/// <summary>
/// Adds a form import button to a PDF document.
/// </summary>
/// <param name="pdfFilename">The filename of PDF document.</param>
/// <param name="loadFilename">The filename of import data file.</param>
public static void AddFormImportButton(string pdfFilename, string loadFilename)
{
    // open PDF document
    using (Vintasoft.Imaging.Pdf.PdfDocument document =
        new Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename))
    {
        // create PDF page
        Vintasoft.Imaging.Pdf.Tree.PdfPage page = new Vintasoft.Imaging.Pdf.Tree.PdfPage(
            document, Vintasoft.Imaging.PaperSizeKind.A6);
        // add page to the PDF document
        document.Pages.Add(page);

        // create a button and add button to PDF page
        Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormPushButtonField button =
            CreateButtonAndAddToPdfPage(page, "Load form");

        // create reference to a file with data that should be imported
        Vintasoft.Imaging.Pdf.Tree.PdfFileReferenceSpecification fileReference =
            new Vintasoft.Imaging.Pdf.Tree.PdfFileReferenceSpecification(document, loadFilename);

        // create the form import action
        Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormImportDataAction action =
            new Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormImportDataAction(document, fileReference);
        // specify that all fields of document must be imported
        action.Fields = document.InteractiveForm.Fields;

        // set the button action
        button.Annotation.ActivateAction = action;

        // save changes to a file
        document.SaveChanges();
    }
}

/// <summary>
/// Creates button and adds it to PDF page.
/// </summary>
/// <param name="page">PDF page.</param>
/// <param name="caption">Caption of button.</param>
public static Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormPushButtonField CreateButtonAndAddToPdfPage(
    Vintasoft.Imaging.Pdf.Tree.PdfPage page, string caption)
{
    // PDF document
    Vintasoft.Imaging.Pdf.PdfDocument document = page.Document;

    // button position on PDF page
    System.Drawing.RectangleF rect = new System.Drawing.RectangleF(50, page.Size.Height - 150, 200, 100);

    // create button
    Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormPushButtonField button =
        new Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormPushButtonField(document, "button", rect);
    // set the border style
    button.Annotation.BorderStyle = new Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationBorderStyle(document);
    button.Annotation.BorderStyle.Style = Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationBorderStyleType.Beveled;
    button.Annotation.BorderStyle.Width = 2;
    // set the appearance characteristics
    button.Annotation.AppearanceCharacteristics =
        new Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationAppearanceCharacteristics(document);
    button.Annotation.AppearanceCharacteristics.BackgroundColor = System.Drawing.Color.LightGray;
    button.Annotation.AppearanceCharacteristics.ButtonNormalCaption = caption;
    // set the text default appearance
    Vintasoft.Imaging.Pdf.Tree.Fonts.PdfFont font = document.FontManager.GetStandardFont(
        Vintasoft.Imaging.Pdf.Tree.Fonts.PdfStandardFontType.TimesRoman);
    button.SetTextDefaultAppearance(font, 15f, System.Drawing.Color.Black);

    // if PDF document does NOT have interactive form
    if (document.InteractiveForm == null)
        // create interactive form in PDF document
        document.InteractiveForm = new Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfDocumentInteractiveForm(document);
    // add button to the interactive form of PDF document
    document.InteractiveForm.Fields.Add(button);

    // if PDF page does NOT have annotation list
    if (page.Annotations == null)
        // create annotation list for PDF page
        page.Annotations = new Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationList(document);
    // add the button annotation to PDF page
    page.Annotations.Add(button.Annotation);

    // update field appearance
    button.UpdateAppearance();

    // return the button
    return button;
}

''' <summary>
''' Adds a form import button to a PDF document.
''' </summary>
''' <param name="pdfFilename">The filename of PDF document.</param>
''' <param name="loadFilename">The filename of import data file.</param>
Public Shared Sub AddFormImportButton(pdfFilename As String, loadFilename As String)
    ' open PDF document
    Using document As New Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename)
        ' create PDF page
        Dim page As New Vintasoft.Imaging.Pdf.Tree.PdfPage(document, Vintasoft.Imaging.PaperSizeKind.A6)
        ' add page to the PDF document
        document.Pages.Add(page)

        ' create a button and add button to PDF page
        Dim button As Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormPushButtonField = CreateButtonAndAddToPdfPage(page, "Load form")

        ' create reference to a file with data that should be imported
        Dim fileReference As New Vintasoft.Imaging.Pdf.Tree.PdfFileReferenceSpecification(document, loadFilename)

        ' create the form import action
        Dim action As New Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormImportDataAction(document, fileReference)
        ' specify that all fields of document must be imported
        action.Fields = document.InteractiveForm.Fields

        ' set the button action
        button.Annotation.ActivateAction = action

        ' save changes to a file
        document.SaveChanges()
    End Using
End Sub

''' <summary>
''' Creates button and adds it to PDF page.
''' </summary>
''' <param name="page">PDF page.</param>
''' <param name="caption">Caption of button.</param>
Public Shared Function CreateButtonAndAddToPdfPage(page As Vintasoft.Imaging.Pdf.Tree.PdfPage, caption As String) As Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormPushButtonField
    ' PDF document
    Dim document As Vintasoft.Imaging.Pdf.PdfDocument = page.Document

    ' button position on PDF page
    Dim rect As New System.Drawing.RectangleF(50, page.Size.Height - 150, 200, 100)

    ' create button
    Dim button As New Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfInteractiveFormPushButtonField(document, "button", rect)
    ' set the border style
    button.Annotation.BorderStyle = New Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationBorderStyle(document)
    button.Annotation.BorderStyle.Style = Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationBorderStyleType.Beveled
    button.Annotation.BorderStyle.Width = 2
    ' set the appearance characteristics
    button.Annotation.AppearanceCharacteristics = New Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationAppearanceCharacteristics(document)
    button.Annotation.AppearanceCharacteristics.BackgroundColor = System.Drawing.Color.LightGray
    button.Annotation.AppearanceCharacteristics.ButtonNormalCaption = caption
    ' set the text default appearance
    Dim font As Vintasoft.Imaging.Pdf.Tree.Fonts.PdfFont = document.FontManager.GetStandardFont(Vintasoft.Imaging.Pdf.Tree.Fonts.PdfStandardFontType.TimesRoman)
    button.SetTextDefaultAppearance(font, 15F, System.Drawing.Color.Black)

    ' if PDF document does NOT have interactive form
    If document.InteractiveForm Is Nothing Then
        ' create interactive form in PDF document
        document.InteractiveForm = New Vintasoft.Imaging.Pdf.Tree.InteractiveForms.PdfDocumentInteractiveForm(document)
    End If
    ' add button to the interactive form of PDF document
    document.InteractiveForm.Fields.Add(button)

    ' if PDF page does NOT have annotation list
    If page.Annotations Is Nothing Then
        ' create annotation list for PDF page
        page.Annotations = New Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationList(document)
    End If
    ' add the button annotation to PDF page
    page.Annotations.Add(button.Annotation)

    ' update field appearance
    button.UpdateAppearance()

    ' return the button
    Return button
End Function