Control 通过Behavior监听键盘操作

<UserControl x:Class="Coinstar.Coin.Kiosk.Administration.Ui.ServiceMode.Views.IOBoardDeviceView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"              xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                          xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"                          mc:Ignorable="d"
             d:DesignHeight="700" d:DesignWidth="1280">
    <i:Interaction.Behaviors>
        <bi:KeyPadPressBehavior PressAction="{Binding KeyPadAction}"/>
    </i:Interaction.Behaviors>
    <Grid>
     ...
     ...
     ...
    </Grid>
</UserControl>

 

public class KeyPadPressBehavior : Behavior<Control>
{
    public readonly static DependencyProperty PressActionProperty = DependencyProperty.Register("PressAction", typeof(Action<Key>), typeof(KeyPadPressBehavior));

    public Action<Key> PressAction
    {
        get { return (Action<Key>)GetValue(PressActionProperty); }
        set { SetValue(PressActionProperty, value); }
    }

    protected override void OnAttached()
    {
        base.OnAttached();
        if (AssociatedObject != null)
        {
            AssociatedObject.KeyDown += new KeyEventHandler(AssociatedObjectKeyDown);
        }
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        if (AssociatedObject != null)
        {
            AssociatedObject.KeyDown -= new KeyEventHandler(AssociatedObjectKeyDown);
        }
    }

    private void AssociatedObjectKeyDown(object sender, KeyEventArgs e)
    {
        if (PressAction != null)
        {
            PressAction.Invoke(e.Key);
        }
    }
}

 

public class TestViewModel : ViewModelBase
{
    private Action<Key> _keyPadAction;

    public Action<Key> KeyPadAction
    {
        get
        {
            return _keyPadAction;
        }
        set
        {
            if (_keyPadAction != value)
            {
                _keyPadAction = value;
                RaisePropertyChanged("KeyPadAction");
            }
        }
    }

    public override void OnActivated()
    {
        base.OnActivated();
        KeyPadAction = new Action<Key>(PressKeyAction);
    }

    private void PressKeyAction(Key key)
    {
        switch(key)
            case Key.A:
                ...
                ...
    }
}