Edit PDF files

/*download fpdfi at - http://www.setasign.com/products/fpdi/downloads/
and fpdf at - http://www.fpdf.org/
original code example - http://stackoverflow.com/questions/7364/pdf-editing-in-php
because this example doens't work for me, I made a new one*/

require_once('fpdf.php');
require_once('fpdi.php');
$pdf = new FPDI();

$pdf->AddPage();

$pdf->setSourceFile('file.pdf');

// import page 1
$tplIdx = $pdf->importPage(1);
//use the imported page and place it at point 0,0; calculate width and height
//automaticallay and ajust the page size to the size of the imported page
$pdf->useTemplate($tplIdx, 0, 0, 0, 0, true);

// now write some text above the imported page
$pdf->SetFont('Arial', '', '13');
$pdf->SetTextColor(0,0,0);
//set position in pdf document
$pdf->SetXY(30, 25);
//first parameter defines the line height
$pdf->Write(0, 'gift code');
//force the browser to download the output
$pdf->Output('file_generated.pdf', 'D');