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>