Creating PDF table of contents

What are PDF Outlines?

Outlines, also known as bookmarks or tables of content, are visual elements that allow users to navigate from one part of a document to another.

Outlines are presented to users as a tree-structured hierarchy of elements, each defining which page (or part of a page) to jump to - while also displaying that they have been selected.

There are currently three types of items defined in the PDF Spec:

• BasicItem

These items are only meant to add some visual separation in the outline tree as no specific task is executed when there are selected.

• DestinationItem

These items contain page index information that needs to be shown and, optionally, any zoom effect to be executed when showing it.

• ActionItem

These items contain the action to execute upon selection (usually a GotoAction that contains the same information as the Destination Item).

Programming outlines

In the following example, we will construct an outline similar to the image above.

// Create a new PDF document:
PdfDocument doc = new PdfDocument(); 

CreatorModule creatorModule = doc.getCreatorModule(); 

// Create a new page:
Page page = Page.createInstance(doc); 

// Recover the page dimensions:
PageFormat pf = page.getPageFormat();
int page_y = (int) pf.getHeight();

// Recover the object that allows the drawing of text on the page:
JPdfGraphics2D g2d = page.getGraphics(); 

/******************************************************
/ Add the First chapter close to the top of the document.
/******************************************************

// Some text element in the page:
g2d.drawString("Chapter 1 Title", 15, 30 + g2d.getFontMetrics().getHeight()); 

// Create the destination and zoom data:
LocalPageDestination destination=LocalPageDestination.createInstance(doc);
destination.setPageIndex(1);
destination.setZoom(new ZoomPosition(new Integer(15), new Integer(30), null)); 

// Create the item:
OutlineItemDestination item0 = OutlineItemDestination.createInstance(doc);

// Set the title of the item and the destination upon activation:
item0.setTitle("Outline Chapter 1"); <britem0.setDestination(destination);

//******************************************************
/ Add the subchapter in the middle of the document.
/******************************************************

// Some text element in the page:
g2d.drawString("Sub Chapter 1.1 Title", 15, page_y  2 +
g2d.getFontMetrics().getHeight());

// Create the destination and zoom data:
destination=LocalPageDestination.createInstance(doc); 
destination.setPageIndex(1);
destination.setZoom(new ZoomPosition(new Integer(15), new Integer(page_y2), null));

// Create the item:
OutlineItemDestination item1 = OutlineItemDestination.createInstance(doc);

// Set the title of the item and the destination upon activation:
item1.setTitle("Outline SubChapter 1.1"); 
item1.setDestination(destination);

// Register it as a child of the first item:
item1.addBelow(item0); 

/******************************************************
/ Add the Second chapter close to the bottom of the document.
/******************************************************

// Some text element in the page:
g2d.drawString("Chapter 2 Title", 15, page_y - 30 +
g2d.getFontMetrics().getHeight()); 

//Create the destination and zoom data:
destination=LocalPageDestination.createInstance(doc); 
destination.setPageIndex(1);

destination.setZoom(new ZoomPosition(new Integer(15), new Integer(page_y - 30), null)); 

// Create the item:
OutlineItemDestination item2 = OutlineItemDestination.createInstance(doc);

// Set the title of the item and the destination upon activation:
item2.setTitle("Outline Chapter 2"); <britem2.setDestination(destination);

// Register it as a next item of the first item:
item2.addAfter(items0); 

//Now register the outline in the document:
Outline outline = creatorModule.createOutline(); 
outline.addItem(items0);

// Important: DO NOT forget to dispose():
g2d.dispose();

Save the document and run the application

Final step: Save the document to a file and close it in order to release memory.

doc.saveAs("SimpleOutlineDemo.pdf");
doc.close();

The full source code of this tutorial is part of the distribution.

Please click on this link to display the generated PDF.