dojo.provide("dojox.gfx.Mover");

dojo.declare("dojox.gfx.Mover", null, {
	constructor: function(shape, e, host){
		// summary: an object, which makes a shape follow the mouse,
		//	used as a default mover, and as a base class for custom movers
		// shape: dojox.gfx.Shape: a shape object to be moved
		// e: Event: a mouse event, which started the move;
		//	only clientX and clientY properties are used
		// host: Object?: object which implements the functionality of the move,
		//	 and defines proper events (onMoveStart and onMoveStop)
		this.shape = shape;
		this.lastX = e.clientX
		this.lastY = e.clientY;
		var h = this.host = host, d = document,
			firstEvent = dojo.connect(d, "onmousemove", this, "onFirstMove");
		this.events = [
			dojo.connect(d, "onmousemove", this, "onMouseMove"),
			dojo.connect(d, "onmouseup",   this, "destroy"),
			// cancel text selection and text dragging
			dojo.connect(d, "ondragstart",   dojo, "stopEvent"),
			dojo.connect(d, "onselectstart", dojo, "stopEvent"),
			firstEvent
		];
		// notify that the move has started
		if(h && h.onMoveStart){
			h.onMoveStart(this);
		}
	},
	// mouse event processors
	onMouseMove: function(e){
		// summary: event processor for onmousemove
		// e: Event: mouse event
		var x = e.clientX;
		var y = e.clientY;
		this.host.onMove(this, {dx: x - this.lastX, dy: y - this.lastY});
		this.lastX = x;
		this.lastY = y;
		dojo.stopEvent(e);
	},
	// utilities
	onFirstMove: function(){
		// summary: it is meant to be called only once
		this.host.onFirstMove(this);
		dojo.disconnect(this.events.pop());
	},
	destroy: function(){
		// summary: stops the move, deletes all references, so the object can be garbage-collected
		dojo.forEach(this.events, dojo.disconnect);
		// undo global settings
		var h = this.host;
		if(h && h.onMoveStop){
			h.onMoveStop(this);
		}
		// destroy objects
		this.events = this.shape = null;
	}
});