/**

  * Created by Administrator on 2014/6/5 0005.  Base-drag 基于Base库的拖拽插件  tags为你要拖拽的元素参数， 数组形式传入

  */

 $().extend('drag', function () {

     var tags = arguments;

     for (var i = 0; i < this.elements.length; i ++) {

         addEvent(this.elements[i], 'mousedown', function (e) {

             if (trim(this.innerHTML).length == 0) e.preventDefault();

             var _this = this;

             var diffX = e.clientX - _this.offsetLeft;

             var diffY = e.clientY - _this.offsetTop;

             //自定义拖拽区域

             var flag = false;

             for (var i = 0; i < tags.length; i ++) {

                 if (e.target == tags[i]) {

                     flag = true;                    //只要有一个是true，就立刻返回

                     break;

                 }

             }

             if (flag) {

                 addEvent(document, 'mousemove', move);

                 addEvent(document, 'mouseup', up);

             } else {

                 removeEvent(document, 'mousemove', move);

                 removeEvent(document, 'mouseup', up);

             }

             function move(e) {

                 var left = e.clientX - diffX;

                 var top = e.clientY - diffY;

                 if (left < 0) {

                     left = 0;

                 } else if (left <= getScroll().left) {

                     left = getScroll().left;

                 } else if (left > getInner().width + getScroll().left - _this.offsetWidth) {

                     left = getInner().width + getScroll().left - _this.offsetWidth;

                 }

                 if (top < 0) {

                     top = 0;

                 } else if (top <= getScroll().top) {

                     top = getScroll().top;

                 } else if (top > getInner().height + getScroll().top - _this.offsetHeight) {

                     top = getInner().height + getScroll().top - _this.offsetHeight;

                 }

                 _this.style.left = left + 'px';

                 _this.style.top = top + 'px';

                 if (typeof _this.setCapture != 'undefined') {

                     _this.setCapture();

                 }

             }

             function up() {

                 removeEvent(document, 'mousemove', move);

                 removeEvent(document, 'mouseup', up);

                 if (typeof _this.releaseCapture != 'undefined') {

                     _this.releaseCapture();

                 }

             }

         });

     }

     return this;

 });