Stage.js

/*
* Stage
* Visit http://createjs.com/ for documentation, updates and examples.
*
* Copyright (c) 2010 gskinner.com, inc.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/

/**
 * @module EaselJS
 */

// namespace:
this.createjs = this.createjs||{};

(function() {
	"use strict";


// constructor:
	/**
	 * A stage is the root level {{#crossLink "Container"}}{{/crossLink}} for a display list. Each time its {{#crossLink "Stage/tick"}}{{/crossLink}}
	 * method is called, it will render its display list to its target canvas.
	 *
	 * <h4>Example</h4>
	 * This example creates a stage, adds a child to it, then uses {{#crossLink "Ticker"}}{{/crossLink}} to update the child
	 * and redraw the stage using {{#crossLink "Stage/update"}}{{/crossLink}}.
	 *
	 *      var stage = new createjs.Stage("canvasElementId");
	 *      var image = new createjs.Bitmap("imagePath.png");
	 *      stage.addChild(image);
	 *      createjs.Ticker.addEventListener("tick", handleTick);
	 *      function handleTick(event) {
	 *          image.x += 10;
	 *          stage.update();
	 *      }
	 *
	 * @class Stage
	 * @extends Container
	 * @constructor
	 * @param {HTMLCanvasElement | String | Object} canvas A canvas object that the Stage will render to, or the string id
	 * of a canvas object in the current document.
	 **/
	function Stage(canvas) {
		this.Container_constructor();
	
	
	// public properties:
		/**
		 * Indicates whether the stage should automatically clear the canvas before each render. You can set this to <code>false</code>
		 * to manually control clearing (for generative art, or when pointing multiple stages at the same canvas for
		 * example).
		 *
		 * <h4>Example</h4>
		 *
		 *      var stage = new createjs.Stage("canvasId");
		 *      stage.autoClear = false;
		 *
		 * @property autoClear
		 * @type Boolean
		 * @default true
		 **/
		this.autoClear = true;
	
		/**
		 * The canvas the stage will render to. Multiple stages can share a single canvas, but you must disable autoClear for all but the
		 * first stage that will be ticked (or they will clear each other's render).
		 *
		 * When changing the canvas property you must disable the events on the old canvas, and enable events on the
		 * new canvas or mouse events will not work as expected. For example:
		 *
		 *      myStage.enableDOMEvents(false);
		 *      myStage.canvas = anotherCanvas;
		 *      myStage.enableDOMEvents(true);
		 *
		 * @property canvas
		 * @type HTMLCanvasElement | Object
		 **/
		this.canvas = (typeof canvas == "string") ? document.getElementById(canvas) : canvas;
	
		/**
		 * The current mouse X position on the canvas. If the mouse leaves the canvas, this will indicate the most recent
		 * position over the canvas, and mouseInBounds will be set to false.
		 * @property mouseX
		 * @type Number
		 * @readonly
		 **/
		this.mouseX = 0;
	
		/**
		 * The current mouse Y position on the canvas. If the mouse leaves the canvas, this will indicate the most recent
		 * position over the canvas, and mouseInBounds will be set to false.
		 * @property mouseY
		 * @type Number
		 * @readonly
		 **/
		this.mouseY = 0;
	
		/**
		 * Specifies the area of the stage to affect when calling update. This can be use to selectively
		 * re-draw specific regions of the canvas. If null, the whole canvas area is drawn.
		 * @property drawRect
		 * @type {Rectangle}
		 */
		this.drawRect = null;
	
		/**
		 * Indicates whether display objects should be rendered on whole pixels. You can set the
		 * {{#crossLink "DisplayObject/snapToPixel"}}{{/crossLink}} property of
		 * display objects to false to enable/disable this behaviour on a per instance basis.
		 * @property snapToPixelEnabled
		 * @type Boolean
		 * @default false
		 **/
		this.snapToPixelEnabled = false;
	
		/**
		 * Indicates whether the mouse is currently within the bounds of the canvas.
		 * @property mouseInBounds
		 * @type Boolean
		 * @default false
		 **/
		this.mouseInBounds = false;
	
		/**
		 * If true, tick callbacks will be called on all display objects on the stage prior to rendering to the canvas.
		 * @property tickOnUpdate
		 * @type Boolean
		 * @default true
		 **/
		this.tickOnUpdate = true;
	
		/**
		 * If true, mouse move events will continue to be called when the mouse leaves the target canvas. See
		 * {{#crossLink "Stage/mouseInBounds:property"}}{{/crossLink}}, and {{#crossLink "MouseEvent"}}{{/crossLink}}
		 * x/y/rawX/rawY.
		 * @property mouseMoveOutside
		 * @type Boolean
		 * @default false
		 **/
		this.mouseMoveOutside = false;
		
		
		/**
		 * Prevents selection of other elements in the html page if the user clicks and drags, or double clicks on the canvas.
		 * This works by calling `preventDefault()` on any mousedown events (or touch equivalent) originating on the canvas.
		 * @property preventSelection
		 * @type Boolean
		 * @default true
		 **/
		this.preventSelection = true;
	
		/**
		 * The hitArea property is not supported for Stage.
		 * @property hitArea
		 * @type {DisplayObject}
		 * @default null
		 */
		 
		 
	// private properties:
		/**
		 * Holds objects with data for each active pointer id. Each object has the following properties:
		 * x, y, event, target, overTarget, overX, overY, inBounds, posEvtObj (native event that last updated position)
		 * @property _pointerData
		 * @type {Object}
		 * @private
		 */
		this._pointerData = {};
	
		/**
		 * Number of active pointers.
		 * @property _pointerCount
		 * @type {Object}
		 * @private
		 */
		this._pointerCount = 0;
	
		/**
		 * The ID of the primary pointer.
		 * @property _primaryPointerID
		 * @type {Object}
		 * @private
		 */
		this._primaryPointerID = null;
	
		/**
		 * @property _mouseOverIntervalID
		 * @protected
		 * @type Number
		 **/
		this._mouseOverIntervalID = null;
		
		/**
		 * @property _nextStage
		 * @protected
		 * @type Stage
		 **/
		this._nextStage = null;
		
		/**
		 * @property _prevStage
		 * @protected
		 * @type Stage
		 **/
		this._prevStage = null;
		
		
	// initialize:
		this.enableDOMEvents(true);
	}
	var p = createjs.extend(Stage, createjs.Container);

	/**
	 * <strong>REMOVED</strong>. Removed in favor of using `MySuperClass_constructor`.
	 * See {{#crossLink "Utility Methods/extend"}}{{/crossLink}} and {{#crossLink "Utility Methods/promote"}}{{/crossLink}}
	 * for details.
	 *
	 * There is an inheritance tutorial distributed with EaselJS in /tutorials/Inheritance.
	 *
	 * @method initialize
	 * @protected
	 * @deprecated
	 */
	// p.initialize = function() {}; // searchable for devs wondering where it is.


// events:
	/**
	 * Dispatched when the user moves the mouse over the canvas.
	 * See the {{#crossLink "MouseEvent"}}{{/crossLink}} class for a listing of event properties.
	 * @event stagemousemove
	 * @since 0.6.0
	 */

	/**
	 * Dispatched when the user presses their left mouse button on the canvas. See the {{#crossLink "MouseEvent"}}{{/crossLink}}
	 * class for a listing of event properties.
	 * @event stagemousedown
	 * @since 0.6.0
	 */

	/**
	 * Dispatched when the user the user presses somewhere on the stage, then releases the mouse button anywhere that the page can detect it (this varies slightly between browsers).
	 * You can use {{#crossLink "Stage/mouseInBounds:property"}}{{/crossLink}} to check whether the mouse is currently within the stage bounds.
	 * See the {{#crossLink "MouseEvent"}}{{/crossLink}} class for a listing of event properties.
	 * @event stagemouseup
	 * @since 0.6.0
	 */

	/**
	 * Dispatched when the mouse moves from within the canvas area (mouseInBounds == true) to outside it (mouseInBounds == false).
	 * This is currently only dispatched for mouse input (not touch). See the {{#crossLink "MouseEvent"}}{{/crossLink}}
	 * class for a listing of event properties.
	 * @event mouseleave
	 * @since 0.7.0
	 */

	/**
	 * Dispatched when the mouse moves into the canvas area (mouseInBounds == false) from outside it (mouseInBounds == true).
	 * This is currently only dispatched for mouse input (not touch). See the {{#crossLink "MouseEvent"}}{{/crossLink}}
	 * class for a listing of event properties.
	 * @event mouseenter
	 * @since 0.7.0
	 */
	 
	/**
	 * Dispatched each update immediately before the tick event is propagated through the display list.
	 * You can call preventDefault on the event object to cancel propagating the tick event.
	 * @event tickstart
	 * @since 0.7.0
	 */
	 
	/**
	 * Dispatched each update immediately after the tick event is propagated through the display list. Does not fire if
	 * tickOnUpdate is false. Precedes the "drawstart" event.
	 * @event tickend
	 * @since 0.7.0
	 */
	 
	/**
	 * Dispatched each update immediately before the canvas is cleared and the display list is drawn to it.
	 * You can call preventDefault on the event object to cancel the draw.
	 * @event drawstart
	 * @since 0.7.0
	 */
	 
	/**
	 * Dispatched each update immediately after the display list is drawn to the canvas and the canvas context is restored.
	 * @event drawend
	 * @since 0.7.0
	 */

	 
// getter / setters:
	/**
	 * Specifies a target stage that will have mouse / touch interactions relayed to it after this stage handles them.
	 * This can be useful in cases where you have multiple layered canvases and want user interactions
	 * events to pass through. For example, this would relay mouse events from topStage to bottomStage:
	 *
	 *      topStage.nextStage = bottomStage;
	 *
	 * To disable relaying, set nextStage to null.
	 * 
	 * MouseOver, MouseOut, RollOver, and RollOut interactions are also passed through using the mouse over settings
	 * of the top-most stage, but are only processed if the target stage has mouse over interactions enabled.
	 * Considerations when using roll over in relay targets:<OL>
	 * <LI> The top-most (first) stage must have mouse over interactions enabled (via enableMouseOver)</LI>
	 * <LI> All stages that wish to participate in mouse over interaction must enable them via enableMouseOver</LI>
	 * <LI> All relay targets will share the frequency value of the top-most stage</LI>
	 * </OL>
	 * To illustrate, in this example the targetStage would process mouse over interactions at 10hz (despite passing
	 * 30 as it's desired frequency):
	 * 	topStage.nextStage = targetStage;
	 * 	topStage.enableMouseOver(10);
	 * 	targetStage.enableMouseOver(30);
	 * 
	 * If the target stage's canvas is completely covered by this stage's canvas, you may also want to disable its
	 * DOM events using:
	 * 
	 *	targetStage.enableDOMEvents(false);
	 * 
	 * @property nextStage
	 * @type {Stage}
	 **/
	p._get_nextStage = function() {
		return this._nextStage;
	};
	p._set_nextStage = function(value) {
		if (this._nextStage) { this._nextStage._prevStage = null; }
		if (value) { value._prevStage = this; }
		this._nextStage = value;
	};
	
	try {
		Object.defineProperties(p, {
			nextStage: { get: p._get_nextStage, set: p._set_nextStage }
		});
	} catch (e) {} // TODO: use Log


// public methods:
	/**
	 * Each time the update method is called, the stage will call {{#crossLink "Stage/tick"}}{{/crossLink}}
	 * unless {{#crossLink "Stage/tickOnUpdate:property"}}{{/crossLink}} is set to false,
	 * and then render the display list to the canvas.
	 *
	 * @method update
	 * @param {Object} [props] Props object to pass to `tick()`. Should usually be a {{#crossLink "Ticker"}}{{/crossLink}} event object, or similar object with a delta property.
	 **/
	p.update = function(props) {
		if (!this.canvas) { return; }
		if (this.tickOnUpdate) { this.tick(props); }
		if (this.dispatchEvent("drawstart")) { return; }
		createjs.DisplayObject._snapToPixelEnabled = this.snapToPixelEnabled;
		var r = this.drawRect, ctx = this.canvas.getContext("2d");
		ctx.setTransform(1, 0, 0, 1, 0, 0);
		if (this.autoClear) {
			if (r) { ctx.clearRect(r.x, r.y, r.width, r.height); }
			else { ctx.clearRect(0, 0, this.canvas.width+1, this.canvas.height+1); }
		}
		ctx.save();
		if (this.drawRect) {
			ctx.beginPath();
			ctx.rect(r.x, r.y, r.width, r.height);
			ctx.clip();
		}
		this.updateContext(ctx);
		this.draw(ctx, false);
		ctx.restore();
		this.dispatchEvent("drawend");
	};
	
	/**
	 * Propagates a tick event through the display list. This is automatically called by {{#crossLink "Stage/update"}}{{/crossLink}}
	 * unless {{#crossLink "Stage/tickOnUpdate:property"}}{{/crossLink}} is set to false.
	 *
	 * If a props object is passed to `tick()`, then all of its properties will be copied to the event object that is
	 * propagated to listeners.
	 *
	 * Some time-based features in EaselJS (for example {{#crossLink "Sprite/framerate"}}{{/crossLink}} require that
	 * a {{#crossLink "Ticker/tick:event"}}{{/crossLink}} event object (or equivalent object with a delta property) be
	 * passed as the `props` parameter to `tick()`. For example:
	 *
	 * 	Ticker.on("tick", handleTick);
	 * 	function handleTick(evtObj) {
	 * 		// clone the event object from Ticker, and add some custom data to it:
	 * 		var evt = evtObj.clone().set({greeting:"hello", name:"world"});
	 * 		
	 * 		// pass it to stage.update():
	 * 		myStage.update(evt); // subsequently calls tick() with the same param
	 * 	}
	 * 	
	 * 	// ...
	 * 	myDisplayObject.on("tick", handleDisplayObjectTick);
	 * 	function handleDisplayObjectTick(evt) {
	 * 		console.log(evt.delta); // the delta property from the Ticker tick event object
	 * 		console.log(evt.greeting, evt.name); // custom data: "hello world"
	 * 	}
	 * 
	 * @method tick
	 * @param {Object} [props] An object with properties that should be copied to the event object. Should usually be a Ticker event object, or similar object with a delta property.
	 **/
	p.tick = function(props) {
		if (!this.tickEnabled || this.dispatchEvent("tickstart")) { return; }
		var evtObj = new createjs.Event("tick");
		if (props) {
			for (var n in props) {
				if (props.hasOwnProperty(n)) { evtObj[n] = props[n]; }
			}
		}
		this._tick(evtObj);
		this.dispatchEvent("tickend");
	};

	/**
	 * Default event handler that calls the Stage {{#crossLink "Stage/update"}}{{/crossLink}} method when a {{#crossLink "DisplayObject/tick:event"}}{{/crossLink}}
	 * event is received. This allows you to register a Stage instance as a event listener on {{#crossLink "Ticker"}}{{/crossLink}}
	 * directly, using:
	 *
	 *      Ticker.addEventListener("tick", myStage");
	 *
	 * Note that if you subscribe to ticks using this pattern, then the tick event object will be passed through to
	 * display object tick handlers, instead of <code>delta</code> and <code>paused</code> parameters.
	 * @property handleEvent
	 * @type Function
	 **/
	p.handleEvent = function(evt) {
		if (evt.type == "tick") { this.update(evt); }
	};

	/**
	 * Clears the target canvas. Useful if {{#crossLink "Stage/autoClear:property"}}{{/crossLink}} is set to `false`.
	 * @method clear
	 **/
	p.clear = function() {
		if (!this.canvas) { return; }
		var ctx = this.canvas.getContext("2d");
		ctx.setTransform(1, 0, 0, 1, 0, 0);
		ctx.clearRect(0, 0, this.canvas.width+1, this.canvas.height+1);
	};

	/**
	 * Returns a data url that contains a Base64-encoded image of the contents of the stage. The returned data url can
	 * be specified as the src value of an image element.
	 * @method toDataURL
	 * @param {String} [backgroundColor] The background color to be used for the generated image. Any valid CSS color
	 * value is allowed. The default value is a transparent background.
	 * @param {String} [mimeType="image/png"] The MIME type of the image format to be create. The default is "image/png". If an unknown MIME type
	 * is passed in, or if the browser does not support the specified MIME type, the default value will be used.
	 * @return {String} a Base64 encoded image.
	 **/
	p.toDataURL = function(backgroundColor, mimeType) {
		var data, ctx = this.canvas.getContext('2d'), w = this.canvas.width, h = this.canvas.height;

		if (backgroundColor) {
			data = ctx.getImageData(0, 0, w, h);
			var compositeOperation = ctx.globalCompositeOperation;
			ctx.globalCompositeOperation = "destination-over";
			
			ctx.fillStyle = backgroundColor;
			ctx.fillRect(0, 0, w, h);
		}

		var dataURL = this.canvas.toDataURL(mimeType||"image/png");

		if(backgroundColor) {
			ctx.putImageData(data, 0, 0);
			ctx.globalCompositeOperation = compositeOperation;
		}

		return dataURL;
	};

	/**
	 * Enables or disables (by passing a frequency of 0) mouse over ({{#crossLink "DisplayObject/mouseover:event"}}{{/crossLink}}
	 * and {{#crossLink "DisplayObject/mouseout:event"}}{{/crossLink}}) and roll over events ({{#crossLink "DisplayObject/rollover:event"}}{{/crossLink}}
	 * and {{#crossLink "DisplayObject/rollout:event"}}{{/crossLink}}) for this stage's display list. These events can
	 * be expensive to generate, so they are disabled by default. The frequency of the events can be controlled
	 * independently of mouse move events via the optional `frequency` parameter.
	 *
	 * <h4>Example</h4>
	 *
	 *      var stage = new createjs.Stage("canvasId");
	 *      stage.enableMouseOver(10); // 10 updates per second
	 *
	 * @method enableMouseOver
	 * @param {Number} [frequency=20] Optional param specifying the maximum number of times per second to broadcast
	 * mouse over/out events. Set to 0 to disable mouse over events completely. Maximum is 50. A lower frequency is less
	 * responsive, but uses less CPU.
	 **/
	p.enableMouseOver = function(frequency) {
		if (this._mouseOverIntervalID) {
			clearInterval(this._mouseOverIntervalID);
			this._mouseOverIntervalID = null;
			if (frequency == 0) {
				this._testMouseOver(true);
			}
		}
		if (frequency == null) { frequency = 20; }
		else if (frequency <= 0) { return; }
		var o = this;
		this._mouseOverIntervalID = setInterval(function(){ o._testMouseOver(); }, 1000/Math.min(50,frequency));
	};

	/**
	 * Enables or disables the event listeners that stage adds to DOM elements (window, document and canvas). It is good
	 * practice to disable events when disposing of a Stage instance, otherwise the stage will continue to receive
	 * events from the page.
	 *
	 * When changing the canvas property you must disable the events on the old canvas, and enable events on the
	 * new canvas or mouse events will not work as expected. For example:
	 *
	 *      myStage.enableDOMEvents(false);
	 *      myStage.canvas = anotherCanvas;
	 *      myStage.enableDOMEvents(true);
	 *
	 * @method enableDOMEvents
	 * @param {Boolean} [enable=true] Indicates whether to enable or disable the events. Default is true.
	 **/
	p.enableDOMEvents = function(enable) {
		if (enable == null) { enable = true; }
		var n, o, ls = this._eventListeners;
		if (!enable && ls) {
			for (n in ls) {
				o = ls[n];
				o.t.removeEventListener(n, o.f, false);
			}
			this._eventListeners = null;
		} else if (enable && !ls && this.canvas) {
			var t = window.addEventListener ? window : document;
			var _this = this;
			ls = this._eventListeners = {};
			ls["mouseup"] = {t:t, f:function(e) { _this._handleMouseUp(e)} };
			ls["mousemove"] = {t:t, f:function(e) { _this._handleMouseMove(e)} };
			ls["dblclick"] = {t:this.canvas, f:function(e) { _this._handleDoubleClick(e)} };
			ls["mousedown"] = {t:this.canvas, f:function(e) { _this._handleMouseDown(e)} };

			for (n in ls) {
				o = ls[n];
				o.t.addEventListener(n, o.f, false);
			}
		}
	};

	/**
	 * Stage instances cannot be cloned.
	 * @method clone
	 **/
	p.clone = function() {
		throw("Stage cannot be cloned.");
	};

	/**
	 * Returns a string representation of this object.
	 * @method toString
	 * @return {String} a string representation of the instance.
	 **/
	p.toString = function() {
		return "[Stage (name="+  this.name +")]";
	};


// private methods:
	/**
	 * @method _getElementRect
	 * @protected
	 * @param {HTMLElement} e
	 **/
	p._getElementRect = function(e) {
		var bounds;
		try { bounds = e.getBoundingClientRect(); } // this can fail on disconnected DOM elements in IE9
		catch (err) { bounds = {top: e.offsetTop, left: e.offsetLeft, width:e.offsetWidth, height:e.offsetHeight}; }

		var offX = (window.pageXOffset || document.scrollLeft || 0) - (document.clientLeft || document.body.clientLeft || 0);
		var offY = (window.pageYOffset || document.scrollTop || 0) - (document.clientTop  || document.body.clientTop  || 0);

		var styles = window.getComputedStyle ? getComputedStyle(e,null) : e.currentStyle; // IE <9 compatibility.
		var padL = parseInt(styles.paddingLeft)+parseInt(styles.borderLeftWidth);
		var padT = parseInt(styles.paddingTop)+parseInt(styles.borderTopWidth);
		var padR = parseInt(styles.paddingRight)+parseInt(styles.borderRightWidth);
		var padB = parseInt(styles.paddingBottom)+parseInt(styles.borderBottomWidth);

		// note: in some browsers bounds properties are read only.
		return {
			left: bounds.left+offX+padL,
			right: bounds.right+offX-padR,
			top: bounds.top+offY+padT,
			bottom: bounds.bottom+offY-padB
		}
	};

	/**
	 * @method _getPointerData
	 * @protected
	 * @param {Number} id
	 **/
	p._getPointerData = function(id) {
		var data = this._pointerData[id];
		if (!data) { data = this._pointerData[id] = {x:0,y:0}; }
		return data;
	};

	/**
	 * @method _handleMouseMove
	 * @protected
	 * @param {MouseEvent} e
	 **/
	p._handleMouseMove = function(e) {
		if(!e){ e = window.event; }
		this._handlePointerMove(-1, e, e.pageX, e.pageY);
	};

	/**
	 * @method _handlePointerMove
	 * @protected
	 * @param {Number} id
	 * @param {Event} e
	 * @param {Number} pageX
	 * @param {Number} pageY
	 * @param {Stage} owner Indicates that the event has already been captured & handled by the indicated stage.
	 **/
	p._handlePointerMove = function(id, e, pageX, pageY, owner) {
		if (this._prevStage && owner === undefined) { return; } // redundant listener.
		if (!this.canvas) { return; }
		var nextStage=this._nextStage, o=this._getPointerData(id);

		var inBounds = o.inBounds;
		this._updatePointerPosition(id, e, pageX, pageY);
		if (inBounds || o.inBounds || this.mouseMoveOutside) {
			if (id === -1 && o.inBounds == !inBounds) {
				this._dispatchMouseEvent(this, (inBounds ? "mouseleave" : "mouseenter"), false, id, o, e);
			}
			
			this._dispatchMouseEvent(this, "stagemousemove", false, id, o, e);
			this._dispatchMouseEvent(o.target, "pressmove", true, id, o, e);
		}
		
		nextStage&&nextStage._handlePointerMove(id, e, pageX, pageY, null);
	};

	/**
	 * @method _updatePointerPosition
	 * @protected
	 * @param {Number} id
	 * @param {Event} e
	 * @param {Number} pageX
	 * @param {Number} pageY
	 **/
	p._updatePointerPosition = function(id, e, pageX, pageY) {
		var rect = this._getElementRect(this.canvas);
		pageX -= rect.left;
		pageY -= rect.top;

		var w = this.canvas.width;
		var h = this.canvas.height;
		pageX /= (rect.right-rect.left)/w;
		pageY /= (rect.bottom-rect.top)/h;
		var o = this._getPointerData(id);
		if (o.inBounds = (pageX >= 0 && pageY >= 0 && pageX <= w-1 && pageY <= h-1)) {
			o.x = pageX;
			o.y = pageY;
		} else if (this.mouseMoveOutside) {
			o.x = pageX < 0 ? 0 : (pageX > w-1 ? w-1 : pageX);
			o.y = pageY < 0 ? 0 : (pageY > h-1 ? h-1 : pageY);
		}

		o.posEvtObj = e;
		o.rawX = pageX;
		o.rawY = pageY;

		if (id === this._primaryPointerID || id === -1) {
			this.mouseX = o.x;
			this.mouseY = o.y;
			this.mouseInBounds = o.inBounds;
		}
	};

	/**
	 * @method _handleMouseUp
	 * @protected
	 * @param {MouseEvent} e
	 **/
	p._handleMouseUp = function(e) {
		this._handlePointerUp(-1, e, false);
	};

	/**
	 * @method _handlePointerUp
	 * @protected
	 * @param {Number} id
	 * @param {Event} e
	 * @param {Boolean} clear
	 * @param {Stage} owner Indicates that the event has already been captured & handled by the indicated stage.
	 **/
	p._handlePointerUp = function(id, e, clear, owner) {
		var nextStage = this._nextStage, o = this._getPointerData(id);
		if (this._prevStage && owner === undefined) { return; } // redundant listener.
		
		if (o.down) { this._dispatchMouseEvent(this, "stagemouseup", false, id, o, e); }
		o.down = false;
		
		var target=null, oTarget = o.target;
		if (!owner && (oTarget || nextStage)) { target = this._getObjectsUnderPoint(o.x, o.y, null, true); }
		if (target == oTarget) { this._dispatchMouseEvent(oTarget, "click", true, id, o, e); }
		this._dispatchMouseEvent(oTarget, "pressup", true, id, o, e);
		
		if (clear) {
			if (id==this._primaryPointerID) { this._primaryPointerID = null; }
			delete(this._pointerData[id]);
		} else { o.target = null; }
		
		nextStage&&nextStage._handlePointerUp(id, e, clear, owner || target && this);
	};

	/**
	 * @method _handleMouseDown
	 * @protected
	 * @param {MouseEvent} e
	 **/
	p._handleMouseDown = function(e) {
		this._handlePointerDown(-1, e, e.pageX, e.pageY);
	};

	/**
	 * @method _handlePointerDown
	 * @protected
	 * @param {Number} id
	 * @param {Event} e
	 * @param {Number} pageX
	 * @param {Number} pageY
	 * @param {Stage} owner Indicates that the event has already been captured & handled by the indicated stage.
	 **/
	p._handlePointerDown = function(id, e, pageX, pageY, owner) {
		if (this.preventSelection) { e.preventDefault(); }
		if (this._primaryPointerID == null || id === -1) { this._primaryPointerID = id; } // mouse always takes over.
		
		if (pageY != null) { this._updatePointerPosition(id, e, pageX, pageY); }
		var target = null, nextStage = this._nextStage, o = this._getPointerData(id);

		if (o.inBounds) { this._dispatchMouseEvent(this, "stagemousedown", false, id, o, e); o.down = true; }
		
		if (!owner) {
			target = o.target = this._getObjectsUnderPoint(o.x, o.y, null, true);
			this._dispatchMouseEvent(o.target, "mousedown", true, id, o, e);
		}

		nextStage&&nextStage._handlePointerDown(id, e, pageX, pageY, owner || target && this);
	};

	/**
	 * @method _testMouseOver
	 * @param {Boolean} clear If true, clears the mouseover / rollover (ie. no target)
	 * @param {Stage} owner Indicates that the event has already been captured & handled by the indicated stage.
	 * @param {Stage} eventTarget The stage that the cursor is actively over.
	 * @protected
	 **/
	p._testMouseOver = function(clear, owner, eventTarget) {
		if (this._prevStage && owner === undefined) { return; } // redundant listener.
		
		var nextStage = this._nextStage;
		if (!this._mouseOverIntervalID) {
			// not enabled for mouseover, but should still relay the event.
			nextStage&&nextStage._testMouseOver(clear, owner, eventTarget);
			return;
		}
		var o = this._getPointerData(-1);
		// only update if the mouse position has changed. This provides a lot of optimization, but has some trade-offs.
		if (!o || (!clear && this.mouseX == this._mouseOverX && this.mouseY == this._mouseOverY && this.mouseInBounds)) { return; }
		
		var e = o.posEvtObj;
		var isEventTarget = eventTarget || e&&(e.target == this.canvas);
		var target=null, common = -1, cursor="", t, i, l;
		
		if (!owner && (clear || this.mouseInBounds && isEventTarget)) {
			target = this._getObjectsUnderPoint(this.mouseX, this.mouseY, null, true);
			this._mouseOverX = this.mouseX;
			this._mouseOverY = this.mouseY;
		}

		var oldList = this._mouseOverTarget||[];
		var oldTarget = oldList[oldList.length-1];
		var list = this._mouseOverTarget = [];

		// generate ancestor list and check for cursor:
		t = target;
		while (t) {
			list.unshift(t);
			if (t.cursor != null) { cursor = t.cursor; }
			t = t.parent;
		}
		this.canvas.style.cursor = cursor;
		if (!owner && eventTarget) { eventTarget.canvas.style.cursor = cursor; }

		// find common ancestor:
		for (i=0,l=list.length; i<l; i++) {
			if (list[i] != oldList[i]) { break; }
			common = i;
		}

		if (oldTarget != target) {
			this._dispatchMouseEvent(oldTarget, "mouseout", true, -1, o, e);
		}

		for (i=oldList.length-1; i>common; i--) {
			this._dispatchMouseEvent(oldList[i], "rollout", false, -1, o, e);
		}

		for (i=list.length-1; i>common; i--) {
			this._dispatchMouseEvent(list[i], "rollover", false, -1, o, e);
		}

		if (oldTarget != target) {
			this._dispatchMouseEvent(target, "mouseover", true, -1, o, e);
		}
		
		nextStage&&nextStage._testMouseOver(clear, owner || target && this, eventTarget || isEventTarget && this);
	};

	/**
	 * @method _handleDoubleClick
	 * @protected
	 * @param {MouseEvent} e
	 * @param {Stage} owner Indicates that the event has already been captured & handled by the indicated stage.
	 **/
	p._handleDoubleClick = function(e, owner) {
		var target=null, nextStage=this._nextStage, o=this._getPointerData(-1);
		if (!owner) {
			target = this._getObjectsUnderPoint(o.x, o.y, null, true);
			this._dispatchMouseEvent(target, "dblclick", true, -1, o, e);
		}
		nextStage&&nextStage._handleDoubleClick(e, owner || target && this);
	};

	/**
	 * @method _dispatchMouseEvent
	 * @protected
	 * @param {DisplayObject} target
	 * @param {String} type
	 * @param {Boolean} bubbles
	 * @param {Number} pointerId
	 * @param {Object} o
	 * @param {MouseEvent} [nativeEvent]
	 **/
	p._dispatchMouseEvent = function(target, type, bubbles, pointerId, o, nativeEvent) {
		// TODO: might be worth either reusing MouseEvent instances, or adding a willTrigger method to avoid GC.
		if (!target || (!bubbles && !target.hasEventListener(type))) { return; }
		/*
		// TODO: account for stage transformations?
		this._mtx = this.getConcatenatedMatrix(this._mtx).invert();
		var pt = this._mtx.transformPoint(o.x, o.y);
		var evt = new createjs.MouseEvent(type, bubbles, false, pt.x, pt.y, nativeEvent, pointerId, pointerId==this._primaryPointerID || pointerId==-1, o.rawX, o.rawY);
		*/
		var evt = new createjs.MouseEvent(type, bubbles, false, o.x, o.y, nativeEvent, pointerId, pointerId === this._primaryPointerID || pointerId === -1, o.rawX, o.rawY);
		target.dispatchEvent(evt);
	};


	createjs.Stage = createjs.promote(Stage, "Container");
}());