/**
* @license
* Copyright The Closure Library Authors.
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @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) {
'use strict';
const result = {};
str = String(str);
const maybeHex = goog.color.prependHashIfNecessaryHelper(str);
if (goog.color.alpha.isValidAlphaHexColor_(maybeHex)) {
result.hex = goog.color.alpha.normalizeAlphaHex_(maybeHex);
result.type = 'hex';
return result;
} else {
const rgba = goog.color.alpha.isValidRgbaColor_(str);
if (rgba.length) {
result.hex = goog.color.alpha.rgbaArrayToHex(rgba);
result.type = 'rgba';
return result;
} else {
const hsla = goog.color.alpha.isValidHslaColor_(str);
if (hsla.length) {
result.hex = goog.color.alpha.hslaArrayToHex(hsla);
result.type = 'hsla';
return result;
}
}
}
throw new 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) {
'use strict';
return goog.color.alpha.rgbaStyle_(goog.color.alpha.hexToRgba(hexColor));
};
/**
* Extracts a substring, from startIdx to endIdx, of the normalized (lowercase
* #rrggbbaa) form of a hex-with-alpha color.
* @param {string} colorWithAlpha The alpha hex color to get the hex color from.
* This may be four or eight digits.
* @param {number} startIdx The start index within the #rrggbbaa color.
* @param {number} endIdx The end index within the #rrggbbbaa color.
* @return {string} The requested startIdx-to-endIdx substring from the color.
* @private
*/
goog.color.alpha.extractColor_ = function(colorWithAlpha, startIdx, endIdx) {
'use strict';
if (goog.color.alpha.isValidAlphaHexColor_(colorWithAlpha)) {
const fullColor = goog.color.prependHashIfNecessaryHelper(colorWithAlpha);
const normalizedColor = goog.color.alpha.normalizeAlphaHex_(fullColor);
return normalizedColor.substring(startIdx, endIdx);
} else {
throw new Error(colorWithAlpha + ' is not a valid 8-hex color string');
}
};
/**
* Gets the hex color part of an alpha hex color. For example, both '#abcd' and
* '#AABBCC12' return '#aabbcc'.
* @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) {
'use strict';
return goog.color.alpha.extractColor_(colorWithAlpha, 0, 7);
};
/**
* Gets the alpha color part of an alpha hex color. For example, both '#123A'
* and '#123456aa' return 'aa'. The result is always two characters long.
* @param {string} colorWithAlpha The alpha hex color to get the hex color from.
* @return {string} The two-character alpha from the given color.
*/
goog.color.alpha.extractAlpha = function(colorWithAlpha) {
'use strict';
return goog.color.alpha.extractColor_(colorWithAlpha, 7, 9);
};
/**
* Regular expression for extracting the digits in a hex color quadruplet.
* @const {!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) {
'use strict';
if (!goog.color.alpha.isValidAlphaHexColor_(hexColor)) {
throw new 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) {
'use strict';
// TODO(user): Enhance code sharing with goog.color, for example by
// adding a goog.color.genericHexToRgb method.
hexColor = goog.color.alpha.normalizeAlphaHex_(hexColor);
const r = parseInt(hexColor.substr(1, 2), 16);
const g = parseInt(hexColor.substr(3, 2), 16);
const b = parseInt(hexColor.substr(5, 2), 16);
const 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) {
'use strict';
const intAlpha = Math.floor(a * 255);
if (isNaN(intAlpha) || intAlpha < 0 || intAlpha > 255) {
// TODO(user): The CSS spec says the value should be clamped.
throw new Error(
'"(' + r + ',' + g + ',' + b + ',' + a +
'") is not a valid RGBA color');
}
const 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) {
'use strict';
const intAlpha = Math.floor(a * 255);
if (isNaN(intAlpha) || intAlpha < 0 || intAlpha > 255) {
// TODO(user): The CSS spec says the value should be clamped.
throw new Error(
'"(' + h + ',' + s + ',' + l + ',' + a +
'") is not a valid HSLA color');
}
const 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) {
'use strict';
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) {
'use strict';
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 new 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) {
'use strict';
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) {
'use strict';
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) {
'use strict';
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) {
'use strict';
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) {
'use strict';
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) {
'use strict';
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) {
'use strict';
return goog.color.alpha.rgbaToHsla(rgba[0], rgba[1], rgba[2], rgba[3]);
};
/**
* Helper for isValidAlphaHexColor_.
* @const {!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) {
'use strict';
return goog.color.alpha.validAlphaHexColorRe_.test(str);
};
/**
* Helper for isNormalizedAlphaHexColor_.
* @const {!RegExp}
* @private
*/
goog.color.alpha.normalizedAlphaHexColorRe_ = /^#[0-9a-f]{8}$/;
/**
* Checks if a string is a normalized alpha hex color.
* We expect strings of the format #RRGGBBAA (ex: #1b3d5f5b)
* using only lowercase letters.
* @param {string} str String to check.
* @return {boolean} Whether the string is a normalized hex color.
* @private
*/
goog.color.alpha.isNormalizedAlphaHexColor_ = function(str) {
'use strict';
return goog.color.alpha.normalizedAlphaHexColorRe_.test(str);
};
/**
* A pattern capturing any 3-digit number (without leading 0s).
* @const {!RegExp}
* @private
*/
goog.color.alpha.re0_999_ = /(0|[1-9]\d{0,2})/;
/**
* A pattern capturing [0.0000000000...1.0000000000].
* @const {!RegExp}
* @private
*/
goog.color.alpha.re0_1_ = /(0|1|0\.\d{1,10}|1\.0{1,10})/;
/**
* Regular expression for matching and capturing RGBA style strings. Helper for
* isValidRgbaColor_.
* @type {!RegExp}
* @private
*/
goog.color.alpha.rgbaColorRe_ = new RegExp(
'^\\s*(?:rgba)?\\(' + //
goog.color.alpha.re0_999_.source + ',\\s*' + //
goog.color.alpha.re0_999_.source + ',\\s*' + //
goog.color.alpha.re0_999_.source + ',\\s*' + //
goog.color.alpha.re0_1_.source + '\\)\\s*$',
'i');
/**
* Regular expression for matching and capturing HSLA style strings. Helper for
* isValidHslaColor_.
* @type {!RegExp}
* @private
*/
goog.color.alpha.hslaColorRe_ = new RegExp(
'^\\s*(?:hsla)?\\(' + //
goog.color.alpha.re0_999_.source + ',\\s*' + //
goog.color.alpha.re0_999_.source + '%,\\s*' + //
goog.color.alpha.re0_999_.source + '%,\\s*' + //
goog.color.alpha.re0_1_.source + '\\)\\s*$',
'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) {
'use strict';
// 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.
const regExpResultArray = str.match(goog.color.alpha.rgbaColorRe_);
if (regExpResultArray) {
const r = Number(regExpResultArray[1]);
const g = Number(regExpResultArray[2]);
const b = Number(regExpResultArray[3]);
const 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) {
'use strict';
// 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.
const regExpResultArray = str.match(goog.color.alpha.hslaColorRe_);
if (regExpResultArray) {
const h = Number(regExpResultArray[1]);
const s = Number(regExpResultArray[2]);
const l = Number(regExpResultArray[3]);
const 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) {
'use strict';
const 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) {
'use strict';
const 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) {
'use strict';
return goog.color.alpha.hsvaToHex(hsva[0], hsva[1], hsva[2], hsva[3]);
};
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