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<?php
//***************************************************************
//** title : An damaged image generator for validating text
//**
//** story : Sometimes you need to verify that the client posting
//** or registering in your site is actually a human. By
//** asking him/her to type in the word s/he sees, you ensure
//** that the client is human, and not a bot/spider which
//** is probably trying to harm your system.
//** Play around with the values when constructing this
//** object, but also feel free to experiment with the
//** maths inside the image manipulating loops.
//** Note that this class is writing a png file on disk,
//** so you might need to have a png with the same name
//** already present in that location with write
//** permissions set.
//**
//** author : Ioannis Cherouvim
//** e-mail : morales@hack.gr
//** date : 2005-06-25
//*******************************************************
class PWImage {
//instantiate class
//$filename : the path+filename of the written png file
//$string : the text that you want to have in the image
//$fact : a magnification factor. play with values>2
//$bcol : the background colour, R, G, B (0-255)
//$fcol : the foreground colour, R, G, B (0-255)
function PWImage($filename, $string, $fact, $bcol, $fcol) {
$font = 5;
$cosrate = rand(10,19);
$sinrate = rand(10,18);
$charwidth = imagefontwidth($font);
$charheight = imagefontheight($font);
$width=(strlen($string)+2)*$charwidth;
$height=2*$charheight;
$im = @imagecreatetruecolor($width, $height) or die("Cannot Initialize new GD image stream");
$im2 = imagecreatetruecolor($width*$fact, $height*$fact);
$bcol = imagecolorallocate($im, $bcol[0], $bcol[1], $bcol[2]);
$fcol = imagecolorallocate($im, $fcol[0], $fcol[1], $fcol[2]);
imagefill($im, 0, 0, $bcol);
imagefill($im2, 0, 0, $bcol);
$dotcol = imagecolorallocate($im, (abs($this->getR($fcol)-$this->getR($bcol)))/2.5,
(abs($this->getG($fcol)-$this->getG($bcol)))/2.5,
(abs($this->getB($fcol)-$this->getB($bcol)))/2.5);
$dotcol2 = imagecolorallocate($im, (abs($this->getR($fcol)-$this->getR($bcol)))/1.5,
(abs($this->getG($fcol)-$this->getG($bcol)))/1.5,
(abs($this->getB($fcol)-$this->getB($bcol)))/3.5);
$linecol = imagecolorallocate($im, (abs($this->getR($fcol)-$this->getR($bcol)))/2.4,
(abs($this->getG($fcol)-$this->getG($bcol)))/2.1,
(abs($this->getB($fcol)-$this->getB($bcol)))/2.5);
for($i=0; $i<$width; $i=$i+rand(1,5)) {
for($j=0; $j<$height; $j=$j+rand(1,5)) {
imagesetpixel($im, $i, $j, $dotcol);
}
}
imagestring($im, $font, $charwidth, $charheight/2, $string, $fcol);
for($j=0; $j<$height*$fact; $j=$j+rand(3,6)) {
imageline($im2, 0, $j, $width*$fact, $j, $linecol);
}
for($i=0; $i<$width*$fact; $i=$i+rand(4,9)) {
imageline($im2, $i, 0, $i, $height*$fact, $linecol);
}
for($i=0; $i<$width*$fact; $i++) {
for($j=0; $j<$height*$fact; $j++) {
$x = abs(((cos($i/$cosrate)*5+sin($j/$sinrate*2)*2+$i)/$fact))%$width;
$y = abs(((sin($j/$sinrate)*5+cos($i/$cosrate*2)*2+$j)/$fact))%$height;
$col = imagecolorat($im, $x, $y);
if ($col!=$bcol) imagesetpixel($im2, $i, $j, $col);
}
}
for($j=0; $j<$height*$fact; $j=$j+rand(1,5)) {
for($i=0; $i<$width*$fact; $i=$i+rand(1,5)) {
imagesetpixel($im2, $i, $j, $dotcol2);
}
}
ob_start();
imagepng($im2);
$buffer = ob_get_contents();
ob_end_clean();
$handle = fopen($filename, "w");
fwrite($handle, $buffer);
fclose($handle);
imagedestroy($im);
imagedestroy($im2);
}
//functions to extract RGB values from combined 24bit color value
function getR($col) {return (($col >> 8) >> 8) % 256;}
function getG($col) {return ($col >> 8) % 256;}
function getB($col) {return $col % 256;}
}
//**********************************************
//*************** example use ******************
//**********************************************
$pw = new PWImage("temp1.png", "some pass", 2, array(0, 0, 0), array(255, 128, 200));
$pw = new PWImage("temp2.png", "WEBERDEV", 4, array(255, 255, 255), array(0, 0, 0));
$pw = new PWImage("temp3.png", "9df2ceA", 3, array(0, 0, 0), array(255, 228, 250));
$pw = new PWImage("temp4.png", "abcdef_g", 1.8, array(0, 0, 0), array(0, 255, 255));
echo "<img src='temp1.png'/><br/>";
echo "<img src='temp2.png'/><br/>";
echo "<img src='temp3.png'/><br/>";
echo "<img src='temp4.png'/><br/>";
?> | |
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