JAVASCRIPT   19

excanvas.js

Guest on 5th August 2021 05:07:01 PM

  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
  35. if (!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.    * @private
  778.    */
  779.   contextPrototype.getCoords_ = function(aX, aY) {
  780.     var m = this.m_;
  781.     return {
  782.       x: Z * (aX * m[0][0] + aY * m[1][0] + m[2][0]) - Z2,
  783.       y: Z * (aX * m[0][1] + aY * m[1][1] + m[2][1]) - Z2
  784.     }
  785.   };
  786.  
  787.   contextPrototype.save = function() {
  788.     var o = {};
  789.     copyState(this, o);
  790.     this.aStack_.push(o);
  791.     this.mStack_.push(this.m_);
  792.     this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);
  793.   };
  794.  
  795.   contextPrototype.restore = function() {
  796.     copyState(this.aStack_.pop(), this);
  797.     this.m_ = this.mStack_.pop();
  798.   };
  799.  
  800.   function matrixIsFinite(m) {
  801.     for (var j = 0; j < 3; j++) {
  802.       for (var k = 0; k < 2; k++) {
  803.         if (!isFinite(m[j][k]) || isNaN(m[j][k])) {
  804.           return false;
  805.         }
  806.       }
  807.     }
  808.     return true;
  809.   }
  810.  
  811.   function setM(ctx, m, updateLineScale) {
  812.     if (!matrixIsFinite(m)) {
  813.       return;
  814.     }
  815.     ctx.m_ = m;
  816.  
  817.     if (updateLineScale) {
  818.       // Get the line scale.
  819.       // Determinant of this.m_ means how much the area is enlarged by the
  820.       // transformation. So its square root can be used as a scale factor
  821.       // for width.
  822.       var det = m[0][0] * m[1][1] - m[0][1] * m[1][0];
  823.       ctx.lineScale_ = sqrt(abs(det));
  824.     }
  825.   }
  826.  
  827.   contextPrototype.translate = function(aX, aY) {
  828.     var m1 = [
  829.       [1,  0,  0],
  830.       [0,  1,  0],
  831.       [aX, aY, 1]
  832.     ];
  833.  
  834.     setM(this, matrixMultiply(m1, this.m_), false);
  835.   };
  836.  
  837.   contextPrototype.rotate = function(aRot) {
  838.     var c = mc(aRot);
  839.     var s = ms(aRot);
  840.  
  841.     var m1 = [
  842.       [c,  s, 0],
  843.       [-s, c, 0],
  844.       [0,  0, 1]
  845.     ];
  846.  
  847.     setM(this, matrixMultiply(m1, this.m_), false);
  848.   };
  849.  
  850.   contextPrototype.scale = function(aX, aY) {
  851.     this.arcScaleX_ *= aX;
  852.     this.arcScaleY_ *= aY;
  853.     var m1 = [
  854.       [aX, 0,  0],
  855.       [0,  aY, 0],
  856.       [0,  0,  1]
  857.     ];
  858.  
  859.     setM(this, matrixMultiply(m1, this.m_), true);
  860.   };
  861.  
  862.   contextPrototype.transform = function(m11, m12, m21, m22, dx, dy) {
  863.     var m1 = [
  864.       [m11, m12, 0],
  865.       [m21, m22, 0],
  866.       [dx,  dy,  1]
  867.     ];
  868.  
  869.     setM(this, matrixMultiply(m1, this.m_), true);
  870.   };
  871.  
  872.   contextPrototype.setTransform = function(m11, m12, m21, m22, dx, dy) {
  873.     var m = [
  874.       [m11, m12, 0],
  875.       [m21, m22, 0],
  876.       [dx,  dy,  1]
  877.     ];
  878.  
  879.     setM(this, m, true);
  880.   };
  881.  
  882.   /******** STUBS ********/
  883.   contextPrototype.clip = function() {
  884.     // TODO: Implement
  885.   };
  886.  
  887.   contextPrototype.arcTo = function() {
  888.     // TODO: Implement
  889.   };
  890.  
  891.   contextPrototype.createPattern = function() {
  892.     return new CanvasPattern_;
  893.   };
  894.  
  895.   // Gradient / Pattern Stubs
  896.   function CanvasGradient_(aType) {
  897.     this.type_ = aType;
  898.     this.x0_ = 0;
  899.     this.y0_ = 0;
  900.     this.r0_ = 0;
  901.     this.x1_ = 0;
  902.     this.y1_ = 0;
  903.     this.r1_ = 0;
  904.     this.colors_ = [];
  905.   }
  906.  
  907.   CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {
  908.     aColor = processStyle(aColor);
  909.     this.colors_.push({offset: aOffset,
  910.                        color: aColor.color,
  911.                        alpha: aColor.alpha});
  912.   };
  913.  
  914.   function CanvasPattern_() {}
  915.  
  916.   // set up externs
  917.   G_vmlCanvasManager = G_vmlCanvasManager_;
  918.   CanvasRenderingContext2D = CanvasRenderingContext2D_;
  919.   CanvasGradient = CanvasGradient_;
  920.   CanvasPattern = CanvasPattern_;
  921.  
  922. })();
  923.  
  924. } // if

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