Question

我遵循本教程http://www.ajaxblender.com/howto-rotate-image-using-javascript-canvas.html，本教程仅适用于单个图像。多个图像怎么样？任何想法？

我有这样的javascript代码：

 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;
        }
    }
}

和我的html一样：

<div><!-- my html code -->
        <img src="image/a.png" 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&deg;</a>
        <a href="javascript:;" id="rotate180">180&deg;</a>
        <a href="javascript:;" id="rotate270">270&deg;</a>
    </p>

这在单张图片中运行良好，是否可以为多张图片运行此操作？我该怎么办？

如何用javascript旋转多个图像？

0 个答案: