// Copyright 2006 Google Inc.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

// Known Issues:

//

// * Patterns are not implemented.

// * Radial gradient are not implemented. The VML version of these look very

//   different from the canvas one.

// * Clipping paths are not implemented.

// * Coordsize. The width and height attribute have higher priority than the

//   width and height style values which isn't correct.

// * Painting mode isn't implemented.

// * Canvas width/height should is using content-box by default. IE in

//   Quirks mode will draw the canvas using border-box. Either change your

//   doctype to HTML5

//   (http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)

//   or use Box Sizing Behavior from WebFX

//   (http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)

// * Optimize. There is always room for speed improvements.

// only add this code if we do not already have a canvas implementation

if (!window.CanvasRenderingContext2D) {

(function () {

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

  var m = Math;

  var mr = m.round;

  var ms = m.sin;

  var mc = m.cos;

  // this is used for sub pixel precision

  var Z = 10;

  var Z2 = Z / 2;

  var G_vmlCanvasManager_ = {

    init: function (opt_doc) {

      var doc = opt_doc || document;

      if (/MSIE/.test(navigator.userAgent) && !window.opera) {

        var self = this;

        doc.attachEvent("onreadystatechange", function () {

          self.init_(doc);

        });

      }

    },

    init_: function (doc) {

      if (doc.readyState == "complete") {

        // create xmlns

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

          doc.namespaces.add("g_vml_", "urn:schemas-microsoft-com:vml");

        }

        // setup default css

        var ss = doc.createStyleSheet();

        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)}";

        // find all canvas elements

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

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

          if (!els[i].getContext) {

            this.initElement(els[i]);

          }

        }

      }

    },

    fixElement_: function (el) {

      // in IE before version 5.5 we would need to add HTML: to the tag name

      // but we do not care about IE before version 6

      var outerHTML = el.outerHTML;

      var newEl = el.ownerDocument.createElement(outerHTML);

      // if the tag is still open IE has created the children as siblings and

      // it has also created a tag with the name "/FOO"

      if (outerHTML.slice(-2) != "/>") {

        var tagName = "/" + el.tagName;

        var ns;

        // remove content

        while ((ns = el.nextSibling) && ns.tagName != tagName) {

          ns.removeNode();

        }

        // remove the incorrect closing tag

        if (ns) {

          ns.removeNode();

        }

      }

      el.parentNode.replaceChild(newEl, el);

      return newEl;

    },

    /**

     * 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) {

      el = this.fixElement_(el);

      el.getContext = function () {

        if (this.context_) {

          return this.context_;

        }

        return this.context_ = new CanvasRenderingContext2D_(this);

      };

      // 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;

    switch (e.propertyName) {

      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.arcScaleX_    = o1.arcScaleX_;

    o2.arcScaleY_    = o1.arcScaleY_;

  }

  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 [str, 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;

  }

  var contextPrototype = CanvasRenderingContext2D_.prototype;

  contextPrototype.clearRect = function() {

    this.element_.innerHTML = "";

    this.currentPath_ = [];

  };

  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) {

    this.currentPath_.push({type: "moveTo", x: aX, y: aY});

    this.currentX_ = aX;

    this.currentY_ = aY;

  };

  contextPrototype.lineTo = function(aX, aY) {

    this.currentPath_.push({type: "lineTo", x: aX, y: aY});

    this.currentX_ = aX;

    this.currentY_ = aY;

  };

  contextPrototype.bezierCurveTo = function(aCP1x, aCP1y,

                                            aCP2x, aCP2y,

                                            aX, aY) {

    this.currentPath_.push({type: "bezierCurveTo",

                           cp1x: aCP1x,

                           cp1y: aCP1y,

                           cp2x: aCP2x,

                           cp2y: aCP2y,

                           x: aX,

                           y: aY});

    this.currentX_ = aX;

    this.currentY_ = aY;

  };

  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 cp1x = this.currentX_ + 2.0 / 3.0 * (aCPx - this.currentX_);

    var cp1y = this.currentY_ + 2.0 / 3.0 * (aCPy - this.currentY_);

    var cp2x = cp1x + (aX - this.currentX_) / 3.0;

    var cp2y = cp1y + (aY - this.currentY_) / 3.0;

    this.bezierCurveTo(cp1x, cp1y, cp2x, cp2y, aX, aY);

  };

  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

    }

    this.currentPath_.push({type: arcType,