Using fpdf to modify existing pdf in php

Question

I have a bank of pdfs on my server which when downloaded need text appended to every page. I am using fpdf to try and open the file, append the text to each page, close the file and serve to the browser.

$pdf = new FPDI();

$pdf->setSourceFile($filename); 
// 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(20, 20);
//first parameter defines the line height
$pdf->Write(0, 'gift code');
//force the browser to download the output
$pdf->Output('gift_coupon_generated.pdf', 'D');

header("location: ".$filename);

At the minute this just tries to put some text anywhere on the pdf and save it but I get the error

FPDF error: You have to add a page first!

If I can get it to do this I then need it to append the text to every page in the document rather than just 1, not sure how to do this having read the documentation

Answer 1

Try following

require_once('fpdf.php');
require_once('fpdi.php');

$pdf =& new FPDI();
$pdf->AddPage();

Use this page as template, then

$pdf->setSourceFile($filename); 
// 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); 

Let me know if you have any errors