FAQ

• 1. What's exactly the license of FPDF? Are there any usage restrictions?
• 2. When I try to create a PDF, a lot of weird characters show on the screen. Why?
• 3. I try to generate a PDF and IE displays a blank page. What happens?
• 4. I can't make line breaks work. I put \n in the string printed by MultiCell but it doesn't work.
• 5. I try to display a variable in the Header method but nothing prints.
• 6. I defined the Header and Footer methods in my PDF class but nothing appears.
• 7. Accented characters are replaced by some strange characters like é.
• 8. I try to display the Euro symbol but it doesn't work.
• 9. I get the following error when I try to generate a PDF: Some data has already been output, can't send PDF file
• 10. I draw a frame with very precise dimensions, but when printed I notice some differences.
• 11. I'd like to use the whole surface of the page, but when printed I always have some margins. How can I get rid of them?
• 12. How can I put a background in my PDF?
• 13. How can I set a specific header or footer on the first page?
• 14. I'd like to use extensions provided by different scripts. How can I combine them?
• 15. How can I send the PDF by email?
• 16. What's the limit of the file sizes I can generate with FPDF?
• 17. Can I modify a PDF with FPDF?
• 18. I'd like to make a search engine in PHP and index PDF files. Can I do it with FPDF?
• 19. Can I convert an HTML page to PDF with FPDF?
• 20. Can I concatenate PDF files with FPDF?

• 1. What's exactly the license of FPDF? Are there any usage restrictions?

  FPDF is released under a permissive license: there is no usage restriction. You may embed it freely in your application (commercial or not), with or without modifications.

• 2. When I try to create a PDF, a lot of weird characters show on the screen. Why?

  These "weird" characters are in fact the actual content of your PDF. This behavior is a bug of IE6. When it first receives an HTML page, then a PDF from the same URL, it displays it directly without launching Acrobat. This happens frequently during the development stage: on the least script error, an HTML page is sent, and after correction, the PDF arrives.
  To solve the problem, simply quit and restart IE. You can also go to another URL and come back.
  To avoid this kind of inconvenience during the development, you can generate the PDF directly to a file and open it through the explorer.

• 3. I try to generate a PDF and IE displays a blank page. What happens?

  First of all, check that you send nothing to the browser after the PDF (not even a space or a carriage return). You can put an exit statement just after the call to the Output() method to be sure. If it still doesn't work, it means you're a victim of the "blank page syndrome". IE used in conjunction with the Acrobat plug-in suffers from many bugs. To avoid these problems in a reliable manner, two main techniques exist:
  
  - Disable the plug-in and use Acrobat as a helper application. To do this, launch Acrobat, go to the Edit menu, Preferences, Internet, and uncheck "Display PDF in browser". Then, the next time you load a PDF in IE, it displays the dialog box "Open it" or "Save it to disk". Uncheck the option "Always ask before opening this type of file" and choose Open. From now on, PDF files will open automatically in an external Acrobat window.
  The drawback of the method is that you need to alter the client configuration, which you can do in an intranet environment but not for the Internet.
  
  - Use a redirection technique. It consists in generating the PDF in a temporary file on the server and redirect the client to it. For example, at the end of the script, you can put the following:

  //Determine a temporary file name in the current directory
  $file = basename(tempnam('.', 'tmp'));
  rename($file, $file.'.pdf');
  $file .= '.pdf';
  //Save PDF to file
  $pdf->Output($file, 'F');
  //Redirect
  header('Location: '.$file);

  This method turns the dynamic PDF into a static one and avoids all troubles. But you have to do some cleaning in order to delete the temporary files. For example:

  function CleanFiles($dir)
  {
      //Delete temporary files
      $t = time();
      $h = opendir($dir);
      while($file=readdir($h))
      {
          if(substr($file,0,3)=='tmp' and substr($file,-4)=='.pdf')
          {
              $path = $dir.'/'.$file;
              if($t-filemtime($path)>3600)
                  @unlink($path);
          }
      }
      closedir($h);
  }

  This function deletes all files of the form tmp*.pdf older than an hour in the specified directory. You may call it where you want, for example in the script which generates the PDF.

• 4. I can't make line breaks work. I put \n in the string printed by MultiCell but it doesn't work.

  You have to enclose your string with double quotes, not single ones.

• 5. I try to display a variable in the Header method but nothing prints.

  You have to use the global keyword to access global variables, for example:

  function Header()
  {
      global $title;
  
      $this->SetFont('Arial', 'B', 15);
      $this->Cell(0, 10, $title, 1, 1, 'C');
  }
  
  $title = 'My title';

  Alternatively, you can use an object property:

  function Header()
  {
      $this->SetFont('Arial', 'B', 15);
      $this->Cell(0, 10, $this->title, 1, 1, 'C');
  }
  
  $pdf->title = 'My title';

• 6. I defined the Header and Footer methods in my PDF class but nothing appears.

  You have to create an object from the PDF class, not FPDF:

  $pdf = new PDF();

• 7. Accented characters are replaced by some strange characters like é.

  Don't use UTF-8 encoding. Standard FPDF fonts use ISO-8859-1 or Windows-1252. It is possible to perform a conversion to ISO-8859-1 with utf8_decode():

  $str = utf8_decode($str);

  But some characters such as Euro won't be translated correctly. If the iconv extension is available, the right way to do it is the following:

  $str = iconv('UTF-8', 'windows-1252', $str);

• 8. I try to display the Euro symbol but it doesn't work.

  The standard fonts have the Euro character at position 128. You can define a constant like this for convenience:

  define('EURO', chr(128));

• 9. I get the following error when I try to generate a PDF: Some data has already been output, can't send PDF file

  You must send nothing to the browser except the PDF itself: no HTML, no space, no carriage return. You may have this other message just before:
  
  Warning: Cannot modify header information - headers already sent by (output started at script.php:X)
  
  It means that script.php outputs something at line X. Go to this line and fix it. In case the warning doesn't show, add this at the very beginning of your script:

  ob_end_clean();

  If you still don't see it, disable zlib.output_compression in your php.ini.

• 10. I draw a frame with very precise dimensions, but when printed I notice some differences.

  To respect dimensions, select "None" for the Page Scaling setting instead of "Shrink to Printable Area" in the print dialog box.

• 11. I'd like to use the whole surface of the page, but when printed I always have some margins. How can I get rid of them?

  Printers have physical margins (different depending on the models); it is therefore impossible to remove them and print on the whole surface of the paper.

• 12. How can I put a background in my PDF?

  For a picture, call Image() in the Header() method, before any other output. To set a background color, use Rect().

• 13. How can I set a specific header or footer on the first page?

  Simply test the page number:

  function Header()
  {
      if($this->PageNo()==1)
      {
          //First page
          ...
      }
      else
      {
          //Other pages
          ...
      }
  }

• 14. I'd like to use extensions provided by different scripts. How can I combine them?

  Use an inheritance chain. If you have two classes, say A in a.php:

  require('fpdf.php');
  
  class A extends FPDF
  {
  ...
  }

  and B in b.php:

  require('fpdf.php');
  
  class B extends FPDF
  {
  ...
  }

  then make B extend A:

  require('a.php');
  
  class B extends A
  {
  ...
  }

  and make your own class extend B:

  require('b.php');
  
  class PDF extends B
  {
  ...
  }
  
  $pdf = new PDF();

• 15. How can I send the PDF by email?

  As any other file, but an easy way is to use PHPMailer and its in-memory attachment:

  $mail = new PHPMailer();
  ...
  $doc = $pdf->Output('', 'S');
  $mail->AddStringAttachment($doc, 'doc.pdf', 'base64', 'application/pdf');
  $mail->Send();

• 16. What's the limit of the file sizes I can generate with FPDF?

  There is no particular limit. There are some constraints, however:
  
  - The maximum memory size allocated to PHP scripts is usually 8MB. For very big documents, especially with images, this limit may be reached (the file being built into memory). The parameter is configured in the php.ini file.
  
  - The maximum execution time allocated defaults to 30 seconds. This limit can of course be easily reached. It is configured in php.ini and may be altered dynamically with set_time_limit().
  
  - Browsers generally have a 5 minute time-out. If you send the PDF directly to the browser and reach the limit, it will be lost. It is therefore advised for very big documents to generate them in a file, and to send some data to the browser from time to time (with a call to flush() to force the output). When the document is finished, you can send a redirection to it or create a link.
  Remark: even if the browser times out, the script may continue to run on the server.

• 17. Can I modify a PDF with FPDF?

  It is possible to import pages from an existing PDF document thanks to the FPDI extension:
  
  http://www.setasign.de/products/pdf-php-solutions/fpdi/
  
  You can then add some content to them.

• 18. I'd like to make a search engine in PHP and index PDF files. Can I do it with FPDF?

  No. But a GPL C utility does exist, pdftotext, which is able to extract the textual content from a PDF. It is provided with the Xpdf package:
  
  http://www.foolabs.com/xpdf/

• 19. Can I convert an HTML page to PDF with FPDF?

  Not real-world pages. But a GPL C utility does exist, htmldoc, which allows to do it and gives good results:
  
  http://www.htmldoc.org

• 20. Can I concatenate PDF files with FPDF?

  Not directly, but it is possible to use FPDI to perform this task. Some free command-line tools also exist:
  
  mbtPdfAsm
  pdftk