dynamic sig. - PHP Code Bank

                <?php
/*
index.php?write=ip_show -> show user ip.
index.php?write=your string -> writing your own string
index.php -> die()
*/
if(!isset($_GET["write"])) // create white image with some description if user not yet set the write variable
	{
		header("Content-type:image/png");
		$img_die=imagecreate(320,50);
		$bg=imagecolorallocate($img_die,0xFF,0xFF,0xFF);
		$t_Die=imagecolorallocate($img_die,0x00,0x00,0x00);
		imagestring($img_die,2,10,6,"sorry this script could not work w/o some string!",$t_Die);
		imagestring($img_die,2,10,20,"eg. sig/index.php?write=your string",$t_Die);
		imagepng($img_die);
		imagedestroy($img_die);
		exit();
		}
else if(isset($_GET["write"]) && $_GET["write"]=="ip_show") // show the user ip who load our image
	{
		header("Content-type:image/jpg");
		$img=imagecreatefromjpeg("bg.jpg");
		$t_Color=imagecolorallocate($img,0x00,0x00,0x00);
		imagestring($img,2,180,5,"Your IP : ".$_SERVER["REMOTE_ADDR"],$t_Color);
		imagejpeg($img,NULL,120);
		imagedestroy($img);
		}
else // writing our string if write variable !ip_show. eg. ?write=hello world!
	{
		header("Content-type:image/jpg");
		$img=imagecreatefromjpeg("bg.jpg");
		$t_Color=imagecolorallocate($img,0x00,0x00,0x00);
		if(strlen($_GET["write"])>=25)
			{
				imagestring($img,2,160,5,$_GET["write"],$t_Color);
				}
		else if(strlen($_GET["write"])<=10)
			{
				imagestring($img,2,267,5,$_GET["write"],$t_Color);
				}
		else
			{
				imagestring($img,2,190,5,$_GET["write"],$t_Color);
				}
		imagejpeg($img,NULL,120);
		imagedestroy($img);
		}
?>