<?php
namespace Gregwar\CaptchaBundle\Generator;
use Symfony\Component\Finder\Finder;
use Symfony\Component\HttpFoundation\Session\SessionInterface;
/**
* Generates a CAPTCHA image
*/
class CaptchaGenerator
{
/**
* @var \Symfony\Component\HttpFoundation\Session\SessionInterface
*/
protected $session;
/**
* Name of folder for captcha images
* @var string
*/
protected $imageFolder;
/**
* Absolute path to public web folder
* @var string
*/
protected $webPath;
/**
* Frequency of garbage collection in fractions of 1
* @var int
*/
protected $gcFreq;
/**
* Maximum age of images in minutes
* @var int
*/
protected $expiration;
/**
* The fingerprint used to generate the image details across requests
* @var array|null
*/
protected $fingerprint;
/**
* Whether this instance should use the fingerprint
* @var bool
*/
protected $useFingerprint;
/**
* The key used to store the value to the session
* @var string
*/
protected $key = 'captcha';
/**
* @param \Symfony\Component\HttpFoundation\Session\SessionInterface $session
* @param string $imageFolder
* @param string $webPath
* @param int $gcFreq
* @param int $expiration
* @param string $url
*/
public function __construct(SessionInterface $session, $imageFolder, $webPath, $gcFreq, $expiration, $url)
{
$this->session = $session;
$this->imageFolder = $imageFolder;
$this->webPath = $webPath;
$this->gcFreq = $gcFreq;
$this->expiration = $expiration;
$this->url = $url;
}
/**
* Get the captcha URL, stream, or filename that will go in the image's src attribute
*
* @param $key
* @param array $options
*
* @return array
*/
public function getCaptchaCode($key, array $options)
{
$this->key = $key;
// Randomly execute garbage collection and returns the image filename
if ($options['as_file']) {
if (mt_rand(1, $this->gcFreq) == 1) {
$this->garbageCollection();
}
return $this->generate($options);
}
// Returns the configured URL for image generation
if ($options['as_url']) {
return $this->url;
}
return 'data:image/jpeg;base64,' . base64_encode($this->generate($options));
}
/**
* Generate the image
*/
public function generate(array $options)
{
$width = $options['width'];
$height = $options['height'];
if ($options['keep_value'] && $this->session->has($this->key.'_fingerprint')) {
$this->fingerprint = $this->session->get($this->key.'_fingerprint');
$this->useFingerprint = true;
} else {
$this->fingerprint = null;
$this->useFingerprint = false;
}
$captchaValue = $this->getCaptchaValue($options['keep_value'], $options['charset'], $options['length']);
$i = imagecreatetruecolor($width,$height);
$col = imagecolorallocate($i, $this->rand(0,110), $this->rand(0,110), $this->rand(0,110));
imagefill($i, 0, 0, 0xFFFFFF);
// Draw random lines
for ($t=0; $t<10; $t++) {
$tcol = imagecolorallocate($i, 100+$this->rand(0,150), 100+$this->rand(0,150), 100+$this->rand(0,150));
$Xa = $this->rand(0, $width);
$Ya = $this->rand(0, $height);
$Xb = $this->rand(0, $width);
$Yb = $this->rand(0, $height);
imageline($i, $Xa, $Ya, $Xb, $Yb, $tcol);
}
// Write CAPTCHA text
$size = $width/strlen($captchaValue);
$font = $options['font'];
$box = imagettfbbox($size, 0, $font, $captchaValue);
$txt_width = $box[2] - $box[0];
$txt_height = $box[1] - $box[7];
imagettftext($i, $size, 0, ($width-$txt_width)/2, ($height-$txt_height)/2+$size, $col, $font, $captchaValue);
// Distort the image
$X = $this->rand(0, $width);
$Y = $this->rand(0, $height);
$Phase=$this->rand(0,10);
$Scale = 1.3 + $this->rand(0,10000)/30000;
$Amp=1+$this->rand(0,1000)/1000;
$out = imagecreatetruecolor($width, $height);
for ($x=0; $x<$width; $x++) {
for ($y=0; $y<$height; $y++) {
$Vx=$x-$X;
$Vy=$y-$Y;
$Vn=sqrt($Vx*$Vx+$Vy*$Vy);
if ($Vn!=0) {
$Vn2=$Vn+4*sin($Vn/8);
$nX=$X+($Vx*$Vn2/$Vn);
$nY=$Y+($Vy*$Vn2/$Vn);
} else {
$nX=$X;
$nY=$Y;
}
$nY = $nY+$Scale*sin($Phase + $nX*0.2);
$p = $this->bilinearInterpolate($nX-floor($nX), $nY-floor($nY),
$this->getCol($i,floor($nX),floor($nY)),
$this->getCol($i,ceil($nX),floor($nY)),
$this->getCol($i,floor($nX),ceil($nY)),
$this->getCol($i,ceil($nX),ceil($nY)));
if ($p==0) {
$p=0xFFFFFF;
}
imagesetpixel($out, $x, $y, $p);
}
}
if ($options['keep_value']) {
$this->session->set($this->key.'_fingerprint', $this->fingerprint);
}
// Renders it
if (!$options['as_file']) {
ob_start();
imagejpeg($out, null, $options['quality']);
return ob_get_clean();
}
// Check if folder exists and create it if not
if (!file_exists($this->webPath . '/' . $this->imageFolder)) {
mkdir($this->webPath . '/' . $this->imageFolder, 0755);
}
$filename = md5(uniqid()) . '.jpg';
$filepath = $this->webPath . '/' . $this->imageFolder . '/' . $filename;
imagejpeg($out, $filepath, 15);
return '/' . $this->imageFolder . '/' . $filename;
}
/**
* Generate a new captcha value or pull the existing one from the session
*
* @param bool $keepValue
* @param string $charset
* @param int $length
*
* @return mixed|string
*/
protected function getCaptchaValue($keepValue, $charset, $length)
{
if ($keepValue && $this->session->has($this->key)) {
return $this->session->get($this->key);
}
$value = '';
$chars = str_split($charset);
for ($i=0; $i < $length; $i++) {
$value .= $chars[array_rand($chars)];
}
$this->session->set($this->key, $value);
return $value;
}
/**
* Deletes all images in the configured folder
* that are older than the configured number of minutes
*
* @return void
*/
protected function garbageCollection()
{
$finder = new Finder();
$criteria = sprintf('<= now - %s minutes', $this->expiration);
$finder->in($this->webPath . '/' . $this->imageFolder)
->date($criteria);
foreach($finder->files() as $file) {
unlink($file->getPathname());
}
}
/**
* Returns a random number or the next number in the
* fingerprint
*/
protected function rand($min, $max)
{
if (!is_array($this->fingerprint)) {
$this->fingerprint = array();
}
if ($this->useFingerprint) {
$value = current($this->fingerprint);
next($this->fingerprint);
} else {
$value = mt_rand($min, $max);
$this->fingerprint[] = $value;
}
return $value;
}
protected function bilinearInterpolate($x, $y, $nw, $ne, $sw, $se)
{
list($r0, $g0, $b0) = $this->getRGB($nw);
list($r1, $g1, $b1) = $this->getRGB($ne);
list($r2, $g2, $b2) = $this->getRGB($sw);
list($r3, $g3, $b3) = $this->getRGB($se);
$cx = 1.0 - $x;
$cy = 1.0 - $y;
$m0 = $cx * $r0 + $x * $r1;
$m1 = $cx * $r2 + $x * $r3;
$r = (int)($cy * $m0 + $y * $m1);
$m0 = $cx * $g0 + $x * $g1;
$m1 = $cx * $g2 + $x * $g3;
$g = (int)($cy * $m0 + $y * $m1);
$m0 = $cx * $b0 + $x * $b1;
$m1 = $cx * $b2 + $x * $b3;
$b = (int)($cy * $m0 + $y * $m1);
return ($r << 16) | ($g << 8) | $b;
}
protected function getCol($image, $x, $y)
{
$L = imagesx($image);
$H = imagesy($image);
if ($x<0 || $x>=$L || $y<0 || $y>=$H) {
return 0xFFFFFF;
}
return imagecolorat($image, $x, $y);
}
protected function getRGB($col) {
return array(
(int)($col >> 16) & 0xff,
(int)($col >> 8) & 0xff,
(int)($col) & 0xff,
);
}
}