Quelle color.js Sprache: JAVA

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

const COLOR_UNIT_PREF = "devtools.defaultColorUnit";
const SPECIALVALUES = new Set([
  "currentcolor",
  "initial",
  "inherit",
  "transparent",
  "unset",
]);

/**
* This module is used to convert between various color types.
*
* Usage:
*   let {colorUtils} = require("devtools/shared/css/color");
*   let color = new colorUtils.CssColor("red");
*   // In order to support css-color-4 color function, pass true to the
*   // second argument.
*   // e.g.
*   //   let color = new colorUtils.CssColor("red", true);
*
*   color.authored === "red"
*   color.hasAlpha === false
*   color.valid === true
*   color.transparent === false // transparent has a special status.
*   color.name === "red"        // returns hex when no name available.
*   color.hex === "#f00"        // returns shortHex when available else returns
*                                  longHex. If alpha channel is present then we
*                                  return this.alphaHex if available,
*                                  or this.longAlphaHex if not.
*   color.alphaHex === "#f00f"  // returns short alpha hex when available
*                                  else returns longAlphaHex.
*   color.longHex === "#ff0000" // If alpha channel is present then we return
*                                  this.longAlphaHex.
*   color.longAlphaHex === "#ff0000ff"
*   color.rgb === "rgb(255, 0, 0)" // If alpha channel is present
*                                  // then we return this.rgba.
*   color.rgba === "rgba(255, 0, 0, 1)"
*   color.hsl === "hsl(0, 100%, 50%)"
*   color.hsla === "hsla(0, 100%, 50%, 1)" // If alpha channel is present
*                                             then we return this.rgba.
*   color.hwb === "hwb(0, 0%, 0%)"
*
*   color.toString() === "#f00"; // Outputs the color type determined in the
*                                   COLOR_UNIT_PREF constant (above).
*
*   Valid values for COLOR_UNIT_PREF are contained in CssColor.COLORUNIT.
*/
class CssColor {
  /**
   * @param  {String} colorValue: Any valid color string
   */
  constructor(colorValue) {
    // Store a lower-cased version of the color to help with format
    // testing.  The original text is kept as well so it can be
    // returned when needed.
    this.#lowerCased = colorValue.toLowerCase();
    this.#authored = colorValue;
  }

  /**
   * Values used in COLOR_UNIT_PREF
   */
  static COLORUNIT = {
    authored: "authored",
    hex: "hex",
    name: "name",
    rgb: "rgb",
    hsl: "hsl",
    hwb: "hwb",
  };

  // The value as-authored.
  #authored = null;
  #currentFormat;
  // A lower-cased copy of |authored|.
  #lowerCased = null;

  get hasAlpha() {
    if (!this.valid) {
      return false;
    }
    return this.getRGBATuple().a !== 1;
  }

  /**
   * Return true if the color is a valid color and we can get rgba tuples from it.
   */
  get valid() {
    // We can't use InspectorUtils.isValidCSSColor as colors can be valid but we can't have
    // their rgba tuples (e.g. currentColor, accentColor, … whose actual values depends on
    // additional context we don't have here).
    return InspectorUtils.colorToRGBA(this.#authored) !== null;
  }

  /**
   * Not a real color type but used to preserve accuracy when converting between
   * e.g. 8 character hex -> rgba -> 8 character hex (hex alpha values are
   * 0 - 255 but rgba alpha values are only 0.0 to 1.0).
   */
  get highResTuple() {
    const type = classifyColor(this.#authored);

    if (type === CssColor.COLORUNIT.hex) {
      return hexToRGBA(this.#authored.substring(1), true);
    }

    // If we reach this point then the alpha value must be in the range
    // 0.0 - 1.0 so we need to multiply it by 255.
    const tuple = InspectorUtils.colorToRGBA(this.#authored);
    tuple.a *= 255;
    return tuple;
  }

  /**
   * Return true for all transparent values e.g. rgba(0, 0, 0, 0).
   */
  get transparent() {
    try {
      const tuple = this.getRGBATuple();
      return !(tuple.r || tuple.g || tuple.b || tuple.a);
    } catch (e) {
      return false;
    }
  }

  get specialValue() {
    return SPECIALVALUES.has(this.#lowerCased) ? this.#authored : null;
  }

  get name() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }

    const tuple = this.getRGBATuple();

    if (tuple.a !== 1) {
      return this.hex;
    }
    const { r, g, b } = tuple;
    return InspectorUtils.rgbToColorName(r, g, b) || this.hex;
  }

  get hex() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }
    if (this.hasAlpha) {
      return this.alphaHex;
    }

    let hex = this.longHex;
    if (
      hex.charAt(1) == hex.charAt(2) &&
      hex.charAt(3) == hex.charAt(4) &&
      hex.charAt(5) == hex.charAt(6)
    ) {
      hex = "#" + hex.charAt(1) + hex.charAt(3) + hex.charAt(5);
    }
    return hex;
  }

  get alphaHex() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }

    let alphaHex = this.longAlphaHex;
    if (
      alphaHex.charAt(1) == alphaHex.charAt(2) &&
      alphaHex.charAt(3) == alphaHex.charAt(4) &&
      alphaHex.charAt(5) == alphaHex.charAt(6) &&
      alphaHex.charAt(7) == alphaHex.charAt(8)
    ) {
      alphaHex =
        "#" +
        alphaHex.charAt(1) +
        alphaHex.charAt(3) +
        alphaHex.charAt(5) +
        alphaHex.charAt(7);
    }
    return alphaHex;
  }

  get longHex() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }
    if (this.hasAlpha) {
      return this.longAlphaHex;
    }

    const tuple = this.getRGBATuple();
    return (
      "#" +
      ((1 << 24) + (tuple.r << 16) + (tuple.g << 8) + (tuple.b << 0))
        .toString(16)
        .substr(-6)
    );
  }

  get longAlphaHex() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }

    const tuple = this.highResTuple;

    return (
      "#" +
      ((1 << 24) + (tuple.r << 16) + (tuple.g << 8) + (tuple.b << 0))
        .toString(16)
        .substr(-6) +
      Math.round(tuple.a).toString(16).padStart(2, "0")
    );
  }

  get rgb() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }
    if (!this.hasAlpha) {
      if (this.#lowerCased.startsWith("rgb(")) {
        // The color is valid and begins with rgb(.
        return this.#authored;
      }
      const tuple = this.getRGBATuple();
      return "rgb(" + tuple.r + ", " + tuple.g + ", " + tuple.b + ")";
    }
    return this.rgba;
  }

  get rgba() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }
    if (this.#lowerCased.startsWith("rgba(")) {
      // The color is valid and begins with rgba(.
      return this.#authored;
    }
    const components = this.getRGBATuple();
    return (
      "rgba(" +
      components.r +
      ", " +
      components.g +
      ", " +
      components.b +
      ", " +
      components.a +
      ")"
    );
  }

  get hsl() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }
    if (this.#lowerCased.startsWith("hsl(")) {
      // The color is valid and begins with hsl(.
      return this.#authored;
    }
    if (this.hasAlpha) {
      return this.hsla;
    }
    return this.#hsl();
  }

  get hsla() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }
    if (this.#lowerCased.startsWith("hsla(")) {
      // The color is valid and begins with hsla(.
      return this.#authored;
    }
    if (this.hasAlpha) {
      const a = this.getRGBATuple().a;
      return this.#hsl(a);
    }
    return this.#hsl(1);
  }

  get hwb() {
    const invalidOrSpecialValue = this.#getInvalidOrSpecialValue();
    if (invalidOrSpecialValue !== false) {
      return invalidOrSpecialValue;
    }
    if (this.#lowerCased.startsWith("hwb(")) {
      // The color is valid and begins with hwb(.
      return this.#authored;
    }
    if (this.hasAlpha) {
      const a = this.getRGBATuple().a;
      return this.#hwb(a);
    }
    return this.#hwb();
  }

  /**
   * Check whether the current color value is in the special list e.g.
   * transparent or invalid.
   *
   * @return {String|Boolean}
   *         - If the current color is a special value e.g. "transparent" then
   *           return the color.
   *         - If the current color is a system value e.g. "accentcolor" then
   *           return the color.
   *         - If the color is invalid or that we can't get rgba components from it
   *           (e.g. "accentcolor"), return an empty string.
   *         - If the color is a regular color e.g. #F06 so we return false
   *           to indicate that the color is neither invalid or special.
   */
  #getInvalidOrSpecialValue() {
    if (this.specialValue) {
      return this.specialValue;
    }
    if (!this.valid) {
      return "";
    }
    return false;
  }

  nextColorUnit() {
    // Reorder the formats array to have the current format at the
    // front so we can cycle through.
    // Put "name" at the end as that provides a hex value if there's
    // no name for the color.
    let formats = ["hex", "hsl", "rgb", "hwb", "name"];

    let currentFormat = this.#currentFormat;
    // If we don't have determined the current format yet
    if (!currentFormat) {
      // If the pref value is COLORUNIT.authored, get the actual unit from the authored color,
      // otherwise use the pref value.
      const defaultFormat = Services.prefs.getCharPref(COLOR_UNIT_PREF);
      currentFormat =
        defaultFormat === CssColor.COLORUNIT.authored
          ? classifyColor(this.#authored)
          : defaultFormat;
    }
    const putOnEnd = formats.splice(0, formats.indexOf(currentFormat));
    formats = [...formats, ...putOnEnd];

    const currentDisplayedColor = this[formats[0]];

    let colorUnit;
    for (const format of formats) {
      if (this[format].toLowerCase() !== currentDisplayedColor.toLowerCase()) {
        colorUnit = CssColor.COLORUNIT[format];
        break;
      }
    }

    this.#currentFormat = colorUnit;
    return this.toString(colorUnit);
  }

  /**
   * Return a string representing a color of type defined in COLOR_UNIT_PREF.
   */
  toString(colorUnit, forceUppercase) {
    let color;

    switch (colorUnit) {
      case CssColor.COLORUNIT.authored:
        color = this.#authored;
        break;
      case CssColor.COLORUNIT.hex:
        color = this.hex;
        break;
      case CssColor.COLORUNIT.hsl:
        color = this.hsl;
        break;
      case CssColor.COLORUNIT.name:
        color = this.name;
        break;
      case CssColor.COLORUNIT.rgb:
        color = this.rgb;
        break;
      case CssColor.COLORUNIT.hwb:
        color = this.hwb;
        break;
      default:
        color = this.rgb;
    }

    if (
      forceUppercase ||
      (colorUnit != CssColor.COLORUNIT.authored &&
        colorIsUppercase(this.#authored))
    ) {
      color = color.toUpperCase();
    }

    return color;
  }

  /**
   * Returns a RGBA 4-Tuple representation of a color or transparent as
   * appropriate.
   */
  getRGBATuple() {
    const tuple = InspectorUtils.colorToRGBA(this.#authored);

    tuple.a = parseFloat(tuple.a.toFixed(2));

    return tuple;
  }

  #hsl(maybeAlpha) {
    if (this.#lowerCased.startsWith("hsl(") && maybeAlpha === undefined) {
      // We can use it as-is.
      return this.#authored;
    }

    const { r, g, b } = this.getRGBATuple();
    const [h, s, l] = rgbToHsl([r, g, b]);
    if (maybeAlpha !== undefined) {
      return "hsla(" + h + ", " + s + "%, " + l + "%, " + maybeAlpha + ")";
    }
    return "hsl(" + h + ", " + s + "%, " + l + "%)";
  }

  #hwb(maybeAlpha) {
    if (this.#lowerCased.startsWith("hwb(") && maybeAlpha === undefined) {
      // We can use it as-is.
      return this.#authored;
    }

    const { r, g, b } = this.getRGBATuple();
    const [hue, white, black] = rgbToHwb([r, g, b]);
    return `hwb(${hue} ${white}% ${black}%${
      maybeAlpha !== undefined ? " / " + maybeAlpha : ""
    })`;
  }

  /**
   * This method allows comparison of CssColor objects using ===.
   */
  valueOf() {
    return this.rgba;
  }

  /**
   * Check whether the color is fully transparent (alpha === 0).
   *
   * @return {Boolean} True if the color is transparent and valid.
   */
  isTransparent() {
    return this.getRGBATuple().a === 0;
  }
}

/**
* Convert rgb value to hsl
*
* @param {array} rgb
*         Array of rgb values
* @return {array}
*         Array of hsl values.
*/
function rgbToHsl([r, g, b]) {
  r = r / 255;
  g = g / 255;
  b = b / 255;

  const max = Math.max(r, g, b);
  const min = Math.min(r, g, b);
  let h;
  let s;
  const l = (max + min) / 2;

  if (max == min) {
    h = s = 0;
  } else {
    const d = max - min;
    s = l > 0.5 ? d / (2 - max - min) : d / (max + min);

    switch (max) {
      case r:
        h = ((g - b) / d) % 6;
        break;
      case g:
        h = (b - r) / d + 2;
        break;
      case b:
        h = (r - g) / d + 4;
        break;
    }
    h *= 60;
    if (h < 0) {
      h += 360;
    }
  }

  return [roundTo(h, 1), roundTo(s * 100, 1), roundTo(l * 100, 1)];
}

/**
* Convert RGB value to HWB
*
* @param {array} rgb
*         Array of RGB values
* @return {array}
*         Array of HWB values.
*/
function rgbToHwb([r, g, b]) {
  const hsl = rgbToHsl([r, g, b]);

  r = r / 255;
  g = g / 255;
  b = b / 255;

  const white = Math.min(r, g, b);
  const black = 1 - Math.max(r, g, b);
  return [roundTo(hsl[0], 1), roundTo(white * 100, 1), roundTo(black * 100, 1)];
}

/**
* Convert rgb value to CIE LAB colorspace (https://en.wikipedia.org/wiki/CIELAB_color_space).
* Formula from http://www.easyrgb.com/en/math.php.
*
* @param {array} rgb
*        Array of rgb values
* @return {array}
*         Array of lab values.
*/
function rgbToLab([r, g, b]) {
  // Convert rgb values to xyz coordinates.
  r = r / 255;
  g = g / 255;
  b = b / 255;

  r = r > 0.04045 ? Math.pow((r + 0.055) / 1.055, 2.4) : r / 12.92;
  g = g > 0.04045 ? Math.pow((g + 0.055) / 1.055, 2.4) : g / 12.92;
  b = b > 0.04045 ? Math.pow((b + 0.055) / 1.055, 2.4) : b / 12.92;

  r = r * 100;
  g = g * 100;
  b = b * 100;

  let [x, y, z] = [
    r * 0.4124 + g * 0.3576 + b * 0.1805,
    r * 0.2126 + g * 0.7152 + b * 0.0722,
    r * 0.0193 + g * 0.1192 + b * 0.9505,
  ];

  // Convert xyz coordinates to lab values.
  // Divisors used are X_10, Y_10, Z_10 (CIE 1964) reference values for D65
  // illuminant (Daylight, sRGB, Adobe-RGB) taken from http://www.easyrgb.com/en/math.php
  x = x / 94.811;
  y = y / 100;
  z = z / 107.304;

  x = x > 0.008856 ? Math.pow(x, 1 / 3) : 7.787 * x + 16 / 116;
  y = y > 0.008856 ? Math.pow(y, 1 / 3) : 7.787 * y + 16 / 116;
  z = z > 0.008856 ? Math.pow(z, 1 / 3) : 7.787 * z + 16 / 116;

  return [116 * y - 16, 500 * (x - y), 200 * (y - z)];
}

/**
* Calculates the CIE Delta-E value for two lab values (http://www.colorwiki.com/wiki/Delta_E%3a_The_Color_Difference#Delta-E_1976).
* Formula from http://www.easyrgb.com/en/math.php.
*
* @param {array} lab1
*        Array of lab values for the first color
* @param {array} lab2
*        Array of lab values for the second color
* @return {Number}
*         DeltaE value between the two colors
*/
function calculateDeltaE([l1, a1, b1], [l2, a2, b2]) {
  return Math.sqrt(
    Math.pow(l1 - l2, 2) + Math.pow(a1 - a2, 2) + Math.pow(b1 - b2, 2)
  );
}

function roundTo(number, digits) {
  const multiplier = Math.pow(10, digits);
  return Math.round(number * multiplier) / multiplier;
}

/**
* Given a color, classify its type as one of the possible color
* units, as known by |CssColor.COLORUNIT|.
*
* @param  {String} value
*         The color, in any form accepted by CSS.
* @return {String}
*         The color classification, one of "rgb", "hsl", "hwb",
*         "hex", "name", or if no format is recognized, "authored".
*/
function classifyColor(value) {
  value = value.toLowerCase();
  if (value.startsWith("rgb(") || value.startsWith("rgba(")) {
    return CssColor.COLORUNIT.rgb;
  } else if (value.startsWith("hsl(") || value.startsWith("hsla(")) {
    return CssColor.COLORUNIT.hsl;
  } else if (value.startsWith("hwb(")) {
    return CssColor.COLORUNIT.hwb;
  } else if (/^#[0-9a-f]+$/.exec(value)) {
    return CssColor.COLORUNIT.hex;
  } else if (/^[a-z\-]+$/.exec(value)) {
    return CssColor.COLORUNIT.name;
  }
  return CssColor.COLORUNIT.authored;
}

/**
* A helper function to convert a hex string like "F0C" or "F0C8" to a color.
*
* @param {String} name the color string
* @param {Boolean} highResolution Forces returned alpha value to be in the
*                  range 0 - 255 as opposed to 0.0 - 1.0.
* @return {Object} an object of the form {r, g, b, a}; or null if the
*         name was not a valid color
*/
function hexToRGBA(name, highResolution) {
  let r,
    g,
    b,
    a = 1;

  if (name.length === 3) {
    // short hex string (e.g. F0C)
    r = parseInt(name.charAt(0) + name.charAt(0), 16);
    g = parseInt(name.charAt(1) + name.charAt(1), 16);
    b = parseInt(name.charAt(2) + name.charAt(2), 16);
  } else if (name.length === 4) {
    // short alpha hex string (e.g. F0CA)
    r = parseInt(name.charAt(0) + name.charAt(0), 16);
    g = parseInt(name.charAt(1) + name.charAt(1), 16);
    b = parseInt(name.charAt(2) + name.charAt(2), 16);
    a = parseInt(name.charAt(3) + name.charAt(3), 16);

    if (!highResolution) {
      a /= 255;
    }
  } else if (name.length === 6) {
    // hex string (e.g. FD01CD)
    r = parseInt(name.charAt(0) + name.charAt(1), 16);
    g = parseInt(name.charAt(2) + name.charAt(3), 16);
    b = parseInt(name.charAt(4) + name.charAt(5), 16);
  } else if (name.length === 8) {
    // alpha hex string (e.g. FD01CDAB)
    r = parseInt(name.charAt(0) + name.charAt(1), 16);
    g = parseInt(name.charAt(2) + name.charAt(3), 16);
    b = parseInt(name.charAt(4) + name.charAt(5), 16);
    a = parseInt(name.charAt(6) + name.charAt(7), 16);

    if (!highResolution) {
      a /= 255;
    }
  } else {
    return null;
  }
  if (!highResolution) {
    a = Math.round(a * 10) / 10;
  }
  return { r, g, b, a };
}

/**
* Calculates the luminance of a rgba tuple based on the formula given in
* https://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
*
* @param {Array} rgba An array with [r,g,b,a] values.
* @return {Number} The calculated luminance.
*/
function calculateLuminance(rgba) {
  for (let i = 0; i < 3; i++) {
    rgba[i] /= 255;
    rgba[i] =
      rgba[i] < 0.03928
        ? rgba[i] / 12.92
        : Math.pow((rgba[i] + 0.055) / 1.055, 2.4);
  }
  return 0.2126 * rgba[0] + 0.7152 * rgba[1] + 0.0722 * rgba[2];
}

/**
* Blend background and foreground colors takign alpha into account.
* @param  {Array} foregroundColor
*         An array with [r,g,b,a] values containing the foreground color.
* @param  {Array} backgroundColor
*         An array with [r,g,b,a] values containing the background color. Defaults to
*         [ 255, 255, 255, 1 ].
* @return {Array}
*         An array with combined [r,g,b,a] colors.
*/
function blendColors(foregroundColor, backgroundColor = [255, 255, 255, 1]) {
  const [fgR, fgG, fgB, fgA] = foregroundColor;
  const [bgR, bgG, bgB, bgA] = backgroundColor;
  if (fgA === 1) {
    return foregroundColor;
  }

  return [
    (1 - fgA) * bgR + fgA * fgR,
    (1 - fgA) * bgG + fgA * fgG,
    (1 - fgA) * bgB + fgA * fgB,
    fgA + bgA * (1 - fgA),
  ];
}

/**
* Calculates the contrast ratio of 2 rgba tuples based on the formula in
* https://www.w3.org/TR/2008/REC-WCAG20-20081211/#visual-audio-contrast7
*
* @param {Array} backgroundColor An array with [r,g,b,a] values containing
* the background color.
* @param {Array} textColor An array with [r,g,b,a] values containing
* the text color.
* @return {Number} The calculated luminance.
*/
function calculateContrastRatio(backgroundColor, textColor) {
  // Do not modify given colors.
  backgroundColor = Array.from(backgroundColor);
  textColor = Array.from(textColor);

  backgroundColor = blendColors(backgroundColor);
  textColor = blendColors(textColor, backgroundColor);

  const backgroundLuminance = calculateLuminance(backgroundColor);
  const textLuminance = calculateLuminance(textColor);
  const ratio = (textLuminance + 0.05) / (backgroundLuminance + 0.05);

  return ratio > 1.0 ? ratio : 1 / ratio;
}

function colorIsUppercase(color) {
  // Specifically exclude the case where the color is
  // case-insensitive.  This makes it so that "#000" isn't
  // considered "upper case" for the purposes of color cycling.
  return color === color.toUpperCase() && color !== color.toLowerCase();
}

module.exports.colorUtils = {
  CssColor,
  rgbToHsl,
  rgbToHwb,
  rgbToLab,
  classifyColor,
  calculateContrastRatio,
  calculateDeltaE,
  calculateLuminance,
  blendColors,
  colorIsUppercase,
};

quality93%

¤ Dauer der Verarbeitung: 0.6 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.