键绑定困境(KeyBinding woes)

我有如下所示，对于一个主细节排序显示的用户控制。 与基础视图模型一个典型的MVVM架构，来完成一个CloseCommand。

我试图范围键绑定，将在TabItem的执行关闭命令，只是无法得到它的工作。

有趣的是，我可以得到它，如果我穿上PersonDetailView（的是，TabControl的可能显示，如下图所示两种可能的用户控件之一）的结合工作，但它应该在的TabControl或包含它的边界。

有什么建议么？

干杯，
Berryl

用户控件

<Grid>

    <ListBox Style="{StaticResource ListBoxStyle}" />

    <GridSplitter 
        HorizontalAlignment="Right" VerticalAlignment="Stretch" Grid.Column="1" 
        ResizeBehavior="PreviousAndNext" Width="5" Background="#FFBCBCBC" KeyboardNavigation.IsTabStop="False"
                  />

    <Border Grid.Column="2" Background="{StaticResource headerBrush}">

        // ** THIS is the scope I want, but it doesn't work
        <Border.InputBindings>
            <KeyBinding Key="F4" Modifiers="Control" Command="{Binding CloseCommand}"/>
        </Border.InputBindings>

        <TabControl Style="{StaticResource TabControlStyle}" >

            <TabControl.Resources>                   
                <DataTemplate DataType="{x:Type personVm:PersonDetailVm}">
                    <local:PersonDetailView />
                </DataTemplate>
                <DataTemplate DataType="{x:Type orgVm:OrganizationDetailVm}">
                    <local:OrganizationDetailView />
                </DataTemplate>
            </TabControl.Resources>

        </TabControl>
    </Border>

</Grid>

TabItem的风格

<Style x:Key="OrangeTabItemStyle" TargetType="{x:Type TabItem}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type TabItem}">
                <Border AllowDrop="true" ToolTip="{Binding DisplayName}">
                    <Border Name="Border" Background="Transparent" BorderBrush="Transparent" BorderThickness="1,1,1,0" CornerRadius="2,2,0,0">
                        <DockPanel x:Name="TitlePanel" TextElement.Foreground="{StaticResource FileTabTextBrush}">
                            <ctrl:GlyphButton 

                                // ** This works as expected
                                Command="{Binding CloseCommand}" CommandParameter="{Binding}"
                                >
                            </ctrl:GlyphButton>

                        </DockPanel>
                    </Border>

                    // ** Can't get it to work from here either **
                    <Border.InputBindings>
                        <KeyBinding Command="{Binding CloseCommand}" Key="F4" Modifiers="Control" />
                    </Border.InputBindings>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

UPDATE

我茫然地设置的RoutedCommand在我的风格

<Style x:Key="OrangeTabItemStyle" TargetType="{x:Type TabItem}">
    <Setter Property="beh:RoutedCommandWire.RoutedCommand" Value="F4"/> **** ?? ****
    <Setter Property="beh:RoutedCommandWire.ICommand" Value="{Binding CloseCommand}"/>
</Style>

以下是我认为答案代码看起来像在C＃

public class RoutedCommandWire
{

    public static readonly DependencyProperty RoutedCommandProperty =
        DependencyProperty.RegisterAttached("RoutedCommand", typeof(RoutedCommand), typeof(RoutedCommandWire), new PropertyMetadata(OnCommandChanged));

    public static RoutedCommand GetRoutedCommand(DependencyObject d) { return (RoutedCommand) d.GetValue(RoutedCommandProperty); }
    public static void SetRoutedCommand(DependencyObject d, RoutedCommand value) { d.SetValue(RoutedCommandProperty, value); }

    public static readonly DependencyProperty ICommandProperty = 
        DependencyProperty.RegisterAttached("Iommand", typeof(ICommand), typeof(RoutedCommandWire));

    public static ICommand GetICommand(DependencyObject d) { return (ICommand) d.GetValue(ICommandProperty); }
    public static void SetICommand(DependencyObject d, ICommand value) { d.SetValue(ICommandProperty, value); }

    private static void OnCommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) {
        var fe = d as FrameworkElement;
        if(fe==null) return;

        if (e.OldValue != null) {
            Detach(fe, (RoutedCommand) e.OldValue);
        }
        if (e.NewValue != null) {
            Attach(fe, (RoutedCommand) e.NewValue, Execute, CanExecute);
        }
    }

    private static void CanExecute(object sender, CanExecuteRoutedEventArgs e) {
        var depObj = sender as DependencyObject;
        if (depObj == null) return;

        var command = GetICommand(depObj);
        if (command == null) return;

        e.CanExecute = command.CanExecute(e.Parameter);
        e.Handled = true;
    }

    private static void Execute(object sender, ExecutedRoutedEventArgs e)
    {
        var depObj = sender as DependencyObject;
        if (depObj == null) return;

        var command = GetICommand(depObj);
        if (command == null) return;

        command.Execute(e.Parameter);
        e.Handled = true;
    }

    public static void Detach(FrameworkElement fe, RoutedCommand command) {
        var bindingCollection = fe.CommandBindings;
        if (bindingCollection.Count == 0) return;

        var matches = bindingCollection.Cast<CommandBinding>().Where(binding => binding.Equals(command));
        foreach (var binding in matches) {
            bindingCollection.Remove(binding);
        }
    }

    public static void Attach(FrameworkElement fe, RoutedCommand command, 
        ExecutedRoutedEventHandler executedHandler, CanExecuteRoutedEventHandler canExecuteHandler, bool preview = false)
    {
        if (command == null || executedHandler == null) return;

        var binding = new CommandBinding(command);
        if (preview)
        {
            binding.PreviewExecuted += executedHandler;
            if (canExecuteHandler != null)
            {
                binding.PreviewCanExecute += canExecuteHandler;
            }
        }
        else
        {
            binding.Executed += executedHandler;
            if (canExecuteHandler != null)
            {
                binding.CanExecute += canExecuteHandler;
            }
        }
        fe.CommandBindings.Add(binding);
    }
}

Answer 1:

KeyBindings work only on controls which accept keyboard input. A Border doesn't. In general, InputBindings are also different from CommandBindings in that you can define a CommandBinding on a parent element so it handles commands when child elements have focus, but you can't define InputBindings on parent elements in order to have them effective on the child elements.

What you can do is to add a default InputGesture to your command's InputGestures collection. That seems to make the command available using that keyboard shortcut from every control that accepts keyboard input (that's much better than to have to specify InputBindings everywhere, isn't it?). In order to take advantage of this, you would have to use a RoutedCommand to invoke your MVVM-ICommand. You can combine the two using attached properties, in a pattern which I call "sticky command" and which is very similar to an attached behaviour.

This code defines the attached properties:

    Public Class Close

    Public Shared ReadOnly CommandProperty As DependencyProperty = DependencyProperty.RegisterAttached("Command", GetType(RoutedCommand), GetType(Close), New PropertyMetadata(AddressOf OnCommandChanged))
    Public Shared Function GetCommand(ByVal d As DependencyObject) As RoutedCommand
        Return d.GetValue(CommandProperty)
    End Function
    Public Shared Sub SetCommand(ByVal d As DependencyObject, ByVal value As RoutedCommand)
        d.SetValue(CommandProperty, value)
    End Sub

    Public Shared ReadOnly MVVMCommandProperty As DependencyProperty = DependencyProperty.RegisterAttached("MVVMCommand", GetType(ICommand), GetType(Close))
    Public Shared Function GetMVVMCommand(ByVal d As DependencyObject) As ICommand
        Return d.GetValue(MVVMCommandProperty)
    End Function
    Public Shared Sub SetMVVMCommand(ByVal d As DependencyObject, ByVal value As ICommand)
        d.SetValue(MVVMCommandProperty, value)
    End Sub


    Private Shared Sub OnCommandChanged(ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
        If e.OldValue IsNot Nothing Then
            Detach(d, DirectCast(e.OldValue, RoutedCommand))
        End If
        If e.NewValue IsNot Nothing Then
             Attach(d, DirectCast(e.NewValue, RoutedCommand), AddressOf DoCloseCommand, AddressOf CanDoCloseCommand)
        End If
    End Sub

    Private Shared Sub CanDoCloseCommand(ByVal sender As Object, ByVal e As CanExecuteRoutedEventArgs)
        If sender IsNot Nothing Then
            Dim com As ICommand = GetMVVMCommand(sender)
            If com IsNot Nothing Then
                e.CanExecute = com.CanExecute(e.Parameter)
                e.Handled = True
            End If
        End If
    End Sub

    Private Shared Sub DoCloseCommand(ByVal sender As Object, ByVal e As ExecutedRoutedEventArgs)
        If sender IsNot Nothing Then
            Dim com As ICommand = GetMVVMCommand(sender)
            If com IsNot Nothing Then
                com.Execute(e.Parameter)
                e.Handled = True
            End If
        End If
    End Sub

    Public Shared Sub Detach(ByVal base As FrameworkElement, ByVal command As RoutedCommand)
        Dim commandBindings As CommandBindingCollection = base.CommandBindings
        If commandBindings IsNot Nothing Then
            Dim bindings = From c As CommandBinding In commandBindings
                           Where c.Command Is command
                           Select c
            Dim bindingList As New List(Of CommandBinding)(bindings)
            For Each c As CommandBinding In bindingList
                commandBindings.Remove(c)
            Next
        End If
    End Sub

    Public Shared Sub Attach(ByVal base As FrameworkElement, ByVal command As RoutedCommand, ByVal executedHandler As ExecutedRoutedEventHandler, ByVal canExecuteHandler As CanExecuteRoutedEventHandler, Optional ByVal preview As Boolean = False)
        If command IsNot Nothing And executedHandler IsNot Nothing Then
            Dim b As CommandBinding = New CommandBinding(command)
            If preview Then
                AddHandler b.PreviewExecuted, executedHandler
                If canExecuteHandler IsNot Nothing Then
                    AddHandler b.PreviewCanExecute, canExecuteHandler
                End If
            Else
                AddHandler b.Executed, executedHandler
                If canExecuteHandler IsNot Nothing Then
                    AddHandler b.CanExecute, canExecuteHandler
                End If
            End If
            base.CommandBindings.Add(b)
            'For Each i As InputGesture In command.InputGestures
            '    GetInputBindings(base).Add(New InputBinding(command, i))
            'Next
        End If
    End Sub

You'd use both of them on your TabItems, I guess, since that is where you want to handle the close command, and you would set Close.Command to a RoutedCommand which has the keyboard shortcut in its InputGestures, and Close.MVVMCommand="{Binding CloseCommand}".

UPDATE

You can define a RoutedCommand like this in your ViewModel:

Public Shared ReadOnly TestCommand As New RoutedUICommand("Test", "TestCommand", GetType(ViewModel))
Shared Sub New()
    TestCommand.InputGestures.Add(New KeyGesture(Key.T, ModifierKeys.Control))
End Sub

The static constructor sets the default keygesture for the command. If you want to do that in XAML, you could also do that using custom attached properties. Anyway, you'd reference the RoutedCommand like this in XAML:

Close.Command="{x:Static my:ViewModel.TestCommand}"

文章来源: KeyBinding woes