<?php
function captcha($config = array()) {
global $set;
// Check for GD library
if( !function_exists('gd_info') ) {
throw new Exception('Required GD library is missing');
}
// Default values
$captcha_config = array(
'code' => '',
'min_length' => 5,
'max_length' => 5,
'png_backgrounds' => array(dirname(__FILE__) . '/default.png'),
'fonts' => array(dirname(__FILE__) . '/times_new_yorker.ttf'),
'characters' => 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789',
'min_font_size' => 24,
'max_font_size' => 30,
'color' => '#000',
'angle_min' => 0,
'angle_max' => 15,
'shadow' => true,
'shadow_color' => '#CCC',
'shadow_offset_x' => -2,
'shadow_offset_y' => 2
);
// Overwrite defaults with custom config values
if( is_array($config) ) {
foreach( $config as $key => $value ) $captcha_config[$key] = $value;
}
// Restrict certain values
if( $captcha_config['min_length'] < 1 ) $captcha_config['min_length'] = 1;
if( $captcha_config['angle_min'] < 0 ) $captcha_config['angle_min'] = 0;
if( $captcha_config['angle_max'] > 10 ) $captcha_config['angle_max'] = 10;
if( $captcha_config['angle_max'] < $captcha_config['angle_min'] ) $captcha_config['angle_max'] = $captcha_config['angle_min'];
if( $captcha_config['min_font_size'] < 10 ) $captcha_config['min_font_size'] = 10;
if( $captcha_config['max_font_size'] < $captcha_config['min_font_size'] ) $captcha_config['max_font_size'] = $captcha_config['min_font_size'];
// Use milliseconds instead of seconds
srand(microtime() * 100);
// Generate CAPTCHA code if not set by user
if( empty($captcha_config['code']) ) {
$captcha_config['code'] = '';
$length = rand($captcha_config['min_length'], $captcha_config['max_length']);
while( strlen($captcha_config['code']) < $length ) {
$captcha_config['code'] .= substr($captcha_config['characters'], rand() % (strlen($captcha_config['characters'])), 1);
}
}
// Generate image src
$image_src = $set->url . '/lib/captcha/captcha.php?_CAPTCHA&t=' . urlencode(microtime());
$_SESSION['_CAPTCHA']['config'] = serialize($captcha_config);
return array(
'code' => $captcha_config['code'],
'image_src' => $image_src
);
}
if( !function_exists('hex2rgb') ) {
function hex2rgb($hex_str, $return_string = false, $separator = ',') {
$hex_str = preg_replace("/[^0-9A-Fa-f]/", '', $hex_str); // Gets a proper hex string
$rgb_array = array();
if( strlen($hex_str) == 6 ) {
$color_val = hexdec($hex_str);
$rgb_array['r'] = 0xFF & ($color_val >> 0x10);
$rgb_array['g'] = 0xFF & ($color_val >> 0x8);
$rgb_array['b'] = 0xFF & $color_val;
} elseif( strlen($hex_str) == 3 ) {
$rgb_array['r'] = hexdec(str_repeat(substr($hex_str, 0, 1), 2));
$rgb_array['g'] = hexdec(str_repeat(substr($hex_str, 1, 1), 2));
$rgb_array['b'] = hexdec(str_repeat(substr($hex_str, 2, 1), 2));
} else {
return false;
}
return $return_string ? implode($separator, $rgb_array) : $rgb_array;
}
}
// Draw the image
if( isset($_GET['_CAPTCHA']) ) {
session_start();
$captcha_config = unserialize($_SESSION['_CAPTCHA']['config']);
unset($_SESSION['_CAPTCHA']);
// Use milliseconds instead of seconds
srand(microtime() * 100);
// Pick random background, get info, and start captcha
$background = $captcha_config['png_backgrounds'][rand(0, count($captcha_config['png_backgrounds']) -1)];
list($bg_width, $bg_height, $bg_type, $bg_attr) = getimagesize($background);
// Create captcha object
$captcha = imagecreatefrompng($background);
imagealphablending($captcha, true);
imagesavealpha($captcha , true);
$color = hex2rgb($captcha_config['color']);
$color = imagecolorallocate($captcha, $color['r'], $color['g'], $color['b']);
// Determine text angle
$angle = rand( $captcha_config['angle_min'], $captcha_config['angle_max'] ) * (rand(0, 1) == 1 ? -1 : 1);
// Select font randomly
$font = $captcha_config['fonts'][rand(0, count($captcha_config['fonts']) - 1)];
// Verify font file exists
if( !file_exists($font) ) throw new Exception('Font file not found: ' . $font);
//Set the font size.
$font_size = rand($captcha_config['min_font_size'], $captcha_config['max_font_size']);
$text_box_size = imagettfbbox($font_size, $angle, $font, $captcha_config['code']);
// Determine text position
$box_width = abs($text_box_size[6] - $text_box_size[2]);
$box_height = abs($text_box_size[5] - $text_box_size[1]);
$text_pos_x_min = 0;
$text_pos_x_max = ($bg_width) - ($box_width);
$text_pos_x = rand($text_pos_x_min, $text_pos_x_max);
$text_pos_y_min = $box_height;
$text_pos_y_max = ($bg_height) - ($box_height / 2);
$text_pos_y = rand($text_pos_y_min, $text_pos_y_max);
// Draw shadow
if( $captcha_config['shadow'] ){
$shadow_color = hex2rgb($captcha_config['shadow_color']);
$shadow_color = imagecolorallocate($captcha, $shadow_color['r'], $shadow_color['g'], $shadow_color['b']);
imagettftext($captcha, $font_size, $angle, $text_pos_x + $captcha_config['shadow_offset_x'], $text_pos_y + $captcha_config['shadow_offset_y'], $shadow_color, $font, $captcha_config['code']);
}
// Draw text
imagettftext($captcha, $font_size, $angle, $text_pos_x, $text_pos_y, $color, $font, $captcha_config['code']);
// Output image
header("Content-type: image/png");
imagepng($captcha);
}
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