/**************************************************
 * 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.
 * 02.22.2007 - Add a Enable and Disable function
 **************************************************/

var Drag = {

    obj : null,

    init : function(o, oRoot, minX, maxX, minY, maxY, bSwapHorzRef, bSwapVertRef, fXMapper, fYMapper)
    {
        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();
        
        o.dragEnabled = true;
    },
    
    Enable : function(o)
    {
			o.dragEnabled = true;
    },
    
    Disable : function (o)
    {
			o.dragEnabled = false;
    },

    start : function(e)
    {
        var o = Drag.obj = this;

        if (o.dragEnabled)
        {
					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;
        if (o.dragEnabled)
        {
					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;
    }
};