packages/charted/lib/core/utils/color.dart - observatory_pub_packages - Git at Google

 //
 // Copyright 2014 Google Inc. All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 //

 part of charted.core.utils;

 /// Represents a single color for use in visualizations.  Currently, supports
 /// representing and conversion between RGB, RGBA, HSL, HSLA and hex formats.
 class Color {
   // Internal representation of RGB
   int _r = 0;
   int _g = 0;
   int _b = 0;

   // Internal representation of HSL
   int _h = 0; // 0 <= _h <= 360
   int _s = 0; // 0 <= _s <= 100
   int _l = 0; // 0 <= _l <= 100

   // Alpha value for this color
   double _a = 0.0;

   // Flags to indicate the color-space for which values are readily available.
   bool _hasRgbColors = false;
   bool _hasHslColors = false;

   /// Create an instance from RGB colors.
   Color.fromRgba(this._r, this._g, this._b, this._a) : _hasRgbColors = true;

   /// Create an instance using a string representing color in RGB color space.
   /// The input string, [value], can be one of the following formats:
   ///
   ///    #RGB
   ///    #RRGGBB
   ///
   ///    rgb(R, G, B)
   ///    rgba(R, G, B, A)
   ///
   /// R, G and B represent intensities of Red, Green and Blue channels and A
   /// represents the alpha channel (transparency)
   ///
   /// When using these formats:
   ///     0 <= R,G,B <= 255
   ///     0 <= A <= 1.0
   factory Color.fromRgbString(String value) =>
       isHexColorString(value) ? _fromHexString(value) : _fromRgbString(value);

   /// Create an instance from HSL colors.
   Color.fromHsla(this._h, this._s, this._l, this._a) : _hasHslColors = true;

   /// Create an instance using a string representing color in HSL color space.
   /// The input string, [value], can be in one of the following formats:
   ///
   ///     hsl(H, S%, L%)
   ///     hsla(H, S%, L%, A)
   ///
   /// H, S and L represent Hue, Saturation and Luminosity respectively.
   ///
   /// When using these formats:
   ///     0 <= H <= 360
   ///     0 <= S,L <= 100
   ///     0 <= A <= 1.0
   factory Color.fromHslString(String value) => _fromHslString(value);

   /// Ensures that the RGB values are available. If they aren't already
   /// available, they are computed from the HSA values.
   ///
   /// Based on color.js from Google Closure library
   void toRgb() {
     if (_hasRgbColors) return;

     num _hueToRgb(num v1, num v2, num vH) {
       vH %= 1.0;

       if ((6 * vH) < 1) {
         return (v1 + (v2 - v1) * 6 * vH);
       } else if (2 * vH < 1) {
         return v2;
       } else if (3 * vH < 2) {
         return (v1 + (v2 - v1) * ((2 / 3) - vH) * 6);
       }
       return v1;
     }

     final h = _h / 360;

     if (_s == 0) {
       _r = _g = _b = (_l * 255).round();
     } else {
       var temp1 = 0;
       var temp2 = 0;
       if (_l < 0.5) {
         temp2 = _l * (1 + _s);
       } else {
         temp2 = _l + _s - (_s * _l);
       }
       temp1 = 2 * _l - temp2;
       _r = (255 * _hueToRgb(temp1, temp2, h + (1 / 3))).round();
       _g = (255 * _hueToRgb(temp1, temp2, h)).round();
       _b = (255 * _hueToRgb(temp1, temp2, h - (1 / 3))).round();
     }
   }

   /// Ensures that the HSA values are available. If they aren't already
   /// available, they are computed from the RGB values.
   ///
   /// Based on color.js in Google Closure library.
   void toHsl() {
     if (_hasHslColors) return;

     final r = _r / 255;
     final g = _g / 255;
     final b = _b / 255;
     final max = math.max(r, math.max(g, b));
     final min = math.min(r, math.min(g, b));

     double l = (max + min) / 2;
     double h = 0.0;
     double s = 0.0;

     // If max and min are equal, the color is gray (h = s = 0)
     if (max != min) {
       if (max == r) {
         h = 60 * (g - b) / (max - min);
       } else if (max == g) {
         h = 60 * (b - r) / (max - min) + 120;
       } else if (max == b) {
         h = 60 * (r - g) / (max - min) + 240;
       }

       if (0 < l && l <= 0.5) {
         s = (max - min) / (2 * l);
       } else {
         s = (max - min) / (2 - 2 * l);
       }
     }

     _h = (h % 360).floor();
     _s = (s * 100).floor();
     _l = (l * 100).floor();
   }

   /// Returns a hex string of the format '#RRGGBB' representing this color.
   /// A new string will be returned each time this function is called.
   String toHexString() {
     toRgb();
     return rgbToHexString(_r, _g, _b);
   }

   /// Returns a string similar to 'rgba(r, g, b, a)' representing this color.
   /// A new string will be returned each time this function is called.
   String toRgbaString() {
     toRgb();
     return 'rgba($_r,$_g,$_b,$_a)';
   }

   /// Returns a string similar to 'hsla(h, s, l, a)' representing this color.
   /// A new string will be returned each time this function is called.
   String toHslaString() {
     toHsl();
     return 'hsla($_h,$_s%,$_l%,$_a)';
   }

   /// Intensity of red from RGB.
   /// Computes RGB values if they are not already available.
   int get r {
     toRgb();
     return _r;
   }

   /// Intensity of green from RGB
   /// Computes RGB values if they are not already available.
   int get g {
     toRgb();
     return _g;
   }

   /// Intensity of blue from RGB.
   /// Computes RGB values if they are not already available.
   int get b {
     toRgb();
     return _b;
   }

   /// Hue value from HSL representation.
   /// Computes HSL values if they are not already available.
   int get h {
     toHsl();
     return _h;
   }

   /// Saturation value from HSL representation.
   /// Computes HSL values if they are not already available.
   int get s {
     toHsl();
     return _s;
   }

   /// Luminosity value from HSL representation.
   /// Computes HSL values if they are not already available.
   int get l {
     toHsl();
     return _l;
   }

   /// Alpha value used by both RGB and HSL representations.
   double get a => _a;

   @override
   String toString() => _hasRgbColors ? toRgbaString() : toHslaString();

   @override
   int get hashCode => toString().hashCode;

   /// Given RGB values create hex string from it.
   static String rgbToHexString(int r, int g, int b) {
     String _hexify(int v) {
       return v < 0x10
           ? "0" + math.max(0, v).toInt().toRadixString(16)
           : math.min(255, v).toInt().toRadixString(16);
     }

     return '#${_hexify(r)}${_hexify(g)}${_hexify(b)}';
   }

   /// RegExp to test if a given string is a hex color string
   static final RegExp hexColorRegExp =
       new RegExp(r'^#([0-9a-f]{3}){1,2}$', caseSensitive: false);

   /// Tests if [str] is a hex color
   static bool isHexColorString(String str) => hexColorRegExp.hasMatch(str);

   /// RegExp to test if a given string is rgb() or rgba() color.
   static final RegExp rgbaColorRegExp = new RegExp(
       r'^(rgb|rgba)?\(\d+,\s?\d+,\s?\d+(,\s?(0|1)?(\.\d)?\d*)?\)$',
       caseSensitive: false);

   /// Tests if [str] is a color represented by rgb() or rgba() or hex string
   static bool isRgbColorString(String str) =>
       isHexColorString(str) || rgbaColorRegExp.hasMatch(str);

   /// RegExp to test if a given string is hsl() or hsla() color.
   static final RegExp hslaColorRegExp = new RegExp(
       r'^(hsl|hsla)?\(\d+,\s?\d+%,\s?\d+%(,\s?(0|1)?(\.\d)?\d*)?\)$',
       caseSensitive: false);

   /// Tests if [str] is a color represented by hsl() or hsla()
   static bool isHslColorString(String str) => hslaColorRegExp.hasMatch(str);

   /// Create an instance using the passed RGB string.
   static Color _fromRgbString(String value) {
     int pos = (value.startsWith('rgb(') || value.startsWith('RGB('))
         ? 4
         : (value.startsWith('rgba(') || value.startsWith('RGBA(')) ? 5 : 0;
     if (pos != 0) {
       final params = value.substring(pos, value.length - 1).split(',');
       int r = int.parse(params[0]),
           g = int.parse(params[1]),
           b = int.parse(params[2]);
       double a = params.length == 3 ? 1.0 : double.parse(params[3]);
       return new Color.fromRgba(r, g, b, a);
     }
     return new Color.fromRgba(0, 0, 0, 0.0);
   }

   /// Create an instance using the passed HEX string.
   /// Assumes that the string starts with a '#' before HEX chars.
   static Color _fromHexString(String hex) {
     if (isNullOrEmpty(hex) || (hex.length != 4 && hex.length != 7)) {
       return new Color.fromRgba(0, 0, 0, 0.0);
     }
     int rgb = 0;

     hex = hex.substring(1);
     if (hex.length == 3) {
       for (int i = 0; i < hex.length; i++) {
         final val = int.parse(hex[i], radix: 16);
         rgb = (rgb * 16 + val) * 16 + val;
       }
     } else if (hex.length == 6) {
       rgb = int.parse(hex, radix: 16);
     }

     return new Color.fromRgba(
         (rgb & 0xff0000) >> 0x10, (rgb & 0xff00) >> 8, (rgb & 0xff), 1.0);
   }

   /// Create an instance using the passed HSL color string.
   static Color _fromHslString(String value) {
     int pos = (value.startsWith('hsl(') || value.startsWith('HSL('))
         ? 4
         : (value.startsWith('hsla(') || value.startsWith('HSLA(')) ? 5 : 0;
     if (pos != 0) {
       final params = value.substring(pos, value.length - 1).split(',');
       int h = int.parse(params[0]),
           s = int.parse(params[1]),
           l = int.parse(params[2]);
       double a = params.length == 3 ? 1.0 : double.parse(params[3]);
       return new Color.fromHsla(h, s, l, a);
     }
     return new Color.fromHsla(0, 0, 0, 0.0);
   }
 }
	//
	// Copyright 2014 Google Inc. All rights reserved.
	//
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file or at
	// https://developers.google.com/open-source/licenses/bsd
	//

	part of charted.core.utils;

	/// Represents a single color for use in visualizations. Currently, supports
	/// representing and conversion between RGB, RGBA, HSL, HSLA and hex formats.
	class Color {
	// Internal representation of RGB
	int _r = 0;
	int _g = 0;
	int _b = 0;

	// Internal representation of HSL
	int _h = 0; // 0 <= _h <= 360
	int _s = 0; // 0 <= _s <= 100
	int _l = 0; // 0 <= _l <= 100

	// Alpha value for this color
	double _a = 0.0;

	// Flags to indicate the color-space for which values are readily available.
	bool _hasRgbColors = false;
	bool _hasHslColors = false;

	/// Create an instance from RGB colors.
	Color.fromRgba(this._r, this._g, this._b, this._a) : _hasRgbColors = true;

	/// Create an instance using a string representing color in RGB color space.
	/// The input string, [value], can be one of the following formats:
	///
	/// #RGB
	/// #RRGGBB
	///
	/// rgb(R, G, B)
	/// rgba(R, G, B, A)
	///
	/// R, G and B represent intensities of Red, Green and Blue channels and A
	/// represents the alpha channel (transparency)
	///
	/// When using these formats:
	/// 0 <= R,G,B <= 255
	/// 0 <= A <= 1.0
	factory Color.fromRgbString(String value) =>
	isHexColorString(value) ? _fromHexString(value) : _fromRgbString(value);

	/// Create an instance from HSL colors.
	Color.fromHsla(this._h, this._s, this._l, this._a) : _hasHslColors = true;

	/// Create an instance using a string representing color in HSL color space.
	/// The input string, [value], can be in one of the following formats:
	///
	/// hsl(H, S%, L%)
	/// hsla(H, S%, L%, A)
	///
	/// H, S and L represent Hue, Saturation and Luminosity respectively.
	///
	/// When using these formats:
	/// 0 <= H <= 360
	/// 0 <= S,L <= 100
	/// 0 <= A <= 1.0
	factory Color.fromHslString(String value) => _fromHslString(value);

	/// Ensures that the RGB values are available. If they aren't already
	/// available, they are computed from the HSA values.
	///
	/// Based on color.js from Google Closure library
	void toRgb() {
	if (_hasRgbColors) return;

	num _hueToRgb(num v1, num v2, num vH) {
	vH %= 1.0;

	if ((6 * vH) < 1) {
	return (v1 + (v2 - v1) * 6 * vH);
	} else if (2 * vH < 1) {
	return v2;
	} else if (3 * vH < 2) {
	return (v1 + (v2 - v1) * ((2 / 3) - vH) * 6);
	}
	return v1;
	}

	final h = _h / 360;

	if (_s == 0) {
	_r = _g = _b = (_l * 255).round();
	} else {
	var temp1 = 0;
	var temp2 = 0;
	if (_l < 0.5) {
	temp2 = _l * (1 + _s);
	} else {
	temp2 = _l + _s - (_s * _l);
	}
	temp1 = 2 * _l - temp2;
	_r = (255 * _hueToRgb(temp1, temp2, h + (1 / 3))).round();
	_g = (255 * _hueToRgb(temp1, temp2, h)).round();
	_b = (255 * _hueToRgb(temp1, temp2, h - (1 / 3))).round();
	}
	}

	/// Ensures that the HSA values are available. If they aren't already
	/// available, they are computed from the RGB values.
	///
	/// Based on color.js in Google Closure library.
	void toHsl() {
	if (_hasHslColors) return;

	final r = _r / 255;
	final g = _g / 255;
	final b = _b / 255;
	final max = math.max(r, math.max(g, b));
	final min = math.min(r, math.min(g, b));

	double l = (max + min) / 2;
	double h = 0.0;
	double s = 0.0;

	// If max and min are equal, the color is gray (h = s = 0)
	if (max != min) {
	if (max == r) {
	h = 60 * (g - b) / (max - min);
	} else if (max == g) {
	h = 60 * (b - r) / (max - min) + 120;
	} else if (max == b) {
	h = 60 * (r - g) / (max - min) + 240;
	}

	if (0 < l && l <= 0.5) {
	s = (max - min) / (2 * l);
	} else {
	s = (max - min) / (2 - 2 * l);
	}
	}

	_h = (h % 360).floor();
	_s = (s * 100).floor();
	_l = (l * 100).floor();
	}

	/// Returns a hex string of the format '#RRGGBB' representing this color.
	/// A new string will be returned each time this function is called.
	String toHexString() {
	toRgb();
	return rgbToHexString(_r, _g, _b);
	}

	/// Returns a string similar to 'rgba(r, g, b, a)' representing this color.
	/// A new string will be returned each time this function is called.
	String toRgbaString() {
	toRgb();
	return 'rgba($_r,$_g,$_b,$_a)';
	}

	/// Returns a string similar to 'hsla(h, s, l, a)' representing this color.
	/// A new string will be returned each time this function is called.
	String toHslaString() {
	toHsl();
	return 'hsla($_h,$_s%,$_l%,$_a)';
	}

	/// Intensity of red from RGB.
	/// Computes RGB values if they are not already available.
	int get r {
	toRgb();
	return _r;
	}

	/// Intensity of green from RGB
	/// Computes RGB values if they are not already available.
	int get g {
	toRgb();
	return _g;
	}

	/// Intensity of blue from RGB.
	/// Computes RGB values if they are not already available.
	int get b {
	toRgb();
	return _b;
	}

	/// Hue value from HSL representation.
	/// Computes HSL values if they are not already available.
	int get h {
	toHsl();
	return _h;
	}

	/// Saturation value from HSL representation.
	/// Computes HSL values if they are not already available.
	int get s {
	toHsl();
	return _s;
	}

	/// Luminosity value from HSL representation.
	/// Computes HSL values if they are not already available.
	int get l {
	toHsl();
	return _l;
	}

	/// Alpha value used by both RGB and HSL representations.
	double get a => _a;

	@override
	String toString() => _hasRgbColors ? toRgbaString() : toHslaString();

	@override
	int get hashCode => toString().hashCode;

	/// Given RGB values create hex string from it.
	static String rgbToHexString(int r, int g, int b) {
	String _hexify(int v) {
	return v < 0x10
	? "0" + math.max(0, v).toInt().toRadixString(16)
	: math.min(255, v).toInt().toRadixString(16);
	}

	return '#${_hexify(r)}${_hexify(g)}${_hexify(b)}';
	}

	/// RegExp to test if a given string is a hex color string
	static final RegExp hexColorRegExp =
	new RegExp(r'^#([0-9a-f]{3}){1,2}$', caseSensitive: false);

	/// Tests if [str] is a hex color
	static bool isHexColorString(String str) => hexColorRegExp.hasMatch(str);

	/// RegExp to test if a given string is rgb() or rgba() color.
	static final RegExp rgbaColorRegExp = new RegExp(
	r'^(rgb\|rgba)?\(\d+,\s?\d+,\s?\d+(,\s?(0\|1)?(\.\d)?\d*)?\)$',
	caseSensitive: false);

	/// Tests if [str] is a color represented by rgb() or rgba() or hex string
	static bool isRgbColorString(String str) =>
	isHexColorString(str) \|\| rgbaColorRegExp.hasMatch(str);

	/// RegExp to test if a given string is hsl() or hsla() color.
	static final RegExp hslaColorRegExp = new RegExp(
	r'^(hsl\|hsla)?\(\d+,\s?\d+%,\s?\d+%(,\s?(0\|1)?(\.\d)?\d*)?\)$',
	caseSensitive: false);

	/// Tests if [str] is a color represented by hsl() or hsla()
	static bool isHslColorString(String str) => hslaColorRegExp.hasMatch(str);

	/// Create an instance using the passed RGB string.
	static Color _fromRgbString(String value) {
	int pos = (value.startsWith('rgb(') \|\| value.startsWith('RGB('))
	? 4
	: (value.startsWith('rgba(') \|\| value.startsWith('RGBA(')) ? 5 : 0;
	if (pos != 0) {
	final params = value.substring(pos, value.length - 1).split(',');
	int r = int.parse(params[0]),
	g = int.parse(params[1]),
	b = int.parse(params[2]);
	double a = params.length == 3 ? 1.0 : double.parse(params[3]);
	return new Color.fromRgba(r, g, b, a);
	}
	return new Color.fromRgba(0, 0, 0, 0.0);
	}

	/// Create an instance using the passed HEX string.
	/// Assumes that the string starts with a '#' before HEX chars.
	static Color _fromHexString(String hex) {
	if (isNullOrEmpty(hex) \|\| (hex.length != 4 && hex.length != 7)) {
	return new Color.fromRgba(0, 0, 0, 0.0);
	}
	int rgb = 0;

	hex = hex.substring(1);
	if (hex.length == 3) {
	for (int i = 0; i < hex.length; i++) {
	final val = int.parse(hex[i], radix: 16);
	rgb = (rgb * 16 + val) * 16 + val;
	}
	} else if (hex.length == 6) {
	rgb = int.parse(hex, radix: 16);
	}

	return new Color.fromRgba(
	(rgb & 0xff0000) >> 0x10, (rgb & 0xff00) >> 8, (rgb & 0xff), 1.0);
	}

	/// Create an instance using the passed HSL color string.
	static Color _fromHslString(String value) {
	int pos = (value.startsWith('hsl(') \|\| value.startsWith('HSL('))
	? 4
	: (value.startsWith('hsla(') \|\| value.startsWith('HSLA(')) ? 5 : 0;
	if (pos != 0) {
	final params = value.substring(pos, value.length - 1).split(',');
	int h = int.parse(params[0]),
	s = int.parse(params[1]),
	l = int.parse(params[2]);
	double a = params.length == 3 ? 1.0 : double.parse(params[3]);
	return new Color.fromHsla(h, s, l, a);
	}
	return new Color.fromHsla(0, 0, 0, 0.0);
	}
	}