在开发拖动效果时,有一个非常恼人的地方要处理时,就是拖动时,文本被选中蓝色一片,容易造成用户分心,有损用户体验。通常我们是用下面代码来清理selection:
if(window.getSelection){//w3c window.getSelection().removeAllRanges(); }else if(document.selection){ document.selection.empty();//IE }
但这东西在谷歌浏览器中,快速拖动还是会出现蓝色(人家的渲染效率就是高),另外,每拖动一像素就清理一次,这频繁的调用对于一些旧式浏览器可不是好事。最近研究CSS3,发现user-select这个东西,终于搞定这问题了。
首先,我们要检测浏览器是否支持它,FF与webkit系浏览器是支持,IE9与opera11是不支持。
//by 司徒正美 //http://www.cnblogs.com/rubylouvre/archive/2011/03/28/1998223.html var getStyleName= (function(){ var prefixes = ['', '-ms-','-moz-', '-webkit-', '-khtml-', '-o-']; var reg_cap = /-([a-z])/g; function getStyleName(css, el) { el = el || document.documentElement; var style = el.style,test; for (var i=0, l=prefixes.length; i对于不支持的浏览器,我们可以借助它们的一些私有属性与事件,如unselectable,onselectstart。当拖动时,我们把它们绑定在文档对象上就行了。
if(typeof userSelect === "string"){ return document.documentElement.style[userSelect] = "none"; } document.unselectable = "on"; document.onselectstart = function(){ return false; }当拖动结束时,我们再让文档变回可选择模式,注意一些值的变化,都是很奇特的名字。
if(typeof userSelect === "string"){ return document.documentElement.style[userSelect] = "text"; } document.unselectable = "off"; document.onselectstart = null;具体应用见下:
//精确获取样式
var getStyle = document.defaultView ? function(el,style){
return document.defaultView.getComputedStyle(el, null).getPropertyValue(style)
} : function(el,style){
style = style.replace(/\-(\w)/g, function($, $1){
return $1.toUpperCase();
});
return el.currentStyle[style];
}
var dragManager = {
y:0,dragStart:function(e){
e = e || event;
var handler = e.target || e.srcElement;
if(handler.nodeName === "TD"){
handler = handler.parentNode;
dragManager.handler = handler;
if(!handler.getAttribute("data-background")){
handler.setAttribute("data-background",getStyle(handler,"background-color"))
}
//显示为可移动的状态
handler.style.backgroundColor = "#ccc";
handler.style.cursor = "move";
dragManager.y = e.clientY;
//★★★★★★★★★★★★★★★★★★★★
if(typeof userSelect === "string"){
return document.documentElement.style[userSelect] = "none";
}
document.unselectable = "on";
document.onselectstart = function(){
return false;
}
//★★★★★★★★★★★★★★★★★★★★
}
},
draging:function(e){//mousemove时拖动行
var handler = dragManager.handler;
if(handler){
e = e || event;var y = e.clientY;
var down = y > dragManager.y;//是否向下移动
var tr = document.elementFromPoint(e.clientX,e.clientY);
if(tr && tr.nodeName == "TD"){
tr = tr.parentNode
dragManager.y = y;
if( handler !== tr){
tr.parentNode.insertBefore(handler, (down ? tr.nextSibling : tr));
}
};
}
},
dragEnd:function(){
var handler = dragManager.handler
if (handler) {
handler.style.backgroundColor = handler.getAttribute("data-background");
handler.style.cursor = "default";
dragManager.handler = null;}
//★★★★★★★★★★★★★★★★★★★★
if(typeof userSelect === "string"){
return document.documentElement.style[userSelect] = "text";
}
document.unselectable = "off";
document.onselectstart = null;
//★★★★★★★★★★★★★★★★★★★★
},
main:function(el){
addEvent(el,"mousedown",dragManager.dragStart);
addEvent(document,"mousemove",dragManager.draging);
addEvent(document,"mouseup",dragManager.dragEnd);}
}
var el = document.getElementById("table");
dragManager.main(el);}
</script>
<style>
.table{
width:60%;
border: 1px solid red;
border-collapse: collapse;
}
.table td{
border: 1px solid red;
height: 20px;
}
</style>
</head>
<body>
<h1>行拖动 by 司徒正美</h1>
<table id="table" class="table">
<tbody>
<tr>
<td>1</td>
<td>One</td>
<td>dom.require</td>
</tr>
<tr id="2" >
<td class="2">2</td>
<td>Two</td>
<td>ControlJS </td>
</tr>
<tr id="3" >
<td class="3">3</td>
<td>Three</td>
<td>HeadJS</td>
</tr>
<tr id="4" >
<td class="4">4</td>
<td>Four</td>
<td>LAB.js</td>
</tr>
<tr id="5" >
<td class="5">5</td>
<td>Five</td>
<td>$script.js</td>
</tr>
<tr id="6" >
<td class="6">6</td>
<td>Six</td>
<td>NBL.js</td>
</tr>
</tbody>
</table>
</body>
</html>