//验证码

class Captcha

{

    private $width;

    private $height;

    private $codeNum;

    private $code;

    private $im;

 

    function __construct($width=80, $height=20, $codeNum=4)

    {

        $this->width = $width;

        $this->height = $height;

        $this->codeNum = $codeNum;

    }

 

    function showImg()

    {

        //创建图片

        $this->createImg();

        //设置干扰元素

        $this->setDisturb();

        //设置验证码

        $this->setCaptcha();

        //输出图片

        $this->outputImg();

    }

 

    function getCaptcha()

    {

        return $this->code;

    }

 

    private function createImg()

    {

        $this->im = imagecreatetruecolor($this->width, $this->height);

        $bgColor = imagecolorallocate($this->im, 0, 0, 0);

        imagefill($this->im, 0, 0, $bgColor);

    }

 

    private function setDisturb()

    {

        $area = ($this->width * $this->height) / 20;

        $disturbNum = ($area > 250) ? 250 : $area;

        //加入点干扰

        for ($i = 0; $i < $disturbNum; $i++) {

            $color = imagecolorallocate($this->im, rand(0, 255), rand(0, 255), rand(0, 255));

            imagesetpixel($this->im, rand(1, $this->width - 2), rand(1, $this->height - 2), $color);

        }

        //加入弧线

        for ($i = 0; $i <= 5; $i++) {

            $color = imagecolorallocate($this->im, rand(128, 255), rand(125, 255), rand(100, 255));

            imagearc($this->im, rand(0, $this->width), rand(0, $this->height), rand(30, 300), rand(20, 200), 50, 30, $color);

        }

    }

 

    private function createCode()

    {

        $str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKMNPQRSTUVWXYZ";

 

        for ($i = 0; $i < $this->codeNum; $i++) {

            $this->code .= $str{rand(0, strlen($str) - 1)};

        }

    }

 

    private function setCaptcha()

    {

        $this->createCode();

 

        for ($i = 0; $i < $this->codeNum; $i++) {

            $color = imagecolorallocate($this->im, rand(50, 250), rand(100, 250), rand(128, 250));

            $size = rand(floor($this->height / 5), floor($this->height / 3));

            $x = floor($this->width / $this->codeNum) * $i + 5;

            $y = rand(0, $this->height - 20);

            imagechar($this->im, $size, $x, $y, $this->code{$i}, $color);

        }

    }

 

    private function outputImg()

    {

        if (imagetypes() & IMG_JPG) {

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

            imagejpeg($this->im);

        } elseif (imagetypes() & IMG_GIF) {

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

            imagegif($this->im);

        } elseif (imagetype() & IMG_PNG) {

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

            imagepng($this->im);

        } else {

            die("Don't support image type!");

        }

    }

//$captcha = new Captcha(80,30,4);

//$captcha->showImg();

}