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();
        },

        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;
        }
};