Issue 3532 - Generate animation images at runtime

lib/icon.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 /** @module icon */
 
 "use strict";
 
-const frameOpacities =  [0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9,
-                         1, 1, 1, 1, 1,
-                         0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0];
+const frameOpacities =  [0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9,
+                         1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0,
+                         0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.0];
 const numberOfFrames = frameOpacities.length;
+const safariPlatform = require("info").platform == "safari";
 
-let stopAnimation = null;
-let animationPlaying = false;
+let frameInterval = null;
+let animationInterval = null;
 let whitelistedState = new ext.PageMap();
 
-let loadImageAsCanvas =
-/**
- * Loads an image and draws it onto a canvas.
- *
- * @param {string} path  Path of the image to load
- * @return {Promise}
- */
-exports.loadImageAsCanvas = function (path, size)
+function loadImage(url)
 {
-  return new Promise((resolve, reject) => {
+  return new Promise((resolve, reject) =>
+  {
     let image = new Image();
-    image.src = path;
+    image.src = url;
     image.addEventListener("load", () =>
     {
-      let canvas = document.createElement("canvas");
-      let context = canvas.getContext("2d");
-      canvas.height = image.height;
-      canvas.width = image.width;
-      context.drawImage(image, 0, 0);
-      resolve(canvas);
+      resolve(image);
     });
-    image.addEventListener("error", () => {
-      reject("Failed to load image " + path);
+    image.addEventListener("error", () =>
+    {
+      reject("Failed to load image " + url);
     });
   });
 };
 
-function getImageData(baseIcon, overlayIcon, opacity, animationStep, frameCache)
+function setIcon(page, notificationType, opacity, frames)
 {
-  let cacheIndex = baseIcon + overlayIcon + opacity;
+  opacity = opacity || 0;
+  let whitelisted = !!whitelistedState.get(page) && !safariPlatform;
 
-  if (frameCache && frameCache[cacheIndex])
-    return frameCache[cacheIndex];
+  if (!notificationType || !frames)
+  {
+    if (opacity > 0.5)
+      page.browserAction.setIcon("icons/abp-$size-notification-"
+                                 + notificationType + ".png");
+    else
+      page.browserAction.setIcon("icons/abp-$size" +
+                                 (whitelisted ? "-whitelisted" : "") + ".png");
+  }
+  else
+  {
+    chrome.browserAction.setIcon({
+      tabId: page._id,
+      imageData: frames["" + opacity + whitelisted]
+    });
+  }
+}
 
-  let imageData = Promise.all(
-    [loadImageAsCanvas(baseIcon),
-     overlayIcon && loadImageAsCanvas(overlayIcon) || Promise.resolve(null)]
-  ).then(icons =>
+function renderFrames(notificationType)
+{
+  if (safariPlatform)
+    return Promise.resolve(null);
+
+  return Promise.all([
+    loadImage("icons/abp-19.png"),
+    loadImage("icons/abp-19-whitelisted.png"),
+    loadImage("icons/abp-19-notification-" + notificationType + ".png"),
+    loadImage("icons/abp-38.png"),
+    loadImage("icons/abp-38-whitelisted.png"),
+    loadImage("icons/abp-38-notification-" + notificationType + ".png"),
+  ]).then(images =>
   {
-    let baseIconCanvas = icons[0];
-    let overlayIconCanvas = icons[1];
-    let context = baseIconCanvas.getContext("2d");
+    let images = {
+      19: { base: [images[0], images[1]], overlay: images[2] },
+      38: { base: [images[3], images[4]], overlay: images[5] }
+    };
 
-    if (overlayIconCanvas && opacity)
+    let frames = {};
+    let canvas = document.createElement("canvas");
+    let context = canvas.getContext("2d");
+
+    for (let whitelisted of [false, true])
     {
-      context.globalAlpha = opacity;
-      context.drawImage(overlayIconCanvas, 0, 0);
+      for (let i = 0, opacity = 0; i <= 10; opacity = ++i / 10)
+      {
+        let imageData = {};
+        for (let size of [19, 38])
+        {
+          canvas.width = size;
+          canvas.height = size;
+          context.globalAlpha = 1;
+          context.drawImage(images[size]["base"][whitelisted | 0], 0, 0);
+          context.globalAlpha = opacity;
+          context.drawImage(images[size]["overlay"], 0, 0);
+          imageData[size] = context.getImageData(0, 0, size, size);
+        }
+        frames["" + opacity + whitelisted] = imageData;
+      }
     }
 
-    return context.getImageData(0, 0, baseIconCanvas.width,
-                                baseIconCanvas.height);
-  });
-  if (frameCache)
-    frameCache[cacheIndex] = imageData;
-  return imageData;
-}
-
-function setIcon(page, animationType, animationStep, frameCache)
-{
-  let safari = require("info").platform == "safari";
-  let opacity = animationType ? frameOpacities[animationStep] : 0;
-  let greyed = whitelistedState.get(page) && !safari;
-  let blending = (animationType && opacity > 0 && opacity < 1);
-
-  let filename = "icons/abp-$size";
-  let baseIcon = filename + (greyed ? "-whitelisted" : "") + ".png";
-  let overlayIcon = animationType && (filename + "-notification-" +
-                                      animationType + ".png");
-
-
-  // If the icon doesn't need any modifications, or the platform doesn't support
-  // data URLs, we can just use the image's filename with the $size placeholder.
-  if (!blending || safari)
-    if (overlayIcon && opacity > 0.5)
-      return page.browserAction.setIcon(overlayIcon);
-    else
-      return page.browserAction.setIcon(baseIcon);
-
-  // Otherwise we must process the images using a canvas and return a data URL
-  // of the result for each size that's required. (19px and 38px are required by
-  // Chrome/Opera.)
-  let imageData = [19, 38].map(size =>
-  {
-    return getImageData(baseIcon.replace("$size", size.toString()),
-                        overlayIcon.replace("$size", size.toString()),
-                        opacity, animationStep, frameCache);
-  });
-  Promise.all(imageData).then(imageData =>
-  {
-    chrome.browserAction.setIcon({tabId: page._id,
-                                  imageData: {19: imageData[0],
-                                              38: imageData[1]}});
+    return frames;
   });
 }
 
-function runAnimation(animationType)
+function runAnimation(notificationType)
 {
-  let frameCache = {};
-  let frameInterval;
+  function playAnimation(frames)
+  {
+    let animationStep = 0;
+    ext.pages.query({active: true}, pages =>
+    {
+      function appendActivePage(page)
+      {
+        pages.push(page);
+      }
+      ext.pages.onActivated.addListener(appendActivePage);
 
-  function playAnimation()
-  {
-    animationPlaying = true;
-    let animationStep = 0;
-    frameInterval = setInterval(() =>
-    {
-      ext.pages.query({active: true}, pages =>
+      frameInterval = setInterval(() =>
       {
-        pages.forEach(page => {
-          setIcon(page, animationType, animationStep++, frameCache);
-        });
-        if (animationStep >= numberOfFrames)
+        let opacity = frameOpacities[animationStep++];
+        for (let page of pages)
+        {
+          if (whitelistedState.has(page))
+            setIcon(page, notificationType, opacity, frames);
+        };
+
+        if (animationStep > numberOfFrames)
         {
           animationStep = 0;
           clearInterval(frameInterval);
-          animationPlaying = false;
+          frameInterval = null;
+          ext.pages.onActivated.removeListener(appendActivePage);
         }
-      });
-    }, 100);
+      }, 100);
+    });
   }
 
-  playAnimation();
-  let animationInterval = setInterval(playAnimation, 10000);
-  return () =>
+  renderFrames(notificationType).then(frames =>
   {
-    clearInterval(frameInterval);
-    clearInterval(animationInterval);
-    animationPlaying = false;
-  };
+    playAnimation(frames);
+    animationInterval = setInterval(() => { playAnimation(frames); }, 10000);
+  });
 }
 
 /**
  * Set the browser action icon for the given page, indicating whether
  * adblocking is active there, and considering the icon animation.
  *
  * @param {Page}    page         The page to set the browser action icon for
  * @param {Boolean} whitelisted  Whether the page has been whitelisted
  */
 exports.updateIcon = function(page, whitelisted)
 {
   whitelistedState.set(page, whitelisted);
-  if (!animationPlaying)
+  if (frameInterval == null)
     setIcon(page);
+};
+
+let stopIconAnimation =
+/**
+ * Stops to animate the browser action icon.
+ */
+exports.stopIconAnimation = function()
+{
+  if (frameInterval != null)
+    clearInterval(frameInterval);
+  if (animationInterval != null)
+    clearInterval(animationInterval);
+  frameInterval = animationInterval = null;
 };
 
 /**
  * Starts to animate the browser action icon to indicate a pending notifcation.
  *
  * @param {string} type  The notification type (i.e: "information" or "critical")
  */
 exports.startIconAnimation = function(type)
 {
-  stopAnimation && stopAnimation();
-  stopAnimation = runAnimation(type);
+  stopIconAnimation();
+  runAnimation(type);
 };
-
-/**
- * Stops to animate the browser action icon.
- */
-exports.stopIconAnimation = function()
-{
-  stopAnimation && stopAnimation();
-};