Merge pull request #1119 from brendon1982/develop

Fixed issue where broken images wouldn't always be rendered.

examples/network/nodeStyles/circularImages.html

@@ -45,7 +45,8 @@
         {id: 12, shape: 'circularImage', image: DIR + '12.png'},
         {id: 13, shape: 'circularImage', image: DIR + '13.png'},
         {id: 14, shape: 'circularImage', image: DIR + '14.png'},
-        {id: 15, shape: 'circularImage', image: DIR + 'missing.png', brokenImage: DIR + 'missingBrokenImage.png', label:"when images\nfail\nto load"}
+        {id: 15, shape: 'circularImage', image: DIR + 'missing.png', brokenImage: DIR + 'missingBrokenImage.png', label:"when images\nfail\nto load"},
+        {id: 16, shape: 'circularImage', image: DIR + 'anotherMissing.png', brokenImage: DIR + '9.png', label:"fallback image in action"}
       ];
 
       // create connections between people
@@ -64,7 +65,8 @@
         {from: 10, to: 11},
         {from: 11, to: 12},
         {from: 12, to: 13},
-        {from: 13, to: 14}
+        {from: 13, to: 14},
+        {from: 9, to: 16}
       ];
 
       // create a network

lib/network/Images.js

@@ -2,71 +2,91 @@
  * @class Images
  * This class loads images and keeps them stored.
  */
-function Images(callback) {
-  this.images = {};
-  this.imageBroken = {};
-  this.callback = callback;
-
-}
-
-/**
- *
- * @param {string} url          Url of the image
- * @param {string} url          Url of an image to use if the url image is not found
- * @return {Image} img          The image object
- */
-Images.prototype.load = function(url, brokenUrl, id) {
-  var img = this.images[url]; // make a pointer
-  if (img === undefined) {
-    // create the image
-    var me = this;
-    img = new Image();
-    img.onload = function () {
-      // IE11 fix -- thanks dponch!
-      if (this.width === 0) {
-        document.body.appendChild(this);
-        this.width = this.offsetWidth;
-        this.height = this.offsetHeight;
-        document.body.removeChild(this);
-      }
-
-      if (me.callback) {
-        me.images[url] = img;
-        me.callback(this);
-      }
-    };
-
-    img.onerror = function () {
-      if (brokenUrl === undefined) {
-        console.error("Could not load image:", url);
-        delete this.src;
-        if (me.callback) {
-          me.callback(this);
+class Images{
+    constructor(callback){
+        this.images = {};
+        this.imageBroken = {};
+        this.callback = callback;
+    }
+    
+    /**
+     * @param {string} url                      The Url to cache the image as 
+      * @return {Image} imageToLoadBrokenUrlOn  The image object
+     */    
+    _addImageToCache (url, imageToCache) {
+        // IE11 fix -- thanks dponch!
+        if (imageToCache.width === 0) {
+            document.body.appendChild(imageToCache);
+            imageToCache.width = imageToCache.offsetWidth;
+            imageToCache.height = imageToCache.offsetHeight;
+            document.body.removeChild(imageToCache);
         }
-      }
-      else {
-        if (me.imageBroken[id] && me.imageBroken[id][url] === true) {
-          console.error("Could not load brokenImage:", brokenUrl);
-          delete this.src;
-          if (me.callback) {
-            me.callback(this);
-          }
+    
+        this.images[url] = imageToCache;
+    }  
+    
+    /**
+     * @param {string} url                      The original Url that failed to load, if the broken image is successfully loaded it will be added to the cache using this Url as the key so that subsequent requests for this Url will return the broken image
+     * @param {string} brokenUrl                Url the broken image to try and load
+     * @return {Image} imageToLoadBrokenUrlOn   The image object
+     */    
+    _tryloadBrokenUrl (url, brokenUrl, imageToLoadBrokenUrlOn) {
+        //If any of the parameters aren't specified then exit the function because nothing constructive can be done
+        if (url === undefined || brokenUrl === undefined || imageToLoadBrokenUrlOn === undefined)  return;
+    
+        //Clear the old subscription to the error event and put a new in place that only handle errors in loading the brokenImageUrl
+        imageToLoadBrokenUrlOn.onerror = () => {
+            console.error("Could not load brokenImage:", brokenUrl);
+            //Add an empty image to the cache so that when subsequent load calls are made for the url we don't try load the image and broken image again
+            this._addImageToCache(url, new Image());
+        };
+        
+        //Set the source of the image to the brokenUrl, this is actually what kicks off the loading of the broken image
+        imageToLoadBrokenUrlOn.src = brokenUrl;
+    }
+    
+    /**
+     * @return {Image} imageToRedrawWith The images that will be passed to the callback when it is invoked
+     */    
+    _redrawWithImage (imageToRedrawWith) {
+        if (this.callback) {
+            this.callback(imageToRedrawWith);
         }
-        else {
-          console.error("Could not load image:", url);
-          this.src = brokenUrl;
-          if (me.imageBroken[id] === undefined) {
-            me.imageBroken[id] = {};
-          }
-          me.imageBroken[id][url] = true;
+    }
+    
+    /**
+     * @param {string} url          Url of the image
+     * @param {string} brokenUrl    Url of an image to use if the url image is not found
+     * @return {Image} img          The image object
+     */     
+    load (url, brokenUrl, id) {
+        //Try and get the image from the cache, if successful then return the cached image   
+        var cachedImage = this.images[url]; 
+        if (cachedImage) return cachedImage;
+        
+        //Create a new image
+        var img = new Image();
+        
+        //Subscribe to the event that is raised if the image loads successfully 
+        img.onload = () => {
+            //Add the image to the cache and then request a redraw
+            this._addImageToCache(url, img);
+            this._redrawWithImage(img);
+        };
+        
+        //Subscribe to the event that is raised if the image fails to load
+        img.onerror = () => {
+            console.error("Could not load image:", url);
+            //Try and load the image specified by the brokenUrl using
+            this._tryloadBrokenUrl(url, brokenUrl, img);
         }
-      }
-    };
-
-    img.src = url;
-  }
-
-  return img;
-};
+        
+        //Set the source of the image to the url, this is actuall what kicks off the loading of the image
+        img.src = url;
+        
+        //Return the new image
+        return img;
+    }          
+}
 
-module.exports = Images;
+export default Images;