Watermarking an existing PDF in Drupal - php

Question

I'm working on a project in DRUPAL and am trying to programatically add an image to an existing pdf - an "Approved" image for invoices. I've Frankensteined the code from the StackExchange post - How can I add a watermark to an existing PDF file using PHP? - and have managed to get it working outside of Drupal (7.0) but once I port the code over, I get nothing, no errors, no warnings, nadda .... Just wondering if someone out there can help me on this issue, it been driving me nuts for a bit now .... Sorry about the sloppy code....
<?php
global $user;
ob_start();
$filename ="approved_".$user->name.".png";
$file = "2pages.pdf";
$op = 100;
////////////////////////////////////////////////////////////////////////////
require('fpdf.php');
require('fpdi.php');
$text = "Text message for watermark goes here";
$name = uniqid();
$font_size = 5;
$ts=explode("\n",$text);
$width=0;
foreach ($ts as $k=>$string) {
$width=max($width,strlen($string));
}
$width = imagefontwidth($font_size)*$width;
$height = imagefontheight($font_size)*count($ts);
$el=imagefontheight($font_size);
$em=imagefontwidth($font_size);
$img = imagecreatetruecolor($width,$height);
// Background color
$bg = imagecolorallocate($img, 255, 255, 255);
imagefilledrectangle($img, 0, 0,$width ,$height , $bg);
// Font color
$color = imagecolorallocate($img, 0, 0, 0);
foreach ($ts as $k=>$string) {
$len = strlen($string);
$ypos = 0;
for($i=0;$i<$len;$i++){
$xpos = $i * $em;
$ypos = $k * $el;
imagechar($img, $font_size, $xpos, $ypos, $string, $color);
$string = substr($string, 1);
}
}
imagecolortransparent($img, $bg);
$blank = imagecreatetruecolor($width, $height);
$tbg = imagecolorallocate($blank, 255, 255, 255);
imagefilledrectangle($blank, 0, 0,$width ,$height , $tbg);
imagecolortransparent($blank, $tbg);
if ( ($op < 0) OR ($op >100) ){
$op = 100;
}
imagecopymerge($blank, $img, 0, 0, 0, 0, $width, $height, $op);
$pdf = new FPDI();
//********************************************************************
if (file_exists($file)){
$pagecount = $pdf->setSourceFile($file);
} else {
return FALSE;
}
/////////////////////////////////////////
for($i=1; $i <= $pagecount; $i++) {
$tpl = $pdf->importPage($i);
$pdf->addPage();
$pdf->useTemplate($tpl, 1, 1, 0, 0, TRUE);
//Put the watermark
$pdf->Image($filename, 0, 0, 40, 25, 'png');}
/////////////////////////////////////////
return $pdf->Output('test10.pdf', 'F');
////////////////////////////////////////////////////////////////////////////
ob_end_flush();
?>
Of note, I am also open you anyone who may have an alternate method to achieve the same end result
thanks in advance!

Answer 1

So after taking some advise from Marc B, I went through the code and isolated the issue. For those looking for the answer to this question, here's the solution I came up with ... Hope it helps!
<?php
ob_start();
function PlaceWatermark($file, $text, $xxx, $yyy, $op, $outdir) {
global $user;
require('fpdf.php');
require('fpdi.php');
$myfilename = 'approved_'.$user->name.'.png';
// Created Watermark Image
$pdf = new FPDI();
//if (file_exists("./".$file)){
$pagecount = $pdf->setSourceFile($file);
//} else {
// return FALSE;
//}
/////////////////////////////////////////
for($i=1; $i <= $pagecount; $i++) {
$tpl = $pdf->importPage($i);
$pdf->addPage();
$pdf->useTemplate($tpl, 1, 1, 0, 0, TRUE);
//Put the watermark
if (file_exists($myfilename)) {
$pdf->Image($myfilename, 0, 0, 40, 25, 'png');
} else {
$pdf->Image('approved.png', 0, 0, 40, 25, 'png');
}
}
/////////////////////////////////////////
return $pdf->Output('test_output.pdf', 'F');
}
PlaceWatermark("Original.pdf", "", 30, 120, 100,TRUE);
ob_end_flush();
?>