js 实现图片旋转角度
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>图片旋转效果</title>
<meta http-equiv="content-type" content="text/html;charset=gb2312">
<!--把下面代码加到<head>与</head>之间-->
<style type="text/css">
ul{padding:0 15px;}
ul li{padding-bottom:15px;border-bottom:1px dashed #EEE;}
.caption{padding:15px 0 5px;}
.caption input{margin-right:10px;padding:0 10px;}
</style>
<script type="text/javascript">
/*
* www.byzuo.com
* ok!: MSIE 6, 7, 8, Firefox 3.6, chrome 4, Safari 4, Opera 10
* o 旋转图片ID;
* p 选择旋转方向，固定值为'left'或'right';
*/
function rotate(o,p){
var img = document.getElementById(o);
if(!img || !p) return false;
var n = img.getAttribute('step');
if(n== null) n=0;
if(p=='right'){
(n==3)? n=0:n++;
}else if(p=='left'){
(n==0)? n=3:n--;
}
img.setAttribute('step',n);
//MSIE
if(document.all) {
img.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation='+ n +')';
//HACK FOR MSIE 8
switch(n){
case 0:
imgimg.parentNode.style.height = img.height;
break;
case 1:
imgimg.parentNode.style.height = img.width;
break;
case 2:
imgimg.parentNode.style.height = img.height;
break;
case 3:
imgimg.parentNode.style.height = img.width;
break;
}
//DOM
}else{
var c = document.getElementById('canvas_'+o);
if(c== null){
img.style.visibility = 'hidden';
img.style.position = 'absolute';
c = document.createElement('canvas');
c.setAttribute("id",'canvas_'+o);
img.parentNode.appendChild(c);
}
var canvasContext = c.getContext('2d');
switch(n) {
default :
case 0 :
c.setAttribute('width', img.width);
c.setAttribute('height', img.height);
canvasContext.rotate(0 * Math.PI / 180);
canvasContext.drawImage(img, 0, 0);
break;
case 1 :
c.setAttribute('width', img.height);
c.setAttribute('height', img.width);
canvasContext.rotate(90 * Math.PI / 180);
canvasContext.drawImage(img, 0, -img.height);
break;
case 2 :
c.setAttribute('width', img.width);
c.setAttribute('height', img.height);
canvasContext.rotate(180 * Math.PI / 180);
canvasContext.drawImage(img, -img.width, -img.height);
break;
case 3 :
c.setAttribute('width', img.height);
c.setAttribute('height', img.width);
canvasContext.rotate(270 * Math.PI / 180);
canvasContext.drawImage(img, -img.width, 0);
break;
}
}
}
</script>
</head>
<body>
<!--把下面代码加到<body>与</body>之间-->
<ul class="clearfix">
<li>
<div class="caption">
<input type="button" value="turn left" onclick="rotate('pic_1','left')">
<input type="button" value="turn right" onclick="rotate('pic_1','right')">
</div>
<div class="cont">
<img alt="javascript 图片旋转效果" id="pic_1" src="image/girl.jpeg" alt="">
</div>
</li>
</ul>
</body>
</html>
