How do I create keyboard input in a wpf application?

Question

I want to make a wpf application in c# that displays some text on screen, and where the user is supposed to write a response and press enter to submit the response. I don't want to use a textbox, since there is only one line for the text input in the window, and I don't want the user to have to click to select the textbox. I want the application to be mouse-free.

My question is: How do I make it so that when the user has written their answer, they can submit the response simply by pressing enter?

I have tried the following snippet of code which I found on a microsoft help website:

private void OnKeyDownHandler(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Return)
        {

            doSomething();
        }
    }

I suppose I have to add some code elsewhere, but I'm not sure where or what I need to add.

Answer 1

If you have a button that you're using for submit, you can easily set it as the default by using the IsDefault=true (wrote a tip about doing this and the cancel for the escape here .)

Other than that, you'll have to have somewhere to write it (yet you don't want a textbox? you can select it by default, or tab into it if you don't have the focus there), and you can handle the keydown to "catch" the Enter otherwise.

Answer 2

If you want to make sure your window process every Enter key press without care what control is focused you can use PreviewKeyDown event:

private void Window_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if (e.Key == Key.Enter)
    {
        //Process user input
        e.Handled = true;
    }
} 

Of course if you are doing mvvm you can create a behavior to encapsulate the event handler:

 public class WindowBehavior : Behavior<Window>
    {
        protected override void OnAttached()
        {
            AssociatedObject.PreviewKeyDown += AssociatedObject_PreviewKeyDown;
        }

    private void AssociatedObject_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Enter)
        {
            MessageBox.Show("Enter from Window");
            e.Handled = true;
        }
    }

    protected override void OnDetaching()
    {
        AssociatedObject.PreviewKeyDown -= AssociatedObject_PreviewKeyDown;
    }

I suggest you to read this article about bubble, tunneling and direct events basic for WPF events.