php Captcha 練習

突然有個想法，就是去寫一個簡單的驗證碼類，其實驗證碼在很多框架有自帶的，網上一搜也一大把，我只是想當作是練習，熟悉一下過程。

session_start();

class He_Captcha{

    

    private $str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVW";

    private $text;

    private $im;

    public    $num;

    public    $size;

    public    $width;

    public    $height;

    public    $session_var;

    public    $ttfs = array(

        'Jura.ttf',

        'AntykwaBold.ttf',

        'Duality.ttf',

        'VeraSansBold.ttf'

    );

    

    /*       生成驗證碼

     *num     顯示的驗證碼字符數

     *size    字符的字體大小

     *session_var   驗證碼會話名稱

     *width   驗證碼圖片的寬

     *height  驗證碼圖片的高

    */

    public function Captcha($num = 4, $size = 15, $session_var = '', $width = 0, $height = 0){



        $this->num = (int)max($this->num, $num);

        $this->size = (int)max($this->size, $size);

        $this->width = $width ? (int)max($this->width, $width) : $this->num * $this->size;

        $this->height = $height ? (int)max($this->height, $height) : $this->size + 10;

        $this->session_var = strlen(trim($session_var))>2 ? trim($session_var):'captcha';

        

        

        $this->_getText($this->num);

        $_SESSION[$this->session_var] = $this->text;

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

         $this->_drowBackground();//畫背景

         $this->_setNoiseLines();//畫干擾線

         $this->_setNoisePoints();//畫干擾點

         $this->_writeText();//畫驗證碼

         $this->_createCaptcha();

    }

    

    /*創建驗證碼內容*/

    private function _getText($num){

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

            $this->text .= $this->str[mt_rand(0,strlen($this->str)-1)];

        }

    }

    

    /*畫背景*/

    private function _drowBackground(){

        $bg_color = imagecolorallocate($this->im, 235, 236, 237);

        imagefilledrectangle($this->im, 0, 0, $this->width, $this->height, $bg_color);

    }

    

    /*畫干擾點*/

    private function _setNoisePoints(){

        $points = 2 * $this->width;

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

            $font_color = imagecolorallocate($this->im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));

            imagesetpixel($this->im, mt_rand(0, $this->width), mt_rand(0, $this->height), $font_color);

        }

    }

    /*畫干擾線*/

    private function _setNoiseLines(){

        $lines = $this->width / 12;

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

            $font_color = imagecolorallocate($this->im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));

            imagearc($this->im, mt_rand( -$this->width, $this->width), mt_rand( -$this->height, $this->height), mt_rand(30, $this->width * 2), mt_rand(20, $this->height * 2), mt_rand(0, 360), mt_rand(0, 360), $font_color);    

        }

    }

    /*畫驗證碼*/

    private function _writeText(){

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

            $ttf = 'fonts/'.$this->ttfs[array_rand($this->ttfs,1)];

            $text_color = imagecolorallocate($this->im, mt_rand(0, 200), mt_rand(0, 120), mt_rand(0, 120));

            @imagefttext($this->im, $this->size, mt_rand(-10,10), $this->size*$i, $this->size+5, $text_color, $ttf, $this->text[$i]);

        }

    }

    

    /*生成驗證碼*/

    private function _createCaptcha(){

        header("Cache-Control: max-age=1, s-maxage=1, no-cache, must-revalidate");

        header("Content-Type: image/png; charset=utf-8");

        imagepng($this->im);

        imagedestroy($this->im);

    }

}

 

下面為調用以及生成效果：

$c = new He_Captcha();

$c->Captcha();

.........