forked from niklasvh/html2canvas
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Canvas.js
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Canvas.js
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/*
html2canvas @VERSION@ <http://html2canvas.hertzen.com>
Copyright (c) 2011 Niklas von Hertzen. All rights reserved.
http://www.twitter.com/niklasvh
Released under MIT License
*/
_html2canvas.Renderer.Canvas = function( options ) {
options = options || {};
var doc = document,
canvas = options.canvas || doc.createElement('canvas'),
usingFlashcanvas = false,
_createCalled = false,
canvasReadyToDraw = false,
methods,
flashMaxSize = 2880; // flash bitmap limited to 2880x2880px // http://stackoverflow.com/questions/2033792/argumenterror-error-2015-invalid-bitmapdata
if (canvas.getContext){
h2clog("html2canvas: Renderer: using canvas renderer");
canvasReadyToDraw = true;
} else if ( options.flashcanvas !== undefined ){
usingFlashcanvas = true;
h2clog("html2canvas: Renderer: canvas not available, using flashcanvas");
var script = doc.createElement("script");
script.src = options.flashcanvas;
script.onload = (function(script, func){
var intervalFunc;
if (script.onload === undefined) {
// IE lack of support for script onload
if( script.onreadystatechange !== undefined ) {
intervalFunc = function() {
if (script.readyState !== "loaded" && script.readyState !== "complete") {
window.setTimeout( intervalFunc, 250 );
} else {
// it is loaded
func();
}
};
window.setTimeout( intervalFunc, 250 );
} else {
h2clog("html2canvas: Renderer: Can't track when flashcanvas is loaded");
}
} else {
return func;
}
})(script, function(){
if (typeof window.FlashCanvas !== "undefined") {
h2clog("html2canvas: Renderer: Flashcanvas initialized");
window.FlashCanvas.initElement( canvas );
canvasReadyToDraw = true;
if ( _createCalled !== false ) {
methods._create.apply( null, _createCalled );
}
}
});
doc.body.appendChild( script );
}
methods = {
_create: function( zStack, options, doc, queue, _html2canvas ) {
if ( !canvasReadyToDraw ) {
_createCalled = arguments;
return canvas;
}
var ctx = canvas.getContext("2d"),
storageContext,
i,
queueLen,
a,
newCanvas,
bounds,
testCanvas = document.createElement("canvas"),
hasCTX = ( testCanvas.getContext !== undefined ),
storageLen,
renderItem,
testctx = ( hasCTX ) ? testCanvas.getContext("2d") : {},
safeImages = [],
fstyle;
canvas.width = canvas.style.width = (!usingFlashcanvas) ? options.width || zStack.ctx.width : Math.min(flashMaxSize, (options.width || zStack.ctx.width) );
canvas.height = canvas.style.height = (!usingFlashcanvas) ? options.height || zStack.ctx.height : Math.min(flashMaxSize, (options.height || zStack.ctx.height) );
fstyle = ctx.fillStyle;
ctx.fillStyle = zStack.backgroundColor;
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = fstyle;
if ( options.svgRendering && zStack.svgRender !== undefined ) {
// TODO: enable async rendering to support this
ctx.drawImage( zStack.svgRender, 0, 0 );
} else {
for ( i = 0, queueLen = queue.length; i < queueLen; i+=1 ) {
storageContext = queue.splice(0, 1)[0];
storageContext.canvasPosition = storageContext.canvasPosition || {};
//this.canvasRenderContext(storageContext,parentctx);
// set common settings for canvas
ctx.textBaseline = "bottom";
if (storageContext.clip){
ctx.save();
ctx.beginPath();
// console.log(storageContext);
ctx.rect(storageContext.clip.left, storageContext.clip.top, storageContext.clip.width, storageContext.clip.height);
ctx.clip();
}
if (storageContext.ctx.storage){
for (a = 0, storageLen = storageContext.ctx.storage.length; a < storageLen; a+=1){
renderItem = storageContext.ctx.storage[a];
switch(renderItem.type){
case "variable":
ctx[renderItem.name] = renderItem['arguments'];
break;
case "function":
if (renderItem.name === "fillRect") {
if (!usingFlashcanvas || renderItem['arguments'][0] + renderItem['arguments'][2] < flashMaxSize && renderItem['arguments'][1] + renderItem['arguments'][3] < flashMaxSize) {
ctx.fillRect.apply( ctx, renderItem['arguments'] );
}
}else if(renderItem.name === "fillText") {
if (!usingFlashcanvas || renderItem['arguments'][1] < flashMaxSize && renderItem['arguments'][2] < flashMaxSize) {
ctx.fillText.apply( ctx, renderItem['arguments'] );
}
}else if(renderItem.name === "drawImage") {
if (renderItem['arguments'][8] > 0 && renderItem['arguments'][7]){
if ( hasCTX && options.taintTest ) {
if ( safeImages.indexOf( renderItem['arguments'][ 0 ].src ) === -1 ) {
testctx.drawImage( renderItem['arguments'][ 0 ], 0, 0 );
try {
testctx.getImageData( 0, 0, 1, 1 );
} catch(e) {
testCanvas = doc.createElement("canvas");
testctx = testCanvas.getContext("2d");
continue;
}
safeImages.push( renderItem['arguments'][ 0 ].src );
}
}
ctx.drawImage.apply( ctx, renderItem['arguments'] );
}
}
break;
default:
}
}
}
if (storageContext.clip){
ctx.restore();
}
}
}
h2clog("html2canvas: Renderer: Canvas renderer done - returning canvas obj");
queueLen = options.elements.length;
if (queueLen === 1) {
if (typeof options.elements[ 0 ] === "object" && options.elements[ 0 ].nodeName !== "BODY" && usingFlashcanvas === false) {
// crop image to the bounds of selected (single) element
bounds = _html2canvas.Util.Bounds( options.elements[ 0 ] );
newCanvas = doc.createElement('canvas');
newCanvas.width = bounds.width;
newCanvas.height = bounds.height;
ctx = newCanvas.getContext("2d");
ctx.drawImage( canvas, bounds.left, bounds.top, bounds.width, bounds.height, 0, 0, bounds.width, bounds.height );
canvas = null;
return newCanvas;
}
} /*else {
// TODO clip and resize multiple elements
for ( i = 0; i < queueLen; i+=1 ) {
if (options.elements[ i ] instanceof Element) {
}
}
}
*/
return canvas;
}
};
return methods;
};