaleFactor));
	}

	double temp2 = lightness < 0.5 ? lightness * (1.0 + saturation) : lightness + saturation - lightness * saturation;
	double temp1 = 2.0 * lightness - temp2;

	return makeRGBA(static_cast<int>(calcHue(temp1, temp2, hue + 1.0 / 3.0) * scaleFactor),
	static_cast<int>(calcHue(temp1, temp2, hue) * scaleFactor),
	static_cast<int>(calcHue(temp1, temp2, hue - 1.0 / 3.0) * scaleFactor),
	static_cast<int>(alpha * scaleFactor));
	}

	// originally moved here from the CSS parser
	bool Color::parseHexColor(const String& name, RGBA32& rgb)
	{
	int len = name.length();
	if (len == 3 \|\| len == 6) {
	bool ok;
	int val = name.deprecatedString().toInt(&ok, 16);
	if (ok) {
	if (len == 6) {
	rgb = 0xFF000000 \| val;
	return true;
	}
	// #abc converts to #aabbcc according to the specs
	rgb = 0xFF000000
	\| (val & 0xF00) << 12 \| (val & 0xF00) << 8
	\| (val & 0xF0) << 8 \| (val & 0xF0) << 4
	\| (val & 0xF) << 4 \| (val & 0xF);
	return true;
	}
	}
	return false;
	}

	int differenceSquared(const Color& c1, const Color& c2)
	{
	int dR = c1.red() - c2.red();
	int dG = c1.green() - c2.green();
	int dB = c1.blue() - c2.blue();
	return dR * dR + dG * dG + dB * dB;
	}

	Color::Color(const String& name)
	{
	if (name.startsWith("#"))
	m_valid = parseHexColor(name.substring(1), m_color);
	else
	setNamedColor(name);
	}

	Color::Color(const char* name)
	{
	if (name[0] == '#')
	m_valid = parseHexColor(&name[1], m_color);
	else {
	const NamedColor* foundColor = findColor(name, strlen(name));
	m_color = foundColor ? foundColor->RGBValue : 0;
	m_color \|= 0xFF000000;
	m_valid = foundColor;
	}
	}

	String Color::name() const
	{
	if (alpha() < 0xFF)
	return String::format("#%02X%02X%02X%02X", red(), green(), blue(), alpha());
	return String::format("#%02X%02X%02X", red(), green(), blue());
	}

	void Color::setNamedColor(const String& name)
	{
	DeprecatedString dname = name.deprecatedString();
	const NamedColor* foundColor = dname.isAllASCII() ? findColor(dname.latin1(), dname.length()) : 0;
	m_color = foundColor ? foundColor->RGBValue : 0;
	m_color \|= 0xFF000000;
	m_valid = foundColor;
	}

	Color Color::light() const
	{
	// Hardcode this common case for speed.
	if (m_color == black)
	return lightenedBlack;

	const float scaleFactor = nextafterf(256.0f, 0.0f);

	float r, g, b, a;
	getRGBA(r, g, b, a);

	float v = max(r, max(g, b));

	if (v == 0.0f)
	// Lightened black with alpha.
	return Color(0x54, 0x54, 0x54, alpha());

	float multiplier = min(1.0f, v + 0.33f) / v;

	return Color(static_cast<int>(multiplier * r * scaleFactor),
	static_cast<int>(multiplier * g * scaleFactor),
	static_cast<int>(multiplier * b * scaleFactor),
	alpha());
	}

	Color Color::dark() const
	{
	// Hardcode this common case for speed.
	if (m_color == white)
	return darkenedWhite;

	const float scaleFactor = nextafterf(256.0f, 0.0f);

	float r, g, b, a;
	getRGBA(r, g, b, a);

	float v = max(r, max(g, b));
	float multiplier = max(0.0f, (v - 0.33f) / v);

	return Color(static_cast<int>(multiplier * r * scaleFactor),
	static_cast<int>(multiplier * g * scaleFactor),
	static_cast<int>(multiplier * b * scaleFactor),
	alpha());
	}

	static int blendComponent(int c, int a)
	{
	// We use white.
	float alpha = a / 255.0f;
	int whiteBlend = 255 - a;
	c -= whiteBlend;
	return static_cast<int>(c / alpha);
	}

	const int cStartAlpha = 153; // 60%
	const int cEndAlpha = 204; // 80%;
	const int cAlphaIncrement = 17; // Increments in between.

	Color Color::blend(const Color& source) const
	{
	if (!alpha() \|\| !source.hasAlpha())
	return source;

	if (!source.alpha())
	return *this;

	int d = 255 * (alpha() + source.alpha()) - alpha() * source.alpha();
	int a = d / 255;
	int r = (red() * alpha() * (255 - source.alpha()) + 255 * source.alpha() * source.red()) / d;
	int g = (green() * alpha() * (255 - source.alpha()) + 255 * source.alpha() * source.green()) / d;
	int b = (blue() * alpha() * (255 - source.alpha()) + 255 * source.alpha() * source.blue()) / d;
	return Color(r, g, b, a);
	}

	Color Color::blendWithWhite() const
	{
	// If the color contains alpha already, we leave it alone.
	if (hasAlpha())
	return *this;

	Color newColor;
	for (int alpha = cStartAlpha; alpha <= cEndAlpha; alpha += cAlphaIncrement) {
	// We have a solid color. Convert to an equivalent color that looks the same when blended with white
	// at the current alpha. Try using less transparency if the numbers end up being negative.
	int r = blendComponent(red(), alpha);
	int g = blendComponent(green(), alpha);
	int b = blendComponent(blue(), alpha);

	newColor = Color(r, g, b, alpha);

	if (r >= 0 && g >= 0 && b >= 0)
	break;
	}
	return newColor;
	}

	void Color::getRGBA(float& r, float& g, float& b, float& a) const
	{
	r = red() / 255.0f;
	g = green() / 255.0f;
	b = blue() / 255.0f;
	a = alpha() / 255.0f;
	}

	void Color::getRGBA(double& r, double& g, double& b, double& a) const
	{
	r = red() / 255.0;
	g = green() / 255.0;
	b = blue() / 255.0;
	a = alpha() / 255.0;
	}

	} // namespace WebCore