Question

I have TextBox I need to format the text if it is put in ctrl + v

I tried:

  String str = Clipboard.GetText();
  (sender as TextBox).Text += str.Replace("\r\n\r\n", "\r\n");

but this code throws an exception

error: Why doesn't Clipboard.GetText work?

Answer 1

Format the text at the TextChanged event handler.

Update after comment:

You don’t need to do anything, just handle the textchange event:

XAML:

<TextBox x:Name="tbTarget" TextChanged="tbTarget_TextChanged" />

Code:

void tbTarget_TextChanged(object sender, TextChangedEventArgs e)
{
  Dim tb = (TextBox)sender;
  tb.Text = tb.Text.ToUpper();
}

If the TextBox is only meant for text pasting, cosider setting its IsReadOnly property to true.

Update after last comment:

Add the following to your code class:

public partial class MainWindow : Window
{
  public MainWindow()
  {
    InitializeComponent();
    DataObject.AddPastingHandler(tb, 
      new DataObjectPastingEventHandler(tb_Pasting));      
  }

  private void tb_Pasting(object sender, DataObjectPastingEventArgs e)
  {
    if (e.SourceDataObject.GetDataPresent(DataFormats.Text))
    {
      var text =
        (string)e.SourceDataObject.GetData(DataFormats.Text) ?? string.Empty;
      e.DataObject = new DataObject(DataFormats.Text, text.ToUpper());
    } 
  }
}