键绑定不起作用

Question

我正在使用Caliburn.Micro和ModernUI进行WPF应用程序。在我看来，我试图用Caliburn键手势和经典MVVM方式捕获键绑定，但是它们都没有捕获键绑定。

这是我的View.xaml：

<UserControl x:Class="IKA.Views.CameraView"
  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" 
  mc:Ignorable="d" 
    xmlns:mui="http://firstfloorsoftware.com/ModernUI"
    xmlns:cal="http://www.caliburnproject.org"
    xmlns:model="clr-namespace:IKA.ViewModels"
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
    xmlns:ika="clr-namespace:IKA"
    d:DesignHeight="300" d:DesignWidth="300"
  cal:Message.Attach="[Gesture Key: Escape] = [Action Cancel()]">
<UserControl.InputBindings>
    <KeyBinding Modifiers="Control" Key="Escape" Command="{Binding Cancel}" />
</UserControl.InputBindings>
<Grid x:Name="grid">
    <Grid.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="/Resources/DirectionControl.xaml" />
                <ResourceDictionary Source="/Resources/MediaPlayer.xaml" />
            </ResourceDictionary.MergedDictionaries>
            <ControlTemplate  x:Key="PlayStyle" TargetType="Button">
                <Button Style="{StaticResource PlayButtonStyle}"  Width="100" Height="100" HorizontalAlignment="Center" />
            </ControlTemplate>
            <ControlTemplate x:Key="StopStyle" TargetType="Button">
                <Button Style="{StaticResource StopButtonStyle}"  Width="100" Height="100" HorizontalAlignment="Center" />
            </ControlTemplate>
        </ResourceDictionary>
    </Grid.Resources>
    <Grid.RowDefinitions>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="2*" />
        <ColumnDefinition Width="*" />
    </Grid.ColumnDefinitions>
    <Rectangle x:Name="BeforeVideo" Fill="Black" Grid.Row="0" Grid.RowSpan="6" />
    <!--<wpf:VlcControl Grid.Row="0" x:Name="myControl"/>-->
    <MediaElement x:Name="myControl"  Grid.Row="0" Grid.RowSpan="6" Stretch="Fill"  LoadedBehavior="Manual" UnloadedBehavior="Stop" />
    <Button x:Name="PlayButton" Grid.Row="0"  Grid.RowSpan="6" Click="OnPlayButtonClick" Template="{StaticResource PlayStyle}">Play</Button>
    <Button x:Name="StopButton" Grid.Row="0" Grid.RowSpan="6" Click="OnStopButtonClick" Template="{StaticResource StopStyle}">Stop</Button>
    <Canvas Grid.Column="1" Grid.Row="4" Grid.RowSpan="2" Height="100" Width="100">
        <Ellipse  Stretch="Fill" Fill="Aqua" Width="100" Height="100" />
        <Line Name="CurrentLine" X1="50" Y1="50" X2="50" Y2="0" Stroke="Black" StrokeThickness="1" RenderTransformOrigin="1,1">
            <Line.RenderTransform>
                <RotateTransform x:Name="LineRotateTransform" Angle="0" ></RotateTransform>
            </Line.RenderTransform>
            <Line.Triggers>
                <EventTrigger RoutedEvent="Line.MouseMove">
                    <BeginStoryboard>
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetProperty="(Line.RenderTransform).(RotateTransform.Angle)" To="160" Duration="0:0:2" />
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </Line.Triggers>
            </Line>
    </Canvas>
</Grid>

我的View.xaml.cs：

public partial class CameraView : UserControl
{

    public CameraView()
    {
        InitializeComponent();
        this.DataContext = ViewModelsContainer.CameraViewModel;
        myControl.Visibility = Visibility.Visible;
        StopButton.Visibility = Visibility.Hidden;
        PlayButton.Visibility = Visibility.Visible;
        string source = "http://192.168.1.159:8080/";
        myControl.Source = new Uri(source);
    }
    private void OnPlayButtonClick(object sender, RoutedEventArgs e)
    {
        BeforeVideo.Visibility = Visibility.Hidden;
        PlayButton.Visibility = Visibility.Hidden;
        myControl.Visibility = Visibility.Visible;
        PlayVideo();
        StopButton.Visibility = Visibility.Visible;
    }

    private void OnStopButtonClick(object sender, RoutedEventArgs e)
    {
        myControl.Pause();
        StopButton.Visibility = Visibility.Hidden;
        PlayButton.Visibility = Visibility.Visible;
    }

    private async void PlayVideo()
    {
        await PlayAsync();
    }

    private Task PlayAsync()
    {
        Task task = Task.Run(() => this.Dispatcher.Invoke(new Action(() => { myControl.Play(); })));
        return task;
    }
}

我的ViewModel：

 public class CameraViewModel:Screen
{
    public CameraViewModel()
    {

    }

    public void Cancel()
    {
        MessageBox.Show("Do you want to cancel?");
    }
}

当我按下Esc键（或其他键）时，没有任何反应。我怎么解决这个问题？我想这可能是关于ModernUI的。

编辑：dkozl评论后在ViewModel中进行编辑。

   public CameraViewModel()
    {
        CreateCancelCommand();  
    }
    private void CreateCancelCommand()
    {
        Cancel = new RelayCommand(CancelExecute);
    }

    public void CancelExecute(object obj)
    {
        MessageBox.Show("Do you want to cancel?");
    }

    public ICommand Cancel{get; internal set; }
}

但它并没有改变任何事情。