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Home » Newsletter » April 2009

By L. Santhanam

One of the less highlighted enhancements in Version 3.2 of PDFOne Java were the improvements in autopagination.

Previously, autopagination occured when a PdfDocument was created or when autopagination property was set to true and a rendering operation on the document causes the content to overflow and a new page got created.

In Version 3.2, autopagination can be manually called using a new method PdfDocument.addPageBreak(). Before using this method, you need to know more as this method behaves differently in creation mode and writing mode.

In Creation Mode

When you create a new document with PdfDocument, a blank page is created by default in the document. This page becomes the focus of subsequent rendering operations - for all PdfDocument methods that do not have a page range argument, such as PdfDocument.writeText().

If you need a new page similar to the above-mentioned blank page, then call the new PdfDocument.addPageBreak() method. The method will create a new page and append it after the current page. The new page will then become the focus of rendering operations.

Here is a code example that illustrates creation-mode pagination.

import java.io.IOException;
 
import com.gnostice.pdfone.PdfAutoPageCreationHandler;
import com.gnostice.pdfone.PdfDocument;
import com.gnostice.pdfone.PdfException;
import com.gnostice.pdfone.PdfMeasurement;
import com.gnostice.pdfone.PdfPage;
import com.gnostice.pdfone.PdfPageSize;
import com.gnostice.pdfone.PdfWriter;
 
public class PdfDocument_addPageBreak_Example 
    implements PdfAutoPageCreationHandler {
 public static void main(String[] args) 
      throws IOException, PdfException {
  // Create a blank new document
  PdfDocument d = new PdfDocument();
 
  // Add a page to the document
  PdfPage p = new PdfPage(PdfPageSize.A4);
  d.add(p);
  // If the above two lines are not used, then
  // the onAutoPageCreation event will be called 
  // for both page 1 and 2
 
  // Make pagination manual
  d.setAutoPaginate(false);
 
  // Set user class to raise onAutoPageCreation event
  // when a new page is created
  d.setAutoPageCreationHandler(
      new PdfDocument_addPageBreak_Example());
 
  // Write text on page 1
  d.writeText("Hello, world!", 30, 50);
 
  // Add a new page
  d.addPageBreak();
 
  // Write text on newly added page (2)
  d.writeText("Hello again, world!", 30, 50);
 
  d.setOpenAfterSave(true);
 
  // Write document to file
  d.save("PdfDocument_addPageBreak.pdf");
  d.close(); 

 }
 
 public double[] onAutoPageCreation(
          PdfDocument d, int creatingPageNum) {
  // Change the page dimensions and margins of the new page
  double[] new_page_sizes = new double[10];
  new_page_sizes[0] = PdfPageSize.CUSTOM; // page size  
  new_page_sizes[1] = 8; // width
  new_page_sizes[2] = 3; // height
  new_page_sizes[3] = 0; // header size
  new_page_sizes[4] = 0; // footer size
  new_page_sizes[5] = 2; // left margin 
  new_page_sizes[6] = 1; // top margin
  new_page_sizes[7] = 2; // right margin       
  new_page_sizes[8] = 1; // bottom margin
  new_page_sizes[9] = PdfMeasurement.MU_INCHES; // measurement unit
 
  // return new page settings
  return new_page_sizes;
 }
}

In Reading Mode

In reading mode, where an existing document is opened, the new method behaves differently. The first page will be the focus of rendering operations as usual. But, when you call PdfDocument.addPageBreak(), the focus will shift to the next page but no new page will be created. If a second page did not exist, only then a new page will be created.