Mover.js

define(["dojo/_base/lang", "dcl/dcl", "dojo/on", "dojo/_base/event", "dpointer/events"],
	function (lang, dcl, on, event) {
		return dcl(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: 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 = on(d, "pointermove", lang.hitch(this, "onFirstMove"));
				this.events = [
					on(d, "pointermove", lang.hitch(this, "onMouseMove")),
					on(d, "pointerup", lang.hitch(this, "destroy")), // cancel text selection and text dragging
					on(d, "dragstart", lang.hitch(event, "stop")), on(d, "selectstart", lang.hitch(event, "stop")),
					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;
				event.stop(e);
			},
			// utilities
			onFirstMove: function () {
				// summary:
				//		it is meant to be called only once
				this.host.onFirstMove(this);
				this.events.pop().remove();
			},
			destroy: function () {
				// summary:
				//		stops the move, deletes all references, so the object can be garbage-collected
				this.events.forEach(function (handle) {
					handle.remove();
				});
				// undo global settings
				var h = this.host;
				if (h && h.onMoveStop) {
					h.onMoveStop(this);
				}
				// destroy objects
				this.events = this.shape = null;
			}
		});
	});