FOP Output Options

Most FOP renderers use a FOP-specific system for font registration. However, the AWT and print renderers use the java awt package, which gets its font information from the operating system registration. This can result in several differences, including actually using different fonts, and having different font metrics for the same font. The net effect is that the layout of a given FO document can be quite different between renderers that do not use the same font information.

The most obvious way to print your document is to use the FOP print renderer, which uses the Java API (AWT). However, you can also send output from the Postscript renderer directly to a Postscript device, or output from the PCL renderer directly to a PCL device.

Here are Windows command-line examples for Postscript and PCL:

fop ... -ps \\computername\printer

fop ... -pcl \\computername\printer

Here is some Java code to accomplish the task in UNIX:

proc = Runtime.getRuntime().exec("lp -d" + print_queue + " -o -dp -");
out = proc.getOutputStream();

Set the OutputStream (out) to the PCLRenderer and it happily sends the PCL to the UNIX printer queue.

PDF has a set of fonts that are always available to all PDF viewers, to quote from the PDF Specification: "PDF prescribes a set of 14 standard fonts that can be used without prior definition. These include four faces each of three Latin text typefaces (Courier, Helvetica, and Times), as well as two symbolic fonts (Symbol and ITC Zapf Dingbats). These fonts, or suitable substitute fonts with the same metrics, are guaranteed to be available in all PDF viewer applications."

FOP does not currently support several desirable PDF features: document properties (title, author, etc.), and watermarks. One workaround is to use Adobe Acrobat (the full version, not the Reader) to process the file manually or with scripting that it supports.

Another popular post-processing tool is iText, which has tools for adding security features, document properties, watermarks, and many other features to PDF files.

Here is some sample code that uses iText to encrypt a FOP-generated PDF. (Note that FOP now supports PDF encryption. However the principles for using iText for other PDF features are similar.)

public static void main(String args[]) {
  try {
    ByteArrayOutputStream fopout=new ByteArrayOutputStream();
    FileOutputStream outfile=new FileOutputStream(args[2]);
    Driver driver =new Driver();
    driver.setOutputStream(fopout);
    driver.setRenderer(Driver.RENDER_PDF);
    Transformer transformer=TransformerFactory
      .newInstance().newTransformer(new StreamSource(new File(args[1])));
    transformer.transform(new StreamSource(new File(args[0])),
       new SAXResult(driver.getContentHandler()));
    PdfReader reader = new PdfReader(fopout.toByteArray());
    int n = reader.getNumberOfPages();
    Document document = new Document(reader.getPageSizeWithRotation(1));
    PdfWriter writer = PdfWriter.getInstance(document, outfile);
    writer.setEncryption(PdfWriter.STRENGTH40BITS, "pdf", null,
      PdfWriter.AllowCopy);
    document.open();
    PdfContentByte cb = writer.getDirectContent();
    PdfImportedPage page;
    int rotation;
    int i = 0;
    while (i < n) {
      i++;
      document.setPageSize(reader.getPageSizeWithRotation(i));
      document.newPage();
      page = writer.getImportedPage(reader, i);
      rotation = reader.getPageRotation(i);
      if (rotation == 90 || rotation == 270) {
        cb.addTemplate(page, 0, -1f, 1f, 0, 0,
         reader.getPageSizeWithRotation(i).height());  }
      else {
        cb.addTemplate(page, 1f, 0, 0, 1f, 0, 0);
      }
      System.out.println("Processed page " + i);
    }
    document.close();
  }
  catch( Exception e) {
    e.printStackTrace();
  }
}

Check the iText tutorial and documentation for setting access flags, password, encryption strength and other parameters.

In addition to the PDF Post-processing options, consider the following workarounds:

• Use a background image for the body region.
• (submitted by Trevor_Campbell@kaz.com.au) Place an image in a region that overlaps the flowing text. For example, make region-before large enough to contain your image. Then include a block (if necessary, use an absolutely positioned block-container) containing the watermark image in the static-content for the region-before. Note that the image will be drawn on top of the normal content.

• Text or graphics outside the left or top of the printable area are not rendered properly. In general things that should print to the left of the printable area are shifted to the right so that they start at the left edge of the printable area and an error message is generated.
• The Helvetica and Times fonts are not well supported among PCL printers so Helvetica is mapped to Arial and Times is mapped to Times New. This is done in the PCLRenderer, no changes are required in the FO's. The metrics and appearance for Helvetica/Arial and Times/Times New are nearly identical, so this has not been a problem so far.
• Only the original fonts built into FOP are supported.
• For the non-symbol fonts, the ISO 8859/1 symbol set is used (PCL set "0N").
• Multibyte characters are not supported.
• SVG support is limited. Currently only lines, rectangles (may be rounded), circles, ellipses, text, simple paths, and images are supported. Colors are supported (dithered black and white) but not gradients.
• Images print black and white only (not dithered). When the renderer prints a color image it uses a threshold value, colors above the threshold are printed as white and below are black. If you need to print a non-monochrome image you should dither it first.
• Image scaling is accomplished by modifying the effective resolution of the image data. The available resolutions are 75, 100, 150, 300, and 600 DPI.
• Color printing is not supported. Colors are rendered by mapping the color intensity to one of the PCL fill shades (from white to black in 9 steps).
• SVG clipping is not supported.

There are some special features that are controlled by some public variables on the PCLRenderer class.

orientation

The logical page orientation is controlled by the public orientation variable. Legal values are:

curdiv, paperheight

The curdiv and paperheight variables allow multiple virtual pages to be printed on a piece of paper. This allows a standard laser printer to use perforated paper where every perforation will represent an individual page. The paperheight sets the height of a piece of paper in decipoints. This will be divided by the page.getHeight() to determine the number of equal sized divisions (pages) that will fit on the paper. The curdiv variable may be read/written to get/set the current division on the page (to set the starting division and read the ending division for multiple invocations).

topmargin, leftmargin

The topmargin and leftmargin may be used to increase the top and left margins for printing.

• Images and SVG may not be display correctly. SVG support is far from being complete. No image transparency is available.
• Character spacing may be wrong.
• No font embedding is supported.
• Multibyte characters are not supported.
• PPD support is still missing.
• The renderer is not yet configurable.