PHP生成图形验证码

    function code($width = 100, $height = 32, $font_size = 13, $code_len = 4, $line_num = 5, $font = './ttf/ARIALUNI.TTF', $interference = 2,$verifyName = 'code'){
        $font=realpath($font);
        $image = imagecreatetruecolor($width, $height);
        $image_color = imagecolorallocate($image,mt_rand(157,255), mt_rand(157,255), mt_rand(157,255));
        imagefilledrectangle($image,0,$height,$width,0,$image_color);
        $x = $width/$code_len;
        $codeStrs = '';
        for($i = 0; $i<$code_len;$i++){
            $str = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
            $font_color = imagecolorallocate($image,mt_rand(0,156),mt_rand(0,156),mt_rand(0,156));
            $codeStrs .= $codeStr = utf8_encode($str[mt_rand(0,strlen($str)-1)]);

            imagettftext($image,$font_size,mt_rand(-30,30),$x*$i+mt_rand(1,3),$height / 1.4,$font_color,$font,$codeStr);
        }
        //session($verifyName,md5(strtolower($codeStrs)));
        //生成线条
        for($i = 0;$i<$line_num;$i++) {
            $line_color = imagecolorallocate($image, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
            imageline($image, mt_rand(0,$width),mt_rand(0,$height),mt_rand(0,$width),mt_rand(0,$height), $line_color);
        }
        for($i=0;$i<$interference;$i++){
            $color = imagecolorallocate($image, mt_rand(200, 255), mt_rand(200, 255), mt_rand(200, 255));
            imagestring($image,mt_rand(1,5),mt_rand(0,$width),mt_rand(0,$height),'*',$color);
        }
        header("Content-type: image/png");
        imagepng($image);
        imagedestroy($image);
    }



 code();