The Tor Browser: browser/metro/modules/colorUtils.jsm@7e26c7da4463 (annotated)

browser/metro/modules/colorUtils.jsm@7e26c7da4463 (annotated)

browser/metro/modules/colorUtils.jsm

Wed, 31 Dec 2014 06:55:50 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:55:50 +0100
changeset 2: 7e26c7da4463
permissions: -rw-r--r--

Added tag UPSTREAM_283F7C6 for changeset ca08bd8f51b2

 // -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; js2-basic-offset: 2; js2-skip-preprocessor-directives: t; -*-
 /* 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';
 Components.utils.import("resource://gre/modules/Services.jsm");
 Components.utils.import("resource://gre/modules/Promise.jsm");
 const ColorAnalyzer = Components.classes["@mozilla.org/places/colorAnalyzer;1"]
                 .getService(Components.interfaces.mozIColorAnalyzer);
 this.EXPORTED_SYMBOLS = ["ColorUtils"];
 let ColorUtils = {
   _initialized: false,
   init: function() {
     if (this._initialized)
         return;
     Services.obs.addObserver(this, "idle-daily", false);
     Services.obs.addObserver(this, "quit-application", false);
     this._initialized = true;
   },
   uninit: function() {
     Services.obs.removeObserver(this, "idle-daily");
     Services.obs.removeObserver(this, "quit-application");
   },
   // default to keeping icon colorInfo for max 1 day
   iconColorCacheMaxAge: 86400000,
   // in-memory store for favicon color data
   _uriColorsMap: (function() {
     let cache = new Map();
     // remove stale entries
     cache.purge = function(maxAgeMs = 0) {
       let cuttoff = Date.now() - (maxAgeMs || ColorUtils.iconColorCacheMaxAge);
       for (let [key, value] of this) {
         if (value.timestamp && value.timestamp >= cuttoff) {
           continue;
         }
         this.delete(key);
       }
     }
     return cache;
   })(),
   get iconColorCache() {
     return ColorUtils._uriColorsMap;
   },
   observe: function (aSubject, aTopic, aData) {
     switch (aTopic) {
       case "idle-daily":
         this.iconColorCache.purge();
         break;
       case "quit-application":
         this.uninit();
         break;
     }
   },
   /** Takes an icon and returns either an object with foreground and background color properties
    *  or a promise for the same.
    *  The foreground is the contrast color, the background is the primary/dominant one
    */
   getForegroundAndBackgroundIconColors: function getForegroundAndBackgroundIconColors(aIconURI) {
     let colorKey = aIconURI.spec;
     let colorInfo = this._uriColorsMap.get(colorKey);
     if (colorInfo) {
       return colorInfo;
     }
     let deferred = Promise.defer();
     let wrappedIcon = aIconURI;
     this._uriColorsMap.set(colorKey, deferred.promise);
     ColorAnalyzer.findRepresentativeColor(wrappedIcon, (success, color) => {
       if (!success) {
         this._uriColorsMap.delete(colorKey);
         deferred.reject();
       } else {
         colorInfo = {
           foreground: this.bestTextColorForContrast(color),
           background: this.convertDecimalToRgbColor(color),
           timestamp: Date.now()
         };
         deferred.resolve(colorInfo);
       }
     });
     return deferred.promise;
   },
   /** returns the best color for text readability on top of aColor
    * return color is in rgb(r,g,b) format, suitable to csss
    * The color bightness algorithm is currently: http://www.w3.org/TR/AERT#color-contrast
    */
   bestTextColorForContrast: function bestTextColorForContrast(aColor) {
     let r = (aColor & 0xff0000) >> 16;
     let g = (aColor & 0x00ff00) >> 8;
     let b = (aColor & 0x0000ff);
     let w3cContrastValue = ((r*299)+(g*587)+(b*114))/1000;
     w3cContrastValue = Math.round(w3cContrastValue);
     let textColor = "rgb(255,255,255)";
     if (w3cContrastValue > 125) {
       // bright/light, use black text
       textColor = "rgb(0,0,0)";
     }
     return textColor;
   },
   toCSSRgbColor: function toCSSRgbColor(r, g, b, a) {
     var values = [Math.round(r), Math.round(g), Math.round(b)];
     if (undefined !== a && a < 1) {
       values.push(a);
       return 'rgba('+values.join(',')+')';
     }
     return 'rgb('+values.join(',')+')';
   },
   /**
    * converts a decimal(base10) number into CSS rgb color value string
    */
   convertDecimalToRgbColor: function convertDecimalToRgbColor(aColor) {
     let [r,g,b,a] = this.unpackDecimalColorWord(aColor);
     return this.toCSSRgbColor(r,g,b,a);
   },
   /**
    * unpack a decimal(base10) word for r,g,b,a values
    */
   unpackDecimalColorWord: function unpackDecimalColorWord(aColor) {
     let a = (aColor & 0xff000000) >> 24;
     let r = (aColor & 0x00ff0000) >> 16;
     let g = (aColor & 0x0000ff00) >> 8;
     let b = (aColor & 0x000000ff);
     // NB: falsy alpha treated as undefined, fully opaque
     return a ? [r,g,b,a/255] : [r,g,b];
   },
   /**
    * create a decimal(base10) word for r,g,b values
    */
   createDecimalColorWord: function createDecimalColorWord(r, g, b, a) {
     let rgb = 0;
     rgb |= b;
     rgb |= (g << 8);
     rgb |= (r << 16);
     // pack alpha value if one is given
     if (undefined !== a && a < 1)
       rgb |= (Math.round(a*255) << 24);
     return rgb;
   },
   /**
    * Add 2 rgb(a) colors to get a flat color
    */
   addRgbColors: function addRgbColors(color1, color2) {
     let [r1, g1, b1] = this.unpackDecimalColorWord(color1);
     let [r2, g2, b2, alpha] = this.unpackDecimalColorWord(color2);
     let color = {};
     // early return if 2nd color is opaque
     if (!alpha || alpha >= 1)
       return color2;
     return this.createDecimalColorWord(
       Math.min(255, alpha * r2 + (1 - alpha) * r1),
       Math.min(255, alpha * g2 + (1 - alpha) * g1),
       Math.min(255, alpha * b2 + (1 - alpha) * b1)
     );
   }
 };

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browser/metro/modules/colorUtils.jsm@7e26c7da4463 (annotated)

browser/metro/modules/colorUtils.jsm