﻿function addEventSimple(obj,evt,fn) {
	if (obj.addEventListener)
		obj.addEventListener(evt,fn,false);
	else if (obj.attachEvent)
		obj.attachEvent('on'+evt,fn);
}

function removeEventSimple(obj,evt,fn) {
	if (obj.removeEventListener)
		obj.removeEventListener(evt,fn,false);
	else if (obj.detachEvent)
		obj.detachEvent('on'+evt,fn);
}
var dragDrop = {
	keyHTML: '<a href="#" class="keyLink">#</a>',
	keySpeed: 10, // pixels per keypress event
	initialMouseX: undefined,
	initialMouseY: undefined,
	startX: undefined,
	startY: undefined,
	dXKeys: undefined,
	dYKeys: undefined,
	draggedObject: undefined,
	initElement: function (element) {
		if (typeof element == 'string')
			element = document.getElementById(element);
		element.onmousedown = dragDrop.startDragMouse;
		element.innerHTML += dragDrop.keyHTML;
		var links = element.getElementsByTagName('a');
		var lastLink = links[links.length-1];
		lastLink.relatedElement = element;
		lastLink.onclick = dragDrop.startDragKeys;
	},
	startDragMouse: function (e) {
		dragDrop.startDrag(this);
		var evt = e || window.event;
		dragDrop.initialMouseX = evt.clientX;
		dragDrop.initialMouseY = evt.clientY;
		addEventSimple(document,'mousemove',dragDrop.dragMouse);
		addEventSimple(document,'mouseup',dragDrop.releaseElement);
		return false;
	},
	startDragKeys: function () {
		dragDrop.startDrag(this.relatedElement);
		dragDrop.dXKeys = dragDrop.dYKeys = 0;
		addEventSimple(document,'keydown',dragDrop.dragKeys);
		addEventSimple(document,'keypress',dragDrop.switchKeyEvents);
		this.blur();
		return false;
	},
	startDrag: function (obj) {
		if (dragDrop.draggedObject)
			dragDrop.releaseElement();
		dragDrop.startX = obj.offsetLeft;
		dragDrop.startY = obj.offsetTop;
		dragDrop.draggedObject = obj;
		obj.className += ' dragged';
	},
	dragMouse: function (e) {
		var evt = e || window.event;
		var dX = evt.clientX - dragDrop.initialMouseX;
		var dY = evt.clientY - dragDrop.initialMouseY;
		dragDrop.setPosition(dX,dY);
		return false;
	},
	dragKeys: function(e) {
		var evt = e || window.event;
		var key = evt.keyCode;
		switch (key) {
			case 37:	// left
			case 63234:
				dragDrop.dXKeys -= dragDrop.keySpeed;
				break;
			case 38:	// up
			case 63232:
				dragDrop.dYKeys -= dragDrop.keySpeed;
				break;
			case 39:	// right
			case 63235:
				dragDrop.dXKeys += dragDrop.keySpeed;
				break;
			case 40:	// down
			case 63233:
				dragDrop.dYKeys += dragDrop.keySpeed;
				break;
			case 13: 	// enter
			case 27: 	// escape
				dragDrop.releaseElement();
				return false;
			default:
				return true;
		}
		dragDrop.setPosition(dragDrop.dXKeys,dragDrop.dYKeys);
		if (evt.preventDefault) // also solves problem in Saf; keypress part of default ???
			evt.preventDefault();
		return false;
	},
	setPosition: function (dx,dy) {
		dragDrop.draggedObject.style.left = dragDrop.startX + dx + 'px';
		dragDrop.draggedObject.style.top = dragDrop.startY + dy + 'px';
	},
	switchKeyEvents: function () {

		// for Opera and Safari 1.3

		removeEventSimple(document,'keydown',dragDrop.dragKeys);
		removeEventSimple(document,'keypress',dragDrop.switchKeyEvents);
		addEventSimple(document,'keypress',dragDrop.dragKeys);
	},
	releaseElement: function() {
		removeEventSimple(document,'mousemove',dragDrop.dragMouse);
		removeEventSimple(document,'mouseup',dragDrop.releaseElement);
		removeEventSimple(document,'keypress',dragDrop.dragKeys);
		removeEventSimple(document,'keypress',dragDrop.switchKeyEvents);
		removeEventSimple(document,'keydown',dragDrop.dragKeys);
		dragDrop.draggedObject.className = dragDrop.draggedObject.className.replace(/dragged/,'');
		dragDrop.draggedObject = null;
	}
}
