excanvas.js

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                                                   aY1, aR1) {
    var gradient = new CanvasGradient_("gradientradial");
    gradient.radius1_ = aR0;
    gradient.radius2_ = aR1;
    gradient.focus_.x = aX0;
    gradient.focus_.y = aY0;
    return gradient;
  };

  contextPrototype.drawImage = function (image, var_args) {
    var dx, dy, dw, dh, sx, sy, sw, sh;
    var w = image.width;
    var h = image.height;

    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 "Invalid number of arguments";
    }

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

    var w2 = (sw / 2);
    var h2 = (sh / 2);

    var vmlStr = [];

    // For some reason that I've now forgotten, using divs didn't work
    vmlStr.push(' <g_vml_:group',
                ' coordsize="1000,1000"',
                ' coordorigin="0, 0"' ,
                ' style="width:100px;height:100px;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='", d.x, "',",
                  "Dy='", d.y, "'");

      // 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 = Math.max(max.x, c2.x, c3.x, c4.x);
      max.y = Math.max(max.y, c2.y, c3.y, c4.y);

      vmlStr.push(" padding:0 ", mr(max.x), "px ", mr(max.y),
                  "px 0;filter:progid:DXImageTransform.Microsoft.Matrix(",
                  filter.join(""), ", sizingmethod='clip');")
    } else {
      vmlStr.push(" top:", d.y, "px;left:", d.x, "px;")
    }

    vmlStr.push(' ">' ,
                '<g_vml_:image src="', image.src, '"',
                ' style="width:', dw, ';',
                ' height:', dh, ';"',
                ' 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 lineOpen = false;
    var a = processStyle(aFill ? this.fillStyle : this.strokeStyle);
    var color = a[0];
    var opacity = a[1] * this.globalAlpha;

    lineStr.push('<g_vml_:shape',
                 ' fillcolor="', color, '"',
                 ' filled="', Boolean(aFill), '"',
                 ' style="position:absolute;width:10;height:10;"',
                 ' coordorigin="0 0" coordsize="100 100"',
                 ' stroked="', !aFill, '"',
                 ' strokeweight="', this.lineWidth, '"',
                 ' strokecolor="', color, '"',
                 ' path="');

    var newSeq = false;
    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];

      if (p.type == "moveTo") {
        lineStr.push(" m ");
        var c = this.getCoords_(p.x, p.y);
        lineStr.push(mr(c.x), ",", mr(c.y));
      } else if (p.type == "lineTo") {
        lineStr.push(" l ");
        var c = this.getCoords_(p.x, p.y);
        lineStr.push(mr(c.x), ",", mr(c.y));
      } else if (p.type == "close") {
        lineStr.push(" x ");
      } else if (p.type == "bezierCurveTo") {
        lineStr.push(" c ");
        var c = this.getCoords_(p.x, p.y);
        var c1 = this.getCoords_(p.cp1x, p.cp1y);
        var c2 = this.getCoords_(p.cp2x, p.cp2y);
        lineStr.push(mr(c1.x), ",", mr(c1.y), ",",
                     mr(c2.x), ",", mr(c2.y), ",",
                     mr(c.x), ",", mr(c.y));
      } else if (p.type == "at" || p.type == "wa") {
        lineStr.push(" ", p.type, " ");
        var c  = this.getCoords_(p.x, p.y);
        var cStart = this.getCoords_(p.xStart, p.yStart);
        var cEnd = this.getCoords_(p.xEnd, p.yEnd);

        lineStr.push(mr(c.x - this.arcScaleX_ * p.radius), ",",
                     mr(c.y - this.arcScaleY_ * p.radius), " ",
                     mr(c.x + this.arcScaleX_ * p.radius), ",",
                     mr(c.y + this.arcScaleY_ * p.radius), " ",
                     mr(cStart.x), ",", mr(cStart.y), " ",
                     mr(cEnd.x), ",", mr(cEnd.y));
      }


      // TODO: Following is broken for curves due to
      //       move to proper paths.

      // Figure out dimensions so we can do gradient fills
      // properly
      if(c) {
        if (min.x == null || c.x < min.x) {
          min.x = c.x;
        }
        if (max.x == null || c.x > max.x) {
          max.x = c.x;
        }
        if (min.y == null || c.y < min.y) {
          min.y = c.y;
        }
        if (max.y == null || c.y > max.y) {
          max.y = c.y;
        }
      }
    }
    lineStr.push(' ">');

    if (typeof this.fillStyle == "object") {
      var focus = {x: "50%", y: "50%"};
      var width = (max.x - min.x);
      var height = (max.y - min.y);
      var dimension = (width > height) ? width : height;

      focus.x = mr((this.fillStyle.focus_.x / width) * 100 + 50) + "%";
      focus.y = mr((this.fillStyle.focus_.y / height) * 100 + 50) + "%";

      var colors = [];

      // inside radius (%)
      if (this.fillStyle.type_ == "gradientradial") {
        var inside = (this.fillStyle.radius1_ / dimension * 100);

        // percentage that outside radius exceeds inside radius
        var expansion = (this.fillStyle.radius2_ / dimension * 100) - inside;
      } else {
        var inside = 0;
        var expansion = 100;
      }

      var insidecolor = {offset: null, color: null};
      var outsidecolor = {offset: null, color: null};

      // We need to sort 'colors' by percentage, from 0 > 100 otherwise ie
      // won't interpret it correctly
      this.fillStyle.colors_.sort(function (cs1, cs2) {
        return cs1.offset - cs2.offset;
      });

      for (var i = 0; i < this.fillStyle.colors_.length; i++) {
        var fs = this.fillStyle.colors_[i];

        colors.push( (fs.offset * expansion) + inside, "% ", fs.color, ",");

        if (fs.offset > insidecolor.offset || insidecolor.offset == null) {
          insidecolor.offset = fs.offset;
          insidecolor.color = fs.color;
        }

        if (fs.offset < outsidecolor.offset || outsidecolor.offset == null) {
          outsidecolor.offset = fs.offset;
          outsidecolor.color = fs.color;
        }
      }
      colors.pop();

      lineStr.push('<g_vml_:fill',
                   ' color="', outsidecolor.color, '"',
                   ' color2="', insidecolor.color, '"',
                   ' type="', this.fillStyle.type_, '"',
                   ' focusposition="', focus.x, ', ', focus.y, '"',
                   ' colors="', colors.join(""), '"',
                   ' opacity="', opacity, '" />');
    } else if (aFill) {
      lineStr.push('<g_vml_:fill color="', color, '" opacity="', opacity, '" />');
    } else {
      lineStr.push(
        '<g_vml_:stroke',
        ' opacity="', opacity,'"',
        ' joinstyle="', this.lineJoin, '"',
        ' miterlimit="', this.miterLimit, '"',
        ' endcap="', processLineCap(this.lineCap) ,'"',
        ' weight="', this.lineWidth, 'px"',
        ' color="', color,'" />'
      );
    }

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

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

    this.currentPath_ = [];
  };

  contextPrototype.fill = function() {
    this.stroke(true);
  }

  contextPrototype.closePath = function() {
    this.currentPath_.push({type: "close"});
  };

  /**
   * @private
   */
  contextPrototype.getCoords_ = function(aX, aY) {
    return {
      x: 10 * (aX * this.m_[0][0] + aY * this.m_[1][0] + this.m_[2][0]) - 5,
      y: 10 * (aX * this.m_[0][1] + aY * this.m_[1][1] + this.m_[2][1]) - 5
    }
  };

  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();
  };

  contextPrototype.translate = function(aX, aY) {
    var m1 = [
      [1,  0,  0],
      [0,  1,  0],
      [aX, aY, 1]
    ];

    this.m_ = matrixMultiply(m1, this.m_);
  };

  contextPrototype.rotate = function(aRot) {
    var c = mc(aRot);
    var s = ms(aRot);

    var m1 = [
      [c,  s, 0],
      [-s, c, 0],
      [0,  0, 1]
    ];

    this.m_ = matrixMultiply(m1, this.m_);
  };

  contextPrototype.scale = function(aX, aY) {
    this.arcScaleX_ *= aX;
    this.arcScaleY_ *= aY;
    var m1 = [
      [aX, 0,  0],
      [0,  aY, 0],
      [0,  0,  1]
    ];

    this.m_ = matrixMultiply(m1, this.m_);
  };

  /******** 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.radius1_ = 0;
    this.radius2_ = 0;
    this.colors_ = [];
    this.focus_ = {x: 0, y: 0};
  }

  CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {
    aColor = processStyle(aColor);
    this.colors_.push({offset: 1-aOffset, color: aColor});
  };

  function CanvasPattern_() {}

  // set up externs
  G_vmlCanvasManager = G_vmlCanvasManager_;
  CanvasRenderingContext2D = CanvasRenderingContext2D_;
  CanvasGradient = CanvasGradient_;
  CanvasPattern = CanvasPattern_;

})();

} // if