fungsi generate qrcode

public function generate_qr_code($value)
    {
        $filename = $value.'.png';
        $fullpath = APPPATH.'../public/files/'.$filename;
        $logopath = APPPATH.'../assets/img/logo/kemdikbud.png';
        if (file_exists($fullpath)) {
            unlink($fullpath);
        }

        if (!file_exists($fullpath)) {
            $this->load->library('ciqrcode');
            $params['data'] = $value;
            $params['level'] = 'H';
            $params['size'] = 10;
            $params['savename'] = $fullpath;
            $this->ciqrcode->generate($params);
            $QR = imagecreatefrompng($fullpath);
             // memulai menggambar logo dalam file qrcode
             $logo = imagecreatefromstring(file_get_contents($logopath));
             imagecolortransparent($logo , imagecolorallocatealpha($logo , 0, 0, 0, 127));

             imagealphablending($logo , false);
             imagesavealpha($logo , true);

             $QR_width = imagesx($QR);//get logo width
             $QR_height = imagesy($QR);//get logo width

             $logo_width = imagesx($logo);
             $logo_height = imagesy($logo);

            // Scale logo to fit in the QR Code
             $logo_qr_width = $QR_width/2;
             $scale = $logo_width/$logo_qr_width;
             $logo_qr_height = $logo_height/$scale;

             imagecopyresampled($QR, $logo, $QR_width/4, $QR_height/3.5, 0, 0, $logo_qr_width, $logo_qr_height, $logo_width, $logo_height);
             // Simpan kode QR lagi, dengan logo di atasnya
             imagepng($QR,$fullpath);
        }
         return $filename;
    }