uppercase alphanumeric CAPTCHA class with imagettftext

captcha.php

<?php 
// captcha class by noidsit
// generate captcha uppercase alphanumeric
// if you want to use upper/lower case alphanumeric add lower case alphabet
// usage string = new Captcha(16,230,32,6); //fontwidth, image witdh, image height, how many characters
// string->captgen(); to generate captcha
class Captcha {
	private $fontwidth;
	private $width;
	private $height;
	private $charcount;
	public $captsession;

public function __construct($ukuranhuruf,$lebar,$tinggi,$jumlahhuruf) {
	$this->fontwidth = $ukuranhuruf;
	$this->width = $lebar;
	$this->height = $tinggi;
	$this->charcount = $jumlahhuruf;
}
public function captcode() {
	$randomstring = '';
	$chars = array(
 	'1', '2', '3', '4', '5','6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z');

	for ($rand = 1; $rand <= $this->charcount; $rand++) {
		$random = rand(0, count($chars) - 1);
		$randomstring .= $chars[$random];
	 }
	 $_SESSION['captchacode'] = $randstr; // store this value in our PHP session
	 
	 return $randstr;
}	
	
public function captgen() {	
	
	$im = imagecreate($this->width,$this->height);
	$code = $this->captcode();
	$this->captsession = $code;
	$background_color = imagecolorallocate($im, 255,255,255);
	$mid = imagecolorallocate($im, 33,153,215);
	$color = imagecolorallocate($im, 204,204,204);
	$fw = $this->fontwidth;     // width of a character
	$l = strlen($code);          // number of characters
	$tw = $l * $fw;	// text width
	$th = $this->fontwidth * 0.6;
	$iw = imagesx($im);          // image width	
	$xpos = ($iw - $tw)/2;
	$ypos = $this->height - $th;
	$font = ABSPATH.'asset/themes/cariperawat/fonts/RobotoCondensed-Regular.ttf'; //change this to your ttf font location
	imagettftext ($im, $this->fontwidth, 0, $xpos, $ypos, $mid, $font, $code);
	drawBorder($im,$color, 1); // draw border for image, optional - delete if not required

	ob_start(); //start byte stream
  imagejpeg($im, NULL, 100);
	
  $rawImageBytes = ob_get_clean();
	imagedestroy( $im );
	?>
    <img src="data:image/jpeg;base64,<?php echo base64_encode( $rawImageBytes ); ?>" class="mt5 fleft inl prel" alt="Kode Keamanan Captcha" /> //remember to change to your class 
	<input type="button" id="reloadcapt" name="reloadcapt" class="borbb fwh blue fleft inl prel ps5 ms3 mt5 pt5 cpointer" value="Ganti Kode"/> //remember to change to your class
	<?php
    }


public function captses() {
	return $this->captsession; //output our captcha code to later use, needed for captcha input comparison
	}
} // end class
?>