PHP利用GB库生成验证码

/**
 *生成验证码
 * @param int $wide 宽度
 * @param int $high 高度
 * @param int $num 位数
 */
 function code($wide=80,$high=60,$num=4){
     //创建画布
     $img = imagecreatetruecolor($wide, $high);
     //设置画布颜色并渲染
     $color = imagecolorallocate($img, rand(128,255), rand(128,255), rand(128,255));
     imagefill($img,0,0,$color);

     //设置干扰元素
     for ($i=0;$i<66;$i++){
         $x = mt_rand(0,$wide);
         $y = mt_rand(0,$high);
         $color = imagecolorallocate($img, rand(128,255), rand(128,255), rand(128,255));
         imagesetpixel($img,$x,$y,$color);
         if($i%6==0){
             $endX = mt_rand(0,$wide);
             $endY = mt_rand(0,$high);
             imageline($img,$x,$y,$endX,$endY,$color);
         }
     }
     //生成随机code
     $string = '123456789ABCDEFG';
     $len = strlen($string)-1;
     $code = '';
     for ($i=0;$i<=$num;$i++){
         $n = mt_rand(0,$len);
         $code.=$string[$n];
     }
     //调试位置并写入
     $fontsize = ceil(($wide-20)/$num);
     $highY = ceil($high/2+$fontsize/2);
     imagettftext($img,$fontsize,0,10,$highY,$color,'E:\phpstudy_pro\WWW\day\1.ttf',$code);

     //告诉浏览器这是个图片
     header("content-type: image/png");
     //保存图片到filename
     imagepng($img);
     //释放资源
     imagedestroy($img);
}

code();