(function() {

  var getPointer = fabric.util.getPointer,
      degreesToRadians = fabric.util.degreesToRadians,
      radiansToDegrees = fabric.util.radiansToDegrees,
      atan2 = Math.atan2,
      abs = Math.abs,

      STROKE_OFFSET = 0.5;

  /**
   * Canvas class
   * @class fabric.Canvas
   * @extends fabric.StaticCanvas
   * @tutorial {@link http://fabricjs.com/fabric-intro-part-1/#canvas}
   * @see {@link fabric.Canvas#initialize} for constructor definition
   *
   * @fires object:modified
   * @fires object:rotating
   * @fires object:scaling
   * @fires object:moving
   * @fires object:selected
   *
   * @fires before:selection:cleared
   * @fires selection:cleared
   * @fires selection:created
   *
   * @fires path:created
   * @fires mouse:down
   * @fires mouse:move
   * @fires mouse:up
   * @fires mouse:over
   * @fires mouse:out
   *
   */
  fabric.Canvas = fabric.util.createClass(fabric.StaticCanvas, /** @lends fabric.Canvas.prototype */ {

    /**
     * Constructor
     * @param {HTMLElement | String} el <canvas> element to initialize instance on
     * @param {Object} [options] Options object
     * @return {Object} thisArg
     */
    initialize: function(el, options) {
      options || (options = { });

      this._initStatic(el, options);
      this._initInteractive();
      this._createCacheCanvas();

      fabric.Canvas.activeInstance = this;
    },

    /**
     * When true, objects can be transformed by one side (unproportionally)
     * @type Boolean
     * @default
     */
    uniScaleTransform:      false,

    /**
     * When true, objects use center point as the origin of scale transformation.
     * <b>Backwards incompatibility note:</b> This property replaces "centerTransform" (Boolean).
     * @since 1.3.4
     * @type Boolean
     * @default
     */
    centeredScaling:        false,

    /**
     * When true, objects use center point as the origin of rotate transformation.
     * <b>Backwards incompatibility note:</b> This property replaces "centerTransform" (Boolean).
     * @since 1.3.4
     * @type Boolean
     * @default
     */
    centeredRotation:       false,

    /**
     * Indicates that canvas is interactive. This property should not be changed.
     * @type Boolean
     * @default
     */
    interactive:            true,

    /**
     * Indicates whether group selection should be enabled
     * @type Boolean
     * @default
     */
    selection:              true,

    /**
     * Color of selection
     * @type String
     * @default
     */
    selectionColor:         'rgba(100, 100, 255, 0.3)', // blue

    /**
     * Default dash array pattern
     * If not empty the selection border is dashed
     * @type Array
     */
    selectionDashArray:     [ ],

    /**
     * Color of the border of selection (usually slightly darker than color of selection itself)
     * @type String
     * @default
     */
    selectionBorderColor:   'rgba(255, 255, 255, 0.3)',

    /**
     * Width of a line used in object/group selection
     * @type Number
     * @default
     */
    selectionLineWidth:     1,

    /**
     * Default cursor value used when hovering over an object on canvas
     * @type String
     * @default
     */
    hoverCursor:            'move',

    /**
     * Default cursor value used when moving an object on canvas
     * @type String
     * @default
     */
    moveCursor:             'move',

    /**
     * Default cursor value used for the entire canvas
     * @type String
     * @default
     */
    defaultCursor:          'default',

    /**
     * Cursor value used during free drawing
     * @type String
     * @default
     */
    freeDrawingCursor:      'crosshair',

    /**
     * Cursor value used for rotation point
     * @type String
     * @default
     */
    rotationCursor:         'crosshair',

    /**
     * Default element class that's given to wrapper (div) element of canvas
     * @type String
     * @default
     */
    containerClass:         'canvas-container',

    /**
     * When true, object detection happens on per-pixel basis rather than on per-bounding-box
     * @type Boolean
     * @default
     */
    perPixelTargetFind:     false,

    /**
     * Number of pixels around target pixel to tolerate (consider active) during object detection
     * @type Number
     * @default
     */
    targetFindTolerance:    0,

    /**
     * When true, target detection is skipped when hovering over canvas. This can be used to improve performance.
     * @type Boolean
     * @default
     */
    skipTargetFind:         false,

    /**
     * @private
     */
    _initInteractive: function() {
      this._currentTransform = null;
      this._groupSelector = null;
      this._initWrapperElement();
      this._createUpperCanvas();
      this._initEventListeners();

      this.freeDrawingBrush = fabric.PencilBrush && new fabric.PencilBrush(this);

      this.calcOffset();
    },

    /**
     * Resets the current transform to its original values and chooses the type of resizing based on the event
     * @private
     * @param {Event} e Event object fired on mousemove
     */
    _resetCurrentTransform: function(e) {
      var t = this._currentTransform;

      t.target.set({
        'scaleX': t.original.scaleX,
        'scaleY': t.original.scaleY,
        'left': t.original.left,
        'top': t.original.top
      });

      if (this._shouldCenterTransform(e, t.target)) {
        if (t.action === 'rotate') {
          this._setOriginToCenter(t.target);
        }
        else {
          if (t.originX !== 'center') {
            if (t.originX === 'right') {
              t.mouseXSign = -1;
            }
            else {
              t.mouseXSign = 1;
            }
          }
          if (t.originY !== 'center') {
            if (t.originY === 'bottom') {
              t.mouseYSign = -1;
            }
            else {
              t.mouseYSign = 1;
            }
          }

          t.originX = 'center';
          t.originY = 'center';
        }
      }
      else {
        t.originX = t.original.originX;
        t.originY = t.original.originY;
      }
    },

    /**
     * Checks if point is contained within an area of given object
     * @param {Event} e Event object
     * @param {fabric.Object} target Object to test against
     * @return {Boolean} true if point is contained within an area of given object
     */
    containsPoint: function (e, target) {
      var pointer = this.getPointer(e),
          xy = this._normalizePointer(target, pointer);

      // http://www.geog.ubc.ca/courses/klink/gis.notes/ncgia/u32.html
      // http://idav.ucdavis.edu/~okreylos/TAship/Spring2000/PointInPolygon.html
      return (target.containsPoint(xy) || target._findTargetCorner(e, this._offset));
    },

    /**
     * @private
     */
    _normalizePointer: function (object, pointer) {
      var activeGroup = this.getActiveGroup(),
          x = pointer.x,
          y = pointer.y;

      var isObjectInGroup = (
        activeGroup &&
        object.type !== 'group' &&
        activeGroup.contains(object)
      );

      if (isObjectInGroup) {
        x -= activeGroup.left;
        y -= activeGroup.top;
      }
      return { x: x, y: y };
    },

    /**
     * Returns true if object is transparent at a certain location
     * @param {fabric.Object} target Object to check
     * @param {Number} x Left coordinate
     * @param {Number} y Top coordinate
     * @return {Boolean}
     */
    isTargetTransparent: function (target, x, y) {
      var hasBorders = target.hasBorders,
          transparentCorners = target.transparentCorners;

      target.hasBorders = target.transparentCorners = false;

      this._draw(this.contextCache, target);

      target.hasBorders = hasBorders;
      target.transparentCorners = transparentCorners;

      var isTransparent = fabric.util.isTransparent(
        this.contextCache, x, y, this.targetFindTolerance);

      this.clearContext(this.contextCache);

      return isTransparent;
    },

    /**
     * @private
     * @param {Event} e Event object
     * @param {fabric.Object} target
     */
    _shouldClearSelection: function (e, target) {
      var activeGroup = this.getActiveGroup(),
          activeObject = this.getActiveObject();

      return (
        !target
        ||
        (target &&
          activeGroup &&
          !activeGroup.contains(target) &&
          activeGroup !== target &&
          !e.shiftKey)
        ||
        (target && !target.evented)
        ||
        (target &&
          !target.selectable &&
          activeObject &&
          activeObject !== target)
      );
    },

    /**
     * @private
     * @param {Event} e Event object
     * @param {fabric.Object} target
     */
    _shouldCenterTransform: function (e, target) {
      if (!target) return;

      var t = this._currentTransform,
          centerTransform;

      if (t.action === 'scale' || t.action === 'scaleX' || t.action === 'scaleY') {
        centerTransform = this.centeredScaling || target.centeredScaling;
      }
      else if (t.action === 'rotate') {
        centerTransform = this.centeredRotation || target.centeredRotation;
      }

      return centerTransform ? !e.altKey : e.altKey;
    },

    /**
     * @private
     */
    _getOriginFromCorner: function(target, corner) {
      var origin = {
        x: target.originX,
        y: target.originY
      };

      if (corner === 'ml' || corner === 'tl' || corner === 'bl') {
        origin.x = 'right';
      }
      else if (corner === 'mr' || corner === 'tr' || corner === 'br') {
        origin.x = 'left';
      }

      if (corner === 'tl' || corner === 'mt' || corner === 'tr') {
        origin.y = 'bottom';
      }
      else if (corner === 'bl' || corner === 'mb' || corner === 'br') {
        origin.y = 'top';
      }

      return origin;
    },

    /**
     * @private
     */
    _getActionFromCorner: function(target, corner) {
      var action = 'drag';
      if (corner) {
        action = (corner === 'ml' || corner === 'mr')
          ? 'scaleX'
          : (corner === 'mt' || corner === 'mb')
            ? 'scaleY'
            : corner === 'mtr'
              ? 'rotate'
              : 'scale';
      }
      return action;
    },

    /**
     * @private
     * @param {Event} e Event object
     * @param {fabric.Object} target
     */
    _setupCurrentTransform: function (e, target) {
      if (!target) return;

      var corner = target._findTargetCorner(e, this._offset),
          pointer = getPointer(e, target.canvas.upperCanvasEl),
          action = this._getActionFromCorner(target, corner),
          origin = this._getOriginFromCorner(target, corner);

      this._currentTransform = {
        target: target,
        action: action,
        scaleX: target.scaleX,
        scaleY: target.scaleY,
        offsetX: pointer.x - target.left,
        offsetY: pointer.y - target.top,
        originX: origin.x,
        originY: origin.y,
        ex: pointer.x,
        ey: pointer.y,
        left: target.left,
        top: target.top,
        theta: degreesToRadians(target.angle),
        width: target.width * target.scaleX,
        mouseXSign: 1,
        mouseYSign: 1
      };

      this._currentTransform.original = {
        left: target.left,
        top: target.top,
        scaleX: target.scaleX,
        scaleY: target.scaleY,
        originX: origin.x,
        originY: origin.y
      };

      this._resetCurrentTransform(e);
    },

    /**
     * Translates object by "setting" its left/top
     * @private
     * @param x {Number} pointer's x coordinate
     * @param y {Number} pointer's y coordinate
     */
    _translateObject: function (x, y) {
      var target = this._currentTransform.target;

      if (!target.get('lockMovementX')) {
        target.set('left', x - this._currentTransform.offsetX);
      }
      if (!target.get('lockMovementY')) {
        target.set('top', y - this._currentTransform.offsetY);
      }
    },

    /**
     * Scales object by invoking its scaleX/scaleY methods
     * @private
     * @param x {Number} pointer's x coordinate
     * @param y {Number} pointer's y coordinate
     * @param by {String} Either 'x' or 'y' - specifies dimension constraint by which to scale an object.
     *                    When not provided, an object is scaled by both dimensions equally
     */
    _scaleObject: function (x, y, by) {
      var t = this._currentTransform,
          offset = this._offset,
          target = t.target,
          lockScalingX = target.get('lockScalingX'),
          lockScalingY = target.get('lockScalingY');

      if (lockScalingX && lockScalingY) return;

      // Get the constraint point
      var constraintPosition = target.translateToOriginPoint(target.getCenterPoint(), t.originX, t.originY);
      var localMouse = target.toLocalPoint(new fabric.Point(x - offset.left, y - offset.top), t.originX, t.originY);

      this._setLocalMouse(localMouse, t);

      // Actually scale the object
      this._setObjectScale(localMouse, t, lockScalingX, lockScalingY, by);

      // Make sure the constraints apply
      target.setPositionByOrigin(constraintPosition, t.originX, t.originY);
    },

    /**
     * @private
     */
    _setObjectScale: function(localMouse, transform, lockScalingX, lockScalingY, by) {
      var target = transform.target;

      transform.newScaleX = target.scaleX;
      transform.newScaleY = target.scaleY;

      if (by === 'equally' && !lockScalingX && !lockScalingY) {
        this._scaleObjectEqually(localMouse, target, transform);
      }
      else if (!by) {
        transform.newScaleX = localMouse.x / (target.width + target.strokeWidth);
        transform.newScaleY = localMouse.y / (target.height + target.strokeWidth);

        lockScalingX || target.set('scaleX', transform.newScaleX);
        lockScalingY || target.set('scaleY', transform.newScaleY);
      }
      else if (by === 'x' && !target.get('lockUniScaling')) {
        transform.newScaleX = localMouse.x / (target.width + target.strokeWidth);
        lockScalingX || target.set('scaleX', transform.newScaleX);
      }
      else if (by === 'y' && !target.get('lockUniScaling')) {
        transform.newScaleY = localMouse.y / (target.height + target.strokeWidth);
        lockScalingY || target.set('scaleY', transform.newScaleY);
      }

      this._flipObject(transform);
    },

    /**
     * @private
     */
    _scaleObjectEqually: function(localMouse, target, transform) {

      var dist = localMouse.y + localMouse.x;

      var lastDist = (target.height + (target.strokeWidth)) * transform.original.scaleY +
                     (target.width + (target.strokeWidth)) * transform.original.scaleX;

      // We use transform.scaleX/Y instead of target.scaleX/Y
      // because the object may have a min scale and we'll loose the proportions
      transform.newScaleX = transform.original.scaleX * dist / lastDist;
      transform.newScaleY = transform.original.scaleY * dist / lastDist;

      target.set('scaleX', transform.newScaleX);
      target.set('scaleY', transform.newScaleY);
    },

    /**
     * @private
     */
    _flipObject: function(transform) {
      if (transform.newScaleX < 0) {
        if (transform.originX === 'left') {
          transform.originX = 'right';
        }
        else if (transform.originX === 'right') {
          transform.originX = 'left';
        }
      }

      if (transform.newScaleY < 0) {
        if (transform.originY === 'top') {
          transform.originY = 'bottom';
        }
        else if (transform.originY === 'bottom') {
          transform.originY = 'top';
        }
      }
    },

    /**
     * @private
     */
    _setLocalMouse: function(localMouse, t) {
      var target = t.target;

      if (t.originX === 'right') {
        localMouse.x *= -1;
      }
      else if (t.originX === 'center') {
        localMouse.x *= t.mouseXSign * 2;

        if (localMouse.x < 0) {
          t.mouseXSign = -t.mouseXSign;
        }
      }

      if (t.originY === 'bottom') {
        localMouse.y *= -1;
      }
      else if (t.originY === 'center') {
        localMouse.y *= t.mouseYSign * 2;

        if (localMouse.y < 0) {
          t.mouseYSign = -t.mouseYSign;
        }
      }

      // adjust the mouse coordinates when dealing with padding
      if (abs(localMouse.x) > target.padding) {
        if (localMouse.x < 0) {
          localMouse.x += target.padding;
        }
        else {
          localMouse.x -= target.padding;
        }
      }
      else { // mouse is within the padding, set to 0
        localMouse.x = 0;
      }

      if (abs(localMouse.y) > target.padding) {
        if (localMouse.y < 0) {
          localMouse.y += target.padding;
        }
        else {
          localMouse.y -= target.padding;
        }
      }
      else {
        localMouse.y = 0;
      }
    },

    /**
     * Rotates object by invoking its rotate method
     * @private
     * @param x {Number} pointer's x coordinate
     * @param y {Number} pointer's y coordinate
     */
    _rotateObject: function (x, y) {

      var t = this._currentTransform,
          o = this._offset;

      if (t.target.get('lockRotation')) return;

      var lastAngle = atan2(t.ey - t.top - o.top, t.ex - t.left - o.left),
          curAngle = atan2(y - t.top - o.top, x - t.left - o.left),
          angle = radiansToDegrees(curAngle - lastAngle + t.theta);

      // normalize angle to positive value
      if (angle < 0) {
        angle = 360 + angle;
      }

      t.target.angle = angle;
    },

    /**
     * @private
     */
    _setCursor: function (value) {
      this.upperCanvasEl.style.cursor = value;
    },

    /**
     * @private
     */
    _resetObjectTransform: function (target) {
      target.scaleX = 1;
      target.scaleY = 1;
      target.setAngle(0);
    },

    /**
     * @private
     */
    _drawSelection: function () {
      var ctx = this.contextTop,
          groupSelector = this._groupSelector,
          left = groupSelector.left,
          top = groupSelector.top,
          aleft = abs(left),
          atop = abs(top);

      ctx.fillStyle = this.selectionColor;

      ctx.fillRect(
        groupSelector.ex - ((left > 0) ? 0 : -left),
        groupSelector.ey - ((top > 0) ? 0 : -top),
        aleft,
        atop
      );

      ctx.lineWidth = this.selectionLineWidth;
      ctx.strokeStyle = this.selectionBorderColor;

      // selection border
      if (this.selectionDashArray.length > 1) {

        var px = groupSelector.ex + STROKE_OFFSET - ((left > 0) ? 0: aleft);
        var py = groupSelector.ey + STROKE_OFFSET - ((top > 0) ? 0: atop);

        ctx.beginPath();

        fabric.util.drawDashedLine(ctx, px, py, px+aleft, py, this.selectionDashArray);
        fabric.util.drawDashedLine(ctx, px, py+atop-1, px+aleft, py+atop-1, this.selectionDashArray);
        fabric.util.drawDashedLine(ctx, px, py, px, py+atop, this.selectionDashArray);
        fabric.util.drawDashedLine(ctx, px+aleft-1, py, px+aleft-1, py+atop, this.selectionDashArray);

        ctx.closePath();
        ctx.stroke();
      }
      else {
        ctx.strokeRect(
          groupSelector.ex + STROKE_OFFSET - ((left > 0) ? 0 : aleft),
          groupSelector.ey + STROKE_OFFSET - ((top > 0) ? 0 : atop),
          aleft,
          atop
        );
      }
    },

    /**
     * @private
     */
    _isLastRenderedObject: function(e) {
      return (
        this.controlsAboveOverlay &&
        this.lastRenderedObjectWithControlsAboveOverlay &&
        this.lastRenderedObjectWithControlsAboveOverlay.visible &&
        this.containsPoint(e, this.lastRenderedObjectWithControlsAboveOverlay) &&
        this.lastRenderedObjectWithControlsAboveOverlay._findTargetCorner(e, this._offset));
    },

    /**
     * Method that determines what object we are clicking on
     * @param {Event} e mouse event
     * @param {Boolean} skipGroup when true, group is skipped and only objects are traversed through
     */
    findTarget: function (e, skipGroup) {
      if (this.skipTargetFind) return;

      if (this._isLastRenderedObject(e)) {
        return this.lastRenderedObjectWithControlsAboveOverlay;
      }

      // first check current group (if one exists)
      var activeGroup = this.getActiveGroup();
      if (activeGroup && !skipGroup && this.containsPoint(e, activeGroup)) {
        return activeGroup;
      }

      var target = this._searchPossibleTargets(e);
      this._fireOverOutEvents(target);
      return target;
    },

    /**
     * @private
     */
    _fireOverOutEvents: function(target) {
      if (target) {
        if (this._hoveredTarget !== target) {
          this.fire('mouse:over', { target: target });
          target.fire('mouseover');
          if (this._hoveredTarget) {
            this.fire('mouse:out', { target: this._hoveredTarget });
            this._hoveredTarget.fire('mouseout');
          }
          this._hoveredTarget = target;
        }
      }
      else if (this._hoveredTarget) {
        this.fire('mouse:out', { target: this._hoveredTarget });
        this._hoveredTarget.fire('mouseout');
        this._hoveredTarget = null;
      }
    },

    /**
     * @private
     */
    _searchPossibleTargets: function(e) {

      // Cache all targets where their bounding box contains point.
      var possibleTargets = [],
          target,
          pointer = this.getPointer(e);

      for (var i = this._objects.length; i--; ) {
        if (this._objects[i] &&
            this._objects[i].visible &&
            this._objects[i].evented &&
            this.containsPoint(e, this._objects[i])) {

          if (this.perPixelTargetFind || this._objects[i].perPixelTargetFind) {
            possibleTargets[possibleTargets.length] = this._objects[i];
          }
          else {
            target = this._objects[i];
            this.relatedTarget = target;
            break;
          }
        }
      }

      for (var j = 0, len = possibleTargets.length; j < len; j++) {
        pointer = this.getPointer(e);
        var isTransparent = this.isTargetTransparent(possibleTargets[j], pointer.x, pointer.y);
        if (!isTransparent) {
          target = possibleTargets[j];
          this.relatedTarget = target;
          break;
        }
      }

      return target;
    },

    /**
     * Returns pointer coordinates relative to canvas.
     * @param {Event} e
     * @return {Object} object with "x" and "y" number values
     */
    getPointer: function (e) {
      var pointer = getPointer(e, this.upperCanvasEl);
      return {
        x: pointer.x - this._offset.left,
        y: pointer.y - this._offset.top
      };
    },

    /**
     * @private
     * @param {HTMLElement|String} canvasEl Canvas element
     * @throws {CANVAS_INIT_ERROR} If canvas can not be initialized
     */
    _createUpperCanvas: function () {
      var lowerCanvasClass = this.lowerCanvasEl.className.replace(/\s*lower-canvas\s*/, '');

      this.upperCanvasEl = this._createCanvasElement();
      fabric.util.addClass(this.upperCanvasEl, 'upper-canvas ' + lowerCanvasClass);

      this.wrapperEl.appendChild(this.upperCanvasEl);

      this._copyCanvasStyle(this.lowerCanvasEl, this.upperCanvasEl);
      this._applyCanvasStyle(this.upperCanvasEl);
      this.contextTop = this.upperCanvasEl.getContext('2d');
    },

    /**
     * @private
     */
    _createCacheCanvas: function () {
      this.cacheCanvasEl = this._createCanvasElement();
      this.cacheCanvasEl.setAttribute('width', this.width);
      this.cacheCanvasEl.setAttribute('height', this.height);
      this.contextCache = this.cacheCanvasEl.getContext('2d');
    },

    /**
     * @private
     * @param {Number} width
     * @param {Number} height
     */
    _initWrapperElement: function () {
      this.wrapperEl = fabric.util.wrapElement(this.lowerCanvasEl, 'div', {
        'class': this.containerClass
      });
      fabric.util.setStyle(this.wrapperEl, {
        width: this.getWidth() + 'px',
        height: this.getHeight() + 'px',
        position: 'relative'
      });
      fabric.util.makeElementUnselectable(this.wrapperEl);
    },

    /**
     * @private
     * @param {Element} element
     */
    _applyCanvasStyle: function (element) {
      var width = this.getWidth() || element.width,
          height = this.getHeight() || element.height;

      fabric.util.setStyle(element, {
        position: 'absolute',
        width: width + 'px',
        height: height + 'px',
        left: 0,
        top: 0
      });
      element.width = width;
      element.height = height;
      fabric.util.makeElementUnselectable(element);
    },

    /**
     * Copys the the entire inline style from one element (fromEl) to another (toEl)
     * @private
     * @param {Element} fromEl Element style is copied from
     * @param {Element} toEl Element copied style is applied to
     */
    _copyCanvasStyle: function (fromEl, toEl) {
      toEl.style.cssText = fromEl.style.cssText;
    },

    /**
     * Returns context of canvas where object selection is drawn
     * @return {CanvasRenderingContext2D}
     */
    getSelectionContext: function() {
      return this.contextTop;
    },

    /**
     * Returns &lt;canvas> element on which object selection is drawn
     * @return {HTMLCanvasElement}
     */
    getSelectionElement: function () {
      return this.upperCanvasEl;
    },

    /**
     * @private
     * @param {Object} object
     */
    _setActiveObject: function(object) {
      if (this._activeObject) {
        this._activeObject.set('active', false);
      }
      this._activeObject = object;
      object.set('active', true);
    },

    /**
     * Sets given object as the only active object on canvas
     * @param {fabric.Object} object Object to set as an active one
     * @param {Event} [e] Event (passed along when firing "object:selected")
     * @return {fabric.Canvas} thisArg
     * @chainable
     */
    setActiveObject: function (object, e) {
      this._setActiveObject(object);
      this.renderAll();
      this.fire('object:selected', { target: object, e: e });
      object.fire('selected', { e: e });
      return this;
    },

    /**
     * Returns currently active object
     * @return {fabric.Object} active object
     */
    getActiveObject: function () {
      return this._activeObject;
    },

    /**
     * @private
     */
    _discardActiveObject: function() {
      if (this._activeObject) {
        this._activeObject.set('active', false);
      }
      this._activeObject = null;
    },

    /**
     * Discards currently active object
     * @return {fabric.Canvas} thisArg
     * @chainable
     */
    discardActiveObject: function (e) {
      this._discardActiveObject();
      this.renderAll();
      this.fire('selection:cleared', { e: e });
      return this;
    },

    /**
     * @private
     * @param {fabric.Group} group
     */
    _setActiveGroup: function(group) {
      this._activeGroup = group;
      if (group) {
        group.canvas = this;
        group.set('active', true);
      }
    },

    /**
     * Sets active group to a speicified one
     * @param {fabric.Group} group Group to set as a current one
     * @return {fabric.Canvas} thisArg
     * @chainable
     */
    setActiveGroup: function (group, e) {
      this._setActiveGroup(group);
      if (group) {
        this.fire('object:selected', { target: group, e: e });
        group.fire('selected', { e: e });
      }
      return this;
    },

    /**
     * Returns currently active group
     * @return {fabric.Group} Current group
     */
    getActiveGroup: function () {
      return this._activeGroup;
    },

    /**
     * @private
     */
    _discardActiveGroup: function() {
      var g = this.getActiveGroup();
      if (g) {
        g.destroy();
      }
      this.setActiveGroup(null);
    },

    /**
     * Discards currently active group
     * @return {fabric.Canvas} thisArg
     */
    discardActiveGroup: function (e) {
      this._discardActiveGroup();
      this.fire('selection:cleared', { e: e });
      return this;
    },

    /**
     * Deactivates all objects on canvas, removing any active group or object
     * @return {fabric.Canvas} thisArg
     */
    deactivateAll: function () {
      var allObjects = this.getObjects(),
          i = 0,
          len = allObjects.length;
      for ( ; i < len; i++) {
        allObjects[i].set('active', false);
      }
      this._discardActiveGroup();
      this._discardActiveObject();
      return this;
    },

    /**
     * Deactivates all objects and dispatches appropriate events
     * @return {fabric.Canvas} thisArg
     */
    deactivateAllWithDispatch: function (e) {
      var activeObject = this.getActiveGroup() || this.getActiveObject();
      if (activeObject) {
        this.fire('before:selection:cleared', { target: activeObject, e: e });
      }
      this.deactivateAll();
      if (activeObject) {
        this.fire('selection:cleared', { e: e });
      }
      return this;
    },

    /**
     * Draws objects' controls (borders/controls)
     * @param {CanvasRenderingContext2D} ctx Context to render controls on
     */
    drawControls: function(ctx) {
      var activeGroup = this.getActiveGroup();
      if (activeGroup) {
        this._drawGroupControls(ctx, activeGroup);
      }
      else {
        this._drawObjectsControls(ctx);
      }
    },

    /**
     * @private
     */
    _drawGroupControls: function(ctx, activeGroup) {
      this._drawControls(ctx, activeGroup, 'Group');
    },

    /**
     * @private
     */
    _drawObjectsControls: function(ctx) {
      for (var i = 0, len = this._objects.length; i < len; ++i) {
        if (!this._objects[i] || !this._objects[i].active) continue;
        this._drawControls(ctx, this._objects[i], 'Object');
        this.lastRenderedObjectWithControlsAboveOverlay = this._objects[i];
      }
    },

    /**
     * @private
     */
    _drawControls: function(ctx, object, klass) {
      ctx.save();
      fabric[klass].prototype.transform.call(object, ctx);
      object.drawBorders(ctx).drawControls(ctx);
      ctx.restore();
    }
  });

  // copying static properties manually to work around Opera's bug,
  // where "prototype" property is enumerable and overrides existing prototype
  for (var prop in fabric.StaticCanvas) {
    if (prop !== 'prototype') {
      fabric.Canvas[prop] = fabric.StaticCanvas[prop];
    }
  }

  if (fabric.isTouchSupported) {
    /** @ignore */
    fabric.Canvas.prototype._setCursorFromEvent = function() { };
  }

  /**
   * @class fabric.Element
   * @alias fabric.Canvas
   * @deprecated Use {@link fabric.Canvas} instead.
   * @constructor
   */
  fabric.Element = fabric.Canvas;
})();