src/third_party/closure_library/closure/goog/color/alpha.js - incubator-pagespeed-debian - Git at Google

 // Copyright 2006 The Closure Library Authors. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS-IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 /**
  * @fileoverview Utilities related to alpha/transparent colors and alpha color
  * conversion.
  */

 goog.provide('goog.color.alpha');

 goog.require('goog.color');


 /**
  * Parses an alpha color out of a string.
  * @param {string} str Color in some format.
  * @return {{hex: string, type: string}} 'hex' is a string containing
  *     a hex representation of the color, and 'type' is a string
  *     containing the type of color format passed in ('hex', 'rgb', 'named').
  */
 goog.color.alpha.parse = function(str) {
   var result = {};
   str = String(str);

   var maybeHex = goog.color.prependHashIfNecessaryHelper(str);
   if (goog.color.alpha.isValidAlphaHexColor_(maybeHex)) {
     result.hex = goog.color.alpha.normalizeAlphaHex_(maybeHex);
     result.type = 'hex';
     return result;
   } else {
     var rgba = goog.color.alpha.isValidRgbaColor_(str);
     if (rgba.length) {
       result.hex = goog.color.alpha.rgbaArrayToHex(rgba);
       result.type = 'rgba';
       return result;
     } else {
       var hsla = goog.color.alpha.isValidHslaColor_(str);
       if (hsla.length) {
         result.hex = goog.color.alpha.hslaArrayToHex(hsla);
         result.type = 'hsla';
         return result;
       }
     }
   }
   throw Error(str + ' is not a valid color string');
 };


 /**
  * Converts a hex representation of a color to RGBA.
  * @param {string} hexColor Color to convert.
  * @return {string} string of the form 'rgba(R,G,B,A)' which can be used in
  *    styles.
  */
 goog.color.alpha.hexToRgbaStyle = function(hexColor) {
   return goog.color.alpha.rgbaStyle_(goog.color.alpha.hexToRgba(hexColor));
 };


 /**
  * Gets the hex color part of an alpha hex color. For example, from '#abcdef55'
  * return '#abcdef'.
  * @param {string} colorWithAlpha The alpha hex color to get the hex color from.
  * @return {string} The hex color where the alpha part has been stripped off.
  */
 goog.color.alpha.extractHexColor = function(colorWithAlpha) {
   if (goog.color.alpha.isValidAlphaHexColor_(colorWithAlpha)) {
     var fullColor = goog.color.prependHashIfNecessaryHelper(colorWithAlpha);
     var normalizedColor = goog.color.alpha.normalizeAlphaHex_(fullColor);
     return normalizedColor.substring(0, 7);
   } else {
     throw Error(colorWithAlpha + ' is not a valid 8-hex color string');
   }
 };


 /**
  * Gets the alpha color part of an alpha hex color. For example, from
  * '#abcdef55' return '55'. The result is guaranteed to be two characters long.
  * @param {string} colorWithAlpha The alpha hex color to get the hex color from.
  * @return {string} The hex color where the alpha part has been stripped off.
  */
 goog.color.alpha.extractAlpha = function(colorWithAlpha) {
   if (goog.color.alpha.isValidAlphaHexColor_(colorWithAlpha)) {
     var fullColor = goog.color.prependHashIfNecessaryHelper(colorWithAlpha);
     var normalizedColor = goog.color.alpha.normalizeAlphaHex_(fullColor);
     return normalizedColor.substring(7, 9);
   } else {
     throw Error(colorWithAlpha + ' is not a valid 8-hex color string');
   }
 };


 /**
  * Regular expression for extracting the digits in a hex color quadruplet.
  * @type {RegExp}
  * @private
  */
 goog.color.alpha.hexQuadrupletRe_ = /#(.)(.)(.)(.)/;


 /**
  * Normalize a hex representation of an alpha color.
  * @param {string} hexColor an alpha hex color string.
  * @return {string} hex color in the format '#rrggbbaa' with all lowercase
  *     literals.
  * @private
  */
 goog.color.alpha.normalizeAlphaHex_ = function(hexColor) {
   if (!goog.color.alpha.isValidAlphaHexColor_(hexColor)) {
     throw Error("'" + hexColor + "' is not a valid alpha hex color");
   }
   if (hexColor.length == 5) { // of the form #RGBA
     hexColor = hexColor.replace(goog.color.alpha.hexQuadrupletRe_,
         '#$1$1$2$2$3$3$4$4');
   }
   return hexColor.toLowerCase();
 };


 /**
  * Converts an 8-hex representation of a color to RGBA.
  * @param {string} hexColor Color to convert.
  * @return {!Array<number>} array containing [r, g, b, a].
  *     r, g, b are ints between 0
  *     and 255, and a is a value between 0 and 1.
  */
 goog.color.alpha.hexToRgba = function(hexColor) {
   // TODO(user): Enhance code sharing with goog.color, for example by
   //     adding a goog.color.genericHexToRgb method.
   hexColor = goog.color.alpha.normalizeAlphaHex_(hexColor);
   var r = parseInt(hexColor.substr(1, 2), 16);
   var g = parseInt(hexColor.substr(3, 2), 16);
   var b = parseInt(hexColor.substr(5, 2), 16);
   var a = parseInt(hexColor.substr(7, 2), 16);

   return [r, g, b, a / 255];
 };


 /**
  * Converts a color from RGBA to hex representation.
  * @param {number} r Amount of red, int between 0 and 255.
  * @param {number} g Amount of green, int between 0 and 255.
  * @param {number} b Amount of blue, int between 0 and 255.
  * @param {number} a Amount of alpha, float between 0 and 1.
  * @return {string} hex representation of the color.
  */
 goog.color.alpha.rgbaToHex = function(r, g, b, a) {
   var intAlpha = Math.floor(a * 255);
   if (isNaN(intAlpha) || intAlpha < 0 || intAlpha > 255) {
     // TODO(user): The CSS spec says the value should be clamped.
     throw Error('"(' + r + ',' + g + ',' + b + ',' + a +
         '") is not a valid RGBA color');
   }
   var hexA = goog.color.prependZeroIfNecessaryHelper(intAlpha.toString(16));
   return goog.color.rgbToHex(r, g, b) + hexA;
 };


 /**
  * Converts a color from HSLA to hex representation.
  * @param {number} h Amount of hue, int between 0 and 360.
  * @param {number} s Amount of saturation, int between 0 and 100.
  * @param {number} l Amount of lightness, int between 0 and 100.
  * @param {number} a Amount of alpha, float between 0 and 1.
  * @return {string} hex representation of the color.
  */
 goog.color.alpha.hslaToHex = function(h, s, l, a) {
   var intAlpha = Math.floor(a * 255);
   if (isNaN(intAlpha) || intAlpha < 0 || intAlpha > 255) {
     // TODO(user): The CSS spec says the value should be clamped.
     throw Error('"(' + h + ',' + s + ',' + l + ',' + a +
         '") is not a valid HSLA color');
   }
   var hexA = goog.color.prependZeroIfNecessaryHelper(intAlpha.toString(16));
   return goog.color.hslToHex(h, s / 100, l / 100) + hexA;
 };


 /**
  * Converts a color from RGBA to hex representation.
  * @param {Array<number>} rgba Array of [r, g, b, a], with r, g, b in [0, 255]
  *     and a in [0, 1].
  * @return {string} hex representation of the color.
  */
 goog.color.alpha.rgbaArrayToHex = function(rgba) {
   return goog.color.alpha.rgbaToHex(rgba[0], rgba[1], rgba[2], rgba[3]);
 };


 /**
  * Converts a color from RGBA to an RGBA style string.
  * @param {number} r Value of red, in [0, 255].
  * @param {number} g Value of green, in [0, 255].
  * @param {number} b Value of blue, in [0, 255].
  * @param {number} a Value of alpha, in [0, 1].
  * @return {string} An 'rgba(r,g,b,a)' string ready for use in a CSS rule.
  */
 goog.color.alpha.rgbaToRgbaStyle = function(r, g, b, a) {
   if (isNaN(r) || r < 0 || r > 255 ||
       isNaN(g) || g < 0 || g > 255 ||
       isNaN(b) || b < 0 || b > 255 ||
       isNaN(a) || a < 0 || a > 1) {
     throw Error('"(' + r + ',' + g + ',' + b + ',' + a +
         ')" is not a valid RGBA color');
   }
   return goog.color.alpha.rgbaStyle_([r, g, b, a]);
 };


 /**
  * Converts a color from RGBA to an RGBA style string.
  * @param {(Array<number>|Float32Array)} rgba Array of [r, g, b, a],
  *     with r, g, b in [0, 255] and a in [0, 1].
  * @return {string} An 'rgba(r,g,b,a)' string ready for use in a CSS rule.
  */
 goog.color.alpha.rgbaArrayToRgbaStyle = function(rgba) {
   return goog.color.alpha.rgbaToRgbaStyle(rgba[0], rgba[1], rgba[2], rgba[3]);
 };


 /**
  * Converts a color from HSLA to hex representation.
  * @param {Array<number>} hsla Array of [h, s, l, a], where h is an integer in
  *     [0, 360], s and l are integers in [0, 100], and a is in [0, 1].
  * @return {string} hex representation of the color, such as '#af457eff'.
  */
 goog.color.alpha.hslaArrayToHex = function(hsla) {
   return goog.color.alpha.hslaToHex(hsla[0], hsla[1], hsla[2], hsla[3]);
 };


 /**
  * Converts a color from HSLA to an RGBA style string.
  * @param {Array<number>} hsla Array of [h, s, l, a], where h is and integer in
  *     [0, 360], s and l are integers in [0, 100], and a is in [0, 1].
  * @return {string} An 'rgba(r,g,b,a)' string ready for use in a CSS rule.
  */
 goog.color.alpha.hslaArrayToRgbaStyle = function(hsla) {
   return goog.color.alpha.hslaToRgbaStyle(hsla[0], hsla[1], hsla[2], hsla[3]);
 };


 /**
  * Converts a color from HSLA to an RGBA style string.
  * @param {number} h Amount of hue, int between 0 and 360.
  * @param {number} s Amount of saturation, int between 0 and 100.
  * @param {number} l Amount of lightness, int between 0 and 100.
  * @param {number} a Amount of alpha, float between 0 and 1.
  * @return {string} An 'rgba(r,g,b,a)' string ready for use in a CSS rule.
  *     styles.
  */
 goog.color.alpha.hslaToRgbaStyle = function(h, s, l, a) {
   return goog.color.alpha.rgbaStyle_(goog.color.alpha.hslaToRgba(h, s, l, a));
 };


 /**
  * Converts a color from HSLA color space to RGBA color space.
  * @param {number} h Amount of hue, int between 0 and 360.
  * @param {number} s Amount of saturation, int between 0 and 100.
  * @param {number} l Amount of lightness, int between 0 and 100.
  * @param {number} a Amount of alpha, float between 0 and 1.
  * @return {!Array<number>} [r, g, b, a] values for the color, where r, g, b
  *     are integers in [0, 255] and a is a float in [0, 1].
  */
 goog.color.alpha.hslaToRgba = function(h, s, l, a) {
   return goog.color.hslToRgb(h, s / 100, l / 100).concat(a);
 };


 /**
  * Converts a color from RGBA color space to HSLA color space.
  * Modified from {@link http://en.wikipedia.org/wiki/HLS_color_space}.
  * @param {number} r Value of red, in [0, 255].
  * @param {number} g Value of green, in [0, 255].
  * @param {number} b Value of blue, in [0, 255].
  * @param {number} a Value of alpha, in [0, 255].
  * @return {!Array<number>} [h, s, l, a] values for the color, with h an int in
  *     [0, 360] and s, l and a in [0, 1].
  */
 goog.color.alpha.rgbaToHsla = function(r, g, b, a) {
   return goog.color.rgbToHsl(r, g, b).concat(a);
 };


 /**
  * Converts a color from RGBA color space to HSLA color space.
  * @param {Array<number>} rgba [r, g, b, a] values for the color, each in
  *     [0, 255].
  * @return {!Array<number>} [h, s, l, a] values for the color, with h in
  *     [0, 360] and s, l and a in [0, 1].
  */
 goog.color.alpha.rgbaArrayToHsla = function(rgba) {
   return goog.color.alpha.rgbaToHsla(rgba[0], rgba[1], rgba[2], rgba[3]);
 };


 /**
  * Helper for isValidAlphaHexColor_.
  * @type {RegExp}
  * @private
  */
 goog.color.alpha.validAlphaHexColorRe_ = /^#(?:[0-9a-f]{4}){1,2}$/i;


 /**
  * Checks if a string is a valid alpha hex color.  We expect strings of the
  * format #RRGGBBAA (ex: #1b3d5f5b) or #RGBA (ex: #3CAF == #33CCAAFF).
  * @param {string} str String to check.
  * @return {boolean} Whether the string is a valid alpha hex color.
  * @private
  */
 // TODO(user): Support percentages when goog.color also supports them.
 goog.color.alpha.isValidAlphaHexColor_ = function(str) {
   return goog.color.alpha.validAlphaHexColorRe_.test(str);
 };


 /**
  * Helper for isNormalizedAlphaHexColor_.
  * @type {RegExp}
  * @private
  */
 goog.color.alpha.normalizedAlphaHexColorRe_ = /^#[0-9a-f]{8}$/;


 /**
  * Checks if a string is a normalized alpha hex color.
  * We expect strings of the format #RRGGBBAA (ex: #1b3d5f5b)
  * using only lowercase letters.
  * @param {string} str String to check.
  * @return {boolean} Whether the string is a normalized hex color.
  * @private
  */
 goog.color.alpha.isNormalizedAlphaHexColor_ = function(str) {
   return goog.color.alpha.normalizedAlphaHexColorRe_.test(str);
 };


 /**
  * Regular expression for matching and capturing RGBA style strings. Helper for
  * isValidRgbaColor_.
  * @type {RegExp}
  * @private
  */
 goog.color.alpha.rgbaColorRe_ =
     /^(?:rgba)?\((0|[1-9]\d{0,2}),\s?(0|[1-9]\d{0,2}),\s?(0|[1-9]\d{0,2}),\s?(0|1|0\.\d{0,10})\)$/i;


 /**
  * Regular expression for matching and capturing HSLA style strings. Helper for
  * isValidHslaColor_.
  * @type {RegExp}
  * @private
  */
 goog.color.alpha.hslaColorRe_ =
     /^(?:hsla)\((0|[1-9]\d{0,2}),\s?(0|[1-9]\d{0,2})\%,\s?(0|[1-9]\d{0,2})\%,\s?(0|1|0\.\d{0,10})\)$/i;


 /**
  * Checks if a string is a valid rgba color.  We expect strings of the format
  * '(r, g, b, a)', or 'rgba(r, g, b, a)', where r, g, b are ints in [0, 255]
  *     and a is a float in [0, 1].
  * @param {string} str String to check.
  * @return {!Array<number>} the integers [r, g, b, a] for valid colors or the
  *     empty array for invalid colors.
  * @private
  */
 goog.color.alpha.isValidRgbaColor_ = function(str) {
   // Each component is separate (rather than using a repeater) so we can
   // capture the match. Also, we explicitly set each component to be either 0,
   // or start with a non-zero, to prevent octal numbers from slipping through.
   var regExpResultArray = str.match(goog.color.alpha.rgbaColorRe_);
   if (regExpResultArray) {
     var r = Number(regExpResultArray[1]);
     var g = Number(regExpResultArray[2]);
     var b = Number(regExpResultArray[3]);
     var a = Number(regExpResultArray[4]);
     if (r >= 0 && r <= 255 &&
         g >= 0 && g <= 255 &&
         b >= 0 && b <= 255 &&
         a >= 0 && a <= 1) {
       return [r, g, b, a];
     }
   }
   return [];
 };


 /**
  * Checks if a string is a valid hsla color.  We expect strings of the format
  * 'hsla(h, s, l, a)', where s in an int in [0, 360], s and l are percentages
  *     between 0 and 100 such as '50%' or '70%', and a is a float in [0, 1].
  * @param {string} str String to check.
  * @return {!Array<number>} the integers [h, s, l, a] for valid colors or the
  *     empty array for invalid colors.
  * @private
  */
 goog.color.alpha.isValidHslaColor_ = function(str) {
   // Each component is separate (rather than using a repeater) so we can
   // capture the match. Also, we explicitly set each component to be either 0,
   // or start with a non-zero, to prevent octal numbers from slipping through.
   var regExpResultArray = str.match(goog.color.alpha.hslaColorRe_);
   if (regExpResultArray) {
     var h = Number(regExpResultArray[1]);
     var s = Number(regExpResultArray[2]);
     var l = Number(regExpResultArray[3]);
     var a = Number(regExpResultArray[4]);
     if (h >= 0 && h <= 360 &&
         s >= 0 && s <= 100 &&
         l >= 0 && l <= 100 &&
         a >= 0 && a <= 1) {
       return [h, s, l, a];
     }
   }
   return [];
 };


 /**
  * Takes an array of [r, g, b, a] and converts it into a string appropriate for
  * CSS styles. The alpha channel value is rounded to 3 decimal places to make
  * sure the produced string is not too long.
  * @param {Array<number>} rgba [r, g, b, a] with r, g, b in [0, 255] and a
  *     in [0, 1].
  * @return {string} string of the form 'rgba(r,g,b,a)'.
  * @private
  */
 goog.color.alpha.rgbaStyle_ = function(rgba) {
   var roundedRgba = rgba.slice(0);
   roundedRgba[3] = Math.round(rgba[3] * 1000) / 1000;
   return 'rgba(' + roundedRgba.join(',') + ')';
 };


 /**
  * Converts from h,s,v,a values to a hex string
  * @param {number} h Hue, in [0, 1].
  * @param {number} s Saturation, in [0, 1].
  * @param {number} v Value, in [0, 255].
  * @param {number} a Alpha, in [0, 1].
  * @return {string} hex representation of the color.
  */
 goog.color.alpha.hsvaToHex = function(h, s, v, a) {
   var alpha = Math.floor(a * 255);
   return goog.color.hsvArrayToHex([h, s, v]) +
          goog.color.prependZeroIfNecessaryHelper(alpha.toString(16));
 };


 /**
  * Converts from an HSVA array to a hex string
  * @param {Array<number>} hsva Array of [h, s, v, a] in
  *     [[0, 1], [0, 1], [0, 255], [0, 1]].
  * @return {string} hex representation of the color.
  */
 goog.color.alpha.hsvaArrayToHex = function(hsva) {
   return goog.color.alpha.hsvaToHex(hsva[0], hsva[1], hsva[2], hsva[3]);
 };
	// Copyright 2006 The Closure Library Authors. All Rights Reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS-IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	/**
	* @fileoverview Utilities related to alpha/transparent colors and alpha color
	* conversion.
	*/

	goog.provide('goog.color.alpha');

	goog.require('goog.color');


	/**
	* Parses an alpha color out of a string.
	* @param {string} str Color in some format.
	* @return {{hex: string, type: string}} 'hex' is a string containing
	* a hex representation of the color, and 'type' is a string
	* containing the type of color format passed in ('hex', 'rgb', 'named').
	*/
	goog.color.alpha.parse = function(str) {
	var result = {};
	str = String(str);

	var maybeHex = goog.color.prependHashIfNecessaryHelper(str);
	if (goog.color.alpha.isValidAlphaHexColor_(maybeHex)) {
	result.hex = goog.color.alpha.normalizeAlphaHex_(maybeHex);
	result.type = 'hex';
	return result;
	} else {
	var rgba = goog.color.alpha.isValidRgbaColor_(str);
	if (rgba.length) {
	result.hex = goog.color.alpha.rgbaArrayToHex(rgba);
	result.type = 'rgba';
	return result;
	} else {
	var hsla = goog.color.alpha.isValidHslaColor_(str);
	if (hsla.length) {
	result.hex = goog.color.alpha.hslaArrayToHex(hsla);
	result.type = 'hsla';
	return result;
	}
	}
	}
	throw Error(str + ' is not a valid color string');
	};


	/**
	* Converts a hex representation of a color to RGBA.
	* @param {string} hexColor Color to convert.
	* @return {string} string of the form 'rgba(R,G,B,A)' which can be used in
	* styles.
	*/
	goog.color.alpha.hexToRgbaStyle = function(hexColor) {
	return goog.color.alpha.rgbaStyle_(goog.color.alpha.hexToRgba(hexColor));
	};


	/**
	* Gets the hex color part of an alpha hex color. For example, from '#abcdef55'
	* return '#abcdef'.
	* @param {string} colorWithAlpha The alpha hex color to get the hex color from.
	* @return {string} The hex color where the alpha part has been stripped off.
	*/
	goog.color.alpha.extractHexColor = function(colorWithAlpha) {
	if (goog.color.alpha.isValidAlphaHexColor_(colorWithAlpha)) {
	var fullColor = goog.color.prependHashIfNecessaryHelper(colorWithAlpha);
	var normalizedColor = goog.color.alpha.normalizeAlphaHex_(fullColor);
	return normalizedColor.substring(0, 7);
	} else {
	throw Error(colorWithAlpha + ' is not a valid 8-hex color string');
	}
	};


	/**
	* Gets the alpha color part of an alpha hex color. For example, from
	* '#abcdef55' return '55'. The result is guaranteed to be two characters long.
	* @param {string} colorWithAlpha The alpha hex color to get the hex color from.
	* @return {string} The hex color where the alpha part has been stripped off.
	*/
	goog.color.alpha.extractAlpha = function(colorWithAlpha) {
	if (goog.color.alpha.isValidAlphaHexColor_(colorWithAlpha)) {
	var fullColor = goog.color.prependHashIfNecessaryHelper(colorWithAlpha);
	var normalizedColor = goog.color.alpha.normalizeAlphaHex_(fullColor);
	return normalizedColor.substring(7, 9);
	} else {
	throw Error(colorWithAlpha + ' is not a valid 8-hex color string');
	}
	};


	/**
	* Regular expression for extracting the digits in a hex color quadruplet.
	* @type {RegExp}
	* @private
	*/
	goog.color.alpha.hexQuadrupletRe_ = /#(.)(.)(.)(.)/;


	/**
	* Normalize a hex representation of an alpha color.
	* @param {string} hexColor an alpha hex color string.
	* @return {string} hex color in the format '#rrggbbaa' with all lowercase
	* literals.
	* @private
	*/
	goog.color.alpha.normalizeAlphaHex_ = function(hexColor) {
	if (!goog.color.alpha.isValidAlphaHexColor_(hexColor)) {
	throw Error("'" + hexColor + "' is not a valid alpha hex color");
	}
	if (hexColor.length == 5) { // of the form #RGBA
	hexColor = hexColor.replace(goog.color.alpha.hexQuadrupletRe_,
	'#$1$1$2$2$3$3$4$4');
	}
	return hexColor.toLowerCase();
	};


	/**
	* Converts an 8-hex representation of a color to RGBA.
	* @param {string} hexColor Color to convert.
	* @return {!Array<number>} array containing [r, g, b, a].
	* r, g, b are ints between 0
	* and 255, and a is a value between 0 and 1.
	*/
	goog.color.alpha.hexToRgba = function(hexColor) {
	// TODO(user): Enhance code sharing with goog.color, for example by
	// adding a goog.color.genericHexToRgb method.
	hexColor = goog.color.alpha.normalizeAlphaHex_(hexColor);
	var r = parseInt(hexColor.substr(1, 2), 16);
	var g = parseInt(hexColor.substr(3, 2), 16);
	var b = parseInt(hexColor.substr(5, 2), 16);
	var a = parseInt(hexColor.substr(7, 2), 16);

	return [r, g, b, a / 255];
	};


	/**
	* Converts a color from RGBA to hex representation.
	* @param {number} r Amount of red, int between 0 and 255.
	* @param {number} g Amount of green, int between 0 and 255.
	* @param {number} b Amount of blue, int between 0 and 255.
	* @param {number} a Amount of alpha, float between 0 and 1.
	* @return {string} hex representation of the color.
	*/
	goog.color.alpha.rgbaToHex = function(r, g, b, a) {
	var intAlpha = Math.floor(a * 255);
	if (isNaN(intAlpha) \|\| intAlpha < 0 \|\| intAlpha > 255) {
	// TODO(user): The CSS spec says the value should be clamped.
	throw Error('"(' + r + ',' + g + ',' + b + ',' + a +
	'") is not a valid RGBA color');
	}
	var hexA = goog.color.prependZeroIfNecessaryHelper(intAlpha.toString(16));
	return goog.color.rgbToHex(r, g, b) + hexA;
	};


	/**
	* Converts a color from HSLA to hex representation.
	* @param {number} h Amount of hue, int between 0 and 360.
	* @param {number} s Amount of saturation, int between 0 and 100.
	* @param {number} l Amount of lightness, int between 0 and 100.
	* @param {number} a Amount of alpha, float between 0 and 1.
	* @return {string} hex representation of the color.
	*/
	goog.color.alpha.hslaToHex = function(h, s, l, a) {
	var intAlpha = Math.floor(a * 255);
	if (isNaN(intAlpha) \|\| intAlpha < 0 \|\| intAlpha > 255) {
	// TODO(user): The CSS spec says the value should be clamped.
	throw Error('"(' + h + ',' + s + ',' + l + ',' + a +
	'") is not a valid HSLA color');
	}
	var hexA = goog.color.prependZeroIfNecessaryHelper(intAlpha.toString(16));
	return goog.color.hslToHex(h, s / 100, l / 100) + hexA;
	};


	/**
	* Converts a color from RGBA to hex representation.
	* @param {Array<number>} rgba Array of [r, g, b, a], with r, g, b in [0, 255]
	* and a in [0, 1].
	* @return {string} hex representation of the color.
	*/
	goog.color.alpha.rgbaArrayToHex = function(rgba) {
	return goog.color.alpha.rgbaToHex(rgba[0], rgba[1], rgba[2], rgba[3]);
	};


	/**
	* Converts a color from RGBA to an RGBA style string.
	* @param {number} r Value of red, in [0, 255].
	* @param {number} g Value of green, in [0, 255].
	* @param {number} b Value of blue, in [0, 255].
	* @param {number} a Value of alpha, in [0, 1].
	* @return {string} An 'rgba(r,g,b,a)' string ready for use in a CSS rule.
	*/
	goog.color.alpha.rgbaToRgbaStyle = function(r, g, b, a) {
	if (isNaN(r) \|\| r < 0 \|\| r > 255 \|\|
	isNaN(g) \|\| g < 0 \|\| g > 255 \|\|
	isNaN(b) \|\| b < 0 \|\| b > 255 \|\|
	isNaN(a) \|\| a < 0 \|\| a > 1) {
	throw Error('"(' + r + ',' + g + ',' + b + ',' + a +
	')" is not a valid RGBA color');
	}
	return goog.color.alpha.rgbaStyle_([r, g, b, a]);
	};


	/**
	* Converts a color from RGBA to an RGBA style string.
	* @param {(Array<number>\|Float32Array)} rgba Array of [r, g, b, a],
	* with r, g, b in [0, 255] and a in [0, 1].
	* @return {string} An 'rgba(r,g,b,a)' string ready for use in a CSS rule.
	*/
	goog.color.alpha.rgbaArrayToRgbaStyle = function(rgba) {
	return goog.color.alpha.rgbaToRgbaStyle(rgba[0], rgba[1], rgba[2], rgba[3]);
	};


	/**
	* Converts a color from HSLA to hex representation.
	* @param {Array<number>} hsla Array of [h, s, l, a], where h is an integer in
	* [0, 360], s and l are integers in [0, 100], and a is in [0, 1].
	* @return {string} hex representation of the color, such as '#af457eff'.
	*/
	goog.color.alpha.hslaArrayToHex = function(hsla) {
	return goog.color.alpha.hslaToHex(hsla[0], hsla[1], hsla[2], hsla[3]);
	};


	/**
	* Converts a color from HSLA to an RGBA style string.
	* @param {Array<number>} hsla Array of [h, s, l, a], where h is and integer in
	* [0, 360], s and l are integers in [0, 100], and a is in [0, 1].
	* @return {string} An 'rgba(r,g,b,a)' string ready for use in a CSS rule.
	*/
	goog.color.alpha.hslaArrayToRgbaStyle = function(hsla) {
	return goog.color.alpha.hslaToRgbaStyle(hsla[0], hsla[1], hsla[2], hsla[3]);
	};


	/**
	* Converts a color from HSLA to an RGBA style string.
	* @param {number} h Amount of hue, int between 0 and 360.
	* @param {number} s Amount of saturation, int between 0 and 100.
	* @param {number} l Amount of lightness, int between 0 and 100.
	* @param {number} a Amount of alpha, float between 0 and 1.
	* @return {string} An 'rgba(r,g,b,a)' string ready for use in a CSS rule.
	* styles.
	*/
	goog.color.alpha.hslaToRgbaStyle = function(h, s, l, a) {
	return goog.color.alpha.rgbaStyle_(goog.color.alpha.hslaToRgba(h, s, l, a));
	};


	/**
	* Converts a color from HSLA color space to RGBA color space.
	* @param {number} h Amount of hue, int between 0 and 360.
	* @param {number} s Amount of saturation, int between 0 and 100.
	* @param {number} l Amount of lightness, int between 0 and 100.
	* @param {number} a Amount of alpha, float between 0 and 1.
	* @return {!Array<number>} [r, g, b, a] values for the color, where r, g, b
	* are integers in [0, 255] and a is a float in [0, 1].
	*/
	goog.color.alpha.hslaToRgba = function(h, s, l, a) {
	return goog.color.hslToRgb(h, s / 100, l / 100).concat(a);
	};


	/**
	* Converts a color from RGBA color space to HSLA color space.
	* Modified from {@link http://en.wikipedia.org/wiki/HLS_color_space}.
	* @param {number} r Value of red, in [0, 255].
	* @param {number} g Value of green, in [0, 255].
	* @param {number} b Value of blue, in [0, 255].
	* @param {number} a Value of alpha, in [0, 255].
	* @return {!Array<number>} [h, s, l, a] values for the color, with h an int in
	* [0, 360] and s, l and a in [0, 1].
	*/
	goog.color.alpha.rgbaToHsla = function(r, g, b, a) {
	return goog.color.rgbToHsl(r, g, b).concat(a);
	};


	/**
	* Converts a color from RGBA color space to HSLA color space.
	* @param {Array<number>} rgba [r, g, b, a] values for the color, each in
	* [0, 255].
	* @return {!Array<number>} [h, s, l, a] values for the color, with h in
	* [0, 360] and s, l and a in [0, 1].
	*/
	goog.color.alpha.rgbaArrayToHsla = function(rgba) {
	return goog.color.alpha.rgbaToHsla(rgba[0], rgba[1], rgba[2], rgba[3]);
	};


	/**
	* Helper for isValidAlphaHexColor_.
	* @type {RegExp}
	* @private
	*/
	goog.color.alpha.validAlphaHexColorRe_ = /^#(?:[0-9a-f]{4}){1,2}$/i;


	/**
	* Checks if a string is a valid alpha hex color. We expect strings of the
	* format #RRGGBBAA (ex: #1b3d5f5b) or #RGBA (ex: #3CAF == #33CCAAFF).
	* @param {string} str String to check.
	* @return {boolean} Whether the string is a valid alpha hex color.
	* @private
	*/
	// TODO(user): Support percentages when goog.color also supports them.
	goog.color.alpha.isValidAlphaHexColor_ = function(str) {
	return goog.color.alpha.validAlphaHexColorRe_.test(str);
	};


	/**
	* Helper for isNormalizedAlphaHexColor_.
	* @type {RegExp}
	* @private
	*/
	goog.color.alpha.normalizedAlphaHexColorRe_ = /^#[0-9a-f]{8}$/;


	/**
	* Checks if a string is a normalized alpha hex color.
	* We expect strings of the format #RRGGBBAA (ex: #1b3d5f5b)
	* using only lowercase letters.
	* @param {string} str String to check.
	* @return {boolean} Whether the string is a normalized hex color.
	* @private
	*/
	goog.color.alpha.isNormalizedAlphaHexColor_ = function(str) {
	return goog.color.alpha.normalizedAlphaHexColorRe_.test(str);
	};


	/**
	* Regular expression for matching and capturing RGBA style strings. Helper for
	* isValidRgbaColor_.
	* @type {RegExp}
	* @private
	*/
	goog.color.alpha.rgbaColorRe_ =
	/^(?:rgba)?\((0\|[1-9]\d{0,2}),\s?(0\|[1-9]\d{0,2}),\s?(0\|[1-9]\d{0,2}),\s?(0\|1\|0\.\d{0,10})\)$/i;


	/**
	* Regular expression for matching and capturing HSLA style strings. Helper for
	* isValidHslaColor_.
	* @type {RegExp}
	* @private
	*/
	goog.color.alpha.hslaColorRe_ =
	/^(?:hsla)\((0\|[1-9]\d{0,2}),\s?(0\|[1-9]\d{0,2})\%,\s?(0\|[1-9]\d{0,2})\%,\s?(0\|1\|0\.\d{0,10})\)$/i;


	/**
	* Checks if a string is a valid rgba color. We expect strings of the format
	* '(r, g, b, a)', or 'rgba(r, g, b, a)', where r, g, b are ints in [0, 255]
	* and a is a float in [0, 1].
	* @param {string} str String to check.
	* @return {!Array<number>} the integers [r, g, b, a] for valid colors or the
	* empty array for invalid colors.
	* @private
	*/
	goog.color.alpha.isValidRgbaColor_ = function(str) {
	// Each component is separate (rather than using a repeater) so we can
	// capture the match. Also, we explicitly set each component to be either 0,
	// or start with a non-zero, to prevent octal numbers from slipping through.
	var regExpResultArray = str.match(goog.color.alpha.rgbaColorRe_);
	if (regExpResultArray) {
	var r = Number(regExpResultArray[1]);
	var g = Number(regExpResultArray[2]);
	var b = Number(regExpResultArray[3]);
	var a = Number(regExpResultArray[4]);
	if (r >= 0 && r <= 255 &&
	g >= 0 && g <= 255 &&
	b >= 0 && b <= 255 &&
	a >= 0 && a <= 1) {
	return [r, g, b, a];
	}
	}
	return [];
	};


	/**
	* Checks if a string is a valid hsla color. We expect strings of the format
	* 'hsla(h, s, l, a)', where s in an int in [0, 360], s and l are percentages
	* between 0 and 100 such as '50%' or '70%', and a is a float in [0, 1].
	* @param {string} str String to check.
	* @return {!Array<number>} the integers [h, s, l, a] for valid colors or the
	* empty array for invalid colors.
	* @private
	*/
	goog.color.alpha.isValidHslaColor_ = function(str) {
	// Each component is separate (rather than using a repeater) so we can
	// capture the match. Also, we explicitly set each component to be either 0,
	// or start with a non-zero, to prevent octal numbers from slipping through.
	var regExpResultArray = str.match(goog.color.alpha.hslaColorRe_);
	if (regExpResultArray) {
	var h = Number(regExpResultArray[1]);
	var s = Number(regExpResultArray[2]);
	var l = Number(regExpResultArray[3]);
	var a = Number(regExpResultArray[4]);
	if (h >= 0 && h <= 360 &&
	s >= 0 && s <= 100 &&
	l >= 0 && l <= 100 &&
	a >= 0 && a <= 1) {
	return [h, s, l, a];
	}
	}
	return [];
	};


	/**
	* Takes an array of [r, g, b, a] and converts it into a string appropriate for
	* CSS styles. The alpha channel value is rounded to 3 decimal places to make
	* sure the produced string is not too long.
	* @param {Array<number>} rgba [r, g, b, a] with r, g, b in [0, 255] and a
	* in [0, 1].
	* @return {string} string of the form 'rgba(r,g,b,a)'.
	* @private
	*/
	goog.color.alpha.rgbaStyle_ = function(rgba) {
	var roundedRgba = rgba.slice(0);
	roundedRgba[3] = Math.round(rgba[3] * 1000) / 1000;
	return 'rgba(' + roundedRgba.join(',') + ')';
	};


	/**
	* Converts from h,s,v,a values to a hex string
	* @param {number} h Hue, in [0, 1].
	* @param {number} s Saturation, in [0, 1].
	* @param {number} v Value, in [0, 255].
	* @param {number} a Alpha, in [0, 1].
	* @return {string} hex representation of the color.
	*/
	goog.color.alpha.hsvaToHex = function(h, s, v, a) {
	var alpha = Math.floor(a * 255);
	return goog.color.hsvArrayToHex([h, s, v]) +
	goog.color.prependZeroIfNecessaryHelper(alpha.toString(16));
	};


	/**
	* Converts from an HSVA array to a hex string
	* @param {Array<number>} hsva Array of [h, s, v, a] in
	* [[0, 1], [0, 1], [0, 255], [0, 1]].
	* @return {string} hex representation of the color.
	*/
	goog.color.alpha.hsvaArrayToHex = function(hsva) {
	return goog.color.alpha.hsvaToHex(hsva[0], hsva[1], hsva[2], hsva[3]);
	};