Outline is a hierarchical list of items used to organize and display the document structure to the user so that the user can interactively navigate to a particular topic or a location in a document. For more information on outline, see PDF specification 1.7 (Section 12.3.3).

GcPdf allows you to define an outline node in a PDF document using OutlineNode class. You can also add child nodes to the outline nodes and choose whether to display the expanded list with visible child nodes or a compact list using Expanded property of the OutlineNode class. This class also provides methods and properties to manipulate document's outline.

Add Outline Node

To add an outline node in the PDF document, pass the instance of OutlineNode class as a parameter to the Add method.

// Add  outline node using Add method
doc.Outlines.Add(new OutlineNode("Chapter 5", new DestinationFitH(8, null)));

Get Outline Node

To get a specific outline node from the PDF document:

1. Create an object of OutlineNodeCollection class.

2. Use the OutlineNodeCollection object to access a particular outline node using the node index.

   // Get the OutlineNodeCollection
   OutlineNodeCollection nodecol = doc.Outlines;
   Console.WriteLine("Outline Title: {0}", nodecol[0].Title);

Modify Outline Node

To modify a specific outline node in a PDF file, get the outline from OutlineNodeCollection by specifying its index and set the new value to its properties such as Title property.

// Modify an outline node
nodecol[6].Title = "Testing Chapter";

Delete Outline Node

To delete all the outline nodes from a PDF document, use Clear method. Apart from this, RemoveAt method can be used to delete a particular outline by specifying its index value.

// Delete all the outline nodes
doc.Outlines.Clear();
        
// Delete a particular outline node
doc.Outlines.RemoveAt(1);

For more information about implementation of outlines using GcPdf, see GcPdf sample browser.