js实现图片旋转的三种方法

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我是靠谱客的博主悲凉自行车，最近开发中收集的这篇文章主要介绍js实现图片旋转的三种方法，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

1 使用jQueryRotate.js实现

示例代码：

复制代码代码如下:

 
<!DOCTYPE html> 
<html> 
<head> 
<title></title> 
<style type="text/css"> 
#div1 { 
width: 800px; 
height: 600px; 
background-color: #ff0; 
position: absolute; 
} 
.imgRotate { 
width: 100px; 
height: 80px; 
position: absolute; 
top: 50%; 
left: 50%; 
margin: -40px 0 0 -50px; 
} 
</style> 
</head> 
<body> 
<div id="div1"> 
<img id="img1" class="imgRotate" src="http://www.uoften.com/uploadfile/2018/0411/20180411012018133.gif" /> 
<input id="input2" type="button" value="btn2"></input> 
</div> 
</body> 
<script type="text/javascript" src="jquery.min.js"></script> 
<script type="text/javascript" src="jQueryRotate.js"></script> 
<script type="text/javascript"> 
var num = 0; 
$("#input2").click(function(){ 
num ++; 
$("#img1").rotate(90*num); 
}); 
</script> 
</html> 

测试结果：chrome下效果正常，旋转后img对象仍为img对象；ie8下效果正常，但旋转后img对象变为下面对象，由于对象变化，若旋转后仍按原来方法获取img对象，则会报js错误。欲获取image对象，可根据class获取。如果图像旋转后，不进行其它操作，则可用此方法。若进行其它操作，如放大、缩小图像，则此方法实现较复杂。

复制代码代码如下:

 
<span ...> 
<rvml:group class="rvml"...> 
<rvml:image class="rvml".../> 
</rvml:group> 
</span> 

2 使用Microsoft提供的Matrix对象

示例代码：

复制代码代码如下:

 
<!DOCTYPE html> 
<html> 
<head> 
<title></title> 
<style type="text/css"> 
#div1 { 
width: 800px; 
height: 600px; 
background-color: #ff0; 
position: absolute; 
} 
.imgRotate { 
width: 100px; 
height: 100px; 
position: absolute; 
top: 50%; 
left: 50%; 
margin: -50px 0 0 -50px; 
} 
#imgRotate { 
width: 100px; 
height: 100px; 
position: absolute; 
top: 50%; 
left: 50%; 
margin: -50px 0 0 -50px; 
} 
</style> 
</head> 
<body> 
<div id="div1"> 
<img id="img1" class="imgRotate" src="http://www.uoften.com/uploadfile/2018/0411/20180411012018133.gif" /> 
<input id="input1" type="button" value="btn1"></input> 
</div> 
</body> 
<script type="text/javascript" src="jquery.min.js"></script> 
<script type="text/javascript"> 
function rotate(id,angle,whence) { 
var p = document.getElementById(id); 

// we store the angle inside the image tag for persistence 
if (!whence) { 
p.angle = ((p.angle==undefined?0:p.angle) + angle) % 360; 
} else { 
p.angle = angle; 
} 

if (p.angle >= 0) { 
var rotation = Math.PI * p.angle / 180; 
} else { 
var rotation = Math.PI * (360+p.angle) / 180; 
} 
var costheta = Math.cos(rotation); 
var sintheta = Math.sin(rotation); 

if (document.all && !window.opera) { 
var canvas = document.createElement('img'); 

canvas.src = p.src; 
canvas.height = p.height; 
canvas.width = p.width; 

canvas.style.filter = "progid:DXImageTransform.Microsoft.Matrix(M11="+costheta+",M12="+(-sintheta)+",M21="+sintheta+",M22="+costheta+",SizingMethod='auto expand')"; 
} else { 
var canvas = document.createElement('canvas'); 
if (!p.oImage) { 
canvas.oImage = new Image(); 
canvas.oImage.src = p.src; 
} else { 
canvas.oImage = p.oImage; 
} 

canvas.style.width = canvas.width = Math.abs(costheta*canvas.oImage.width) + Math.abs(sintheta*canvas.oImage.height); 
canvas.style.height = canvas.height = Math.abs(costheta*canvas.oImage.height) + Math.abs(sintheta*canvas.oImage.width); 

var context = canvas.getContext('2d'); 
context.save(); 
if (rotation <= Math.PI/2) { 
context.translate(sintheta*canvas.oImage.height,0); 
} else if (rotation <= Math.PI) { 
context.translate(canvas.width,-costheta*canvas.oImage.height); 
} else if (rotation <= 1.5*Math.PI) { 
context.translate(-costheta*canvas.oImage.width,canvas.height); 
} else { 
context.translate(0,-sintheta*canvas.oImage.width); 
} 
context.rotate(rotation); 
context.drawImage(canvas.oImage, 0, 0, canvas.oImage.width, canvas.oImage.height); 
context.restore(); 
} 
canvas.id = p.id; 
canvas.angle = p.angle; 
p.parentNode.replaceChild(canvas, p); 
} 

function rotateRight(id,angle) { 
rotate(id,angle==undefined?90:angle); 
} 

function rotateLeft(id,angle) { 
rotate(id,angle==undefined?-90:-angle); 
} 
$("#input1").click(function(){ 
$("img.imgRotate").attr("id","imgRotate"); 
rotateLeft("imgRotate",90); 
$("#imgRotate").attr("top","50%"); 
$("#imgRotate").attr("left","50%"); 
$("#imgRotate").attr("margin","-50px 0 0 -50px"); 
}); 
</script> 
</html> 

测试结果：chrome下效果正常，但旋转后img对象变为canvas对象；ie8下效果正常，旋转后img对象仍为img对象。Matrix()参数较多，使用时需较多计算。

3 使用Microsoft提供的BasicImage对象

示例代码：

复制代码代码如下:

 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 
</head> 
<body> 
<img id="image" src="http://www.uoften.com/uploadfile/2018/0411/20180411012018133.gif" /> 
<input id="input2" type="button" value="btn2"></input> 
</body> 
<script type="text/javascript" src="jquery.min.js"></script> 

<script type="text/javascript"> 
var num = 0; 
$("#input2").click(function(){ 
num = (num + 1) % 4; 
document.getElementById('image').style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation='+num+')'; 
}); 
</script> 
</html> 

测试结果：chrome下不能旋转；ie8下效果正常，旋转后img对象仍为img对象。BasicImage()仅一个参数。

查看这三种方法的代码会发现，本质上是一种解决方案：chrome下使用canvas对象实现，ie8下使用VML或者Matrix()或BasicImage()实现。本人近期改造一个组件：其中涉及到旋转、放大图片，由于jQueryRotate.js在ie8下会生成一个新的对象，导致放大图片前选择图片时，需要进行特殊处理。后决定对chrome、ie8分开处理，chrome下使用jQueryRotate实现，ie8下使用BasicImage()实现，保证了代码的简洁性和可读性。