<?php
class Captcha {
	protected $code;
	protected $width = 35;
	protected $height = 150;

	function __construct() { 
		$this->code = substr(sha1(mt_rand()), 17, 6); 
	}

	function getCode(){
		return $this->code;
	}

	function showImage() {
		$image = imagecreatetruecolor($this->height, $this->width);

		$width = imagesx($image);
		$height = imagesy($image);

		$black = imagecolorallocate($image, 0, 0, 0);
		$white = imagecolorallocate($image, 255, 255, 255);
		$red = imagecolorallocatealpha($image, 255, 0, 0, 75);
		$green = imagecolorallocatealpha($image, 0, 255, 0, 75);
		$blue = imagecolorallocatealpha($image, 0, 0, 255, 75);

		imagefilledrectangle($image, 0, 0, $width, $height, $white);

		imagefilledellipse($image, ceil(rand(5, 145)), ceil(rand(0, 35)), 30, 30, $red);
		imagefilledellipse($image, ceil(rand(5, 145)), ceil(rand(0, 35)), 30, 30, $green);
		imagefilledellipse($image, ceil(rand(5, 145)), ceil(rand(0, 35)), 30, 30, $blue);

		imagefilledrectangle($image, 0, 0, $width, 0, $black);
		imagefilledrectangle($image, $width - 1, 0, $width - 1, $height - 1, $black);
		imagefilledrectangle($image, 0, 0, 0, $height - 1, $black);
		imagefilledrectangle($image, 0, $height - 1, $width, $height - 1, $black);

		imagestring($image, 10, intval(($width - (strlen($this->code) * 9)) / 2),  intval(($height - 15) / 2), $this->code, $black);

		header('Content-type: image/jpeg');

		imagejpeg($image);

		imagedestroy($image);		
	}
}
?>