Membuat Code Captcha Sendiri Menggunakan Php

Pada kesempatan kali ini mimin mau mambagikan tutorial membuat kode captcha dengan bantuan Php. Dimana kode captcha ini berfungsi untuk menjaga web kita dari serangan - serangan robot jahil yang akan mengganggu web kebanggaan kita.

Dengan adanya kode captcha ini kita bisa meminimalisir kejahilan - kejahilan yang dilakukan oleh pihak yang tidak bertanggung jawab. Kebanyakan kode captcha ini dipasang pada web - web forum yang banyak dikunjungi oleh orang.

Ok untuk tidak berlama - lama mari kita simak pembahasan step by stepnya dibawah ini dengan seksama ya.

Pertama Kita buat fungsi captcha terlebih dahulu.

<?php
class fungsi_captcha 
{
    
    var $word = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    var $length = 5;
    var $img_width = 160;
    var $img_height = 50;
    var $font_path = '';
    var $font_size = 25;
    var $expiration = 7200;
    var $bg_color = '#ffffff';
    var $border_color = '#996666';
    var $text_color = '#cc9999';
    var $grid_color = '#ffb6b6';
    var $shadow_color = '#fff0f0';
    
    public function __construct($config = array()){
        ob_start();
        session_start();
        if (count($config) > 0){
            foreach ($config as $key => $val){
                if (isset($this->$key)){
                    $method = 'set_'.$key;
                    if (method_exists($this, $method)){
                        $this->$method($val);
                    }else{
                        $this->$key = $val;
                    }
                }
            }
        }
        
        if ( ! extension_loaded('gd')){
            return FALSE;
        }
    }
    
    public function createCaptcha(){
        $str = '';
        for ($i = 0; $i < $this->length; $i++){
            $str .= substr($this->word, mt_rand(0, strlen($this->word) -1), 1);
        }
        $word = $str;

       
        $length = strlen($word);
        $angle  = ($length >= 6) ? rand(-($length-6), ($length-6)) : 0;
        $x_axis = rand(6, (360/$length)-16);
        $y_axis = ($angle >= 0 ) ? rand($this->img_height, $this->img_width) : rand(6, $this->img_height);

       
        if (function_exists('imagecreatetruecolor')){
            $im = imagecreatetruecolor($this->img_width, $this->img_height);
        }else{
            $im = imagecreate($this->img_width, $this->img_height);
        }

       
        $bgColorRgb     = $this->hexToRgb($this->bg_color);
        $borderColorRgb = $this->hexToRgb($this->border_color);
        $textColorRgb   = $this->hexToRgb($this->text_color);
        $gridColorRgb   = $this->hexToRgb($this->grid_color);
        $shadowColorRgb = $this->hexToRgb($this->shadow_color);
        $bg_color       = imagecolorallocate ($im, $bgColorRgb[0], $bgColorRgb[1], $bgColorRgb[2]);
        $border_color   = imagecolorallocate ($im, $borderColorRgb[0], $borderColorRgb[1], $borderColorRgb[2]);
        $text_color     = imagecolorallocate ($im, $textColorRgb[0], $textColorRgb[1], $textColorRgb[2]);
        $grid_color     = imagecolorallocate($im, $gridColorRgb[0], $gridColorRgb[1], $gridColorRgb[2]);
        $shadow_color   = imagecolorallocate($im, $shadowColorRgb[0], $shadowColorRgb[1], $shadowColorRgb[2]);

       
        ImageFilledRectangle($im, 0, 0, $this->img_width, $this->img_height, $bg_color);

       
        $theta   = 1;
        $thetac  = 7;
        $radius  = 16;
        $circles = 20;
        $points  = 32;

        for ($i = 0; $i < ($circles * $points) - 1; $i++){
            $theta = $theta + $thetac;
            $rad   = $radius * ($i / $points );
            $x     = ($rad * cos($theta)) + $x_axis;
            $y     = ($rad * sin($theta)) + $y_axis;
            $theta = $theta + $thetac;
            $rad1  = $radius * (($i + 1) / $points);
            $x1    = ($rad1 * cos($theta)) + $x_axis;
            $y1    = ($rad1 * sin($theta )) + $y_axis;
            imageline($im, $x, $y, $x1, $y1, $grid_color);
            $theta = $theta - $thetac;
        }

       
        $use_font = ($this->font_path != '' AND file_exists($this->font_path) AND function_exists('imagettftext')) ? TRUE : FALSE;

        $x = rand(0, $this->img_width/($length/1.5));
        $y = $this->font_size+2;

        for ($i = 0; $i < strlen($word); $i++)
        {
            if ($use_font == FALSE){
                $y = rand(0 , $this->img_height/2);
                imagestring($im, $this->font_size, $x, $y, substr($word, $i, 1), $text_color);
                $x += ($this->font_size);
            }else{
                $y = rand($this->img_height/2, $this->img_height-3);
                imagettftext($im, $this->font_size, $angle, $x, $y, $text_color, $this->font_path, substr($word, $i, 1));
                $x += $this->font_size;
            }
        }

        
        imagerectangle($im, 0, 0, $this->img_width-1, $this->img_height-1, $border_color);

       
        imagejpeg($im,NULL,90);
        header('Content-Type: image/jpeg');
        imagedestroy($im);
        
       
        if(empty(session_id()))
        unset($_SESSION['captchaCode']);
        $_SESSION['captchaCode'] = $word;
    }
    
    public function hexToRgb($hex){
        $hex = str_replace("#", "", $hex);
        if(strlen($hex) == 3) {
           $r = hexdec(substr($hex,0,1).substr($hex,0,1));
           $g = hexdec(substr($hex,1,1).substr($hex,1,1));
           $b = hexdec(substr($hex,2,1).substr($hex,2,1));
        } else {
           $r = hexdec(substr($hex,0,2));
           $g = hexdec(substr($hex,2,2));
           $b = hexdec(substr($hex,4,2));
        }
        $rgb = array($r, $g, $b);
        return $rgb;
    }
}

?>

Langkah selanjutnya mari kita buat form nya .

<?php
session_start();
if(isset($_POST['submit']) && !empty($_POST['submit'])){
    if(!empty($_POST['captcha_code'])){
        
        $captchaCode = $_SESSION['captchaCode'];
        $enteredcaptchaCode = $_POST['captcha_code'];
        if($enteredcaptchaCode === $captchaCode){
            $succMsg = 'Berhasil , captcha cocok.';
        }else{
            $errMsg = 'captcha Tidak Cocok Silahkan coba Kembali.';
        }
        
    }else{
        $errMsg = 'Silahkan Masukan Code captcha .';
    }
}
?>

<?php if(!empty($errMsg)) echo '<p style="color:#EA4335;">'.$errMsg.'</p>';?>
<?php if(!empty($succMsg)) echo '<p style="color:#34A853;">'.$succMsg.'</p>';?>

<img src="captcha.php" id="capImage"/>
<br/>refresh jika captcha tidak muncul <a href="javascript:void(0);" onclick="javascript:$('#capImage').attr('src','captcha.php');">refresh</a>.
<form method="post">
    Masukan code: <input name="captcha_code" type="text" value="">
    <input type="submit" name="submit" value="SUBMIT">
</form>

Disini kita juga memerlukan bantuk jqury untuk reload image captcha  saat captcha tidak muncul . silahkan tambahkan code berikut :

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

Untuk Penerapannya adalah sebagai berikut :

<?php
include 'fungsi_captcha.php';
$captchaConfig = array(
     'img_width' => '200',
     'img_height' => '50',
     'font_size' => '30',
     'font_path' => 'fonts/monofont.ttf',
 );
$captcha = new fungsi_captcha($captchaConfig);
$captcha->createCaptcha();
?>

Selamat mencoba semoga sukses. Dan tutorial ini dapat membantu sahabat yang memerlukannya.