当TextBox具有焦点时,UserControl中的KeyBinding不起作用

Question

以下情况.我有一个带有五个键绑定的UserControl.当TextBox具有焦点时,UserControl的键绑定将停止触发..

有没有办法解决这个'问题'？

<UserControl.InputBindings>
    <KeyBinding Key="PageDown" Modifiers="Control" Command="{Binding NextCommand}"></KeyBinding>
    <KeyBinding Key="PageUp" Modifiers="Control" Command="{Binding PreviousCommand}"></KeyBinding>
    <KeyBinding Key="End" Modifiers="Control"  Command="{Binding LastCommand}"></KeyBinding>
    <KeyBinding Key="Home" Modifiers="Control" Command="{Binding FirstCommand}"></KeyBinding>
    <KeyBinding Key="F" Modifiers="Control" Command="{Binding SetFocusCommand}"></KeyBinding>
</UserControl.InputBindings>
<TextBox Text="{Binding FilterText, UpdateSourceTrigger=PropertyChanged}">
    <TextBox.InputBindings>
        <KeyBinding Gesture="Enter" Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl }}, Path=DataContext.FilterCommand}"></KeyBinding>
    </TextBox.InputBindings>
</TextBox>

似乎功能键(F1等)和ALT+ [key]工作.我假设CTRL和SHIFT修饰符以某种方式"阻止"事件冒泡到UserControl.

Answer 1

一些输入绑定有效的原因,有些则不是TextBox控件捕获并处理一些键绑定.例如,它处理CTRL+ V用于粘贴,CTRL+ Home用于转到文本的开头等.另一方面,其他键组合(如CTRL+)F3不由TextBox处理,因此它们将冒泡.

如果您只是想禁用TextBox的输入绑定,那么这很简单 - 您可以使用该ApplicationCommands.NotACommand命令来禁用默认行为.例如,在以下情况下,将禁用使用CTRL+ 粘贴V:

<TextBox>
    <TextBox.InputBindings>
        <KeyBinding Key="V" Modifiers="Control" Command="ApplicationCommands.NotACommand" />
    </TextBox.InputBindings>
</TextBox>

然而,让它冒泡到用户控件有点棘手.我的建议是创建一个附加行为,该行为将应用于UserControl,注册到其PreviewKeyDown事件,并在到达TextBox之前根据需要执行其输入绑定.执行输入绑定时,这将优先于UserControl.

我写了一个基本的行为,实现了这个功能,让你开始:

public class InputBindingsBehavior
{
    public static readonly DependencyProperty TakesInputBindingPrecedenceProperty =
        DependencyProperty.RegisterAttached("TakesInputBindingPrecedence", typeof(bool), typeof(InputBindingsBehavior), new UIPropertyMetadata(false, OnTakesInputBindingPrecedenceChanged));

    public static bool GetTakesInputBindingPrecedence(UIElement obj)
    {
        return (bool)obj.GetValue(TakesInputBindingPrecedenceProperty);
    }

    public static void SetTakesInputBindingPrecedence(UIElement obj, bool value)
    {
        obj.SetValue(TakesInputBindingPrecedenceProperty, value);
    }

    private static void OnTakesInputBindingPrecedenceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        ((UIElement)d).PreviewKeyDown += new KeyEventHandler(InputBindingsBehavior_PreviewKeyDown);
    }

    private static void InputBindingsBehavior_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        var uielement = (UIElement)sender;

        var foundBinding = uielement.InputBindings
            .OfType<KeyBinding>()
            .FirstOrDefault(kb => kb.Key == e.Key && kb.Modifiers == e.KeyboardDevice.Modifiers);

        if (foundBinding != null)
        {
            e.Handled = true;
            if (foundBinding.Command.CanExecute(foundBinding.CommandParameter))
            {
                foundBinding.Command.Execute(foundBinding.CommandParameter);
            }
        }
    }
}

用法:

<UserControl local:InputBindingsBehavior.TakesInputBindingPrecedence="True">
    <UserControl.InputBindings>
        <KeyBinding Key="Home" Modifiers="Control" Command="{Binding MyCommand}" />
    </UserControl.InputBindings>
    <TextBox ... />
</UserControl>

希望这可以帮助.

Answer 2

阿迪·莱斯特的解决方案效果很好。这是使用行为的类似解决方案。C# 代码：

public class AcceptKeyBinding : Behavior<UIElement>
{


    private TextBox _textBox;



    /// <summary>
    ///  Subscribes to the PreviewKeyDown event of the <see cref="TextBox"/>.
    /// </summary>
    protected override void OnAttached()
    {
        base.OnAttached();

        _textBox = AssociatedObject as TextBox;

        if (_textBox == null)
        {
            return;
        }

        _textBox.PreviewKeyDown += TextBoxOnPreviewKeyDown;
    }

    private void TextBoxOnPreviewKeyDown(object sender, KeyEventArgs keyEventArgs)
    {
        var uielement = (UIElement)sender;

        var foundBinding = uielement.InputBindings
            .OfType<KeyBinding>()
            .FirstOrDefault(kb => kb.Key == keyEventArgs.Key && kb.Modifiers ==           keyEventArgs.KeyboardDevice.Modifiers);

        if (foundBinding != null)
        {
            keyEventArgs.Handled = true;
            if (foundBinding.Command.CanExecute(foundBinding.CommandParameter))
            {
                foundBinding.Command.Execute(foundBinding.CommandParameter);
            }
        }
    }

    /// <summary>
    ///     Unsubscribes to the PreviewKeyDown event of the <see cref="TextBox"/>.
    /// </summary>
    protected override void OnDetaching()
    {
        if (_textBox == null)
        {
            return;
        }

        _textBox.PreviewKeyDown -= TextBoxOnPreviewKeyDown;

        base.OnDetaching();
    }

}

以及 XAML：

<TextBox>
  <TextBox.InputBindings>
      <KeyBinding Key="Enter" Modifiers="Shift" Command="{Binding CommandManager[ExecuteCommand]}"
          CommandParameter="{Binding ExecuteText}" />
  </TextBox.InputBindings>
      <i:Interaction.Behaviors>
         <behaviours:AcceptKeyBinding />
      </i:Interaction.Behaviors>
</TextBox>

Answer 3

除了阿迪·莱斯特（Adi Lester）的（非常有帮助的）回答之外，我还想建议一些有助于我实施的改进/扩展。

手势匹配

也可以通过调用Gesture.Matches 来完成foundBinding。将foundBinding Linq 查询更改为以下内容：

KeyBinding foundBinding = ((UIElement)this).InputBindings
            .OfType<KeyBinding>()
            .FirstOrDefault(inputBinding => inputBinding.Gesture.Matches(sender, eventArgs));

鼠标绑定

此外，您还可以定义 MouseBindings。

<MouseBinding Command="{Binding DataContext.AddInputValueCommand, ElementName=root}" CommandParameter="{Binding}" Gesture="Shift+MiddleClick" />

然后，您还需要订阅 PreviewMouseEvents，例如 PreviewMouseUp 和 PreviewMouseDoubleClick。其实现与 KeyBindings 几乎相同。

private void OnTextBoxPreviewMouseUp(object sender, MouseButtonEventArgs eventArgs)
{
    MouseBinding foundBinding = ((UIElement)this).InputBindings
        .OfType<MouseBinding>()
        .FirstOrDefault(inputBinding => inputBinding.Gesture.Matches(sender, eventArgs));

    if (foundBinding != null)
    {
        eventArgs.Handled = true;
        if (foundBinding.Command.CanExecute(foundBinding.CommandParameter))
        {
            foundBinding.Command.Execute(foundBinding.CommandParameter);
        }
    }
}