_html2canvas.Preload = function( options ) {
var images = {
numLoaded: 0, // also failed are counted here
numFailed: 0,
numTotal: 0,
cleanupDone: false
},
pageOrigin,
methods,
i,
count = 0,
element = options.elements[0] || document.body,
doc = element.ownerDocument,
domImages = doc.images, // TODO probably should limit it to images present in the element only
imgLen = domImages.length,
link = doc.createElement("a"),
supportCORS = (function( img ){
return (img.crossOrigin !== undefined);
})(new Image()),
timeoutTimer;
link.href = window.location.href;
pageOrigin = link.protocol + link.host;
function isSameOrigin(url){
link.href = url;
link.href = link.href; // YES, BELIEVE IT OR NOT, that is required for IE9 - http://jsfiddle.net/niklasvh/2e48b/
var origin = link.protocol + link.host;
return (origin === pageOrigin);
}
function start(){
h2clog("html2canvas: start: images: " + images.numLoaded + " / " + images.numTotal + " (failed: " + images.numFailed + ")");
if (!images.firstRun && images.numLoaded >= images.numTotal){
h2clog("Finished loading images: # " + images.numTotal + " (failed: " + images.numFailed + ")");
if (typeof options.complete === "function"){
options.complete(images);
}
}
}
// TODO modify proxy to serve images with CORS enabled, where available
function proxyGetImage(url, img, imageObj){
var callback_name,
scriptUrl = options.proxy,
script;
link.href = url;
url = link.href; // work around for pages with base href="" set - WARNING: this may change the url
callback_name = 'html2canvas_' + (count++);
imageObj.callbackname = callback_name;
if (scriptUrl.indexOf("?") > -1) {
scriptUrl += "&";
} else {
scriptUrl += "?";
}
scriptUrl += 'url=' + encodeURIComponent(url) + '&callback=' + callback_name;
script = doc.createElement("script");
window[callback_name] = function(a){
if (a.substring(0,6) === "error:"){
imageObj.succeeded = false;
images.numLoaded++;
images.numFailed++;
start();
} else {
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)
try {
delete window[callback_name]; // for all browser that support this
} catch(ex) {}
script.parentNode.removeChild(script);
script = null;
delete imageObj.script;
delete imageObj.callbackname;
};
script.setAttribute("type", "text/javascript");
script.setAttribute("src", scriptUrl);
imageObj.script = script;
window.document.body.appendChild(script);
}
function getImages (el) {
var contents = _html2canvas.Util.Children(el),
i,
background_image,
src,
img,
elNodeType = false;
// Firefox fails with permission denied on pages with iframes
try {
var contentsLen = contents.length;
for (i = 0; i < contentsLen; i+=1 ){
getImages(contents[i]);
}
}
catch( e ) {}
try {
elNodeType = el.nodeType;
} catch (ex) {
elNodeType = false;
h2clog("html2canvas: failed to access some element's nodeType - Exception: " + ex.message);
}
if (elNodeType === 1 || elNodeType === undefined){
// opera throws exception on external-content.html
try {
background_image = _html2canvas.Util.getCSS(el, 'backgroundImage');
}catch(e) {
h2clog("html2canvas: failed to get background-image - Exception: " + e.message);
}
if ( background_image && background_image !== "1" && background_image !== "none" ) {
// TODO add multi image background support
if (/^(-webkit|-o|-moz|-ms|linear)-/.test( background_image )) {
img = _html2canvas.Generate.Gradient( background_image, _html2canvas.Util.Bounds( el ) );
if ( img !== undefined ){
images[background_image] = {
img: img,
succeeded: true
};
images.numTotal++;
images.numLoaded++;
start();
}
} else {
src = _html2canvas.Util.backgroundImage(background_image.match(/data:image\/.*;base64,/i) ? background_image : background_image.split(",")[0]);
methods.loadImage(src);
}
}
}
}
function setImageLoadHandlers(img, imageObj) {
img.onload = function() {
if ( imageObj.timer !== undefined ) {
// CORS succeeded
window.clearTimeout( imageObj.timer );
}
images.numLoaded++;
imageObj.succeeded = true;
img.onerror = img.onload = null;
start();
};
img.onerror = function() {
if (img.crossOrigin === "anonymous") {
// CORS failed
window.clearTimeout( imageObj.timer );
// let's try with proxy instead
if ( options.proxy ) {
var src = img.src;
img = new Image();
imageObj.img = img;
img.src = src;
proxyGetImage( img.src, img, imageObj );
return;
}
}
images.numLoaded++;
images.numFailed++;
imageObj.succeeded = false;
img.onerror = img.onload = null;
start();
};
// TODO Opera has no load/error event for SVG images
// Opera ninja onload's cached images
/*
window.setTimeout(function(){
if ( img.width !== 0 && imageObj.succeeded === undefined ) {
img.onload();
}
}, 100); // needs a reflow for base64 encoded images? interestingly timeout of 0 doesn't work but 1 does.
*/
}
methods = {
loadImage: function( src ) {
var img, imageObj;
if ( src && images[src] === undefined ) {
img = new Image();
if ( src.match(/data:image\/.*;base64,/i) ) {
img.src = src.replace(/url\(['"]{0,}|['"]{0,}\)$/ig, '');
imageObj = images[src] = {
img: img
};
images.numTotal++;
setImageLoadHandlers(img, imageObj);
} else if ( isSameOrigin( src ) || options.allowTaint === true ) {
imageObj = images[src] = {
img: img
};
images.numTotal++;
setImageLoadHandlers(img, imageObj);
img.src = src;
} else if ( supportCORS && !options.allowTaint && options.useCORS ) {
// attempt to load with CORS
img.crossOrigin = "anonymous";
imageObj = images[src] = {
img: img
};
images.numTotal++;
setImageLoadHandlers(img, imageObj);
img.src = src;
// work around for https://bugs.webkit.org/show_bug.cgi?id=80028
img.customComplete = function () {
if (!this.img.complete) {
this.timer = window.setTimeout(this.img.customComplete, 100);
} else {
this.img.onerror();
}
}.bind(imageObj);
img.customComplete();
} else if ( options.proxy ) {
imageObj = images[src] = {
img: img
};
images.numTotal++;
proxyGetImage( src, img, imageObj );
}
}
},
cleanupDOM: function(cause) {
var img, src;
if (!images.cleanupDone) {
if (cause && typeof cause === "string") {
h2clog("html2canvas: Cleanup because: " + cause);
} else {
h2clog("html2canvas: Cleanup after timeout: " + options.timeout + " ms.");
}
for (src in images) {
if (images.hasOwnProperty(src)) {
img = images[src];
if (typeof img === "object" && img.callbackname && img.succeeded === undefined) {
// cancel proxy image request
window[img.callbackname] = undefined; // to work with IE<9 // NOTE: that the undefined callback property-name still exists on the window object (for IE<9)
try {
delete window[img.callbackname]; // for all browser that support this
} catch(ex) {}
if (img.script && img.script.parentNode) {
img.script.setAttribute("src", "about:blank"); // try to cancel running request
img.script.parentNode.removeChild(img.script);
}
images.numLoaded++;
images.numFailed++;
h2clog("html2canvas: Cleaned up failed img: '" + src + "' Steps: " + images.numLoaded + " / " + images.numTotal);
}
}
}
// cancel any pending requests
if(window.stop !== undefined) {
window.stop();
} else if(document.execCommand !== undefined) {
document.execCommand("Stop", false);
}
if (document.close !== undefined) {
document.close();
}
images.cleanupDone = true;
if (!(cause && typeof cause === "string")) {
start();
}
}
},
renderingDone: function() {
if (timeoutTimer) {
window.clearTimeout(timeoutTimer);
}
}
};
if (options.timeout > 0) {
timeoutTimer = window.setTimeout(methods.cleanupDOM, options.timeout);
}
h2clog('html2canvas: Preload starts: finding background-images');
images.firstRun = true;
getImages( element );
h2clog('html2canvas: Preload: Finding images');
// load <img> images
for (i = 0; i < imgLen; i+=1){
methods.loadImage( domImages[i].getAttribute( "src" ) );
}
images.firstRun = false;
h2clog('html2canvas: Preload: Done.');
if ( images.numTotal === images.numLoaded ) {
start();
}
return methods;
};