Are there any specific functions or methods in FPDF for rotating PDF files?

To rotate a PDF file using FPDF, you can use the `Rotate()` method provided by the library. This method allows you to rotate the current page in the PDF document by a specified angle. By using this method, you can easily rotate the pages in your PDF file to the desired orientation.

require('fpdf.php');

class PDF extends FPDF {
    function Rotate($angle,$x=-1,$y=-1) {
        if($x == -1)
            $x = $this->x;
        if($y == -1)
            $y = $this->y;
        if($this->angle != 0)
            $this->_out('Q');
        $this->angle = $angle;
        if($angle != 0) {
            $angle *= M_PI/180;
            $c = cos($angle);
            $s = sin($angle);
            $cx = $x*$this->k;
            $cy = ($this->h-$y)*$this->k;
            $this->_out(sprintf('q %.5f %.5f %.5f %.5f %.2f %.2f cm 1 0 0 1 %.2f %.2f cm',$c,$s,-$s,$c,$cx,$cy,-$cx,-$cy));
        }
    }

    function _endpage() {
        if($this->angle != 0) {
            $this->angle = 0;
            $this->_out('Q');
        }
        parent::_endpage();
    }
}

$pdf = new PDF();
$pdf->AddPage();
$pdf->SetFont('Arial','B',16);
$pdf->Cell(40,10,'Hello World!');
$pdf->Rotate(90);
$pdf->Cell(40,10,'Rotated!');
$pdf->Output();