Public Partial Class WindowWithPdfEditorTool
    Inherits System.Windows.Window
    '...
    Private _imageViewer As Vintasoft.Imaging.Wpf.UI.WpfImageViewer
    Private _contentEditorTool As Vintasoft.Imaging.Pdf.Wpf.UI.WpfPdfContentEditorTool
    '...

    Public Sub New()
        '...
        ' initialize Vintasoft.Imaging.Pdf.Office.UI assembly
        Vintasoft.Imaging.PdfOfficeWpfUIAssembly.Init()

        ' create visual tool that allows to edit content on PDF page
        _contentEditorTool = New Vintasoft.Imaging.Pdf.Wpf.UI.WpfPdfContentEditorTool()
        ' create visual tool that allows to edit text in text content on PDF page
        Dim visualEditorTextTool As New Vintasoft.Imaging.Office.OpenXml.Wpf.UI.VisualTools.UserInteraction.WpfOfficeDocumentVisualEditorTextTool()

        ' specify that content editor tool should add and edit content on PDF page
        _contentEditorTool.AppendMode = False
        ' specify that content editor tool should highlight content figures
        _contentEditorTool.FiguresHighlight = True
        ' specify that visual tool should work only with content of specified types
        _contentEditorTool.InteractiveContentType = Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.Text Or Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.Image Or Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.Form Or Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.StrokePath Or Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.FillPath

        ' create the composite visual tool and set it as a current tool of image viewer
        _imageViewer.VisualTool = New Vintasoft.Imaging.Wpf.UI.VisualTools.WpfCompositeVisualTool(visualEditorTextTool, _contentEditorTool)
    End Sub

    '...

    Private Sub drawEllipseToolStripButton_Click(sender As Object, e As System.Windows.RoutedEventArgs)
        ' start building an ellipse
        _contentEditorTool.StartBuildEllipse(New Vintasoft.Imaging.Pdf.Drawing.PdfPen(System.Drawing.Color.Red, 5), New Vintasoft.Imaging.Pdf.Drawing.PdfBrush(System.Drawing.Color.Green))
    End Sub
End Class

public partial class WindowWithPdfEditorTool : System.Windows.Window
{
    //...
    Vintasoft.Imaging.Wpf.UI.WpfImageViewer _imageViewer;
    Vintasoft.Imaging.Pdf.Wpf.UI.WpfPdfContentEditorTool _contentEditorTool;
    //...

    public WindowWithPdfEditorTool()
    {
        //...
        // initialize Vintasoft.Imaging.Pdf.Office.UI assembly
        Vintasoft.Imaging.PdfOfficeWpfUIAssembly.Init();

        // create visual tool that allows to edit content on PDF page
        _contentEditorTool = new Vintasoft.Imaging.Pdf.Wpf.UI.WpfPdfContentEditorTool();
        // create visual tool that allows to edit text in text content on PDF page
        Vintasoft.Imaging.Office.OpenXml.Wpf.UI.VisualTools.UserInteraction.WpfOfficeDocumentVisualEditorTextTool visualEditorTextTool =
            new Vintasoft.Imaging.Office.OpenXml.Wpf.UI.VisualTools.UserInteraction.WpfOfficeDocumentVisualEditorTextTool();

        // specify that content editor tool should add and edit content on PDF page
        _contentEditorTool.AppendMode = false;
        // specify that content editor tool should highlight content figures
        _contentEditorTool.FiguresHighlight = true;
        // specify that visual tool should work only with content of specified types
        _contentEditorTool.InteractiveContentType =
            Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.Text |
            Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.Image |
            Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.Form |
            Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.StrokePath |
            Vintasoft.Imaging.Pdf.Drawing.GraphicsFigures.GraphicsFigureContentType.FillPath;

        // create the composite visual tool and set it as a current tool of image viewer
        _imageViewer.VisualTool = new Vintasoft.Imaging.Wpf.UI.VisualTools.WpfCompositeVisualTool(visualEditorTextTool, _contentEditorTool);
    }

    //...

    private void drawEllipseToolStripButton_Click(object sender, System.Windows.RoutedEventArgs e)
    {
        // start building an ellipse
        _contentEditorTool.StartBuildEllipse(
            new Vintasoft.Imaging.Pdf.Drawing.PdfPen(System.Drawing.Color.Red, 5),
            new Vintasoft.Imaging.Pdf.Drawing.PdfBrush(System.Drawing.Color.Green));
    }
}