var DragHandler = {
// private property.
_oElem : null,
// public method. Attach drag handler to an element.
attach : function(oElem) {
oElem.onmousedown = DragHandler._dragBegin;
// callbacks
oElem.dragBegin = new Function();
oElem.drag = new Function();
oElem.dragEnd = new Function();
return oElem;
},
// private method. Begin drag process.
_dragBegin : function(e) {
var oElem = DragHandler._oElem = this;
if (isNaN(parseInt(oElem.style.left))) { oElem.style.left = '0px'; }
if (isNaN(parseInt(oElem.style.top))) { oElem.style.top = '0px'; }
var x = parseInt(oElem.style.left);
var y = parseInt(oElem.style.top);
e = e ? e : window.event;
oElem.mouseX = e.clientX;
oElem.mouseY = e.clientY;
oElem.dragBegin(oElem, x, y);
document.onmousemove = DragHandler._drag;
document.onmouseup = DragHandler._dragEnd;
return false;
},
// private method. Drag (move) element.
_drag : function(e) {
var oElem = DragHandler._oElem;
var x = parseInt(oElem.style.left);
var y = parseInt(oElem.style.top);
e = e ? e : window.event;
oElem.style.left = x + (e.clientX - oElem.mouseX) + 'px';
oElem.style.top = y + (e.clientY - oElem.mouseY) + 'px';
oElem.mouseX = e.clientX;
oElem.mouseY = e.clientY;
oElem.drag(oElem, x, y);
return false;
},
// private method. Stop drag process.
_dragEnd : function() {
var oElem = DragHandler._oElem;
var x = parseInt(oElem.style.left);
var y = parseInt(oElem.style.top);
oElem.dragEnd(oElem, x, y);
document.onmousemove = null;
document.onmouseup = null;
DragHandler._oElem = null;
}
}
