JQuery插件让图片旋转任意角度小插件

引入下方的jquery.rotate.js文件，然后通过$("选择器").rotate(角度);可以旋转任意角度，

例如$("#rotate-image").rotate(45);把这句放在$(document).ready(function(){ });中

就是将id为rotate-image的图片旋转45度。

不过，貌似在Chrome中总是不显示。

唉，找了两个小时，才发现Chrome太坑爹了，没法获取图片的长宽。

解决办法是，把$("#rotate-image").rotate(45);放在

$(window).load(function(){ });中，因为在Chrome中图片在执行$(document).ready(function(){ });中的语句时并没有加载完图片，坑爹啊。

另外可以更方便的通过调用$("选择器").rotateRight()和$("选择器").rotateLeft()来分别向右旋转90度和向左旋转90度。

jquery.rotate.js:

jQuery.fn.rotate = function(angle,whence) { 
     var p = this.get(0); 
     
     // 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.round(Math.cos(rotation) * 1000) / 1000; 
     var sintheta = Math.round(Math.sin(rotation) * 1000) / 1000; 
     //alert(costheta+","+sintheta); 
      
     if (document.all && !window.opera) { 
         var canvas = document.createElement('img'); 
     
         canvas. 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. 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); 
 } 
     
 jQuery.fn.rotateRight = function(angle) { 
     this.rotate(angle==undefined?90:angle); 
 } 
     
 jQuery.fn.rotateLeft = function(angle) { 
     this.rotate(angle==undefined?-90:-angle); 
 }