Public Partial Class FormWithPdfContentEditorTool
    Inherits System.Windows.Forms.Form
    '...
    Private _imageViewer As Vintasoft.Imaging.UI.ImageViewer
    '...

    ''' <summary>
    ''' The content editor tool.
    ''' </summary>
    Private _contentEditorTool As Vintasoft.Imaging.Pdf.UI.PdfContentEditorTool

    ''' <summary>
    ''' The undo manager.
    ''' </summary>
    Private _undoManager As New Vintasoft.Imaging.Undo.UndoManager(20)

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

        ' create visual tool that allows to edit content on PDF page
        _contentEditorTool = New Vintasoft.Imaging.Pdf.UI.PdfContentEditorTool()

        ' 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

        ' disable figure rendering when current page is changed in image viewer
        _contentEditorTool.RenderFiguresWhenImageIndexChanging = False

        ' enable figure rendering when content editor tool is deactivating
        _contentEditorTool.RenderFiguresWhenDeactivating = True

        ' specify undo manager
        _contentEditorTool.UndoManager = _undoManager

        ' 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 visual tool that allows to edit text in text content on PDF page
        Dim contentEditorTextTool As New Vintasoft.Imaging.Office.OpenXml.UI.VisualTools.UserInteraction.OfficeDocumentVisualEditorTextTool()

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

    '...

    Private Sub drawEllipseToolStripButton_Click(sender As Object, e As System.EventArgs)
        ' 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 FormWithPdfContentEditorTool : System.Windows.Forms.Form
{
    //...
    Vintasoft.Imaging.UI.ImageViewer _imageViewer;
    //...

    /// <summary>
    /// The content editor tool.
    /// </summary>
    Vintasoft.Imaging.Pdf.UI.PdfContentEditorTool _contentEditorTool;

    /// <summary>
    /// The undo manager.
    /// </summary>
    Vintasoft.Imaging.Undo.UndoManager _undoManager = new Vintasoft.Imaging.Undo.UndoManager(20);

    public FormWithPdfContentEditorTool()
    {
        //...
        // initialize Vintasoft.Imaging.Pdf.Office.UI assembly
        Vintasoft.Imaging.PdfOfficeUIAssembly.Init();

        // create visual tool that allows to edit content on PDF page
        _contentEditorTool = new Vintasoft.Imaging.Pdf.UI.PdfContentEditorTool();

        // 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;

        // disable figure rendering when current page is changed in image viewer
        _contentEditorTool.RenderFiguresWhenImageIndexChanging = false;
        
        // enable figure rendering when content editor tool is deactivating
        _contentEditorTool.RenderFiguresWhenDeactivating = true;

        // specify undo manager
        _contentEditorTool.UndoManager = _undoManager;

        // 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 visual tool that allows to edit text in text content on PDF page
        Vintasoft.Imaging.Office.OpenXml.UI.VisualTools.UserInteraction.OfficeDocumentVisualEditorTextTool contentEditorTextTool =
            new Vintasoft.Imaging.Office.OpenXml.UI.VisualTools.UserInteraction.OfficeDocumentVisualEditorTextTool();

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

    //...

    private void drawEllipseToolStripButton_Click(object sender, System.EventArgs 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));
    }
}