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javascript—-图片旋转

2016年11月18日 ⁄ 综合 ⁄ 共 2388字 ⁄ 字号 评论关闭

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>

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