C# – Printing using Word Interop with Print Dialog

Maybe see this previous Q&A: send-document-to-printer-with-c#

Or, for a WPF app that prints a FlowDocument :

    private void DoThePrint(System.Windows.Documents.FlowDocument document)
    {
        // Clone the source document's content into a new FlowDocument.
        // This is because the pagination for the printer needs to be 
        // done differently than the pagination for the displayed page. 
        // We print the copy, rather that the original FlowDocument. 
        System.IO.MemoryStream s = new System.IO.MemoryStream();
        TextRange source = new TextRange(document.ContentStart, document.ContentEnd);
        source.Save(s, DataFormats.Xaml);
        FlowDocument copy = new FlowDocument();
        TextRange dest = new TextRange(copy.ContentStart, copy.ContentEnd);
        dest.Load(s, DataFormats.Xaml);

        // Create a XpsDocumentWriter object, implicitly opening a Windows common print dialog, 
        // and allowing the user to select a printer.

        // get information about the dimensions of the seleted printer+media. 
        System.Printing.PrintDocumentImageableArea ia = null;
        System.Windows.Xps.XpsDocumentWriter docWriter = System.Printing.PrintQueue.CreateXpsDocumentWriter(ref ia);

        if (docWriter != null && ia != null)
        {
            DocumentPaginator paginator = ((IDocumentPaginatorSource)copy).DocumentPaginator;

            // Change the PageSize and PagePadding for the document to match the CanvasSize for the printer device.
            paginator.PageSize = new Size(ia.MediaSizeWidth, ia.MediaSizeHeight);
            Thickness t = new Thickness(72);  // copy.PagePadding;
            copy.PagePadding = new Thickness(
                             Math.Max(ia.OriginWidth, t.Left),
                               Math.Max(ia.OriginHeight, t.Top),
                               Math.Max(ia.MediaSizeWidth - (ia.OriginWidth + ia.ExtentWidth), t.Right),
                               Math.Max(ia.MediaSizeHeight - (ia.OriginHeight + ia.ExtentHeight), t.Bottom));

            copy.ColumnWidth = double.PositiveInfinity;
            //copy.PageWidth = 528; // allow the page to be the natural with of the output device

            // Send content to the printer.
            docWriter.Write(paginator);
        }

    }

The print dialog is accessible from .NET and will run just fine on Excel 2007 using the 12.0 PIAs. The Dialog.Show() command, however, has 30 optional parameters. In the future, C# 4.0 will allow for omitting optional parameters (thank goodness), and VB.NET does not require them, but if using C# 3.0 or below, we have to provide Type.Missing for the optional parameters. All 30 of them:

bool userDidntCancel =
    excelApp.Dialogs[Excel.XlBuiltInDialog.xlDialogPrint].Show(
        Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
        Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
        Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
        Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
        Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
        Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);

The the Show() method returns 'true' to indicate that the operation succeeded; it returns 'false' to indicate that the user hit the cancel button or the escape (esc) key, so no action occurred.

Hope this gets you going...