How to: Replace Standard PDF Viewer Control Command with your own Custom Command

  • 3 minutes to read

This example shows how to modify the functionality of an existing PdfViewer command.

The PdfViewer exposes the IPdfViewerCommandFactoryService interface that enables you to substitute the default command with your own custom command.

To accomplish this task:

  • Create a custom command class (e.g., a CustomNextPageCommand class), inherited from the command that you wish to replace (e.g., PdfNextPageCommand).
  • Override the required method of the command. The main functionality and command specifics are located in the Execute method.
  • Create a class (e.g., CustomPdfViewerCommandFactoryService) implementing the IPdfViewerCommandFactoryService. You should override the IPdfViewerCommandFactoryService.CreateCommand method to create an instance of a custom command class if an identifier of a certain command is passed as a parameter. So, instead of the default command, a custom command will be used by the PdfViewer.
  • Use the created class to substitute for the default PdfViewer's service.
using DevExpress.XtraPdfViewer;
using System;
using System.Windows.Forms;

namespace ViewerCustomCommand {
    public partial class Form1 : Form {

        void ReplacePdfViewerCommandFactoryService(PdfViewer control) {
            IPdfViewerCommandFactoryService service = control.GetService<IPdfViewerCommandFactoryService>();
            if (service == null)
                return;
            control.RemoveService(typeof(IPdfViewerCommandFactoryService));
            control.AddService(typeof(IPdfViewerCommandFactoryService), new CustomPdfViewerCommandFactoryService(control,service));
        }

        public Form1() {
            InitializeComponent();
            pdfViewer1.LoadDocument("..\\..\\Demo.pdf");
            ReplacePdfViewerCommandFactoryService(pdfViewer1);
        }     
    }
}