// 10 reasons why QR codes are awesome
$data = 'https://www.youtube.com/watch?v=DLzxrzFCyOs&t=43s';

// no, for serious, we want to display a QR code for a mobile authenticator
// https://github.com/codemasher/php-googleauth
$data = 'otpauth://totp/test?secret=B3JX4VCVJDVNXNZ5&issuer=chillerlan.net';

echo '<img src="'.(new QRCode($data, new QRImage))->output().'" />';

// the built-in QROutputInterface classes
$outputInterface = new QRImage;
$outputInterface = new QRMarkup;
$outputInterface = new QRString;

// invoke a fresh QRCode instance
$qrcode = new QRCode($data, $outputInterface);

// and dump the output
$qrcode->output();

// image -> QRImageOptions
$outputOptions = new QRImageOptions;
$outputOptions->type = QRCode::OUTPUT_IMAGE_GIF;
$outputInterface = new QRImage($outputOptions);

// string -> QRStringOptions
$outputOptions = new QRStringOptions;
$outputOptions->type = QRCode::OUTPUT_STRING_TEXT;
$outputInterface = new QRString($outputOptions);

// QROptions
$qrOptions = new QROptions;
$qrOptions->errorCorrectLevel = QRCode::ERROR_CORRECT_LEVEL_L;

$qrcode = new QRCode($data, $outputInterface, $qrOptions);

$qrcode->setData($data);
$qrcode->setData($data, $qrOptions);

$qrcode->output();

$matrix = $qrcode->getRawData();

foreach($matrix as $row){
	foreach($row as $dark){
		if($dark){
			// do stuff
		}
		else{
			// do other stuff
		}
	}
}

$qrcode = new QRCode($data, new MyCustomOutput($myCustomOutputOptions), $qrOptions)

class MyCustomOutput extends QROutputAbstract{
	
	// inherited from QROutputAbstract
	protected $matrix; // array
	protected $pixelCount; // int
	protected $options; // MyCustomOutputOptions (if present)
	
	// optional constructor
	public function __construct(QROutputOptionsInterface $outputOptions = null){
		$this->options = $outputOptions;

		if(!$this->options){
			// MyCustomOutputOptions should supply default values
			$this->options = new MyCustomOutputOptions;
		}

	}

	public function dump(){
	
		$output = '';

		for($row = 0; $row < $this->pixelCount; $row++){
			for($col = 0; $col < $this->pixelCount; $col++){
				$output .= (string)(int)$this->matrix[$row][$col];
			}
		}

		return $output;
	}

}