实现dom元素拖动

本文主要写一下如何实现dom元素拖动,目前使用jquery库实现之。

主要的注释附在代码中,大家可以根据代码画一个小的窗口模型图,以便于理解。

 1 <!DOCTYPE html>
 2 <html>
 3 <head>
 4     <meta charset="utf-8">
 5     <title>实现dom元素拖动</title>
 6     <style>
 7         .dialog {
 8             position: absolute;
 9             top: 0;
10             left: 0;
11             width: 500px;
12             height: 400px;
13             background-color: blue;
14         }
15     </style>
16     <script src="js/jquery-1.7.2.js"></script>
17 </head>
18 <body>
19     <div class="dialog dialog-drag">拖动</div>
20     <script>
21         (function($) {
22             var windowWidth,
23                 windowHeight,
24                 mouseToDialogX,
25                 mouseToDialogY,
26                 dialogWidth,
27                 dialogHeight;
28             var $target,
29                 $doc = $(document);
30             var _move = function(e) {
31                 var nowTop,
32                     nowLeft,
33                     pageX = e.pageX,
34                     pageY = e.pageY;
35                 // top
36                 // 界限值:当对话框拖动到上边界时,将top置为0
37                 if (pageY - mouseToDialogY < 0) {
38                     nowTop = 0;
39                 } 
40                 // 界限值:当对话框拖动到下边界时,将top置为(窗口高度-对画框高度),即将对话框底部与页面平齐
41                 else if (dialogHeight + (pageY - mouseToDialogY) > windowHeight) {
42                     nowTop = windowHeight - dialogHeight;
43                 } 
44                 // 正常值:鼠标纵向坐标-鼠标纵向坐标与对话框上边缘的距离
45                 else {
46                     nowTop = pageY - mouseToDialogY;
47                 }
48                 // left - 解释同上
49                 if (pageX - mouseToDialogX < 0) {
50                     nowLeft = 0;
51                 } else if (dialogWidth + (pageX - mouseToDialogX) > windowWidth) {
52                     nowLeft = windowWidth - dialogWidth;
53                 } else {
54                     nowLeft = pageX - mouseToDialogX;
55                 }
56                 $target.css({
57                     left: nowLeft,
58                     top: nowTop
59                 });
60             };
61             // 拖动开始
62             $doc.on('mousedown', '.dialog-drag', function (e) {
63                 var $this = $(this),
64                     $win = $(window);
65                 $target = $this;
66                 windowWidth = $win.width();
67                 windowHeight = $win.height();
68                 mouseToDialogX = e.pageX - $this.offset().left;
69                 mouseToDialogY = e.pageY - $this.offset().top;
70                 dialogWidth = $this.width();
71                 dialogHeight = $this.height();
72                 // 只有对话框拖动时,才会有mousemove事件
73                 $(document).on('mousemove', _move);
74             });
75             // 拖动结束
76             $doc.on('mouseup', '.dialog-drag', function (e) {
77                 $target = null;
78                 // 当拖动结束时, 解绑mousemove事件
79                 $(document).off('mousemove', _move);
80             });
81         })(jQuery);
82         
83     </script>
84 </body>
85 </html>

 

posted @ 2014-11-03 21:38  金广国  阅读(2837)  评论(0编辑  收藏  举报