html5拖拽实现

1.需求

做一个h5正方形的拖拽框

2.分析

使用touchstart,touchmove,touchend这3个事件实现.

需要记录的数据有三组数据，分别是下图的(x0,y0),(x1,y1),(x2,y2)。A点表示最开始的点击位置

3.代码实现

下面是html和css部分，很简单的一部分

<style>
        #outer{
            position: relative;
            width: 300px;
            height: 300px;
            background: green;
        }
        #inner{
            position: absolute;
            left: 0;
            top:0;
            width: 100px;
            height: 100px;

            background: red;
        }
    </style>


<div id="outer">
    <div id="inner">
    </div>
</div>

 

下面是js代码实现部分

记得要引入jq库哦！~

<script src="jquery-1.7.2.min.js"></script>
<script>

var outer =document.getElementById(\'outer\');
var inner =document.getElementById(\'inner\');


var move={
    sLeft:0,
    sTop:0,
    curLeft:0,
    curTop:0,
    startX:0,
    startY:0,
    makeMove:function(e){
        var e= e || window.event;
        var touch =e.changedTouches[0];
        var x=touch.clientX;
        var y=touch.clientY;

        l = x - this.sLeft;
        t = y - this.sTop;

        //边界判断最小值

        l = l<0?0:l;
        t = t<0?0:t;
        //边界判断最da值
        var maxLeft = 300-100;
        var maxTop = 300-100;

        l = l>maxLeft ?maxLeft:l;
        t = t>maxTop?maxTop:t;

        move.curLeft = l;
        move.curTop = t;
        $(\'#inner\').css({
            \'left\':move.curLeft +\'px\',
            \'top\':move.curTop+\'px\'
        })

    }
}
inner.addEventListener(\'touchstart\',function(e){
    //获得初始坐标
    var e= e || window.event;
    var touch =e.changedTouches[0];
    var x=touch.clientX;
    var y=touch.clientY;

    //对象属性赋值
    move.sLeft = x-move.curLeft;
    move.sTop = y-move.curTop;
    move.startX=x;
    move.startY=y;


    $(\'#inner\').css({
        \'left\':move.curLeft+\'px\',
        \'top\':move.curTop+\'px\'
    })
},false);

inner.addEventListener(\'touchmove\',function(e){
    //获得坐标
    var e= e || window.event;
    var touch =e.changedTouches[0];
    var x=touch.clientX;
    var y=touch.clientY;

    //获得偏移的值
    move.makeMove(e);

},false);

inner.addEventListener(\'touchend\',function(e){

},false);

</script>