From afc358fb12a2e0daab3d7d7600cb50ca1e876dd0 Mon Sep 17 00:00:00 2001
From: Obexer Christoph <cobexer@gmail.com>
Date: Sun, 12 Feb 2012 23:33:13 +0100
Subject: [PATCH] fix image loaded through the proxy hanging the preload
 process

images loaded through the proxy could hang the preload process if
they finish loading through the proxy but then fail to decode
and thus don't call the onload handler of the image object.
---
 src/Preload.js | 98 ++++++++++++++++++++------------------------------
 1 file changed, 39 insertions(+), 59 deletions(-)

diff --git a/src/Preload.js b/src/Preload.js
index 542399f..3b54cb6 100644
--- a/src/Preload.js
+++ b/src/Preload.js
@@ -61,17 +61,16 @@ html2canvas.Preload = function(element, opts){
         }
     }
     
-    function proxyGetImage(url, img){
+    function proxyGetImage(url, img, imageObj){
         var callback_name,
         scriptUrl = options.proxy,
-        script,
-        imgObj = images[url];
+        script;
 
         link.href = url;
-        url = link.href; // work around for pages with base href="" set - WARNING: this may change the url -> so access imgObj from images map before changing that url!
+        url = link.href; // work around for pages with base href="" set - WARNING: this may change the url
 
-        callback_name = 'html2canvas_' + count;
-        imgObj.callbackname = callback_name;
+        callback_name = 'html2canvas_' + (count++);
+        imageObj.callbackname = callback_name;
         
         if (scriptUrl.indexOf("?") > -1) {
             scriptUrl += "&";
@@ -79,19 +78,16 @@ html2canvas.Preload = function(element, opts){
             scriptUrl += "?";
         }
         scriptUrl += 'url=' + encodeURIComponent(url) + '&callback=' + callback_name;
-    
+        script = doc.createElement("script");
+
         window[callback_name] = function(a){
             if (a.substring(0,6) === "error:"){
-                imgObj.succeeded = false;
+                imageObj.succeeded = false;
                 images.numLoaded++;
                 images.numFailed++;
                 start();  
             } else {
-                img.onload = function(){
-                    imgObj.succeeded = true;
-                    images.numLoaded++;
-                    start();
-                };
+                setImageLoadHandlers(img, imageObj);
                 img.src = a; 
             }
             window[callback_name] = undefined; // to work with IE<9  // NOTE: that the undefined callback property-name still exists on the window object (for IE<9)
@@ -100,15 +96,13 @@ html2canvas.Preload = function(element, opts){
             } catch(ex) {}
             script.parentNode.removeChild(script);
             script = null;
-            imgObj.callbackname = undefined;
+            delete imageObj.script;
+            delete imageObj.callbackname;
         };
 
-        count += 1;
-        
-        script = doc.createElement("script");        
-        script.setAttribute("src", scriptUrl);
         script.setAttribute("type", "text/javascript");
-        imgObj.script = script;
+        script.setAttribute("src", scriptUrl);
+        imageObj.script = script;
         window.document.body.appendChild(script);
 
     /*
@@ -219,54 +213,41 @@ html2canvas.Preload = function(element, opts){
         }
     }  
     
+    function setImageLoadHandlers(img, imageObj) {
+        img.onload = function() {
+            images.numLoaded++;
+            imageObj.succeeded = true;
+            start();
+        };
+        img.onerror = function() {
+            images.numLoaded++;
+            images.numFailed++;
+            imageObj.succeeded = false;
+            start();
+        };
+    }
+
     methods = {
         loadImage: function( src ) {
-            var img;
+            var img, imageObj;
             if ( src && images[src] === undefined ) {
+                img = new Image();
                 if ( src.match(/data:image\/.*;base64,/i) ) {
-                
-                    //Base64 src                  
-                    img = new Image();
                     img.src = src.replace(/url\(['"]{0,}|['"]{0,}\)$/ig, '');
-                    images[src] = {
-                        img: img, 
-                        succeeded: true
-                    };
+                    imageObj = images[src] = { img: img };
                     images.numTotal++;
-                    images.numLoaded++;
-                    start();
-                    
-                }else if ( isSameOrigin( src ) ) {
-            
-                    img = new Image();
-                    images[src] = {
-                        img: img
-                    };
+                    setImageLoadHandlers(img, imageObj);
+                }
+                else if ( isSameOrigin( src ) ) {
+                    imageObj = images[src] = { img: img };
                     images.numTotal++;
-                    
-                    img.onload = function() {
-                        images.numLoaded++;
-                        images[src].succeeded = true;
-                        start();
-                    };	
-                    
-                    img.onerror = function() {
-                        images.numLoaded++;
-                        images.numFailed++;
-                        images[src].succeeded = false;
-                        start();
-                    };
-                    
+                    setImageLoadHandlers(img, imageObj);
                     img.src = src;
-            
-                }else if ( options.proxy ){
-                    //    console.log('b'+src);
-                    img = new Image();
-                    images[src] = {
-                        img: img
-                    };
+                }
+                else if ( options.proxy ) {
+                    imageObj = images[src] = { img: img };
                     images.numTotal++;
-                    proxyGetImage( src, img );
+                    proxyGetImage( src, img, imageObj );
                 }
             }     
           
@@ -326,7 +307,6 @@ html2canvas.Preload = function(element, opts){
     if (options.timeout > 0) {
         timeoutTimer = window.setTimeout(methods.cleanupDOM, options.timeout);
     }
-    var startTime = (new Date()).getTime();
     html2canvas.log('html2canvas: Preload starts: finding background-images');
     images.firstRun = true;