function DrawImage(ImgD,FitWidth,FitHeight){
   var image=new Image();
   image.src=ImgD.src;
   if(image.width>0 && image.height>0){
    flag=true;
    if(image.width/image.height>= FitWidth/FitHeight){
     if(image.width>FitWidth){  
     ImgD.width=FitWidth;
     ImgD.height=(image.height*FitWidth)/image.width;
     }else{
     ImgD.width=image.width;  
     ImgD.height=image.height;
     }
     ImgD.alt="点击图片放大("+image.width+"×"+image.height+")";
     }
    else{
     if(image.height>FitHeight){  
     ImgD.height=FitHeight;
     ImgD.width=(image.width*FitHeight)/image.height;    
     }else{
     ImgD.width=image.width;  
     ImgD.height=image.height;
     }
     ImgD.alt="点击图片放大("+image.width+"×"+image.height+")";
     }
    }
}