iNextrix / ASTPP

(function() {

  // alias some functions to make (compiled) code shorter

  var mr = m.round;

  var ms = m.sin;

  var mc = m.cos;

  var abs = m.abs;

  var sqrt = m.sqrt;

  // this is used for sub pixel precision

  var Z = 10;

  var Z2 = Z / 2;

  /**

   * This funtion is assigned to the <canvas> elements as element.getContext().

   * @this {HTMLElement}

   * @return {CanvasRenderingContext2D_}

   */

  function getContext() {

    return this.context_ ||

        (this.context_ = new CanvasRenderingContext2D_(this));

  }

  var slice = Array.prototype.slice;

  /**

   * Binds a function to an object. The returned function will always use the

   * passed in {@code obj} as {@code this}.

   *

   * Example:

   *

   *   g = bind(f, obj, a, b)

   *   g(c, d) // will do f.call(obj, a, b, c, d)

   *

   * @param {Function} f The function to bind the object to

   * @param {Object} obj The object that should act as this when the function

   *     is called

   * @param {*} var_args Rest arguments that will be used as the initial

   *     arguments when the function is called

   * @return {Function} A new function that has bound this

   */

    var a = slice.call(arguments, 2);

    return function() {

      return f.apply(obj, a.concat(slice.call(arguments)));

    };

  }

  var G_vmlCanvasManager_ = {

    init: function(opt_doc) {

        var doc = opt_doc || document;

        // Create a dummy element so that IE will allow canvas elements to be

        // recognized.

        doc.createElement('canvas');

        doc.attachEvent('onreadystatechange', bind(this.init_, this, doc));

      }

    },

    init_: function(doc) {

      // create xmlns

      if (!doc.namespaces['g_vml_']) {

        doc.namespaces.add('g_vml_', 'urn:schemas-microsoft-com:vml',

                           '#default#VML');

      }

      if (!doc.namespaces['g_o_']) {

        doc.namespaces.add('g_o_', 'urn:schemas-microsoft-com:office:office',

                           '#default#VML');

      }

      // Setup default CSS.  Only add one style sheet per document

      if (!doc.styleSheets['ex_canvas_']) {

        var ss = doc.createStyleSheet();

        ss.owningElement.id = 'ex_canvas_';

        ss.cssText = 'canvas{display:inline-block;overflow:hidden;' +

            // default size is 300x150 in Gecko and Opera

            'text-align:left;width:300px;height:150px}' +

            'g_vml_\\:*{behavior:url(#default#VML)}' +

            'g_o_\\:*{behavior:url(#default#VML)}';

      }

      // find all canvas elements

      var els = doc.getElementsByTagName('canvas');

      for (var i = 0; i < els.length; i++) {

        this.initElement(els[i]);

      }

    },

    /**

     * Public initializes a canvas element so that it can be used as canvas

     * element from now on. This is called automatically before the page is

     * loaded but if you are creating elements using createElement you need to

     * make sure this is called on the element.

     * @param {HTMLElement} el The canvas element to initialize.

     * @return {HTMLElement} the element that was created.

     */

    initElement: function(el) {

      if (!el.getContext) {

        el.getContext = getContext;

        // Remove fallback content. There is no way to hide text nodes so we

        // just remove all childNodes. We could hide all elements and remove

        // text nodes but who really cares about the fallback content.

        el.innerHTML = '';

        // do not use inline function because that will leak memory

        el.attachEvent('onpropertychange', onPropertyChange);

        el.attachEvent('onresize', onResize);

        var attrs = el.attributes;

        if (attrs.width && attrs.width.specified) {

          // TODO: use runtimeStyle and coordsize

          // el.getContext().setWidth_(attrs.width.nodeValue);

          el.style.width = attrs.width.nodeValue + 'px';

        } else {

          el.width = el.clientWidth;

        }

        if (attrs.height && attrs.height.specified) {

          // TODO: use runtimeStyle and coordsize

          // el.getContext().setHeight_(attrs.height.nodeValue);

          el.style.height = attrs.height.nodeValue + 'px';

        } else {

          el.height = el.clientHeight;

        }

        //el.getContext().setCoordsize_()

      }

      return el;

    }

  };

  function onPropertyChange(e) {

    var el = e.srcElement;

      case 'width':

        el.style.width = el.attributes.width.nodeValue + 'px';

        el.getContext().clearRect();

        break;

      case 'height':

        el.style.height = el.attributes.height.nodeValue + 'px';

        el.getContext().clearRect();

        break;

    }

  }

  function onResize(e) {

    var el = e.srcElement;

    if (el.firstChild) {

      el.firstChild.style.width =  el.clientWidth + 'px';

      el.firstChild.style.height = el.clientHeight + 'px';

    }

  }

  G_vmlCanvasManager_.init();

  // precompute "00" to "FF"

  var dec2hex = [];

  for (var i = 0; i < 16; i++) {

    for (var j = 0; j < 16; j++) {

      dec2hex[i * 16 + j] = i.toString(16) + j.toString(16);

    }

  }

  function createMatrixIdentity() {

    return [

      [1, 0, 0],

      [0, 1, 0],

      [0, 0, 1]

    ];

  }

  function matrixMultiply(m1, m2) {

    var result = createMatrixIdentity();

    for (var x = 0; x < 3; x++) {

      for (var y = 0; y < 3; y++) {

        var sum = 0;

        for (var z = 0; z < 3; z++) {

          sum += m1[x][z] * m2[z][y];

        }

        result[x][y] = sum;

      }

    }

    return result;

  }

  function copyState(o1, o2) {

    o2.fillStyle     = o1.fillStyle;

    o2.lineCap       = o1.lineCap;

    o2.lineJoin      = o1.lineJoin;

    o2.lineWidth     = o1.lineWidth;

    o2.miterLimit    = o1.miterLimit;

    o2.shadowBlur    = o1.shadowBlur;

    o2.shadowColor   = o1.shadowColor;

    o2.shadowOffsetX = o1.shadowOffsetX;

    o2.shadowOffsetY = o1.shadowOffsetY;

    o2.strokeStyle   = o1.strokeStyle;

    o2.globalAlpha   = o1.globalAlpha;

    o2.arcScaleX_    = o1.arcScaleX_;

    o2.arcScaleY_    = o1.arcScaleY_;

    o2.lineScale_    = o1.lineScale_;

  }

  function processStyle(styleString) {

    var str, alpha = 1;

    styleString = String(styleString);

    if (styleString.substring(0, 3) == 'rgb') {

      var start = styleString.indexOf('(', 3);

      var end = styleString.indexOf(')', start + 1);

      var guts = styleString.substring(start + 1, end).split(',');

      str = '#';

      for (var i = 0; i < 3; i++) {

        str += dec2hex[Number(guts[i])];

      }

      if (guts.length == 4 && styleString.substr(3, 1) == 'a') {

        alpha = guts[3];

      }

    } else {

      str = styleString;

    }

    return {color: str, alpha: alpha};

  }

  function processLineCap(lineCap) {

    switch (lineCap) {

      case 'butt':

        return 'flat';

      case 'round':

        return 'round';

      case 'square':

      default:

        return 'square';

    }

  }

  /**

   * This class implements CanvasRenderingContext2D interface as described by

   * the WHATWG.

   * @param {HTMLElement} surfaceElement The element that the 2D context should

   * be associated with

   */

  function CanvasRenderingContext2D_(surfaceElement) {

    this.m_ = createMatrixIdentity();

    this.mStack_ = [];

    this.aStack_ = [];

    this.currentPath_ = [];

    // Canvas context properties

    this.strokeStyle = '#000';

    this.fillStyle = '#000';

    this.lineWidth = 1;

    this.lineJoin = 'miter';

    this.lineCap = 'butt';

    this.miterLimit = Z * 1;

    this.globalAlpha = 1;

    this.canvas = surfaceElement;

    var el = surfaceElement.ownerDocument.createElement('div');

    el.style.width =  surfaceElement.clientWidth + 'px';

    el.style.height = surfaceElement.clientHeight + 'px';

    el.style.overflow = 'hidden';

    el.style.position = 'absolute';

    surfaceElement.appendChild(el);

    this.element_ = el;

    this.arcScaleX_ = 1;

    this.arcScaleY_ = 1;

    this.lineScale_ = 1;

  }

  var contextPrototype = CanvasRenderingContext2D_.prototype;

  contextPrototype.clearRect = function() {

    this.element_.innerHTML = '';

  };

  contextPrototype.beginPath = function() {

    // TODO: Branch current matrix so that save/restore has no effect

    //       as per safari docs.

    this.currentPath_ = [];

  };

  contextPrototype.moveTo = function(aX, aY) {

    var p = this.getCoords_(aX, aY);

    this.currentPath_.push({type: 'moveTo', x: p.x, y: p.y});

    this.currentX_ = p.x;

    this.currentY_ = p.y;

  };

  contextPrototype.lineTo = function(aX, aY) {

    var p = this.getCoords_(aX, aY);

    this.currentPath_.push({type: 'lineTo', x: p.x, y: p.y});

    this.currentX_ = p.x;

    this.currentY_ = p.y;

  };

  contextPrototype.bezierCurveTo = function(aCP1x, aCP1y,

                                            aCP2x, aCP2y,

                                            aX, aY) {

    var p = this.getCoords_(aX, aY);

    var cp1 = this.getCoords_(aCP1x, aCP1y);

    var cp2 = this.getCoords_(aCP2x, aCP2y);

    bezierCurveTo(this, cp1, cp2, p);

  };

  // Helper function that takes the already fixed cordinates.

  function bezierCurveTo(self, cp1, cp2, p) {

    self.currentPath_.push({

      type: 'bezierCurveTo',

      cp1x: cp1.x,

      cp1y: cp1.y,

      cp2x: cp2.x,

      cp2y: cp2.y,

      x: p.x,

      y: p.y

    });

    self.currentX_ = p.x;

    self.currentY_ = p.y;

  }

  contextPrototype.quadraticCurveTo = function(aCPx, aCPy, aX, aY) {

    // the following is lifted almost directly from

    // http://developer.mozilla.org/en/docs/Canvas_tutorial:Drawing_shapes

    var cp = this.getCoords_(aCPx, aCPy);

    var p = this.getCoords_(aX, aY);

    var cp1 = {

      x: this.currentX_ + 2.0 / 3.0 * (cp.x - this.currentX_),

      y: this.currentY_ + 2.0 / 3.0 * (cp.y - this.currentY_)

    };

    var cp2 = {

      x: cp1.x + (p.x - this.currentX_) / 3.0,

      y: cp1.y + (p.y - this.currentY_) / 3.0

    };

    bezierCurveTo(this, cp1, cp2, p);

  };

  contextPrototype.arc = function(aX, aY, aRadius,

                                  aStartAngle, aEndAngle, aClockwise) {

    aRadius *= Z;

    var arcType = aClockwise ? 'at' : 'wa';

    var xStart = aX + mc(aStartAngle) * aRadius - Z2;

    var yStart = aY + ms(aStartAngle) * aRadius - Z2;

    var xEnd = aX + mc(aEndAngle) * aRadius - Z2;

    var yEnd = aY + ms(aEndAngle) * aRadius - Z2;

    // IE won't render arches drawn counter clockwise if xStart == xEnd.

    if (xStart == xEnd && !aClockwise) {

      xStart += 0.125; // Offset xStart by 1/80 of a pixel. Use something

                       // that can be represented in binary

    }

    var p = this.getCoords_(aX, aY);

    var pStart = this.getCoords_(xStart, yStart);

    var pEnd = this.getCoords_(xEnd, yEnd);

    this.currentPath_.push({type: arcType,

                           x: p.x,

                           y: p.y,

                           radius: aRadius,

                           xStart: pStart.x,

                           yStart: pStart.y,

                           xEnd: pEnd.x,

                           yEnd: pEnd.y});

  };

  contextPrototype.rect = function(aX, aY, aWidth, aHeight) {

    this.moveTo(aX, aY);

    this.lineTo(aX + aWidth, aY);

    this.lineTo(aX + aWidth, aY + aHeight);

    this.lineTo(aX, aY + aHeight);

    this.closePath();

  };

  contextPrototype.strokeRect = function(aX, aY, aWidth, aHeight) {

    var oldPath = this.currentPath_;

    this.beginPath();

    this.moveTo(aX, aY);

    this.lineTo(aX + aWidth, aY);

    this.lineTo(aX + aWidth, aY + aHeight);

    this.lineTo(aX, aY + aHeight);

    this.closePath();

    this.stroke();

    this.currentPath_ = oldPath;

  };

  contextPrototype.fillRect = function(aX, aY, aWidth, aHeight) {

    var oldPath = this.currentPath_;

    this.beginPath();

    this.moveTo(aX, aY);

    this.lineTo(aX + aWidth, aY);

    this.lineTo(aX + aWidth, aY + aHeight);

    this.lineTo(aX, aY + aHeight);

    this.closePath();

    this.fill();

    this.currentPath_ = oldPath;

  };

  contextPrototype.createLinearGradient = function(aX0, aY0, aX1, aY1) {

    var gradient = new CanvasGradient_('gradient');

    gradient.x0_ = aX0;

    gradient.y0_ = aY0;

    gradient.x1_ = aX1;

    gradient.y1_ = aY1;

    return gradient;

  };

  contextPrototype.createRadialGradient = function(aX0, aY0, aR0,

                                                   aX1, aY1, aR1) {

    var gradient = new CanvasGradient_('gradientradial');

    gradient.x0_ = aX0;

    gradient.y0_ = aY0;

    gradient.r0_ = aR0;

    gradient.x1_ = aX1;

    gradient.y1_ = aY1;

    gradient.r1_ = aR1;

    return gradient;

  };

    var dx, dy, dw, dh, sx, sy, sw, sh;

    // to find the original width we overide the width and height

    var oldRuntimeWidth = image.runtimeStyle.width;

    var oldRuntimeHeight = image.runtimeStyle.height;

    image.runtimeStyle.width = 'auto';

    image.runtimeStyle.height = 'auto';

    // get the original size

    var w = image.width;

    var h = image.height;

    // and remove overides

    image.runtimeStyle.width = oldRuntimeWidth;

    image.runtimeStyle.height = oldRuntimeHeight;

    if (arguments.length == 3) {

      dx = arguments[1];

      dy = arguments[2];

      sx = sy = 0;

      sw = dw = w;

      sh = dh = h;

    } else if (arguments.length == 5) {

      dx = arguments[1];

      dy = arguments[2];

      dw = arguments[3];

      dh = arguments[4];

      sx = sy = 0;

      sw = w;

      sh = h;

    } else if (arguments.length == 9) {

      sx = arguments[1];

      sy = arguments[2];

      sw = arguments[3];

      sh = arguments[4];

      dx = arguments[5];

      dy = arguments[6];

      dw = arguments[7];

      dh = arguments[8];

    } else {

      throw Error('Invalid number of arguments');

    }

    var d = this.getCoords_(dx, dy);

    var vmlStr = [];

    var W = 10;

    var H = 10;

    // For some reason that I've now forgotten, using divs didn't work

    vmlStr.push(' <g_vml_:group',

                ' coordsize="', Z * W, ',', Z * H, '"',

                ' coordorigin="0,0"' ,

                ' style="width:', W, 'px;height:', H, 'px;position:absolute;');

    // If filters are necessary (rotation exists), create them

    // filters are bog-slow, so only create them if abbsolutely necessary

    // The following check doesn't account for skews (which don't exist

    // in the canvas spec (yet) anyway.

    if (this.m_[0][0] != 1 || this.m_[0][1]) {

      var filter = [];

      // Note the 12/21 reversal

      filter.push('M11=', this.m_[0][0], ',',

                  'M12=', this.m_[1][0], ',',

                  'M21=', this.m_[0][1], ',',

                  'M22=', this.m_[1][1], ',',

                  'Dx=', mr(d.x / Z), ',',

                  'Dy=', mr(d.y / Z), '');

      // Bounding box calculation (need to minimize displayed area so that

      // filters don't waste time on unused pixels.

      var max = d;

      var c2 = this.getCoords_(dx + dw, dy);

      var c3 = this.getCoords_(dx, dy + dh);

      var c4 = this.getCoords_(dx + dw, dy + dh);

      max.x = m.max(max.x, c2.x, c3.x, c4.x);

      max.y = m.max(max.y, c2.y, c3.y, c4.y);

      vmlStr.push('padding:0 ', mr(max.x / Z), 'px ', mr(max.y / Z),

                  'px 0;filter:progid:DXImageTransform.Microsoft.Matrix(',

                  filter.join(''), ", sizingmethod='clip');")

    } else {

      vmlStr.push('top:', mr(d.y / Z), 'px;left:', mr(d.x / Z), 'px;');

    }

    vmlStr.push(' ">' ,

                '<g_vml_:image src="', image.src, '"',

                ' style="width:', Z * dw, 'px;',

                ' height:', Z * dh, 'px;"',

                ' cropleft="', sx / w, '"',

                ' croptop="', sy / h, '"',

                ' cropright="', (w - sx - sw) / w, '"',

                ' cropbottom="', (h - sy - sh) / h, '"',

                ' />',

                '</g_vml_:group>');

    this.element_.insertAdjacentHTML('BeforeEnd',

                                    vmlStr.join(''));

  };

  contextPrototype.stroke = function(aFill) {

    var lineStr = [];

    var a = processStyle(aFill ? this.fillStyle : this.strokeStyle);

    var color = a.color;

    var opacity = a.alpha * this.globalAlpha;

    var W = 10;

    var H = 10;

    lineStr.push('<g_vml_:shape',

                 ' filled="', !!aFill, '"',

                 ' style="position:absolute;width:', W, 'px;height:', H, 'px;"',

                 ' coordorigin="0 0" coordsize="', Z * W, ' ', Z * H, '"',

                 ' stroked="', !aFill, '"',

                 ' path="');

    var min = {x: null, y: null};

    var max = {x: null, y: null};

    for (var i = 0; i < this.currentPath_.length; i++) {

      var p = this.currentPath_[i];

      var c;

        case 'moveTo':

          lineStr.push(' m ', mr(p.x), ',', mr(p.y));

          break;

        case 'lineTo':

          lineStr.push(' l ', mr(p.x), ',', mr(p.y));

          break;

        case 'close':

          lineStr.push(' x ');

          p = null;

          break;

        case 'bezierCurveTo':

          lineStr.push(' c ',

                       mr(p.cp1x), ',', mr(p.cp1y), ',',

                       mr(p.cp2x), ',', mr(p.cp2y), ',',

                       mr(p.x), ',', mr(p.y));

          break;

        case 'at':

        case 'wa':

          lineStr.push(' ', p.type, ' ',

                       mr(p.x - this.arcScaleX_ * p.radius), ',',

                       mr(p.y - this.arcScaleY_ * p.radius), ' ',

                       mr(p.x + this.arcScaleX_ * p.radius), ',',

                       mr(p.y + this.arcScaleY_ * p.radius), ' ',

                       mr(p.xStart), ',', mr(p.yStart), ' ',

                       mr(p.xEnd), ',', mr(p.yEnd));

          break;

      }

      // TODO: Following is broken for curves due to

      //       move to proper paths.

      // Figure out dimensions so we can do gradient fills

      // properly

      if (p) {

        if (min.x == null || p.x < min.x) {

          min.x = p.x;

        }

        if (max.x == null || p.x > max.x) {

          max.x = p.x;

        }

        if (min.y == null || p.y < min.y) {

          min.y = p.y;

        }

        if (max.y == null || p.y > max.y) {

          max.y = p.y;

        }

      }

    }

    lineStr.push(' ">');

    if (!aFill) {

      var lineWidth = this.lineScale_ * this.lineWidth;

      // VML cannot correctly render a line if the width is less than 1px.

      // In that case, we dilute the color to make the line look thinner.

      if (lineWidth < 1) {

        opacity *= lineWidth;

      }

      lineStr.push(

        '<g_vml_:stroke',

        ' opacity="', opacity, '"',

        ' joinstyle="', this.lineJoin, '"',

        ' miterlimit="', this.miterLimit, '"',

        ' endcap="', processLineCap(this.lineCap), '"',

        ' weight="', lineWidth, 'px"',

        ' color="', color, '" />'

      );

    } else if (typeof this.fillStyle == 'object') {

      var fillStyle = this.fillStyle;

      var angle = 0;

      var focus = {x: 0, y: 0};

      // additional offset

      var shift = 0;

      // scale factor for offset

      var expansion = 1;

      if (fillStyle.type_ == 'gradient') {

        var x0 = fillStyle.x0_ / this.arcScaleX_;

        var y0 = fillStyle.y0_ / this.arcScaleY_;

        var x1 = fillStyle.x1_ / this.arcScaleX_;

        var y1 = fillStyle.y1_ / this.arcScaleY_;

        var p0 = this.getCoords_(x0, y0);

        var p1 = this.getCoords_(x1, y1);

        var dx = p1.x - p0.x;

        var dy = p1.y - p0.y;

        angle = Math.atan2(dx, dy) * 180 / Math.PI;

        // The angle should be a non-negative number.

        if (angle < 0) {

          angle += 360;

        }

        // Very small angles produce an unexpected result because they are

        // converted to a scientific notation string.

        if (angle < 1e-6) {

          angle = 0;

        }

      } else {

        var width  = max.x - min.x;

        var height = max.y - min.y;

        focus = {

          x: (p0.x - min.x) / width,

          y: (p0.y - min.y) / height

        };

        width  /= this.arcScaleX_ * Z;

        height /= this.arcScaleY_ * Z;

        var dimension = m.max(width, height);

        shift = 2 * fillStyle.r0_ / dimension;

        expansion = 2 * fillStyle.r1_ / dimension - shift;

      }

      // We need to sort the color stops in ascending order by offset,

      // otherwise IE won't interpret it correctly.

      var stops = fillStyle.colors_;

      stops.sort(function(cs1, cs2) {

        return cs1.offset - cs2.offset;

      });

      var length = stops.length;

      var color1 = stops[0].color;

      var color2 = stops[length - 1].color;

      var opacity1 = stops[0].alpha * this.globalAlpha;

      var opacity2 = stops[length - 1].alpha * this.globalAlpha;

      var colors = [];

        var stop = stops[i];

        colors.push(stop.offset * expansion + shift + ' ' + stop.color);

      }

      // When colors attribute is used, the meanings of opacity and o:opacity2

      // are reversed.

      lineStr.push('<g_vml_:fill type="', fillStyle.type_, '"',

                   ' method="none" focus="100%"',

                   ' color="', color1, '"',

                   ' color2="', color2, '"',

                   ' colors="', colors.join(','), '"',

                   ' opacity="', opacity2, '"',

                   ' g_o_:opacity2="', opacity1, '"',

                   ' angle="', angle, '"',

                   ' focusposition="', focus.x, ',', focus.y, '" />');

    } else {

      lineStr.push('<g_vml_:fill color="', color, '" opacity="', opacity,

                   '" />');

    }

    lineStr.push('</g_vml_:shape>');

    this.element_.insertAdjacentHTML('beforeEnd', lineStr.join(''));

  };

  contextPrototype.fill = function() {

    this.stroke(true);

  }

  contextPrototype.closePath = function() {

    this.currentPath_.push({type: 'close'});

  };

  /**

   * @private

   */

  contextPrototype.getCoords_ = function(aX, aY) {

    var m = this.m_;

    return {

      x: Z * (aX * m[0][0] + aY * m[1][0] + m[2][0]) - Z2,

      y: Z * (aX * m[0][1] + aY * m[1][1] + m[2][1]) - Z2

    }

  };

  contextPrototype.save = function() {

    var o = {};

    copyState(this, o);

    this.aStack_.push(o);

    this.mStack_.push(this.m_);

    this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);

  };

  contextPrototype.restore = function() {

    copyState(this.aStack_.pop(), this);

    this.m_ = this.mStack_.pop();

  };

  function matrixIsFinite(m) {

    for (var j = 0; j < 3; j++) {

      for (var k = 0; k < 2; k++) {

        if (!isFinite(m[j][k]) || isNaN(m[j][k])) {

          return false;

        }

      }

    }

    return true;

  }

  function setM(ctx, m, updateLineScale) {

    if (!matrixIsFinite(m)) {

      return;

    }

    ctx.m_ = m;

    if (updateLineScale) {

      // Get the line scale.

      // Determinant of this.m_ means how much the area is enlarged by the

      // transformation. So its square root can be used as a scale factor

      // for width.

      var det = m[0][0] * m[1][1] - m[0][1] * m[1][0];

      ctx.lineScale_ = sqrt(abs(det));

    }

  }

  contextPrototype.translate = function(aX, aY) {

    var m1 = [

      [1,  0,  0],

      [0,  1,  0],

      [aX, aY, 1]

    ];

    setM(this, matrixMultiply(m1, this.m_), false);

  };

  contextPrototype.rotate = function(aRot) {

    var c = mc(aRot);

    var s = ms(aRot);

    var m1 = [

      [c,  s, 0],

      [-s, c, 0],

      [0,  0, 1]

    ];

    setM(this, matrixMultiply(m1, this.m_), false);

  };

  contextPrototype.scale = function(aX, aY) {

    this.arcScaleX_ *= aX;

    this.arcScaleY_ *= aY;

    var m1 = [

      [aX, 0,  0],

      [0,  aY, 0],

      [0,  0,  1]

    ];

    setM(this, matrixMultiply(m1, this.m_), true);

  };

  contextPrototype.transform = function(m11, m12, m21, m22, dx, dy) {

    var m1 = [

      [m11, m12, 0],

      [m21, m22, 0],

      [dx,  dy,  1]

    ];

    setM(this, matrixMultiply(m1, this.m_), true);

  };

  contextPrototype.setTransform = function(m11, m12, m21, m22, dx, dy) {

    var m = [

      [m11, m12, 0],

      [m21, m22, 0],

      [dx,  dy,  1]

    ];

    setM(this, m, true);

  };

  /******** STUBS ********/

  contextPrototype.clip = function() {

    // TODO: Implement

  };

  contextPrototype.arcTo = function() {

    // TODO: Implement

  };

  contextPrototype.createPattern = function() {

    return new CanvasPattern_;

  };

  // Gradient / Pattern Stubs

  function CanvasGradient_(aType) {

    this.type_ = aType;

    this.x0_ = 0;

    this.y0_ = 0;

    this.r0_ = 0;

    this.x1_ = 0;

    this.y1_ = 0;

    this.r1_ = 0;

    this.colors_ = [];

  }

  CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {

    aColor = processStyle(aColor);

    this.colors_.push({offset: aOffset,

                       color: aColor.color,

                       alpha: aColor.alpha});

  };

  function CanvasPattern_() {}

  // set up externs

})();