PHP图像操作__验证码生成函数

header('Content-type:text/html;charset=utf-8;');
function imgcode($x,$y,$fontsize,$number,$fontfile,$bet=0)
{
    $initimg=imagecreate($x,$y);
    $bgcolor=imagecolorallocate($initimg,mt_rand(200,255),mt_rand(200,255),mt_rand(200,255));
    imagefill($initimg,0,0,$bgcolor);

    for($i=0;$i<150;$i++)
    {
    $pxcolor=imagecolorallocate($initimg,mt_rand(0,155),mt_rand(0,155),mt_rand(0,155));
    imagesetpixel($initimg,mt_rand(10,$x-10),mt_rand(10,$y-10),$pxcolor);
    }
    for($i=0;$i<3;$i++)
    {
    $linecolor=imagecolorallocate($initimg,mt_rand(0,155),mt_rand(0,155),mt_rand(0,155));
    imageline($initimg,mt_rand(10,30),mt_rand(10,$y-10),mt_rand($x-30,$x-10),mt_rand(10,$y-10),$linecolor);
    }
    $str="1234567890abcdefghijklmnopqtuvwxyzABCDEFGHIJKLMNOQWTUVWXYZ";
    $strimg="";
    $strtotal="";
    for($i=0;$i<$number;$i++)
    {
        $strimg=substr(str_shuffle($str),0,1);
        $strtotal.=$strimg;
        $textcolor=imagecolorallocate($initimg,mt_rand(0,100),mt_rand(0,100),mt_rand(0,100));
        imagettftext($initimg,$fontsize,mt_rand(-20,20),($x-$fontsize*$number)/($number+1)+($bet+$fontsize)*$i,($y-$fontsize)/2+$fontsize,$textcolor,realpath($fontfile),$strimg);
    }
    
    header('Content-type:image/jpeg');
    imagejpeg($initimg,null,100);
    imagedestroy($initimg);
    return $strtotal;
}

$x=isset($_REQUEST['x'])?$_REQUEST['x']:200;
$y=isset($_REQUEST['y'])?$_REQUEST['y']:100;
$size=isset($_REQUEST['size'])?$_REQUEST['size']:20;
$num=isset($_REQUEST['num'])?$_REQUEST['num']:4;
$spac=isset($_REQUEST['spac'])?$_REQUEST['spac']:5;
imgcode($x,$y,$size,$num,'./FRAMDCN.TTF',$spac);