/**************************************************
 * dom-drag.js
 * 09.25.2001
 * www.youngpup.net
 **************************************************
 * 10.28.2001 - fixed minor bug where events
 * sometimes fired off the handle, not the root.
 **************************************************/

var Drag = {

	obj: null,

	init: function(o, oRoot, minX, maxX, minY, maxY, bSwapHorzRef, bSwapVertRef, fXMapper, fYMapper) {
		if (o != null) {

			o.onmousedown = Drag.start;

			o.hmode = bSwapHorzRef ? false : true;
			o.vmode = bSwapVertRef ? false : true;

			o.root = oRoot && oRoot != null ? oRoot : o;

			if (o.hmode && isNaN(parseInt(o.root.style.left))) o.root.style.left = "0px";
			if (o.vmode && isNaN(parseInt(o.root.style.top))) o.root.style.top = "0px";
			if (!o.hmode && isNaN(parseInt(o.root.style.right))) o.root.style.right = "0px";
			if (!o.vmode && isNaN(parseInt(o.root.style.bottom))) o.root.style.bottom = "0px";

			o.minX = typeof minX != 'undefined' ? minX : null;
			o.minY = typeof minY != 'undefined' ? minY : null;
			o.maxX = typeof maxX != 'undefined' ? maxX : null;
			o.maxY = typeof maxY != 'undefined' ? maxY : null;

			o.xMapper = fXMapper ? fXMapper : null;
			o.yMapper = fYMapper ? fYMapper : null;

			o.root.onDragStart = new Function();
			o.root.onDragEnd = new Function();
			o.root.onDrag = new Function();
		}
	},

	start: function(e) {
		var o = Drag.obj = this;
		e = Drag.fixE(e);
		var y = parseInt(o.vmode ? o.root.style.top : o.root.style.bottom);
		var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right);
		o.root.onDragStart(x, y);

		o.lastMouseX = e.clientX;
		o.lastMouseY = e.clientY;

		if (o.hmode) {
			if (o.minX != null) o.minMouseX = e.clientX - x + o.minX;
			if (o.maxX != null) o.maxMouseX = o.minMouseX + o.maxX - o.minX;
		} else {
			if (o.minX != null) o.maxMouseX = -o.minX + e.clientX + x;
			if (o.maxX != null) o.minMouseX = -o.maxX + e.clientX + x;
		}

		if (o.vmode) {
			if (o.minY != null) o.minMouseY = e.clientY - y + o.minY;
			if (o.maxY != null) o.maxMouseY = o.minMouseY + o.maxY - o.minY;
		} else {
			if (o.minY != null) o.maxMouseY = -o.minY + e.clientY + y;
			if (o.maxY != null) o.minMouseY = -o.maxY + e.clientY + y;
		}

		document.onmousemove = Drag.drag;
		document.onmouseup = Drag.end;

		return false;
	},

	drag: function(e) {
		e = Drag.fixE(e);
		var o = Drag.obj;

		var ey = e.clientY;
		var ex = e.clientX;
		var y = parseInt(o.vmode ? o.root.style.top : o.root.style.bottom);
		var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right);
		var nx, ny;

		if (o.minX != null) ex = o.hmode ? Math.max(ex, o.minMouseX) : Math.min(ex, o.maxMouseX);
		if (o.maxX != null) ex = o.hmode ? Math.min(ex, o.maxMouseX) : Math.max(ex, o.minMouseX);
		if (o.minY != null) ey = o.vmode ? Math.max(ey, o.minMouseY) : Math.min(ey, o.maxMouseY);
		if (o.maxY != null) ey = o.vmode ? Math.min(ey, o.maxMouseY) : Math.max(ey, o.minMouseY);

		nx = x + ((ex - o.lastMouseX) * (o.hmode ? 1 : -1));
		ny = y + ((ey - o.lastMouseY) * (o.vmode ? 1 : -1));

		if (o.xMapper) nx = o.xMapper(y)
		else if (o.yMapper) ny = o.yMapper(x)

		Drag.obj.root.style[o.hmode ? "left" : "right"] = nx + "px";
		Drag.obj.root.style[o.vmode ? "top" : "bottom"] = ny + "px";
		Drag.obj.lastMouseX = ex;
		Drag.obj.lastMouseY = ey;

		Drag.obj.root.onDrag(nx, ny);
		return false;
	},

	end: function() {
		document.onmousemove = null;
		document.onmouseup = null;
		Drag.obj.root.onDragEnd(parseInt(Drag.obj.root.style[Drag.obj.hmode ? "left" : "right"]),
									parseInt(Drag.obj.root.style[Drag.obj.vmode ? "top" : "bottom"]));
		Drag.obj = null;
	},

	fixE: function(e) {
		if (typeof e == 'undefined') e = window.event;
		if (typeof e.layerX == 'undefined') e.layerX = e.offsetX;
		if (typeof e.layerY == 'undefined') e.layerY = e.offsetY;
		return e;
	}
};