// 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)

// * Non uniform scaling does not correctly scale strokes.

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

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

if (!document.createElement('canvas').getContext) {

(function() {

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

  var m = Math;

  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

   */

  function bind(f, obj, var_args) {

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

    return function() {

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

    };

  }

  var G_vmlCanvasManager_ = {

    init: function(opt_doc) {

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

        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;

    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.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,