https://zhudayu522.com/Scripts/excanvas.min.js

1// Copyright 2006 Google Inc.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//   http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15
16// Known Issues:
17//
18// * Patterns are not implemented.
19// * Radial gradient are not implemented. The VML version of these look very
20//   different from the canvas one.
21// * Clipping paths are not implemented.
22// * Coordsize. The width and height attribute have higher priority than the
23//   width and height style values which isn't correct.
24// * Painting mode isn't implemented.
25// * Canvas width/height should is using content-box by default. IE in
26//   Quirks mode will draw the canvas using border-box. Either change your
27//   doctype to HTML5
28//   (http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)
29//   or use Box Sizing Behavior from WebFX
30//   (http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)
31// * Non uniform scaling does not correctly scale strokes.
32// * Optimize. There is always room for speed improvements.
33
34// Only add this code if we do not already have a canvas implementation
35if (!document.createElement('canvas').getContext) {
36
37(function() {
38
39  // alias some functions to make (compiled) code shorter
40  var m = Math;
41  var mr = m.round;
42  var ms = m.sin;
43  var mc = m.cos;
44  var abs = m.abs;
45  var sqrt = m.sqrt;
46
47  // this is used for sub pixel precision
48  var Z = 10;
49  var Z2 = Z / 2;
50
51  /**
52   * This funtion is assigned to the <canvas> elements as element.getContext().
53   * @this {HTMLElement}
54   * @return {CanvasRenderingContext2D_}
55   */
56  function getContext() {
57    return this.context_ ||
58        (this.context_ = new CanvasRenderingContext2D_(this));
59  }
60
61  var slice = Array.prototype.slice;
62
63  /**
64   * Binds a function to an object. The returned function will always use the
65   * passed in {@code obj} as {@code this}.
66   *
67   * Example:
68   *
69   *   g = bind(f, obj, a, b)
70   *   g(c, d) // will do f.call(obj, a, b, c, d)
71   *
72   * @param {Function} f The function to bind the object to
73   * @param {Object} obj The object that should act as this when the function
74   *     is called
75   * @param {*} var_args Rest arguments that will be used as the initial
76   *     arguments when the function is called
77   * @return {Function} A new function that has bound this
78   */
79  function bind(f, obj, var_args) {
80    var a = slice.call(arguments, 2);
81    return function() {
82      return f.apply(obj, a.concat(slice.call(arguments)));
83    };
84  }
85
86  var G_vmlCanvasManager_ = {
87    init: function(opt_doc) {
88      if (/MSIE/.test(navigator.userAgent) && !window.opera) {
89        var doc = opt_doc || document;
90        // Create a dummy element so that IE will allow canvas elements to be
91        // recognized.
92        doc.createElement('canvas');
93        doc.attachEvent('onreadystatechange', bind(this.init_, this, doc));
94      }
95    },
96
97    init_: function(doc) {
98      // create xmlns
99      if (!doc.namespaces['g_vml_']) {
100        doc.namespaces.add('g_vml_', 'urn:schemas-microsoft-com:vml',
101                           '#default#VML');
102
103      }
104      if (!doc.namespaces['g_o_']) {
105        doc.namespaces.add('g_o_', 'urn:schemas-microsoft-com:office:office',
106                           '#default#VML');
107      }
108
109      // Setup default CSS.  Only add one style sheet per document
110      if (!doc.styleSheets['ex_canvas_']) {
111        var ss = doc.createStyleSheet();
112        ss.owningElement.id = 'ex_canvas_';
113        ss.cssText = 'canvas{display:inline-block;overflow:hidden;' +
114            // default size is 300x150 in Gecko and Opera
115            'text-align:left;width:300px;height:150px}' +
116            'g_vml_\\:*{behavior:url(#default#VML)}' +
117            'g_o_\\:*{behavior:url(#default#VML)}';
118
119      }
120
121      // find all canvas elements
122      var els = doc.getElementsByTagName('canvas');
123      for (var i = 0; i < els.length; i++) {
124        this.initElement(els[i]);
125      }
126    },
127
128    /**
129     * Public initializes a canvas element so that it can be used as canvas
130     * element from now on. This is called automatically before the page is
131     * loaded but if you are creating elements using createElement you need to
132     * make sure this is called on the element.
133     * @param {HTMLElement} el The canvas element to initialize.
134     * @return {HTMLElement} the element that was created.
135     */
136    initElement: function(el) {
137      if (!el.getContext) {
138
139        el.getContext = getContext;
140
141        // Remove fallback content. There is no way to hide text nodes so we
142        // just remove all childNodes. We could hide all elements and remove
143        // text nodes but who really cares about the fallback content.
144        el.innerHTML = '';
145
146        // do not use inline function because that will leak memory
147        el.attachEvent('onpropertychange', onPropertyChange);
148        el.attachEvent('onresize', onResize);
149
150        var attrs = el.attributes;
151        if (attrs.width && attrs.width.specified) {
152          // TODO: use runtimeStyle and coordsize
153          // el.getContext().setWidth_(attrs.width.nodeValue);
154          el.style.width = attrs.width.nodeValue + 'px';
155        } else {
156          el.width = el.clientWidth;
157        }
158        if (attrs.height && attrs.height.specified) {
159          // TODO: use runtimeStyle and coordsize
160          // el.getContext().setHeight_(attrs.height.nodeValue);
161          el.style.height = attrs.height.nodeValue + 'px';
162        } else {
163          el.height = el.clientHeight;
164        }
165        //el.getContext().setCoordsize_()
166      }
167      return el;
168    }
169  };
170
171  function onPropertyChange(e) {
172    var el = e.srcElement;
173
174    switch (e.propertyName) {
175      case 'width':
176        el.style.width = el.attributes.width.nodeValue + 'px';
177        el.getContext().clearRect();
178        break;
179      case 'height':
180        el.style.height = el.attributes.height.nodeValue + 'px';
181        el.getContext().clearRect();
182        break;
183    }
184  }
185
186  function onResize(e) {
187    var el = e.srcElement;
188    if (el.firstChild) {
189      el.firstChild.style.width =  el.clientWidth + 'px';
190      el.firstChild.style.height = el.clientHeight + 'px';
191    }
192  }
193
194  G_vmlCanvasManager_.init();
195
196  // precompute "00" to "FF"
197  var dec2hex = [];
198  for (var i = 0; i < 16; i++) {
199    for (var j = 0; j < 16; j++) {
200      dec2hex[i * 16 + j] = i.toString(16) + j.toString(16);
201    }
202  }
203
204  function createMatrixIdentity() {
205    return [
206      [1, 0, 0],
207      [0, 1, 0],
208      [0, 0, 1]
209    ];
210  }
211
212  function matrixMultiply(m1, m2) {
213    var result = createMatrixIdentity();
214
215    for (var x = 0; x < 3; x++) {
216      for (var y = 0; y < 3; y++) {
217        var sum = 0;
218
219        for (var z = 0; z < 3; z++) {
220          sum += m1[x][z] * m2[z][y];
221        }
222
223        result[x][y] = sum;
224      }
225    }
226    return result;
227  }
228
229  function copyState(o1, o2) {
230    o2.fillStyle     = o1.fillStyle;
231    o2.lineCap       = o1.lineCap;
232    o2.lineJoin      = o1.lineJoin;
233    o2.lineWidth     = o1.lineWidth;
234    o2.miterLimit    = o1.miterLimit;
235    o2.shadowBlur    = o1.shadowBlur;
236    o2.shadowColor   = o1.shadowColor;
237    o2.shadowOffsetX = o1.shadowOffsetX;
238    o2.shadowOffsetY = o1.shadowOffsetY;
239    o2.strokeStyle   = o1.strokeStyle;
240    o2.globalAlpha   = o1.globalAlpha;
241    o2.arcScaleX_    = o1.arcScaleX_;
242    o2.arcScaleY_    = o1.arcScaleY_;
243    o2.lineScale_    = o1.lineScale_;
244  }
245
246  function processStyle(styleString) {
247    var str, alpha = 1;
248
249    styleString = String(styleString);
250    if (styleString.substring(0, 3) == 'rgb') {
251      var start = styleString.indexOf('(', 3);
252      var end = styleString.indexOf(')', start + 1);
253      var guts = styleString.substring(start + 1, end).split(',');
254
255      str = '#';
256      for (var i = 0; i < 3; i++) {
257        str += dec2hex[Number(guts[i])];
258      }
259
260      if (guts.length == 4 && styleString.substr(3, 1) == 'a') {
261        alpha = guts[3];
262      }
263    } else {
264      str = styleString;
265    }
266
267    return {color: str, alpha: alpha};
268  }
269
270  function processLineCap(lineCap) {
271    switch (lineCap) {
272      case 'butt':
273        return 'flat';
274      case 'round':
275        return 'round';
276      case 'square':
277      default:
278        return 'square';
279    }
280  }
281
282  /**
283   * This class implements CanvasRenderingContext2D interface as described by
284   * the WHATWG.
285   * @param {HTMLElement} surfaceElement The element that the 2D context should
286   * be associated with
287   */
288  function CanvasRenderingContext2D_(surfaceElement) {
289    this.m_ = createMatrixIdentity();
290
291    this.mStack_ = [];
292    this.aStack_ = [];
293    this.currentPath_ = [];
294
295    // Canvas context properties
296    this.strokeStyle = '#000';
297    this.fillStyle = '#000';
298
299    this.lineWidth = 1;
300    this.lineJoin = 'miter';
301    this.lineCap = 'butt';
302    this.miterLimit = Z * 1;
303    this.globalAlpha = 1;
304    this.canvas = surfaceElement;
305
306    var el = surfaceElement.ownerDocument.createElement('div');
307    el.style.width =  surfaceElement.clientWidth + 'px';
308    el.style.height = surfaceElement.clientHeight + 'px';
309    el.style.overflow = 'hidden';
310    el.style.position = 'absolute';
311    surfaceElement.appendChild(el);
312
313    this.element_ = el;
314    this.arcScaleX_ = 1;
315    this.arcScaleY_ = 1;
316    this.lineScale_ = 1;
317  }
318
319  var contextPrototype = CanvasRenderingContext2D_.prototype;
320  contextPrototype.clearRect = function() {
321    this.element_.innerHTML = '';
322  };
323
324  contextPrototype.beginPath = function() {
325    // TODO: Branch current matrix so that save/restore has no effect
326    //       as per safari docs.
327    this.currentPath_ = [];
328  };
329
330  contextPrototype.moveTo = function(aX, aY) {
331    var p = this.getCoords_(aX, aY);
332    this.currentPath_.push({type: 'moveTo', x: p.x, y: p.y});
333    this.currentX_ = p.x;
334    this.currentY_ = p.y;
335  };
336
337  contextPrototype.lineTo = function(aX, aY) {
338    var p = this.getCoords_(aX, aY);
339    this.currentPath_.push({type: 'lineTo', x: p.x, y: p.y});
340
341    this.currentX_ = p.x;
342    this.currentY_ = p.y;
343  };
344
345  contextPrototype.bezierCurveTo = function(aCP1x, aCP1y,
346                                            aCP2x, aCP2y,
347                                            aX, aY) {
348    var p = this.getCoords_(aX, aY);
349    var cp1 = this.getCoords_(aCP1x, aCP1y);
350    var cp2 = this.getCoords_(aCP2x, aCP2y);
351    bezierCurveTo(this, cp1, cp2, p);
352  };
353
354  // Helper function that takes the already fixed cordinates.
355  function bezierCurveTo(self, cp1, cp2, p) {
356    self.currentPath_.push({
357      type: 'bezierCurveTo',
358      cp1x: cp1.x,
359      cp1y: cp1.y,
360      cp2x: cp2.x,
361      cp2y: cp2.y,
362      x: p.x,
363      y: p.y
364    });
365    self.currentX_ = p.x;
366    self.currentY_ = p.y;
367  }
368
369  contextPrototype.quadraticCurveTo = function(aCPx, aCPy, aX, aY) {
370    // the following is lifted almost directly from
371    // http://developer.mozilla.org/en/docs/Canvas_tutorial:Drawing_shapes
372
373    var cp = this.getCoords_(aCPx, aCPy);
374    var p = this.getCoords_(aX, aY);
375
376    var cp1 = {
377      x: this.currentX_ + 2.0 / 3.0 * (cp.x - this.currentX_),
378      y: this.currentY_ + 2.0 / 3.0 * (cp.y - this.currentY_)
379    };
380    var cp2 = {
381      x: cp1.x + (p.x - this.currentX_) / 3.0,
382      y: cp1.y + (p.y - this.currentY_) / 3.0
383    };
384
385    bezierCurveTo(this, cp1, cp2, p);
386  };
387
388  contextPrototype.arc = function(aX, aY, aRadius,
389                                  aStartAngle, aEndAngle, aClockwise) {
390    aRadius *= Z;
391    var arcType = aClockwise ? 'at' : 'wa';
392
393    var xStart = aX + mc(aStartAngle) * aRadius - Z2;
394    var yStart = aY + ms(aStartAngle) * aRadius - Z2;
395
396    var xEnd = aX + mc(aEndAngle) * aRadius - Z2;
397    var yEnd = aY + ms(aEndAngle) * aRadius - Z2;
398
399    // IE won't render arches drawn counter clockwise if xStart == xEnd.
400    if (xStart == xEnd && !aClockwise) {
401      xStart += 0.125; // Offset xStart by 1/80 of a pixel. Use something
402                       // that can be represented in binary
403    }
404
405    var p = this.getCoords_(aX, aY);
406    var pStart = this.getCoords_(xStart, yStart);
407    var pEnd = this.getCoords_(xEnd, yEnd);
408
409    this.currentPath_.push({type: arcType,
410                           x: p.x,
411                           y: p.y,
412                           radius: aRadius,
413                           xStart: pStart.x,
414                           yStart: pStart.y,
415                           xEnd: pEnd.x,
416                           yEnd: pEnd.y});
417
418  };
419
420  contextPrototype.rect = function(aX, aY, aWidth, aHeight) {
421    this.moveTo(aX, aY);
422    this.lineTo(aX + aWidth, aY);
423    this.lineTo(aX + aWidth, aY + aHeight);
424    this.lineTo(aX, aY + aHeight);
425    this.closePath();
426  };
427
428  contextPrototype.strokeRect = function(aX, aY, aWidth, aHeight) {
429    var oldPath = this.currentPath_;
430    this.beginPath();
431
432    this.moveTo(aX, aY);
433    this.lineTo(aX + aWidth, aY);
434    this.lineTo(aX + aWidth, aY + aHeight);
435    this.lineTo(aX, aY + aHeight);
436    this.closePath();
437    this.stroke();
438
439    this.currentPath_ = oldPath;
440  };
441
442  contextPrototype.fillRect = function(aX, aY, aWidth, aHeight) {
443    var oldPath = this.currentPath_;
444    this.beginPath();
445
446    this.moveTo(aX, aY);
447    this.lineTo(aX + aWidth, aY);
448    this.lineTo(aX + aWidth, aY + aHeight);
449    this.lineTo(aX, aY + aHeight);
450    this.closePath();
451    this.fill();
452
453    this.currentPath_ = oldPath;
454  };
455
456  contextPrototype.createLinearGradient = function(aX0, aY0, aX1, aY1) {
457    var gradient = new CanvasGradient_('gradient');
458    gradient.x0_ = aX0;
459    gradient.y0_ = aY0;
460    gradient.x1_ = aX1;
461    gradient.y1_ = aY1;
462    return gradient;
463  };
464
465  contextPrototype.createRadialGradient = function(aX0, aY0, aR0,
466                                                   aX1, aY1, aR1) {
467    var gradient = new CanvasGradient_('gradientradial');
468    gradient.x0_ = aX0;
469    gradient.y0_ = aY0;
470    gradient.r0_ = aR0;
471    gradient.x1_ = aX1;
472    gradient.y1_ = aY1;
473    gradient.r1_ = aR1;
474    return gradient;
475  };
476
477  contextPrototype.drawImage = function(image, var_args) {
478    var dx, dy, dw, dh, sx, sy, sw, sh;
479
480    // to find the original width we overide the width and height
481    var oldRuntimeWidth = image.runtimeStyle.width;
482    var oldRuntimeHeight = image.runtimeStyle.height;
483    image.runtimeStyle.width = 'auto';
484    image.runtimeStyle.height = 'auto';
485
486    // get the original size
487    var w = image.width;
488    var h = image.height;
489
490    // and remove overides
491    image.runtimeStyle.width = oldRuntimeWidth;
492    image.runtimeStyle.height = oldRuntimeHeight;
493
494    if (arguments.length == 3) {
495      dx = arguments[1];
496      dy = arguments[2];
497      sx = sy = 0;
498      sw = dw = w;
499      sh = dh = h;
500    } else if (arguments.length == 5) {
501      dx = arguments[1];
502      dy = arguments[2];
503      dw = arguments[3];
504      dh = arguments[4];
505      sx = sy = 0;
506      sw = w;
507      sh = h;
508    } else if (arguments.length == 9) {
509      sx = arguments[1];
510      sy = arguments[2];
511      sw = arguments[3];
512      sh = arguments[4];
513      dx = arguments[5];
514      dy = arguments[6];
515      dw = arguments[7];
516      dh = arguments[8];
517    } else {
518      throw Error('Invalid number of arguments');
519    }
520
521    var d = this.getCoords_(dx, dy);
522
523    var w2 = sw / 2;
524    var h2 = sh / 2;
525
526    var vmlStr = [];
527
528    var W = 10;
529    var H = 10;
530
531    // For some reason that I've now forgotten, using divs didn't work
532    vmlStr.push(' <g_vml_:group',
533                ' coordsize="', Z * W, ',', Z * H, '"',
534                ' coordorigin="0,0"' ,
535                ' style="width:', W, 'px;height:', H, 'px;position:absolute;');
536
537    // If filters are necessary (rotation exists), create them
538    // filters are bog-slow, so only create them if abbsolutely necessary
539    // The following check doesn't account for skews (which don't exist
540    // in the canvas spec (yet) anyway.
541
542    if (this.m_[0][0] != 1 || this.m_[0][1]) {
543      var filter = [];
544
545      // Note the 12/21 reversal
546      filter.push('M11=', this.m_[0][0], ',',
547                  'M12=', this.m_[1][0], ',',
548                  'M21=', this.m_[0][1], ',',
549                  'M22=', this.m_[1][1], ',',
550                  'Dx=', mr(d.x / Z), ',',
551                  'Dy=', mr(d.y / Z), '');
552
553      // Bounding box calculation (need to minimize displayed area so that
554      // filters don't waste time on unused pixels.
555      var max = d;
556      var c2 = this.getCoords_(dx + dw, dy);
557      var c3 = this.getCoords_(dx, dy + dh);
558      var c4 = this.getCoords_(dx + dw, dy + dh);
559
560      max.x = m.max(max.x, c2.x, c3.x, c4.x);
561      max.y = m.max(max.y, c2.y, c3.y, c4.y);
562
563      vmlStr.push('padding:0 ', mr(max.x / Z), 'px ', mr(max.y / Z),
564                  'px 0;filter:progid:DXImageTransform.Microsoft.Matrix(',
565                  filter.join(''), ", sizingmethod='clip');")
566    } else {
567      vmlStr.push('top:', mr(d.y / Z), 'px;left:', mr(d.x / Z), 'px;');
568    }
569
570    vmlStr.push(' ">' ,
571                '<g_vml_:image src="', image.src, '"',
572                ' style="width:', Z * dw, 'px;',
573                ' height:', Z * dh, 'px;"',
574                ' cropleft="', sx / w, '"',
575                ' croptop="', sy / h, '"',
576                ' cropright="', (w - sx - sw) / w, '"',
577                ' cropbottom="', (h - sy - sh) / h, '"',
578                ' />',
579                '</g_vml_:group>');
580
581    this.element_.insertAdjacentHTML('BeforeEnd',
582                                    vmlStr.join(''));
583  };
584
585  contextPrototype.stroke = function(aFill) {
586    var lineStr = [];
587    var lineOpen = false;
588    var a = processStyle(aFill ? this.fillStyle : this.strokeStyle);
589    var color = a.color;
590    var opacity = a.alpha * this.globalAlpha;
591
592    var W = 10;
593    var H = 10;
594
595    lineStr.push('<g_vml_:shape',
596                 ' filled="', !!aFill, '"',
597                 ' style="position:absolute;width:', W, 'px;height:', H, 'px;"',
598                 ' coordorigin="0 0" coordsize="', Z * W, ' ', Z * H, '"',
599                 ' stroked="', !aFill, '"',
600                 ' path="');
601
602    var newSeq = false;
603    var min = {x: null, y: null};
604    var max = {x: null, y: null};
605
606    for (var i = 0; i < this.currentPath_.length; i++) {
607      var p = this.currentPath_[i];
608      var c;
609
610      switch (p.type) {
611        case 'moveTo':
612          c = p;
613          lineStr.push(' m ', mr(p.x), ',', mr(p.y));
614          break;
615        case 'lineTo':
616          lineStr.push(' l ', mr(p.x), ',', mr(p.y));
617          break;
618        case 'close':
619          lineStr.push(' x ');
620          p = null;
621          break;
622        case 'bezierCurveTo':
623          lineStr.push(' c ',
624                       mr(p.cp1x), ',', mr(p.cp1y), ',',
625                       mr(p.cp2x), ',', mr(p.cp2y), ',',
626                       mr(p.x), ',', mr(p.y));
627          break;
628        case 'at':
629        case 'wa':
630          lineStr.push(' ', p.type, ' ',
631                       mr(p.x - this.arcScaleX_ * p.radius), ',',
632                       mr(p.y - this.arcScaleY_ * p.radius), ' ',
633                       mr(p.x + this.arcScaleX_ * p.radius), ',',
634                       mr(p.y + this.arcScaleY_ * p.radius), ' ',
635                       mr(p.xStart), ',', mr(p.yStart), ' ',
636                       mr(p.xEnd), ',', mr(p.yEnd));
637          break;
638      }
639
640
641      // TODO: Following is broken for curves due to
642      //       move to proper paths.
643
644      // Figure out dimensions so we can do gradient fills
645      // properly
646      if (p) {
647        if (min.x == null || p.x < min.x) {
648          min.x = p.x;
649        }
650        if (max.x == null || p.x > max.x) {
651          max.x = p.x;
652        }
653        if (min.y == null || p.y < min.y) {
654          min.y = p.y;
655        }
656        if (max.y == null || p.y > max.y) {
657          max.y = p.y;
658        }
659      }
660    }
661    lineStr.push(' ">');
662
663    if (!aFill) {
664      var lineWidth = this.lineScale_ * this.lineWidth;
665
666      // VML cannot correctly render a line if the width is less than 1px.
667      // In that case, we dilute the color to make the line look thinner.
668      if (lineWidth < 1) {
669        opacity *= lineWidth;
670      }
671
672      lineStr.push(
673        '<g_vml_:stroke',
674        ' opacity="', opacity, '"',
675        ' joinstyle="', this.lineJoin, '"',
676        ' miterlimit="', this.miterLimit, '"',
677        ' endcap="', processLineCap(this.lineCap), '"',
678        ' weight="', lineWidth, 'px"',
679        ' color="', color, '" />'
680      );
681    } else if (typeof this.fillStyle == 'object') {
682      var fillStyle = this.fillStyle;
683      var angle = 0;
684      var focus = {x: 0, y: 0};
685
686      // additional offset
687      var shift = 0;
688      // scale factor for offset
689      var expansion = 1;
690
691      if (fillStyle.type_ == 'gradient') {
692        var x0 = fillStyle.x0_ / this.arcScaleX_;
693        var y0 = fillStyle.y0_ / this.arcScaleY_;
694        var x1 = fillStyle.x1_ / this.arcScaleX_;
695        var y1 = fillStyle.y1_ / this.arcScaleY_;
696        var p0 = this.getCoords_(x0, y0);
697        var p1 = this.getCoords_(x1, y1);
698        var dx = p1.x - p0.x;
699        var dy = p1.y - p0.y;
700        angle = Math.atan2(dx, dy) * 180 / Math.PI;
701
702        // The angle should be a non-negative number.
703        if (angle < 0) {
704          angle += 360;
705        }
706
707        // Very small angles produce an unexpected result because they are
708        // converted to a scientific notation string.
709        if (angle < 1e-6) {
710          angle = 0;
711        }
712      } else {
713        var p0 = this.getCoords_(fillStyle.x0_, fillStyle.y0_);
714        var width  = max.x - min.x;
715        var height = max.y - min.y;
716        focus = {
717          x: (p0.x - min.x) / width,
718          y: (p0.y - min.y) / height
719        };
720
721        width  /= this.arcScaleX_ * Z;
722        height /= this.arcScaleY_ * Z;
723        var dimension = m.max(width, height);
724        shift = 2 * fillStyle.r0_ / dimension;
725        expansion = 2 * fillStyle.r1_ / dimension - shift;
726      }
727
728      // We need to sort the color stops in ascending order by offset,
729      // otherwise IE won't interpret it correctly.
730      var stops = fillStyle.colors_;
731      stops.sort(function(cs1, cs2) {
732        return cs1.offset - cs2.offset;
733      });
734
735      var length = stops.length;
736      var color1 = stops[0].color;
737      var color2 = stops[length - 1].color;
738      var opacity1 = stops[0].alpha * this.globalAlpha;
739      var opacity2 = stops[length - 1].alpha * this.globalAlpha;
740
741      var colors = [];
742      for (var i = 0; i < length; i++) {
743        var stop = stops[i];
744        colors.push(stop.offset * expansion + shift + ' ' + stop.color);
745      }
746
747      // When colors attribute is used, the meanings of opacity and o:opacity2
748      // are reversed.
749      lineStr.push('<g_vml_:fill type="', fillStyle.type_, '"',
750                   ' method="none" focus="100%"',
751                   ' color="', color1, '"',
752                   ' color2="', color2, '"',
753                   ' colors="', colors.join(','), '"',
754                   ' opacity="', opacity2, '"',
755                   ' g_o_:opacity2="', opacity1, '"',
756                   ' angle="', angle, '"',
757                   ' focusposition="', focus.x, ',', focus.y, '" />');
758    } else {
759      lineStr.push('<g_vml_:fill color="', color, '" opacity="', opacity,
760                   '" />');
761    }
762
763    lineStr.push('</g_vml_:shape>');
764
765    this.element_.insertAdjacentHTML('beforeEnd', lineStr.join(''));
766  };
767
768  contextPrototype.fill = function() {
769    this.stroke(true);
770  }
771
772  contextPrototype.closePath = function() {
773    this.currentPath_.push({type: 'close'});
774
775  };
776
777  /**
778   * @private
779   */
780  contextPrototype.getCoords_ = function(aX, aY) {
781    var m = this.m_;
782    return {
783      x: Z * (aX * m[0][0] + aY * m[1][0] + m[2][0]) - Z2,
784      y: Z * (aX * m[0][1] + aY * m[1][1] + m[2][1]) - Z2
785    }
786  };
787
788  contextPrototype.save = function() {
789    var o = {};
790    copyState(this, o);
791    this.aStack_.push(o);
792    this.mStack_.push(this.m_);
793    this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);
794  };
795
796  contextPrototype.restore = function() {
797    copyState(this.aStack_.pop(), this);
798    this.m_ = this.mStack_.pop();
799  };
800
801  function matrixIsFinite(m) {
802    for (var j = 0; j < 3; j++) {
803      for (var k = 0; k < 2; k++) {
804        if (!isFinite(m[j][k]) || isNaN(m[j][k])) {
805          return false;
806        }
807      }
808    }
809    return true;
810  }
811
812  function setM(ctx, m, updateLineScale) {
813    if (!matrixIsFinite(m)) {
814      return;
815    }
816    ctx.m_ = m;
817
818    if (updateLineScale) {
819      // Get the line scale.
820      // Determinant of this.m_ means how much the area is enlarged by the
821      // transformation. So its square root can be used as a scale factor
822      // for width.
823      var det = m[0][0] * m[1][1] - m[0][1] * m[1][0];
824      ctx.lineScale_ = sqrt(abs(det));
825    }
826  }
827
828  contextPrototype.translate = function(aX, aY) {
829    var m1 = [
830      [1,  0,  0],
831      [0,  1,  0],
832      [aX, aY, 1]
833    ];
834
835    setM(this, matrixMultiply(m1, this.m_), false);
836  };
837
838  contextPrototype.rotate = function(aRot) {
839    var c = mc(aRot);
840    var s = ms(aRot);
841
842    var m1 = [
843      [c,  s, 0],
844      [-s, c, 0],
845      [0,  0, 1]
846    ];
847
848    setM(this, matrixMultiply(m1, this.m_), false);
849  };
850
851  contextPrototype.scale = function(aX, aY) {
852    this.arcScaleX_ *= aX;
853    this.arcScaleY_ *= aY;
854    var m1 = [
855      [aX, 0,  0],
856      [0,  aY, 0],
857      [0,  0,  1]
858    ];
859
860    setM(this, matrixMultiply(m1, this.m_), true);
861  };
862
863  contextPrototype.transform = function(m11, m12, m21, m22, dx, dy) {
864    var m1 = [
865      [m11, m12, 0],
866      [m21, m22, 0],
867      [dx,  dy,  1]
868    ];
869
870    setM(this, matrixMultiply(m1, this.m_), true);
871  };
872
873  contextPrototype.setTransform = function(m11, m12, m21, m22, dx, dy) {
874    var m = [
875      [m11, m12, 0],
876      [m21, m22, 0],
877      [dx,  dy,  1]
878    ];
879
880    setM(this, m, true);
881  };
882
883  /******** STUBS ********/
884  contextPrototype.clip = function() {
885    // TODO: Implement
886  };
887
888  contextPrototype.arcTo = function() {
889    // TODO: Implement
890  };
891
892  contextPrototype.createPattern = function() {
893    return new CanvasPattern_;
894  };
895
896  // Gradient / Pattern Stubs
897  function CanvasGradient_(aType) {
898    this.type_ = aType;
899    this.x0_ = 0;
900    this.y0_ = 0;
901    this.r0_ = 0;
902    this.x1_ = 0;
903    this.y1_ = 0;
904    this.r1_ = 0;
905    this.colors_ = [];
906  }
907
908  CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {
909    aColor = processStyle(aColor);