js/canvg/flashcanvas.js

   1 /*
   2  * FlashCanvas
   3  *
   4  * Copyright (c) 2009      Tim Cameron Ryan
   5  * Copyright (c) 2009-2011 FlashCanvas Project
   6  * Released under the MIT/X License
   7  */
   8
   9 // Reference:
  10 //   http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html
  11 //   http://dev.w3.org/html5/spec/the-canvas-element.html
  12
  13 // If the browser is IE and does not support HTML5 Canvas
  14 if (window["ActiveXObject"] && !window["CanvasRenderingContext2D"]) {
  15
  16 (function(window, document, undefined) {
  17
  18 /*
  19  * Constant
  20  */
  21
  22 var NULL                        = null;
  23 var CANVAS                      = "canvas";
  24 var CANVAS_RENDERING_CONTEXT_2D = "CanvasRenderingContext2D";
  25 var CANVAS_GRADIENT             = "CanvasGradient";
  26 var CANVAS_PATTERN              = "CanvasPattern";
  27 var FLASH_CANVAS                = "FlashCanvas";
  28 var G_VML_CANVAS_MANAGER        = "G_vmlCanvasManager";
  29 var OBJECT_ID_PREFIX            = "external";
  30 var ON_FOCUS                    = "onfocus";
  31 var ON_PROPERTY_CHANGE          = "onpropertychange";
  32 var ON_READY_STATE_CHANGE       = "onreadystatechange";
  33 var ON_UNLOAD                   = "onunload";
  34
  35 var config   = window[FLASH_CANVAS + "Options"] || {};
  36 var BASE_URL = config["swfPath"] || getScriptUrl().replace(/[^\/]+$/, "");
  37 var SWF_URL  = BASE_URL + "flashcanvas.swf";
  38
  39 // DOMException code
  40 var INDEX_SIZE_ERR              =  1;
  41 var NOT_SUPPORTED_ERR           =  9;
  42 var INVALID_STATE_ERR           = 11;
  43 var SYNTAX_ERR                  = 12;
  44 var TYPE_MISMATCH_ERR           = 17;
  45 var SECURITY_ERR                = 18;
  46
  47 /**
  48  * @constructor
  49  */
  50 function Lookup(array) {
  51     for (var i = 0, n = array.length; i < n; i++)
  52         this[array[i]] = i;
  53 }
  54
  55 var properties = new Lookup([
  56     // Canvas element
  57     "toDataURL",
  58
  59     // CanvasRenderingContext2D
  60     "save",
  61     "restore",
  62     "scale",
  63     "rotate",
  64     "translate",
  65     "transform",
  66     "setTransform",
  67     "globalAlpha",
  68     "globalCompositeOperation",
  69     "strokeStyle",
  70     "fillStyle",
  71     "createLinearGradient",
  72     "createRadialGradient",
  73     "createPattern",
  74     "lineWidth",
  75     "lineCap",
  76     "lineJoin",
  77     "miterLimit",
  78     "shadowOffsetX",
  79     "shadowOffsetY",
  80     "shadowBlur",
  81     "shadowColor",
  82     "clearRect",
  83     "fillRect",
  84     "strokeRect",
  85     "beginPath",
  86     "closePath",
  87     "moveTo",
  88     "lineTo",
  89     "quadraticCurveTo",
  90     "bezierCurveTo",
  91     "arcTo",
  92     "rect",
  93     "arc",
  94     "fill",
  95     "stroke",
  96     "clip",
  97     "isPointInPath",
  98 //  "drawFocusRing",
  99     "font",
 100     "textAlign",
 101     "textBaseline",
 102     "fillText",
 103     "strokeText",
 104     "measureText",
 105     "drawImage",
 106     "createImageData",
 107     "getImageData",
 108     "putImageData",
 109
 110     // CanvasGradient
 111     "addColorStop",
 112
 113     // Internal use
 114     "direction",
 115     "resize"
 116 ]);
 117
 118 // Whether swf is ready for use
 119 var isReady = {};
 120
 121 // Monitor the number of loading files
 122 var lock = {};
 123
 124 // Canvas elements
 125 var canvases = {};
 126
 127 // SPAN element embedded in the canvas
 128 var spans = {};
 129
 130 /**
 131  * 2D context
 132  * @constructor
 133  */
 134 var CanvasRenderingContext2D = function(canvas, swf) {
 135     // back-reference to the canvas
 136     this.canvas = canvas;
 137
 138     // back-reference to the swf
 139     this._swf = swf;
 140
 141     // unique ID of canvas
 142     this._canvasId = swf.id.slice(8);
 143
 144     // initialize drawing states
 145     this._initialize();
 146
 147     // Count CanvasGradient and CanvasPattern objects
 148     this._gradientPatternId = 0;
 149
 150     // Directionality of the canvas element
 151     this._direction = "";
 152
 153     // frame update interval
 154     var self = this;
 155     setInterval(function() {
 156         if (lock[self._canvasId] === 0) {
 157             self._executeCommand();
 158         }
 159     }, 30);
 160 };
 161
 162 CanvasRenderingContext2D.prototype = {
 163     /*
 164      * state
 165      */
 166
 167     save: function() {
 168         // write all properties
 169         this._setCompositing();
 170         this._setShadows();
 171         this._setStrokeStyle();
 172         this._setFillStyle();
 173         this._setLineStyles();
 174         this._setFontStyles();
 175
 176         // push state
 177         this._stateStack.push([
 178             this._globalAlpha,
 179             this._globalCompositeOperation,
 180             this._strokeStyle,
 181             this._fillStyle,
 182             this._lineWidth,
 183             this._lineCap,
 184             this._lineJoin,
 185             this._miterLimit,
 186             this._shadowOffsetX,
 187             this._shadowOffsetY,
 188             this._shadowBlur,
 189             this._shadowColor,
 190             this._font,
 191             this._textAlign,
 192             this._textBaseline
 193         ]);
 194
 195         this._queue.push(properties.save);
 196     },
 197
 198     restore: function() {
 199         // pop state
 200         var stateStack = this._stateStack;
 201         if (stateStack.length) {
 202             var state = stateStack.pop();
 203             this.globalAlpha              = state[0];
 204             this.globalCompositeOperation = state[1];
 205             this.strokeStyle              = state[2];
 206             this.fillStyle                = state[3];
 207             this.lineWidth                = state[4];
 208             this.lineCap                  = state[5];
 209             this.lineJoin                 = state[6];
 210             this.miterLimit               = state[7];
 211             this.shadowOffsetX            = state[8];
 212             this.shadowOffsetY            = state[9];
 213             this.shadowBlur               = state[10];
 214             this.shadowColor              = state[11];
 215             this.font                     = state[12];
 216             this.textAlign                = state[13];
 217             this.textBaseline             = state[14];
 218         }
 219
 220         this._queue.push(properties.restore);
 221     },
 222
 223     /*
 224      * transformations
 225      */
 226
 227     scale: function(x, y) {
 228         this._queue.push(properties.scale, x, y);
 229     },
 230
 231     rotate: function(angle) {
 232         this._queue.push(properties.rotate, angle);
 233     },
 234
 235     translate: function(x, y) {
 236         this._queue.push(properties.translate, x, y);
 237     },
 238
 239     transform: function(m11, m12, m21, m22, dx, dy) {
 240         this._queue.push(properties.transform, m11, m12, m21, m22, dx, dy);
 241     },
 242
 243     setTransform: function(m11, m12, m21, m22, dx, dy) {
 244         this._queue.push(properties.setTransform, m11, m12, m21, m22, dx, dy);
 245     },
 246
 247     /*
 248      * compositing
 249      */
 250
 251     _setCompositing: function() {
 252         var queue = this._queue;
 253         if (this._globalAlpha !== this.globalAlpha) {
 254             this._globalAlpha = this.globalAlpha;
 255             queue.push(properties.globalAlpha, this._globalAlpha);
 256         }
 257         if (this._globalCompositeOperation !== this.globalCompositeOperation) {
 258             this._globalCompositeOperation = this.globalCompositeOperation;
 259             queue.push(properties.globalCompositeOperation, this._globalCompositeOperation);
 260         }
 261     },
 262
 263     /*
 264      * colors and styles
 265      */
 266
 267     _setStrokeStyle: function() {
 268         if (this._strokeStyle !== this.strokeStyle) {
 269             var style = this._strokeStyle = this.strokeStyle;
 270             this._queue.push(properties.strokeStyle, (typeof style === "object") ? style.id : style);
 271         }
 272     },
 273
 274     _setFillStyle: function() {
 275         if (this._fillStyle !== this.fillStyle) {
 276             var style = this._fillStyle = this.fillStyle;
 277             this._queue.push(properties.fillStyle, (typeof style === "object") ? style.id : style);
 278         }
 279     },
 280
 281     createLinearGradient: function(x0, y0, x1, y1) {
 282         // If any of the arguments are not finite numbers, throws a
 283         // NOT_SUPPORTED_ERR exception.
 284         if (!(isFinite(x0) && isFinite(y0) && isFinite(x1) && isFinite(y1))) {
 285             throwException(NOT_SUPPORTED_ERR);
 286         }
 287
 288         this._queue.push(properties.createLinearGradient, x0, y0, x1, y1);
 289         return new CanvasGradient(this);
 290     },
 291
 292     createRadialGradient: function(x0, y0, r0, x1, y1, r1) {
 293         // If any of the arguments are not finite numbers, throws a
 294         // NOT_SUPPORTED_ERR exception.
 295         if (!(isFinite(x0) && isFinite(y0) && isFinite(r0) &&
 296               isFinite(x1) && isFinite(y1) && isFinite(r1))) {
 297             throwException(NOT_SUPPORTED_ERR);
 298         }
 299
 300         // If either of the radii are negative, throws an INDEX_SIZE_ERR
 301         // exception.
 302         if (r0 < 0 || r1 < 0) {
 303             throwException(INDEX_SIZE_ERR);
 304         }
 305
 306         this._queue.push(properties.createRadialGradient, x0, y0, r0, x1, y1, r1);
 307         return new CanvasGradient(this);
 308     },
 309
 310     createPattern: function(image, repetition) {
 311         // If the image is null, the implementation must raise a
 312         // TYPE_MISMATCH_ERR exception.
 313         if (!image) {
 314             throwException(TYPE_MISMATCH_ERR);
 315         }
 316
 317         var tagName = image.tagName, src;
 318         var canvasId = this._canvasId;
 319
 320         // If the first argument isn't an img, canvas, or video element,
 321         // throws a TYPE_MISMATCH_ERR exception.
 322         if (tagName) {
 323             tagName = tagName.toLowerCase();
 324             if (tagName === "img") {
 325                 src = image.getAttribute("src", 2);
 326             } else if (tagName === CANVAS || tagName === "video") {
 327                 // For now, only HTMLImageElement is supported.
 328                 return;
 329             } else {
 330                 throwException(TYPE_MISMATCH_ERR);
 331             }
 332         }
 333
 334         // Additionally, we accept any object that has a src property.
 335         // This is useful when you'd like to specify a long data URI.
 336         else if (image.src) {
 337             src = image.src;
 338         } else {
 339             throwException(TYPE_MISMATCH_ERR);
 340         }
 341
 342         // If the second argument isn't one of the allowed values, throws a
 343         // SYNTAX_ERR exception.
 344         if (!(repetition === "repeat"   || repetition === "no-repeat" ||
 345               repetition === "repeat-x" || repetition === "repeat-y"  ||
 346               repetition === ""         || repetition === NULL)) {
 347             throwException(SYNTAX_ERR);
 348         }
 349
 350         // Special characters in the filename need escaping.
 351         this._queue.push(properties.createPattern, encodeXML(src), repetition);
 352
 353         if (isReady[canvasId]) {
 354             this._executeCommand();
 355             ++lock[canvasId];
 356         }
 357
 358         return new CanvasPattern(this);
 359     },
 360
 361     /*
 362      * line caps/joins
 363      */
 364
 365     _setLineStyles: function() {
 366         var queue = this._queue;
 367         if (this._lineWidth !== this.lineWidth) {
 368             this._lineWidth = this.lineWidth;
 369             queue.push(properties.lineWidth, this._lineWidth);
 370         }
 371         if (this._lineCap !== this.lineCap) {
 372             this._lineCap = this.lineCap;
 373             queue.push(properties.lineCap, this._lineCap);
 374         }
 375         if (this._lineJoin !== this.lineJoin) {
 376             this._lineJoin = this.lineJoin;
 377             queue.push(properties.lineJoin, this._lineJoin);
 378         }
 379         if (this._miterLimit !== this.miterLimit) {
 380             this._miterLimit = this.miterLimit;
 381             queue.push(properties.miterLimit, this._miterLimit);
 382         }
 383     },
 384
 385     /*
 386      * shadows
 387      */
 388
 389     _setShadows: function() {
 390         var queue = this._queue;
 391         if (this._shadowOffsetX !== this.shadowOffsetX) {
 392             this._shadowOffsetX = this.shadowOffsetX;
 393             queue.push(properties.shadowOffsetX, this._shadowOffsetX);
 394         }
 395         if (this._shadowOffsetY !== this.shadowOffsetY) {
 396             this._shadowOffsetY = this.shadowOffsetY;
 397             queue.push(properties.shadowOffsetY, this._shadowOffsetY);
 398         }
 399         if (this._shadowBlur !== this.shadowBlur) {
 400             this._shadowBlur = this.shadowBlur;
 401             queue.push(properties.shadowBlur, this._shadowBlur);
 402         }
 403         if (this._shadowColor !== this.shadowColor) {
 404             this._shadowColor = this.shadowColor;
 405             queue.push(properties.shadowColor, this._shadowColor);
 406         }
 407     },
 408
 409     /*
 410      * rects
 411      */
 412
 413     clearRect: function(x, y, w, h) {
 414         this._queue.push(properties.clearRect, x, y, w, h);
 415     },
 416
 417     fillRect: function(x, y, w, h) {
 418         this._setCompositing();
 419         this._setShadows();
 420         this._setFillStyle();
 421         this._queue.push(properties.fillRect, x, y, w, h);
 422     },
 423
 424     strokeRect: function(x, y, w, h) {
 425         this._setCompositing();
 426         this._setShadows();
 427         this._setStrokeStyle();
 428         this._setLineStyles();
 429         this._queue.push(properties.strokeRect, x, y, w, h);
 430     },
 431
 432     /*
 433      * path API
 434      */
 435
 436     beginPath: function() {
 437         this._queue.push(properties.beginPath);
 438     },
 439
 440     closePath: function() {
 441         this._queue.push(properties.closePath);
 442     },
 443
 444     moveTo: function(x, y) {
 445         this._queue.push(properties.moveTo, x, y);
 446     },
 447
 448     lineTo: function(x, y) {
 449         this._queue.push(properties.lineTo, x, y);
 450     },
 451
 452     quadraticCurveTo: function(cpx, cpy, x, y) {
 453         this._queue.push(properties.quadraticCurveTo, cpx, cpy, x, y);
 454     },
 455
 456     bezierCurveTo: function(cp1x, cp1y, cp2x, cp2y, x, y) {
 457         this._queue.push(properties.bezierCurveTo, cp1x, cp1y, cp2x, cp2y, x, y);
 458     },
 459
 460     arcTo: function(x1, y1, x2, y2, radius) {
 461         // Throws an INDEX_SIZE_ERR exception if the given radius is negative.
 462         if (radius < 0 && isFinite(radius)) {
 463             throwException(INDEX_SIZE_ERR);
 464         }
 465
 466         this._queue.push(properties.arcTo, x1, y1, x2, y2, radius);
 467     },
 468
 469     rect: function(x, y, w, h) {
 470         this._queue.push(properties.rect, x, y, w, h);
 471     },
 472
 473     arc: function(x, y, radius, startAngle, endAngle, anticlockwise) {
 474         // Throws an INDEX_SIZE_ERR exception if the given radius is negative.
 475         if (radius < 0 && isFinite(radius)) {
 476             throwException(INDEX_SIZE_ERR);
 477         }
 478
 479         this._queue.push(properties.arc, x, y, radius, startAngle, endAngle, anticlockwise ? 1 : 0);
 480     },
 481
 482     fill: function() {
 483         this._setCompositing();
 484         this._setShadows();
 485         this._setFillStyle();
 486         this._queue.push(properties.fill);
 487     },
 488
 489     stroke: function() {
 490         this._setCompositing();
 491         this._setShadows();
 492         this._setStrokeStyle();
 493         this._setLineStyles();
 494         this._queue.push(properties.stroke);
 495     },
 496
 497     clip: function() {
 498         this._queue.push(properties.clip);
 499     },
 500
 501     isPointInPath: function(x, y) {
 502         // TODO: Implement
 503     },
 504
 505     /*
 506      * text
 507      */
 508
 509     _setFontStyles: function() {
 510         var queue = this._queue;
 511         if (this._font !== this.font) {
 512             try {
 513                 var span = spans[this._canvasId];
 514                 span.style.font = this._font = this.font;
 515
 516                 var style = span.currentStyle;
 517                 var fontSize = span.offsetHeight;
 518                 var font = [style.fontStyle, style.fontWeight, fontSize, style.fontFamily].join(" ");
 519                 queue.push(properties.font, font);
 520             } catch(e) {
 521                 // If this.font cannot be parsed as a CSS font value, then it
 522                 // must be ignored.
 523             }
 524         }
 525         if (this._textAlign !== this.textAlign) {
 526             this._textAlign = this.textAlign;
 527             queue.push(properties.textAlign, this._textAlign);
 528         }
 529         if (this._textBaseline !== this.textBaseline) {
 530             this._textBaseline = this.textBaseline;
 531             queue.push(properties.textBaseline, this._textBaseline);
 532         }
 533         if (this._direction !== this.canvas.currentStyle.direction) {
 534             this._direction = this.canvas.currentStyle.direction;
 535             queue.push(properties.direction, this._direction);
 536         }
 537     },
 538
 539     fillText: function(text, x, y, maxWidth) {
 540         this._setCompositing();
 541         this._setFillStyle();
 542         this._setShadows();
 543         this._setFontStyles();
 544         this._queue.push(properties.fillText, encodeXML(text), x, y,
 545                          maxWidth === undefined ? Infinity : maxWidth);
 546     },
 547
 548     strokeText: function(text, x, y, maxWidth) {
 549         this._setCompositing();
 550         this._setStrokeStyle();
 551         this._setShadows();
 552         this._setFontStyles();
 553         this._queue.push(properties.strokeText, encodeXML(text), x, y,
 554                          maxWidth === undefined ? Infinity : maxWidth);
 555     },
 556
 557     measureText: function(text) {
 558         var span = spans[this._canvasId];
 559         try {
 560             span.style.font = this.font;
 561         } catch(e) {
 562             // If this.font cannot be parsed as a CSS font value, then it must
 563             // be ignored.
 564         }
 565
 566         // Replace space characters with tab characters because innerText
 567         // removes trailing white spaces.
 568         span.innerText = text.replace(/[ \n\f\r]/g, "\t");
 569
 570         return new TextMetrics(span.offsetWidth);
 571     },
 572
 573     /*
 574      * drawing images
 575      */
 576
 577     drawImage: function(image, x1, y1, w1, h1, x2, y2, w2, h2) {
 578         // If the image is null, the implementation must raise a
 579         // TYPE_MISMATCH_ERR exception.
 580         if (!image) {
 581             throwException(TYPE_MISMATCH_ERR);
 582         }
 583
 584         var tagName = image.tagName, src, argc = arguments.length;
 585         var canvasId = this._canvasId;
 586
 587         // If the first argument isn't an img, canvas, or video element,
 588         // throws a TYPE_MISMATCH_ERR exception.
 589         if (tagName) {
 590             tagName = tagName.toLowerCase();
 591             if (tagName === "img") {
 592                 src = image.getAttribute("src", 2);
 593             } else if (tagName === CANVAS || tagName === "video") {
 594                 // For now, only HTMLImageElement is supported.
 595                 return;
 596             } else {
 597                 throwException(TYPE_MISMATCH_ERR);
 598             }
 599         }
 600
 601         // Additionally, we accept any object that has a src property.
 602         // This is useful when you'd like to specify a long data URI.
 603         else if (image.src) {
 604             src = image.src;
 605         } else {
 606             throwException(TYPE_MISMATCH_ERR);
 607         }
 608
 609         this._setCompositing();
 610         this._setShadows();
 611
 612         // Special characters in the filename need escaping.
 613         src = encodeXML(src);
 614
 615         if (argc === 3) {
 616             this._queue.push(properties.drawImage, argc, src, x1, y1);
 617         } else if (argc === 5) {
 618             this._queue.push(properties.drawImage, argc, src, x1, y1, w1, h1);
 619         } else if (argc === 9) {
 620             // If one of the sw or sh arguments is zero, the implementation
 621             // must raise an INDEX_SIZE_ERR exception.
 622             if (w1 === 0 || h1 === 0) {
 623                 throwException(INDEX_SIZE_ERR);
 624             }
 625
 626             this._queue.push(properties.drawImage, argc, src, x1, y1, w1, h1, x2, y2, w2, h2);
 627         } else {
 628             return;
 629         }
 630
 631         if (isReady[canvasId]) {
 632             this._executeCommand();
 633             ++lock[canvasId];
 634         }
 635     },
 636
 637     /*
 638      * pixel manipulation
 639      */
 640
 641     // ImageData createImageData(in float sw, in float sh);
 642     // ImageData createImageData(in ImageData imagedata);
 643     createImageData: function() {
 644         // TODO: Implement
 645     },
 646
 647     // ImageData getImageData(in float sx, in float sy, in float sw, in float sh);
 648     getImageData: function(sx, sy, sw, sh) {
 649         // TODO: Implement
 650     },
 651
 652     // void putImageData(in ImageData imagedata, in float dx, in float dy, [Optional] in float dirtyX, in float dirtyY, in float dirtyWidth, in float dirtyHeight);
 653     putImageData: function(imagedata, dx, dy, dirtyX, dirtyY, dirtyWidth, dirtyHeight) {
 654         // TODO: Implement
 655     },
 656
 657     /*
 658      * private methods
 659      */
 660
 661     _initialize: function() {
 662         // compositing
 663         this.globalAlpha = this._globalAlpha = 1.0;
 664         this.globalCompositeOperation = this._globalCompositeOperation = "source-over";
 665
 666         // colors and styles
 667         this.strokeStyle = this._strokeStyle = "#000000";
 668         this.fillStyle   = this._fillStyle   = "#000000";
 669
 670         // line caps/joins
 671         this.lineWidth  = this._lineWidth  = 1.0;
 672         this.lineCap    = this._lineCap    = "butt";
 673         this.lineJoin   = this._lineJoin   = "miter";
 674         this.miterLimit = this._miterLimit = 10.0;
 675
 676         // shadows
 677         this.shadowOffsetX = this._shadowOffsetX = 0;
 678         this.shadowOffsetY = this._shadowOffsetY = 0;
 679         this.shadowBlur    = this._shadowBlur    = 0;
 680         this.shadowColor   = this._shadowColor   = "rgba(0, 0, 0, 0.0)";
 681
 682         // text
 683         this.font         = this._font         = "10px sans-serif";
 684         this.textAlign    = this._textAlign    = "start";
 685         this.textBaseline = this._textBaseline = "alphabetic";
 686
 687         // command queue
 688         this._queue = [];
 689
 690         // stack of drawing states
 691         this._stateStack = [];
 692     },
 693
 694     _flush: function() {
 695         var queue = this._queue;
 696         this._queue = [];
 697         return queue;
 698     },
 699
 700     _executeCommand: function() {
 701         // execute commands
 702         var commands = this._flush();
 703         if (commands.length > 0) {
 704             return eval(this._swf.CallFunction(
 705                 '<invoke name="executeCommand" returntype="javascript"><arguments><string>'
 706                 + commands.join("&#0;") + "</string></arguments></invoke>"
 707             ));
 708         }
 709     },
 710
 711     _resize: function(width, height) {
 712         // Flush commands in the queue
 713         this._executeCommand();
 714
 715         // Clear back to the initial state
 716         this._initialize();
 717
 718         // Adjust the size of Flash to that of the canvas
 719         if (width > 0) {
 720             this._swf.width = width;
 721         }
 722         if (height > 0) {
 723             this._swf.height = height;
 724         }
 725
 726         // Execute a resize command at the start of the next frame
 727         this._queue.push(properties.resize, width, height);
 728     }
 729 };
 730
 731 /**
 732  * CanvasGradient stub
 733  * @constructor
 734  */
 735 var CanvasGradient = function(ctx) {
 736     this._ctx = ctx;
 737     this.id   = ctx._gradientPatternId++;
 738 };
 739
 740 CanvasGradient.prototype = {
 741     addColorStop: function(offset, color) {
 742         // Throws an INDEX_SIZE_ERR exception if the offset is out of range.
 743         if (isNaN(offset) || offset < 0 || offset > 1) {
 744             throwException(INDEX_SIZE_ERR);
 745         }
 746
 747         this._ctx._queue.push(properties.addColorStop, this.id, offset, color);
 748     }
 749 };
 750
 751 /**
 752  * CanvasPattern stub
 753  * @constructor
 754  */
 755 var CanvasPattern = function(ctx) {
 756     this.id = ctx._gradientPatternId++;
 757 };
 758
 759 /**
 760  * TextMetrics stub
 761  * @constructor
 762  */
 763 var TextMetrics = function(width) {
 764     this.width = width;
 765 };
 766
 767 /**
 768  * DOMException
 769  * @constructor
 770  */
 771 var DOMException = function(code) {
 772     this.code    = code;
 773     this.message = DOMExceptionNames[code];
 774 };
 775
 776 DOMException.prototype = new Error;
 777
 778 var DOMExceptionNames = {
 779     1:  "INDEX_SIZE_ERR",
 780     9:  "NOT_SUPPORTED_ERR",
 781     11: "INVALID_STATE_ERR",
 782     12: "SYNTAX_ERR",
 783     17: "TYPE_MISMATCH_ERR",
 784     18: "SECURITY_ERR"
 785 };
 786
 787 /*
 788  * Event handlers
 789  */
 790
 791 function onReadyStateChange() {
 792     if (document.readyState === "complete") {
 793         document.detachEvent(ON_READY_STATE_CHANGE, onReadyStateChange);
 794
 795         var canvases = document.getElementsByTagName(CANVAS);
 796         for (var i = 0, n = canvases.length; i < n; ++i) {
 797             FlashCanvas.initElement(canvases[i]);
 798         }
 799     }
 800 }
 801
 802 function onFocus() {
 803     // forward the event to the parent
 804     var swf = event.srcElement, canvas = swf.parentNode;
 805     swf.blur();
 806     canvas.focus();
 807 }
 808
 809 function onPropertyChange() {
 810     var prop = event.propertyName;
 811     if (prop === "width" || prop === "height") {
 812         var canvas = event.srcElement;
 813         var value  = canvas[prop];
 814         var number = parseInt(value, 10);
 815
 816         if (isNaN(number) || number < 0) {
 817             number = (prop === "width") ? 300 : 150;
 818         }
 819
 820         if (value === number) {
 821             canvas.style[prop] = number + "px";
 822             canvas.getContext("2d")._resize(canvas.width, canvas.height);
 823         } else {
 824             canvas[prop] = number;
 825         }
 826     }
 827 }
 828
 829 function onUnload() {
 830     window.detachEvent(ON_UNLOAD, onUnload);
 831
 832     for (var canvasId in canvases) {
 833         var canvas = canvases[canvasId], swf = canvas.firstChild, prop;
 834
 835         // clean up the references of swf.executeCommand and swf.resize
 836         for (prop in swf) {
 837             if (typeof swf[prop] === "function") {
 838                 swf[prop] = NULL;
 839             }
 840         }
 841
 842         // clean up the references of canvas.getContext and canvas.toDataURL
 843         for (prop in canvas) {
 844             if (typeof canvas[prop] === "function") {
 845                 canvas[prop] = NULL;
 846             }
 847         }
 848
 849         // remove event listeners
 850         swf.detachEvent(ON_FOCUS, onFocus);
 851         canvas.detachEvent(ON_PROPERTY_CHANGE, onPropertyChange);
 852     }
 853
 854     // delete exported symbols
 855     window[CANVAS_RENDERING_CONTEXT_2D] = NULL;
 856     window[CANVAS_GRADIENT]             = NULL;
 857     window[CANVAS_PATTERN]              = NULL;
 858     window[FLASH_CANVAS]                = NULL;
 859     window[G_VML_CANVAS_MANAGER]        = NULL;
 860 }
 861
 862 /*
 863  * FlashCanvas API
 864  */
 865
 866 var FlashCanvas = {
 867     initElement: function(canvas) {
 868         // Check whether the initialization is required or not.
 869         if (canvas.getContext) {
 870             return canvas;
 871         }
 872
 873         // initialize lock
 874         var canvasId      = getUniqueId();
 875         var objectId      = OBJECT_ID_PREFIX + canvasId;
 876         isReady[canvasId] = false;
 877         lock[canvasId]    = 1;
 878
 879         // Set the width and height attributes.
 880         setCanvasSize(canvas);
 881
 882         // embed swf and SPAN element
 883         canvas.innerHTML =
 884             '<object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000"' +
 885             ' codebase="' + location.protocol + '//fpdownload.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=9,0,0,0"' +
 886             ' width="100%" height="100%" id="' + objectId + '">' +
 887             '<param name="allowScriptAccess" value="always">' +
 888             '<param name="flashvars" value="id=' + objectId + '">' +
 889             '<param name="wmode" value="transparent">' +
 890             '</object>' +
 891             '<span style="margin:0;padding:0;border:0;display:inline-block;position:static;height:1em;overflow:visible;white-space:nowrap">' +
 892             '</span>';
 893
 894         canvases[canvasId] = canvas;
 895         var swf            = canvas.firstChild;
 896         spans[canvasId]    = canvas.lastChild;
 897
 898         // Check whether the canvas element is in the DOM tree
 899         var documentContains = document.body.contains;
 900         if (documentContains(canvas)) {
 901             // Load swf file immediately
 902             swf["movie"] = SWF_URL;
 903         } else {
 904             // Wait until the element is added to the DOM tree
 905             var intervalId = setInterval(function() {
 906                 if (documentContains(canvas)) {
 907                     clearInterval(intervalId);
 908                     swf["movie"] = SWF_URL;
 909                 }
 910             }, 0);
 911         }
 912
 913         // If the browser is IE6 or in quirks mode
 914         if (document.compatMode === "BackCompat" || !window.XMLHttpRequest) {
 915             spans[canvasId].style.overflow = "hidden";
 916         }
 917
 918         // initialize context
 919         var ctx = new CanvasRenderingContext2D(canvas, swf);
 920
 921         // canvas API
 922         canvas.getContext = function(contextId) {
 923             return contextId === "2d" ? ctx : NULL;
 924         };
 925
 926         canvas.toDataURL = function(type, quality) {
 927             if (("" + type).replace(/[A-Z]+/g, toLowerCase) === "image/jpeg") {
 928                 ctx._queue.push(properties.toDataURL, type,
 929                                 typeof quality === "number" ? quality : "");
 930             } else {
 931                 ctx._queue.push(properties.toDataURL, type);
 932             }
 933             return ctx._executeCommand();
 934         };
 935
 936         // add event listener
 937         swf.attachEvent(ON_FOCUS, onFocus);
 938
 939         return canvas;
 940     },
 941
 942     saveImage: function(canvas) {
 943         var swf = canvas.firstChild;
 944         swf.saveImage();
 945     },
 946
 947     setOptions: function(options) {
 948         // TODO: Implement
 949     },
 950
 951     trigger: function(canvasId, type) {
 952         var canvas = canvases[canvasId];
 953         canvas.fireEvent("on" + type);
 954     },
 955
 956     unlock: function(canvasId, ready) {
 957         if (lock[canvasId]) {
 958             --lock[canvasId];
 959         }
 960         if (ready) {
 961             var canvas = canvases[canvasId];
 962             var swf    = canvas.firstChild;
 963             var width;
 964             var height;
 965
 966             // Set the width and height attributes of the canvas element.
 967             setCanvasSize(canvas);
 968             width  = canvas.width;
 969             height = canvas.height;
 970
 971             canvas.style.width  = width  + "px";
 972             canvas.style.height = height + "px";
 973
 974             // Adjust the size of Flash to that of the canvas
 975             if (width > 0) {
 976                 swf.width = width;
 977             }
 978             if (height > 0) {
 979                 swf.height = height;
 980             }
 981             swf.resize(width, height);
 982
 983             // Add event listener
 984             canvas.attachEvent(ON_PROPERTY_CHANGE, onPropertyChange);
 985
 986             // ExternalInterface is now ready for use
 987             isReady[canvasId] = true;
 988         }
 989     }
 990 };
 991
 992 /*
 993  * Utility methods
 994  */
 995
 996 // Get the absolute URL of flashcanvas.js
 997 function getScriptUrl() {
 998     var scripts = document.getElementsByTagName("script");
 999     var script  = scripts[scripts.length - 1];
1000
1001     // @see http://msdn.microsoft.com/en-us/library/ms536429(VS.85).aspx
1002     if (document.documentMode >= 8) {
1003         return script.src;
1004     } else {
1005         return script.getAttribute("src", 4);
1006     }
1007 }
1008
1009 // Get a unique ID composed of alphanumeric characters.
1010 function getUniqueId() {
1011     return Math.random().toString(36).slice(2) || "0";
1012 }
1013
1014 // Escape characters not permitted in XML.
1015 function encodeXML(str) {
1016     return ("" + str).replace(/&/g, "&amp;").replace(/</g, "&lt;");
1017 }
1018
1019 function toLowerCase(str) {
1020     return str.toLowerCase();
1021 }
1022
1023 function throwException(code) {
1024     throw new DOMException(code);
1025 }
1026
1027 // The width and height attributes of a canvas element must have values that
1028 // are valid non-negative integers.
1029 function setCanvasSize(canvas) {
1030     var width  = parseInt(canvas.width, 10);
1031     var height = parseInt(canvas.height, 10);
1032
1033     if (isNaN(width) || width < 0) {
1034         width = 300;
1035     }
1036     if (isNaN(height) || height < 0) {
1037         height = 150;
1038     }
1039
1040     canvas.width  = width;
1041     canvas.height = height;
1042 }
1043
1044 /*
1045  * initialization
1046  */
1047
1048 // IE HTML5 shiv
1049 document.createElement(CANVAS);
1050
1051 // setup default CSS
1052 document.createStyleSheet().cssText =
1053     CANVAS + "{display:inline-block;overflow:hidden;width:300px;height:150px}";
1054
1055 // initialize canvas elements
1056 if (document.readyState === "complete") {
1057     onReadyStateChange();
1058 } else {
1059     document.attachEvent(ON_READY_STATE_CHANGE, onReadyStateChange);
1060 }
1061
1062 // prevent IE6 memory leaks
1063 window.attachEvent(ON_UNLOAD, onUnload);
1064
1065 // preload SWF file if it's in the same domain
1066 if (SWF_URL.indexOf(location.protocol + "//" + location.host + "/") === 0) {
1067     var req = new ActiveXObject("Microsoft.XMLHTTP");
1068     req.open("GET", SWF_URL, false);
1069     req.send(NULL);
1070 }
1071
1072 /*
1073  * public API
1074  */
1075
1076 window[CANVAS_RENDERING_CONTEXT_2D] = CanvasRenderingContext2D;
1077 window[CANVAS_GRADIENT]             = CanvasGradient;
1078 window[CANVAS_PATTERN]              = CanvasPattern;
1079 window[FLASH_CANVAS]                = FlashCanvas;
1080
1081 // ExplorerCanvas-compatible APIs for convenience
1082 window[G_VML_CANVAS_MANAGER] = {
1083     init:  function(){},
1084     init_: function(){},
1085     initElement: FlashCanvas.initElement
1086 };
1087
1088 // Prevent Closure Compiler from removing the function.
1089 keep = CanvasRenderingContext2D.measureText;
1090
1091 })(window, document);
1092
1093 }