KeyDown event sent to WPF TextBox does not trigger text input

Question

I am attempting to simulate keyboard input to a WPF TextBox control (the reasons for doing this are outside the scope of this question). However, I am having difficulty in getting text to appear.

I've made a simple WPF application containing a single button and a single textbox, and I want to simulate a keyboard press when clicking the button, causing a single character of text (the letter "A") to be typed into the textbox. This is what I have so far:

private void button_Click(object sender, RoutedEventArgs e)
{
    var key = Key.A;
    var target = textBox1; // Keyboard.FocusedElement;

    // None of these actually induce text to appear in the textbox
    target.RaiseEvent(new KeyEventArgs(Keyboard.PrimaryDevice, PresentationSource.FromVisual((Visual)target), 0, key) { RoutedEvent = Keyboard.PreviewKeyDownEvent });
    target.RaiseEvent(new KeyEventArgs(Keyboard.PrimaryDevice, PresentationSource.FromVisual((Visual)target), 0, key) { RoutedEvent = Keyboard.PreviewKeyUpEvent });
    target.RaiseEvent(new KeyEventArgs(Keyboard.PrimaryDevice, PresentationSource.FromVisual((Visual)target), 0, key) { RoutedEvent = Keyboard.KeyDownEvent });
    target.RaiseEvent(new KeyEventArgs(Keyboard.PrimaryDevice, PresentationSource.FromVisual((Visual)target), 0, key) { RoutedEvent = Keyboard.KeyUpEvent });
}

I have tried attaching event handlers to the textbox, and I can see and verify that the event are being received by the textbox. However, none of them actually make any text appear.

How can I go about triggering text input by raising an event?

Any help is much appreciated, thanks.

Answer 1

Have you tried getting the control's AutomationPeer, eg:

TextBox tb;
TextBoxAutomationPeer tbap = new TextBoxAutomationPeer(tb);

IValueProvider vp = tbap.GetPattern(PatternInterface.Value) as IValueProvider;
vp.SetValue("Your text here.");