javascript

Chapter 18: Advanced Techniques
(continued)
event = EventUtil.getEvent(event);
var target = EventUtil.getTarget(event);
//determine the type of event
switch(event.type){
case “mousedown”:
if (target.className.indexOf(“draggable”) > -1){
dragging = target;
diffX = event.clientX - target.offsetLeft;
diffY = event.clientY - target.offsetTop;
dragdrop.fire({type:”dragstart”, target: dragging,
x: event.clientX, y: event.clientY});
}
break;
case “mousemove”:
if (dragging !== null){
//get event
event = EventUtil.getEvent(event);
//assign location
dragging.style.left = (event.clientX - diffX) + “px”;
dragging.style.top = (event.clientY - diffY) + “px”;
//fire custom event
dragdrop.fire({type:”drag”, target: dragging,
x: event.clientX, y: event.clientY});
}
break;
};
}
case “mouseup”:
dragdrop.fire({type:”dragend”, target: dragging,
x: event.clientX, y: event.clientY});
dragging = null;
break;
//public interface
dragdrop.enable = function(){
EventUtil.addHandler(document, “mousedown”, handleEvent);
EventUtil.addHandler(document, “mousemove”, handleEvent);
EventUtil.addHandler(document, “mouseup”, handleEvent);
};
dragdrop.disable = function(){
EventUtil.removeHandler(document, “mousedown”, handleEvent);
EventUtil.removeHandler(document, “mousemove”, handleEvent);
614