jquery简单的拖动效果实现原理及示例
代码如下:
<!doctype html>
<html>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>简单拖曵原理实例</title>
<style type="text/css">
#drag{width:400px;height:300px;background:url(http://upload.yxgz.cn/uploadfile/2009/0513/20090513052611873.jpg);cursor:move;position:absolute;top:100px;left:100px;border:solid 1px #ccc;}
h2{color:#fff;background: none repeat scroll 0 0 rgba(16, 90, 31, 0.7);color:#ffffff;height:40px;line-height:40px;margin:0;}
</style>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js" type="text/javascript"></script>
<script type="text/javascript">
$(function(){
/*--------------拖曳效果----------------
*原理：标记拖曳状态dragging ,坐标位置ix, iy
* mousedown:fn(){dragging = true, 记录起始坐标位置，设置鼠标捕获}
* mouver:fn(){判断如果dragging = true, 则当前坐标位置 - 记录起始坐标位置，绝对定位的元素获得差值}
* mouseup:fn(){dragging = false, 释放鼠标捕获，防止冒泡}
*/
var dragging = false;
var ix, iy;
$("#drag").mousedown(function(e) {
dragging = true;
ix = e.clientx - this.offsetleft;
iy = e.clienty - this.offsettop;
this.setcapture && this.setcapture();
return false;
});
document.onmousemove = function(e) {
if (dragging) {
var e = e || window.event;
var ox = e.clientx - ix;
var oy = e.clienty - iy;
$("#drag").css({"left":ox + "px", "top":oy + "px"});
return false;
}
};
$(document).mouseup(function(e) {
dragging = false;
$("#drag")[0].releasecapture();
e.cancelbubble = true;
})
})
</script>
</head>
<body>
<p id="drag">
<h2>来拖动我啊</h2>
</p>
</body>
</html>
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