How do I run some simple C# code for a given keypress?

Question

I have a button on a XAML form that calls the btnName_Click() code in the backing cs file.

I also want to assign a keyboard shortcut to run that same code. Basically CTRL<- or something similar.

This needs to work regardless of the control I'm currently in (there's a TextBox for example that I want to ensure doesn't capture the event if I'm in there).

I've read up on routed commands but that seems like a lot of work for something which should be simple.

Is there an easy way to do this or do I need to create routed commands? If I do need to use them, what's the simplest way to achieve what I want?

Answer 1

In the root Window element hook into the KeyDown event:

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        Keyboard.KeyDown="Window_KeyDown"
        >

Code behind:

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        this.DoSomething();
    }

    private void Window_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Right && e.KeyboardDevice.Modifiers == ModifierKeys.Control)
        {
            this.DoSomething();
        }
    }

    private void DoSomething()
    {
        MessageBox.Show("Whatever");
    }

On a side note, I would suggest looking into the M-V-VM approach, and more specifically Commands and Attached behaviors. That would make this much more unit testable.

Answer 2

Have your XAML as

<StackPanel PreviewKeyDown="StackPanel_PreviewKeyDown">
    <Button x:Name="btnName" Click="btnName_Click" Height="Auto" Width="Auto" Content="Name"></Button>
    <TextBox x:Name="tb"></TextBox>
</StackPanel>

and your cs as

public MainWindow()
{
    InitializeComponent();
}

private void btnName_Click(object sender, RoutedEventArgs e)
{
    MessageBox.Show("This is from btnName");
}

private void StackPanel_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if (Keyboard.Modifiers == ModifierKeys.Control && e.Key == Key.Left)
    {
        btnName_Click(sender, new RoutedEventArgs());
        e.Handled = true;
    }
}

You should put the PreviewKeydown event on the topmost control like your window so that once Ctrl <- is hit only the window or top control handles it and no one else.

PreviewKeyDown is a tunneled event - it originates at the topmost control and goes down to actual control.