<?php
$width=80;
$height=20;
$lines=8;
/* Dichiara che lo stream trasmesso รจ un file immagine PNG */
header("Content-Type: image/png");
/* Inizializza la sessione */
session_start();
$verify="";
for ($i=0;$i<6;$i++)
$verify.=$i % 2==0?mt_rand(0,9):chr(mt_rand(65,90));
$_SESSION['verification_string']=$verify;
$im = imagecreate($width,$height);
$white = imagecolorallocate($im, 255, 255, 255);
$black = imagecolorallocate($im, 0, 0, 0);
$grey = imagecolorallocate($im, 150, 150, 150);
imagefill($im, 0,0, $black);
for ($i=0;$i<$lines;$i++)
{
if ($i % 2==0)//pari=linee verticali
{
$x1=mt_rand(0,$width);
$y1=0;
$x2=$x1;
$y2=$height;
}
else //dispari=linee orizzontali
{
$x1=0;
$y1=mt_rand(0,$height);
$x2=$width;
$y2=$y1;
}
imageline($im, $x1, $y1, $x2, $y2, $grey);
}
/* seleziona un font a caso tra quelli di sistema */
$font=mt_rand(3,5);
$w=strlen($verify)*imagefontwidth($font);
$h=imagefontheight($font);
$x=mt_rand(1,($width-$w-1));
$y=mt_rand(1,($height-$h-1));
imagestring($im, $font, $x, $y, $verify, $white);
/* output al browser*/
imagepng($im);
/* Distruggo l'immagine in memoria */
imagedestroy($im);
?>
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