Positioning text over pdf file in PHP

Question

I'm developing an e-Certificate web page. I've managed loading the certificate template and writing on top of it (Attendee Name, Event Title and Event Date). But in positioning those three pieces of information, I couldn't position them at the center no matter how long they are. they always start from x point.

Check my work result:

Code:

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

$pdf =& new FPDI();
$pdf->addPage('L');
$pagecount = $pdf->setSourceFile('Certificate.pdf');
$tplIdx = $pdf->importPage(1); 
$pdf->useTemplate($tplIdx); 
$pdf->SetFont('Times','I',18);
$pdf->SetTextColor(0,0,0); 
$pdf->SetXY(120, 62); 
$pdf->Write(0, "Attendee Name"); 

$pdf->SetXY(120, 102); 
$pdf->Write(0, "Event Name"); 

$pdf->SetXY(120, 140); 
$pdf->Write(0, "Event Date"); 
$pdf->Output();
?>

Is there away to center the text no matter how long is it?

meaning without fixing the x point. however, the y point result is very good.

Answer 1

So 2 ways I've done this before, the most likely easiest way: Since you only have 1 entry on the row (Attendee Name or Event Name, etc) Start a cell at the left most point, and have the cell run the full width of the page, then specify the center option:

$pdf->SetXY(0,62);
//0 extends full width, $height needs to be set to cell height.
$pdf->Cell(0, $height, "Attendee Name", 0, 0, 'C');

The other option is to calculate the center, and set X accordingly:

//how wide is the page?
$midPtX = $pdf->GetPageWidth() / 2;
//now we need to know how long the write string is
$attendeeNameWidth = $pdf->GetStringWidth($attendeeName);
//now we need to divide that by two to calculate the shift
$shiftLeft = $attendeeNameWidth / 2;
//now calculate our new X value
$x = $midPtX - $shiftLeft;
//now apply your shift for the answer
$pdf->setXY($x, 62); 
$pdf->Write(0, "Attendee Name"); 

You can then repeat the above for each of the other elements.