javascript----图片旋转
javaxp微博中的图片旋转我就是参看下面的代码做的：
说明：图片的旋转都是通过操作画布(canvas),但是IE和其他浏览器不一样的地方在于IE通过filter操作，其他浏览器直接改变其属性值就可以了。
<!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" />
<title>JavaScript Demos - Rotate Image using Canvas</title>
<script type="text/javascript" src="jquery-1.8.2.min.js"></script>
<script type="text/javascript">
var img = null, canvas = null;
$(document).ready(function(){
// Initialize image and canvas
img = document.getElementById('image');
canvas = document.getElementById('canvas');
if(!canvas || !canvas.getContext){
canvas.parentNode.removeChild(canvas);
} else {
img.style.position = 'absolute';
img.style.visibility = 'hidden';
}
rotateImage(0);
// Handle clicks for control links
$('#resetImage').click(function(){ rotateImage(0); });
$('#rotate90').click(function(){ rotateImage(90); });
$('#rotate180').click(function(){ rotateImage(180); });
$('#rotate270').click(function(){ rotateImage(270); });
});
function rotateImage(degree)
{
if(document.getElementById('canvas')){
var cContext = canvas.getContext('2d');
var cw = img.width, ch = img.height, cx = 0, cy = 0;
// Calculate new canvas size and x/y coorditates for image
switch(degree){
case 90:
cw = img.height;
ch = img.width;
cy = img.height * (-1);
break;
case 180:
cx = img.width * (-1);
cy = img.height * (-1);
break;
case 270:
cw = img.height;
ch = img.width;
cx = img.width * (-1);
break;
}
// Rotate image
canvas.setAttribute('width', cw);
canvas.setAttribute('height', ch);
cContext.rotate(degree * Math.PI / 180);
cContext.drawImage(img, cx, cy);
} else {
// Use DXImageTransform.Microsoft.BasicImage filter for MSIE
switch(degree){
case 0: image.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation=0)'; break;
case 90: image.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation=1)'; break;
case 180: image.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation=2)'; break;
case 270: image.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation=3)'; break;
}
}
}
</script>
<style type="text/css">
</style>
</head>
<body>
<div id="page">
<h1>How to Rotate Images using JavaScript</h1>
<div>
<img src="1.jpg" alt="" id="image" />
<canvas id="canvas"></canvas>
</div>
<p>
<strong>Rotate Image: </strong>
<a href="javascript:;" id="resetImage">Reset Image</a>
<a href="javascript:;" id="rotate90">90°</a>
<a href="javascript:;" id="rotate180">180°</a>
<a href="javascript:;" id="rotate270">270°</a>
</p>
</body>
</html>