jq拖拽插件

(function ($) {
var move = false; //标记控件是否处于被拖动状态
var dragOffsetX = 0; //控件左边界和鼠标X轴的差
var dragOffsetY = 0; //控件上边界和鼠标Y轴的差
var dragObj = null; //用于存储当前对象

$.fn.mydrag = function () {
dragObj = this;

this.mousedown(function (e) {
move = true;

//获取鼠标和该控件的位置偏移量，并存入全局变量供后续调用
dragOffsetX = e.clientX - e.currentTarget.offsetLeft;
dragOffsetY = e.clientY - e.currentTarget.offsetTop;
});

$(document).mousemove(function (e) {
if (move) {
//不断获取鼠标新的坐标，并计算出控件的新坐标
var newX = e.clientX - dragOffsetX;
var newY = e.clientY - dragOffsetY;

//边界控制，document.documentElement.clientWidth：可见区域宽度 document.documentElement.clientHeight：可见区域高度
newX = newX < 0 ? 0 : newX;
newY = newY < 0 ? 0 : newY;
newX = newX > (document.documentElement.clientWidth - dragObj.outerWidth()) ? (document.documentElement.clientWidth - dragObj.outerWidth()) : newX;
newY = newY > (document.documentElement.clientHeight - dragObj.outerHeight()) ? (document.documentElement.clientHeight - dragObj.outerHeight()) : newY;

//把新的坐标重新赋值给控件
dragObj.css({ left: newX + "px", top: newY + "px", position: 'absolute' });
}
});

$(document).mouseup(function () {
if (move) {
move = false;
}
});
};
})(jQuery);