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<?php
/**
* Generate a CAPTCHA and display the image
*
* @author Constantinos Neophytou
* @link http://www.cneophytou.com/
* @license Creative Commons Attribution-Noncommercial-Share Alike 3.0 License
* {@link http://creativecommons.org/licenses/by-nc-sa/3.0/}
**/
/**
* Initialize page
**/
session_start();
header("Content-Type: image/png");
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // Date in the past
header("Last-Modified: ".gmdate("D, d M Y H:i:s")." GMT");
create_image();
exit;
/**
* Generate a random string, and create a CAPTCHA image out of it
*/
function create_image()
{
// generate pronouncable pass
$pass = genPassword(5, 6);
$font = './captcha.ttf';
$maxsize = 50;
$sizeVar = 25;
$rotate = 20;
$bgcol = 50; // + 50
$bgtextcol = 80; // + 50
$textcol = 205; // + 50
// remember the pass
$_SESSION["captcha"] = $pass;
// calculate dimentions required for pass
$box = @imageTTFBbox($maxsize,0,$font,$pass);
$minwidth = abs($box[4] - $box[0]);
$minheight = abs($box[5] - $box[1]);
// allow spacing for rotating letters
$width = $minwidth + 100;
$height = $minheight + rand(5,15); // give some air for the letters to breathe
// create initial image
$image = ImageCreatetruecolor($width, $height);
if (function_exists('imageantialias')) {
imageantialias($image, true);
}
// define background color - never the same, close to black
$clr_black = ImageColorAllocate($image, rand($bgcol, $bgcol+30),
rand($bgcol, $bgcol+30), rand($bgcol, $bgcol+30));
imagefill($image, 0, 0, $clr_black);
// calculate starting positions for letters
$x = rand(10, 25);//($width / 2) - ($minwidth / 2);
$xinit = $x;
$y = ($minheight-abs($box[1])) + (($height - $minheight) / 2);
// fill the background with big letters, colored a bit lightly, to vary the bg.
$bgx = $x / 2;
$size = rand($maxsize - 10, $maxsize);
for($i = 0; $i < strlen($pass); $i++) {
// modify color a bit
$clr_white = ImageColorAllocate($image, rand($bgtextcol, $bgtextcol+50),
rand($bgtextcol, $bgtextcol+50), rand($bgtextcol, $bgtextcol+50));
$angle = rand(0-$rotate, $rotate);
$letter = substr($pass, $i, 1);
imagettftext($image, $size*2, $angle, $bgx, $y, $clr_white, $font, $letter);
list($x1, $a, $a, $a, $x2) = @imageTTFBbox($size,$angle,$font,$letter);
$bgx += abs($x2 - $x1);
}
// for each letter, decide a color, decide a rotation, put it on the image,
// and figure out width to place next letter correctly
for($i = 0; $i < strlen($pass); $i++) {
// modify color a bit
$clr_white = ImageColorAllocate($image, rand($textcol, $textcol+50),
rand($textcol, $textcol+50), rand($textcol, $textcol+50));
$angle = rand(0-$rotate, $rotate);
$letter = substr($pass, $i, 1);
$size = rand($maxsize - $sizeVar, $maxsize);
$tempbox = @imageTTFBbox($size,$angle,$font,$letter);
$y = (abs($tempbox[5] - $tempbox[1])) +
(($height - abs($tempbox[5] - $tempbox[1])) / 2);
imagettftext($image, $size, $angle, $x, $y, $clr_white, $font, $letter);
$x += abs($tempbox[4]-$tempbox[0]);
}
// figure out final width (same space at the end as there was at the beginning)
$width = $xinit + $x;
// throw in some lines
$clr_white = ImageColorAllocate($image, rand(160, 200), rand(160, 200),
rand(160, 200));
imagelinethick($image, rand(0, 10), rand(0, $height / 2), rand($width - 10, $width),
rand($height / 2, $height), $clr_white, rand(1, 2));
$clr_white = ImageColorAllocate($image, rand(160, 200), rand(160, 200),
rand(160, 200));
imagelinethick($image, rand(($width / 2) - 10, $width / 2),
rand($height / 2, $height), rand(($width / 2)+ 10, $width),
rand(0, ($height / 2)), $clr_white, rand(1, 2));
// generate final image by cropping initial image to the proper width,
// which we didn't know till now.
$finalimage = ImageCreatetruecolor($width, $height);
if (function_exists('imageantialias')) {
imageantialias($finalimage, true);
}
imagecopy($finalimage, $image, 0, 0, 0, 0, $width, $height);
// clear some memory
imagedestroy($image);
// dump image
imagepng($finalimage);
// clear some more memory
imagedestroy($finalimage);
}
/**
* Draw lines through an image
* @param resource
* @param int
* @param int
* @param int
* @param int
* @param int - the color to use for the line
* @param int - line thickness
* @return bool - true on success
*/
function imagelinethick($image, $x1, $y1, $x2, $y2, $color, $thick = 1) {
if ($thick == 1) {
return imageline($image, $x1, $y1, $x2, $y2, $color);
}
$t = $thick / 2 - 0.5;
if ($x1 == $x2 || $y1 == $y2) {
return imagefilledrectangle($image, round(min($x1, $x2) - $t),
round(min($y1, $y2) - $t),
round(max($x1, $x2) + $t),
round(max($y1, $y2) + $t),
$color);
}
$k = ($y2 - $y1) / ($x2 - $x1); //y = kx + q
$a = $t / sqrt(1 + pow($k, 2));
$points = array(
round($x1 - (1+$k)*$a), round($y1 + (1-$k)*$a),
round($x1 - (1-$k)*$a), round($y1 - (1+$k)*$a),
round($x2 + (1+$k)*$a), round($y2 - (1-$k)*$a),
round($x2 + (1-$k)*$a), round($y2 + (1+$k)*$a),
);
imagefilledpolygon($image, $points, 4, $color);
return imagepolygon($image, $points, 4, $color);
}
/**
* Generate a random, pronouncable password
* Modified to exclude letters which don't show up well in the CAPTCHA
* @link http://www.zend.com/code/codex.php?id=215&single=1
* @author Rival7 {@link http://www.zend.com/code/search_code_author.php?author=Rival7}
* @author Constantinos Neophytou
*/
function genPassword($minlen, $maxlen) {
srand((double)microtime()*1000000);
$vowels = array('a', 'e', 'i', 'o', 'u');
$cons = array('b', 'c', 'd', 'g', 'h', 'j', 'k', 'm', 'n', 'p', 'r', 's', 't', 'v',
'w', 'tr', 'cr', 'br', 'fr', 'th', 'dr', 'ch', 'ph', 'wr', 'st', 'sp', 'sw', 'pr');
// removed 'l', 'sl', 'cl'
$num_vowels = count($vowels);
$num_cons = count($cons);
$length = rand($minlen, $maxlen);
$start = rand(0, 1);
if ($start) {
$first = $cons;
$num_first = $num_cons;
$second = $vowels;
$num_second = $num_vowels;
} else {
$first = $vowels;
$num_first = $num_vowels;
$second = $cons;
$num_second = $num_cons;
}
for($i = 0; $i < $length; $i++) {
$add = $first[rand(0, $num_first - 1)] . $second[rand(0, $num_second - 1)];
$password .= $add;
$i += (strlen($add) - 1);
}
//$password = substr($password, 0, $length);
return $password;
}
?>
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