captcha.class.php

<?php

/**
 * Captcha
 * Class responsible to create and validate a captcha
 *
 * Created by Gonçalo Gonçalves - goncalofbg@gmail.com
 *
 */
class Captcha {

	public $devMode          = true;
	public $captchaCode      = "";
	public $imageWidth       = 180;
	public $imageHeight      = 50;
	public $charNumber       = 6;
	public $arrayFonts       = array('claredon.ttf', 'courier_bold.ttf', 'toledo.ttf','valken.ttf', 'impact.ttf');
	public $possibleChars  = '23456789ABCDEFGHKLMNPQRSTUVYWXZ';
	//public $possibleChars    = 'ABCDEFGHKLMNPQRSTUVYWXZ';
	public $fontPath         = "";
	public $addDots          = true;
	public $addLines         = false;
	public $addRectangles    = false;
	public $addCircles       = false;
	public $numberDots       = 3000;
	public $numberLines      = 10;
	public $numberRectangles = 20;
	public $numberCircles    = 30;

	/**
	 * Construct
	 * @param string $fontPath the path of the fonts
	 */
	public function __construct($fontPath = "fonts/"){
		$this->fontPath = $fontPath;
	}

	/**
	 * Create a new captcha
	 * @return string html of the captcha
	 */
	public function createCaptcha() {

		ob_start();

		$temp_code = '';
		$i = 0;
		// create temp code
		while ($i < $this->charNumber) {
			// get random letter
			$temp_code .= substr($this->possibleChars, mt_rand(0, strlen($this->possibleChars)-1), 1);
			$i++;
		}

		//header('Content-Type: image/png');
		$image = imagecreatetruecolor($this->imageWidth , $this->imageHeight);
		$colorWhite = imagecolorallocate($image, 255, 255, 255);

		// background rectangle
		imagefilledrectangle($image, 0, 0, $this->imageWidth, $this->imageHeight, $colorWhite);

		// add dots
		if ($this->addDots) {
			for ($c = 0; $c < $this->numberDots; $c++){
				$colorGrey = rand(0, 200);
				$colorDot  = imagecolorallocate($image, $colorGrey, $colorGrey, $colorGrey);
				$x = rand(0,$this->imageWidth-1);
				$y = rand(0,$this->imageHeight-1);
				imagesetpixel($image, $x, $y, $colorDot);
			}
		}

		// add lines
		if ($this->addLines) {
			for ($c = 0; $c < $this->numberLines; $c++){
				$randomColor = strtoupper(dechex(rand(0,10000000)));
				$x 	= rand(0,$this->imageWidth-1);
				$y 	= rand(0,$this->imageHeight-1);
				$x2 = rand(0,$this->imageWidth-1);
				$y2 = rand(0,$this->imageHeight-1);
				imageline($image, $x, $y, $x2, $y2, $randomColor);
			}
		}

		// add rectangles
		if ($this->addRectangles) {
			for ($c = 0; $c < $this->numberRectangles; $c++){
				$randomColor = strtoupper(dechex(rand(0,10000000)));
				$x 	= rand(0,$this->imageWidth-1);
				$y 	= rand(0,$this->imageHeight-1);
				$x2 = rand(0,$this->imageWidth-1);
				$y2 = rand(0,$this->imageHeight-1);
				imagerectangle($image, $x, $y, $x2, $y2, $randomColor);
			}
		}

		// add circles
		if ($this->addCircles) {
			for ($c = 0; $c < $this->numberCircles; $c++){
				$colorGrey   = rand(0, 200);
				$colorCircle = imagecolorallocate($image, $colorGrey, $colorGrey, $colorGrey);
				$x 	= rand(0,$this->imageWidth-1);
				$y 	= rand(0,$this->imageHeight-1);
				$circleSize = rand(3, 6);
				imagefilledellipse($image, $x, $y, $circleSize, $circleSize, $colorCircle);
			}
		}

		// add text, letter by letter
		for ($c = 0; $c < $this->charNumber; $c++){
			$colorGrey  = rand(0, 100);
			$colorText  = imagecolorallocate($image, $colorGrey, $colorGrey, $colorGrey);
			$font       = $this->fontPath.$this->arrayFonts[rand(0, sizeof($this->arrayFonts)-1)];
			$angle      = rand(-20, 20);
			$letterSize = rand(20, 28);
			$x = $c*25+15;
			$y = rand(30,40);
			$letter = substr($this->possibleChars, mt_rand(0, strlen($this->possibleChars)-1), 1);

			// bonus
			switch ($c) {
			    case 0: $letter = "G"; break;
			    case 1: $letter = "I"; break;
			    case 2: $letter = "T"; break;
			    case 3: $letter = "H"; break;
			    case 4: $letter = "U"; break;
			    case 5: $letter = "B"; break;
			    //case 6: $letter = ""; break;
			}

			imagettftext($image, $letterSize, $angle, $x, $y, $colorText, $font, $letter);
			$this->captchaCode = $this->captchaCode.$letter;
		}

		imagepng($image);
		imagedestroy($image);
		$finalImage = ob_get_clean();

		session_start();
		$_SESSION['captchaCode'] = $this->captchaCode;

		$htmlCaptchaImage = "<img alt='Captcha' title='Captcha' src='data:image/jpeg;base64," . base64_encode( $finalImage )."'>";

		$htmlCaptcha = '<table class="captcha-table">';
		if (isset($_GET['captcha_state']) && $_GET['captcha_state'] == "false") {
			$htmlCaptcha .= '<tr><td class="captcha-wrong">Wrong code!</td></tr>';
		}
		$htmlCaptcha .= '
		<tr>
			<td>'.$htmlCaptchaImage.'
				<div class="captcha-bar-tools">
					<a href="javascript:createCaptcha();" title="Change image"><img src="imgs/refresh.png" alt="create new captcha"></a>
				</div>
			</td>
		</tr>
		<tr>
			<td><input id="user-input-captcha" name="user-input-captcha" class="captcha-input"></td>
		</tr>';

		if ($this->devMode == true) {
			$htmlCaptcha .= '<tr><td>'.$this->captchaCode.'</td></tr>';
		}

		$htmlCaptcha .= '</table>';

		return $htmlCaptcha;
	}

	/**
	 * Validate captcha code
	 * @param  string $value the string inserted by the user
	 * @return boolean       if code is correct
	 */
	public function validateCaptcha($value){

		$validCode = false;
		session_start();
		$captchaCode = $_SESSION['captchaCode'];

		if ($captchaCode == $value) {
			$validCode = true;
		}

		return $validCode;
	}

}

?>