How to print the richtextbox formatting and not only the text?

See more:

C#

WPF

RichTextBox

My starting point is that I have a Side Panel in my MainWindow, in this Panel are my Buttons with my formatting Comand. which looks like that:

<Button Tag="{DynamicResource Add}" Command="IncreaseFontSize" ToolTip="Größer" Content=" Fett" Style="{StaticResource ButtonStyle}"
                                       Background="Transparent" Foreground="Gray" HorizontalAlignment="Center"  Width="240" />

And beside the Panel I have an Frame in which I open my Pages. These Pages has RichTextBoxes in it. After I made the text Bold I want to print it. But I only get the Text without the formatting.

What I have tried:

With my Print Button click on my MainWindow there comes this Code:

string richText = new TextRange((PagesNavigation.Content as A4Page).rtb0.Document.ContentStart, (PagesNavigation.Content as A4Page).rtb0.Document.ContentEnd).Text;
string richText2 = new TextRange((PagesNavigation.Content as A4Page).rtb1.Document.ContentStart, (PagesNavigation.Content as A4Page).rtb1.Document.ContentEnd).Text;
string richText3 = new TextRange((PagesNavigation.Content as A4Page).rtb2.Document.ContentStart, (PagesNavigation.Content as A4Page).rtb2.Document.ContentEnd).Text;
string richText4 = new TextRange((PagesNavigation.Content as A4Page).rtb3.Document.ContentStart, (PagesNavigation.Content as A4Page).rtb3.Document.ContentEnd).Text;

if (richText != "")
    vm.TextBox1 = richText;
if (richText2 != "")
    vm.TextBox2 = richText2;
if (richText3 != "")
    vm.TextBox3 = richText3;
if (richText4 != "")
    vm.TextBox4 = richText4;

window.ShowDialog();

A4Page is here the name of my Page which I want to Print. After that I open an little Print dialog. I have there an another Print button which looks like that:

A4Page page = new A4Page();
          
            var vm = (ViewModel)this.DataContext;
            if (inputQuantity.Text == "0")
                MessageBox.Show("Der wert darf nicht 0 sein!!");

            else if (vm.selected_printer == null)
                MessageBox.Show("Bitt Geben Sie einen Drucker an!!");
            else if (vm.selected_printer != null && inputQuantity.Text != "0")
                page.print();

And thats opening my Page in which is an Print method where I want to print my Page.

var vm = (ViewModel)this.DataContext;

            vm.printcontrol = true;
            PrintDialog printDlg = new PrintDialog();

            printDlg.PrintQueue = new PrintQueue(new PrintServer(), vm.selected_printer);
            printDlg.PrintTicket.CopyCount = vm.PrintCount;

            PageMediaSize pageSize = new PageMediaSize(PageMediaSizeName.NorthAmericaLetter);


            ///leert die RichTextBox und platziert denn neuen Text
            rtb0.Document.Blocks.Clear();
            rtb0.Document.Blocks.Add(new Paragraph(new Run(vm.TextBox1)));

            rtb1.Document.Blocks.Clear();
            rtb1.Document.Blocks.Add(new Paragraph(new Run(vm.TextBox2)));

            rtb2.Document.Blocks.Clear();
            rtb2.Document.Blocks.Add(new Paragraph(new Run(vm.TextBox3)));

            rtb3.Document.Blocks.Clear();
            rtb3.Document.Blocks.Add(new Paragraph(new Run(vm.TextBox4)));
            printDlg.PrintTicket.PageMediaSize = pageSize;///Setzt die Richtige Größe
            printDlg.PrintTicket.PageOrientation = PageOrientation.Portrait;///Setzt das Document auf Vertical Drucken

            printDlg.PrintVisual(previewprint, "Border Printing.");
            vm.printcontrol = false;

So the Text in the Preview where the User can type in Data would look like that:

Test

but the text would look like this in the Print output:

Test

without any Formatting