在一些有弹出框的页面，会经常用到拖拽效果来增加用户体验，避免因弹出框遮挡一些元素。如果用原生的js来写的话，js兼容性很不好控制，经常由于浏览器事件的不统一而影响效果，今天给大家介绍一个拖拽插件easydrag,EasyDrag可以指定可拖动的区域,一个setHandler搞定,不错开源是个好东西,只需要一行代码便可轻松在主流浏览器上
使用方法示例：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Easydrag</title>
<script src="js/jquery.min.js"></script>
<script src="js/jquery.easydrag.js"></script>
<script >
$(document).ready ( function(){
$("#divPanel").easydrag();
$("#divPanel").setHandler("divTitle");
});
</script>
</head>
<body>
<form id="form1" runat="server">
使用标题进行拖拽
<div id="divPanel" style="width:300px;height:300px;background:white;border:1px solid #000000;position:absolute;left:5px;top:50px" >
<div id="divTitle" style="width:100%;height:25px;background:lavender"> Title</div>
<div style="width:100%"></div>
</div>
</form>
</body>
</html>
你可以点击这里下载示例
easydrag源代码：
/**
* EasyDrag 1.5 - Drag & Drop jQuery Plug-in
*
* Thanks for the community that is helping the improvement
* of this little piece of code.
*
* For usage instructions please visit http://fromvega.com/scripts
*/
(function($){
// 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 = {};
// bubbling status
var bubblings = {};
// global position records
var lastMouseX;
var lastMouseY;
var lastElemTop;
var lastElemLeft;
// track element dragStatus
var dragStatus = {};
// if user is holding any handle or not
var holdingHandler = false;
// 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 && dragStatus[currentElement.id] != ‘false‘){
// update the position and call the registered function
$.updatePosition(e);
if(dragCallbacks[currentElement.id] != undefined){
dragCallbacks[currentElement.id](e, currentElement);
}
return false;
}
});
// when the mouse button is released
$(document).mouseup(function(e){
if(isMouseDown && dragStatus[currentElement.id] != ‘false‘){
isMouseDown = false;
if(dropCallbacks[currentElement.id] != undefined){
dropCallbacks[currentElement.id](e, currentElement);
}
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;
});
};
// disable the dragging feature for the element
$.fn.dragOff = function(){
return this.each(function(){
dragStatus[this.id] = ‘off‘;
});
};
// enable the dragging feature for the element
$.fn.dragOn = function(){
return this.each(function(){
dragStatus[this.id] = ‘on‘;
});
};
// set a child element as a handler
$.fn.setHandler = function(handlerId){
return this.each(function(){
var draggable = this;
// enable event bubbling so the user can reach the handle
bubblings[this.id] = true;
// reset cursor style
$(draggable).css("cursor", "");
// set current drag status
dragStatus[draggable.id] = "handler";
// change handle cursor type
$("#"+handlerId).css("cursor", "move");
// bind event handler
$("#"+handlerId).mousedown(function(e){
holdingHandler = true;
$(draggable).trigger(‘mousedown‘, e);
});
// bind event handler
$("#"+handlerId).mouseup(function(e){
holdingHandler = false;
});
});
}
// set an element as draggable - allowBubbling enables/disables event bubbling
$.fn.easydrag = function(allowBubbling){
return this.each(function(){
// if no id is defined assign a unique one
if(undefined == this.id || !this.id.length) this.id = "easydrag"+(new Date().getTime());
// save event bubbling status
bubblings[this.id] = allowBubbling ? true : false;
// set dragStatus
dragStatus[this.id] = "on";
// change the mouse pointer
$(this).css("cursor", "move");
// when an element receives a mouse press
$(this).mousedown(function(e){
// just when "on" or "handler"
if((dragStatus[this.id] == "off") || (dragStatus[this.id] == "handler" && !holdingHandler))
return bubblings[this.id];
// set it as absolute positioned
$(this).css("position", "absolute");
// set z-index
$(this).css("z-index", parseInt( new Date().getTime()/1000 ));
// 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 bubblings[this.id];
});
});
};
})(jQuery);