/**
* EasyDrag 1.3 - Drag & Drop jQuery Plug-in
*
* For usage instructions please visit http://fromvega.com
*
* Copyright (c) 2007 fromvega
*/

(function($){

 // to track if the mouse button is pressed
 var isMouseDown = false;

 // to track the current element being dragged
 var currentElement = null;

 // callback holders
 var dropCallbacks = {};
 var dragCallbacks = {};

 // global position records
 var lastMouseX;
 var lastMouseY;
 var lastElemTop;
 var lastElemLeft;

 // returns the mouse (cursor) current position
 $.getMousePosition = function(e){
 var posx = 0;
 var posy = 0;

 if (!e) var e = window.event;

 if (e.pageX || e.pageY) {
 posx = e.pageX;
 posy = e.pageY;
 }
 else if (e.clientX || e.clientY) {
 posx = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
 posy = e.clientY + document.body.scrollTop + document.documentElement.scrollTop;
 }

 return { 'x': posx, 'y': posy };
 }

 // updates the position of the current element being dragged
 $.updatePosition = function(e) {
 var pos = $.getMousePosition(e);

 var spanX = (pos.x - lastMouseX);
 var spanY = (pos.y - lastMouseY);

 $(currentElement).css("top", (lastElemTop + spanY));
 $(currentElement).css("left", (lastElemLeft + spanX));
 }

 // when the mouse is moved while the mouse button is pressed
 $(document).mousemove(function(e){
 if(isMouseDown){
 // update the position and call the registered function
 $.updatePosition(e);
 if(dragCallbacks[currentElement.id] != undefined){
 dragCallbacks[currentElement.id](e);
 }

 return false;
 }
 });

 // when the mouse button is released
 $(document).mouseup(function(e){
 if(isMouseDown){
 isMouseDown = false;
 if(dropCallbacks[currentElement.id] != undefined){
 dropCallbacks[currentElement.id](e);
 }
 return false;
 }
 });

 // register the function to be called while an element is being dragged
 $.fn.ondrag = function(callback){
 return this.each(function(){
 dragCallbacks[this.id] = callback;
 });
 }

 // register the function to be called when an element is dropped
 $.fn.ondrop = function(callback){
 return this.each(function(){
 dropCallbacks[this.id] = callback;
 });
 }

 // set an element as draggable - allowBubbling enables/disables event bubbling
 $.fn.easydrag = function(allowBubbling, handle_ids){

 return this.each(function(){

 // if no id is defined assign a unique one
 if(undefined == this.id) this.id = 'easydrag'+time();

/* if (handle_ids) {
 // 修改鼠标光标为移动的形状
 for (var i=0; i<handle_ids.length; i++) {
 $("#" + handle_ids[i]).css("cursor", "move");
 }
 } else {
 $(this).css("cursor", "move");
 }
 */
// when an element receives a mouse press
 $(this).mousedown(function(e){
 if (handle_ids) {
 // 判断是否是在拖动某个 handle
 var srcElement;
/* if (e)
 srcElement = e.srcElement;
 else
 srcElement = window.event.srcElement;
 */
 srcElement = e.target;
var exists = false;
 if (srcElement.id != undefined) {
 for (var i=0; i<handle_ids.length; i++) {
 if (handle_ids[i] == srcElement.id) {
 exists = true;
 break;
 }
 }
 }
 if (!exists)
 return false;
 }
 // set it as absolute positioned
 //$(this).css("position", "absolute");

 // set z-index
 //$(this).css("z-index", "10000");

 // update track variables
 isMouseDown = true;
 currentElement = this;

 // retrieve positioning properties
 var pos = $.getMousePosition(e);
 lastMouseX = pos.x;
 lastMouseY = pos.y;

 lastElemTop = this.offsetTop;
 lastElemLeft = this.offsetLeft;

 $.updatePosition(e);

 return allowBubbling ? true : false;
 });
 });
 }

})(jQuery);