原生JS实现图片拖拽移动与缩放

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
#box {
width: 100px;
height: 100px;
background-color: aquamarine;
position: absolute;
}
#father {
width: 600px;
height: 500px;
background-color: rgb(226, 117, 184);
position: relative;
}
img {
width: 100%;
height: 100%;
cursor: move;
}
#scale {
width: 10px;
height: 10px;
overflow: hidden;
cursor: se-resize;
position: absolute;
right: 0;
bottom: 0;
background-color: rgb(122, 191, 238);
}
</style>

</head>
<body>
<div id="father">
<div id="box">
<img src="http://img4.imgtn.bdimg.com/it/u=4245161611,1195625695&fm=27&gp=0.jpg"/>
<div id="scale"></div>
</div>
</div>
<script type="text/javascript">
// box是装图片的容器,fa是图片移动缩放的范围,scale是控制缩放的小图标
var box = document.getElementById("box");
var fa = document.getElementById('father');
var scale = document.getElementById("scale");
// 图片移动效果
box.onmousedown=function(ev) {
var oEvent = ev;
// 浏览器有一些图片的默认事件,这里要阻止
oEvent.preventDefault();
var disX = oEvent.clientX - box.offsetLeft;
var disY = oEvent.clientY - box.offsetTop;
fa.onmousemove=function (ev) {
oEvent = ev;
oEvent.preventDefault();
var x = oEvent.clientX -disX;
var y = oEvent.clientY -disY;

// 图形移动的边界判断
x = x <= 0 ? 0 : x;
x = x >= fa.offsetWidth-box.offsetWidth ? fa.offsetWidth-box.offsetWidth : x;
y = y <= 0 ? 0 : y;
y = y >= fa.offsetHeight-box.offsetHeight ? fa.offsetHeight-box.offsetHeight : y;
box.style.left = x + 'px';
box.style.top = y + 'px';
}
// 图形移出父盒子取消移动事件,防止移动过快触发鼠标移出事件,导致鼠标弹起事件失效
fa.onmouseleave = function () {
fa.onmousemove=null;
fa.onmouseup=null;
}
// 鼠标弹起后停止移动
fa.onmouseup=function() {
fa.onmousemove=null;
fa.onmouseup=null;
}
}
// 图片缩放效果
scale.onmousedown = function (e) {
// 阻止冒泡,避免缩放时触发移动事件
e.stopPropagation();
e.preventDefault();
var pos = {
'w': box.offsetWidth,
'h': box.offsetHeight,
'x': e.clientX,
'y': e.clientY
};
fa.onmousemove = function (ev) {
ev.preventDefault();
// 设置图片的最小缩放为30*30
var w = Math.max(30, ev.clientX - pos.x + pos.w)
var h = Math.max(30,ev.clientY - pos.y + pos.h)
// console.log(w,h)

// 设置图片的最大宽高
w = w >= fa.offsetWidth-box.offsetLeft ? fa.offsetWidth-box.offsetLeft : w
h = h >= fa.offsetHeight-box.offsetTop ? fa.offsetHeight-box.offsetTop : h
box.style.width = w + 'px';
box.style.height = h + 'px';
// console.log(box.offsetWidth,box.offsetHeight)
}
fa.onmouseleave = function () {
fa.onmousemove=null;
fa.onmouseup=null;
}
fa.onmouseup=function() {
fa.onmousemove=null;
fa.onmouseup=null;
}
}

</script>
</body>
</html>

来源：oschina

链接：https://my.oschina.net/u/4399738/blog/3700568

标签

javascript

aquamarine