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|
<?php
class Mathcaptcha{
#session_start();
public function image(){
/*===============================================================
General captcha settings
===============================================================*/
// captcha width
$captcha_w = 150;
// captcha height
$captcha_h = 35 ;
// minimum font size; each operation element changes size
$min_font_size = 12;
// maximum font size
$max_font_size = 18;
// rotation angle
$angle = 20;
// background grid size
$bg_size = 13;
// path to font - needed to display the operation elements
$font_path = '/font/courbd.ttf';
// array of possible operators
$operators=array('+','-','*');
// first number random value; keep it lower than $second_num
$first_num = rand(1,5);
// second number random value
$second_num = rand(6,11);
/*===============================================================
From here on you may leave the code intact unless you want
or need to make it specific changes.
===============================================================*/
shuffle($operators);
$expression = $second_num.$operators[0].$first_num;
#echo "=";
/*
operation result is stored in $session_var
*/
eval("\$session_var=".$second_num.$operators[0].$first_num.";");
/*
save the operation result in session to make verifications
*/
$_SESSION['Captcha'] = $session_var;
#$this->Session->write('security_number',$session_var);
/*
start the captcha image
*/
$img = imagecreate( $captcha_w, $captcha_h );
/*
Some colors. Text is $black, background is $white, grid is $grey
*/
$black = imagecolorallocate($img,0,0,0);
$white = imagecolorallocate($img,255,255,255);
$grey = imagecolorallocate($img,215,215,215);
/*
make the background white
*/
imagefill( $img, 0, 0, $white );
/* the background grid lines - vertical lines */
for ($t = $bg_size; $t<$captcha_w; $t+=$bg_size){
imageline($img, $t, 0, $t, $captcha_h, $grey);
}
/* background grid - horizontal lines */
for ($t = $bg_size; $t<$captcha_h; $t+=$bg_size){
imageline($img, 0, $t, $captcha_w, $t, $grey);
}
/*
this determinates the available space for each operation element
it's used to position each element on the image so that they don't overlap
*/
$item_space = $captcha_w/3;
/* first number */
imagettftext(
$img,
rand(
$min_font_size,
$max_font_size
),
rand( -$angle , $angle ),
rand( 10, $item_space-20 ),
rand( 25, $captcha_h-25 ),
$black,
$font_path,
$second_num);
/* operator */
imagettftext(
$img,
rand(
$min_font_size,
$max_font_size
),
rand( -$angle, $angle ),
rand( $item_space, 2*$item_space-20 ),
rand( 25, $captcha_h-25 ),
$black,
$font_path,
$operators[0]);
/* second number */
imagettftext(
$img,
rand(
$min_font_size,
$max_font_size
),
rand( -$angle, $angle ),
rand( 2*$item_space, 3*$item_space-20),
rand( 25, $captcha_h-25 ),
$black,
$font_path,
$first_num);
/* image is .jpg */
header("Content-type:image/jpeg");
/* name is secure.jpg */
header("Content-Disposition:inline ; filename=secure.jpg");
/* output image */
return imagejpeg($img);
}
}
?> |
