<?php
// file by Airex (airex@tiscali.it) 
// realizzato  per la generazione di un'immagine per la pagina di registrazione
// dei forum phpBB2 piu' difficile da indovinare da parte di script/bot

// rilasciato sotto licenza GPL

// $chars = array('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',  'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',  'U', 'V', 'W', 'X', 'Y', 'Z', '1', '2', '3', '4', '5', '6', '7', '8', '9');

$image = "";

$max_h = 50;
$max_l = 320;

$delay = 50;
                                                                                                                                                                                   
// Output image                                                                                                                                                            
header('Content-Type: image/gif');                                                                                                                                         
header('Cache-control: no-cache, no-store');                                                                                                                               


function bitstring_to_int($val,$len) {
    $ret = 0;
    for ($i=0;$i<$len;$i++) {
	$ret += ord($val{$i}) << (8*$i);
    }
    return $ret;
}

function get_gif_header($gif_data) {
    $header = array();
    $header["signature"] = substr($gif_data,0,3);
    $header["version"]   = substr($gif_data,3,3);
    $header["logical_screen_width"]  = substr($gif_data,6,2);
    $header["logical_screen_height"] = substr($gif_data,8,2);
    $header["packed"] = substr($gif_data,10,1);
    $header["background_color_index"] = substr($gif_data,11,1);
    $header["pixel_aspect_ratio"] = substr($gif_data,12,1);
    $packed = ord($header["packed"]);
    if (($packed >> 7) & 0x1) {
	$gct = $packed & 3;
	$gct_size = 3 * pow(2,$gct+1);
	$header["global_color_table"] = substr($gif_data,13,$gct_size);
    }
    return $header;
}

function strip_gif_header($gif_data) {
    $without_header = "";
    $header_len = 0;
    $header = get_gif_header($gif_data);
    foreach ($header as $k=>$v)
	$header_len += strlen($v);
    return substr($gif_data,$header_len,strlen($gif_data)-$header_len);
}

function get_gif_image_data($gif_data) {
    $no_header = strip_gif_header($gif_data);
    $no_header = substr($no_header,0,strlen($no_header)-1);
    return $no_header;
}

function get_gif_image_descriptor($image_data) {
    $header = array();
    $header["image_separator"] = substr($image_data,0,1);
    $header["image_left_position"]  = substr($image_data,1,2);
    $header["image_top_position"] = substr($image_data,3,2);
    $header["image_width"]  = substr($image_data,5,2);
    $header["image_height"] = substr($image_data,7,2);
    $header["packed"] = substr($image_data,9,1);
    $packed = ord($header["packed"]);
    if (($packed >> 7) & 0x1) {
	$lct = $packed & 3;
	$lct_size = 3 * pow(2,$lct+1);
	$header["local_color_table"] = substr($image_data,10,$lct_size);
    }
    return $header;
}

function strip_gif_image_descriptor($imgdata) {
    $descriptor = get_gif_image_descriptor($imgdata);
    $len = 0;
    foreach ($descriptor as $k=>$v)
	$len += strlen($v);
    return substr($imgdata,$len,strlen($imgdata)-$len);
}

function make_gifanim($gifs) {
    $head0 = get_gif_header($gifs[0]);
    $head0["packed"] = chr( ord($head0["packed"]) & (7 << 4) );
    $head0["background_color_index"] = chr(0);
    $head0["pixel_aspect_ratio"] = chr(0);
    unset($head0["global_color_table"]);
    $anim_gif = implode("",$head0);
    $extra_info = array( chr(0x21), chr(0xff) ,chr(0x0B), "NETSCAPE2.0",chr(0x03), chr(0x01), chr(0x00).chr(0x00), chr(0x00) );
    $anim_gif .= implode("",$extra_info);
    foreach ($gifs as $gif) {
	$header = get_gif_header($gif);
	$imgdata = get_gif_image_data($gif);	
	$image_header = get_gif_image_descriptor($imgdata);
	$image_only = strip_gif_image_descriptor($imgdata);
	$control_block = array();
	$control_block["extension_introducer"] = chr(0x21);	
	$control_block["graphic_control_label"]  = chr(0xF9);
	$control_block["block_size"] = chr(4);
	$control_block["packed"] = chr(0);
	$control_block["delay"] = chr(50).chr(0);
	$control_block["transparent_color_index"] = chr(0);
	$control_block["terminator"] = chr(0);
	if (!isset($image_header["local_color_table"]) && isset($header["global_color_table"])) {
	    $image_header["local_color_table"] = $header["global_color_table"];
	    $size_gct = (ord($header["packed"]) & 3);
	    $image_header["packed"] = chr( ord($image_header["packed"]) | (0x1 << 7) | ($size_gct) );
	}
	$anim_gif .= implode("",$control_block).implode("",$image_header).$image_only;
    }
    $anim_gif .= chr(0);
    return $anim_gif;
}

$tot_frames = 30;
$anim_len = 10;
$start_dummy = rand(0,10);
$end_dummy = rand($start_dummy+$anim_len,30);
$files = array();

$new_code = $code;

$new_code_tmp = "";
for ($f=0;$f<strlen($new_code);$f++) {
    if ((rand(0,7504)%2)==0)
	for ($c=0;$c<rand(2,5);$c++)
	    $new_code_tmp .= " ";
    $new_code_tmp .= $new_code{$f};	
}
$new_code = $new_code_tmp;


for ($f=0;$f<$tot_frames;$f++) {
    $im = @imagecreatetruecolor($max_l, $max_h)
	or die("Cannot Initialize new GD image stream");
    if ($new_code == "")
	$new_code = "P R O V A 1 2 3";
    $background_color = imagecolorallocate($im, rand(0,255), rand(0,255), rand(0,255));
    $tot_rects = rand(1,5);
    $rl = intval($max_l / $tot_rects);
    for ($r=0;$r<$tot_rects;$r++) {
        $rect_color = imagecolorallocate($im, rand(0,255), rand(0,255), rand(0,255));
	$rx = ($rl*$r);
	imagefilledrectangle($im,$rx,0,$rx+$rl,$max_h,$rect_color);
    }    
    $cur_x = 0;
    if ($f>$start_dummy && $f<$end_dummy)
	for ($i=0;$i<strlen($new_code);$i++) {
	    $font = rand(3,5);
            $y = rand(0,$max_h - imagefontheight($font));
            do {
		    $text_color = imagecolorallocate($im, rand(0,255), rand(0,255), rand(0,255));
    	    } while ($background_color == $text_color);
            imagestring($im, $font , $cur_x, $y,  $new_code{$i}, $text_color);
	    $cur_x += imagefontwidth($font)+3;
        }
    ob_start();
    imagegif($im);
    $files[] = ob_get_clean();
    imagedestroy($im);
}

echo make_gifanim($files);

exit;

?>