WPF KeyBinding 命令未在自定义控件中触发

Question

我正在构建 WPF 自定义控件（注意：不是用户控件）。控件的c#代码定义如下：

using System.Windows;
using System.Windows.Controls;
using MvvmFoundation.Wpf;

namespace TextBoxWithInputBinding
{
    public class AutoComp : Control
    {
        static AutoComp()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(AutoComp), new FrameworkPropertyMetadata(typeof(AutoComp)));
        }

        public AutoComp()
        {
            DownCommand = new RelayCommand(() =>
            {
                System.Diagnostics.Debug.WriteLine("Down");
            });
            PressedCommand = new RelayCommand(() =>
            {
                System.Diagnostics.Debug.WriteLine("Pressed");
            });
        }

        public RelayCommand DownCommand
        {
            get { return (RelayCommand)GetValue(DownCommandProperty); }
            set { SetValue(DownCommandProperty, value); }
        }

        public static readonly DependencyProperty DownCommandProperty =
            DependencyProperty.Register("DownCommand", typeof(RelayCommand), typeof(AutoComp), new PropertyMetadata(null));

        public RelayCommand PressedCommand
        {
            get { return (RelayCommand)GetValue(PressedCommandProperty); }
            set { SetValue(PressedCommandProperty, value); }
        }

        public static readonly DependencyProperty PressedCommandProperty =
            DependencyProperty.Register("PressedCommand", typeof(RelayCommand), typeof(AutoComp), new PropertyMetadata(null));
    }
}

我为Generic.xaml中的控件定义模板如下：

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:TextBoxWithInputBinding">
    <Style TargetType="{x:Type local:AutoComp}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:AutoComp}">
                    <Border Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}"
                            >
                        <StackPanel>
                            <TextBox>
                                <TextBox.InputBindings>
                                    <KeyBinding Key="Down" Command="{TemplateBinding DownCommand}"/>
                                </TextBox.InputBindings>
                            </TextBox>
                            <Button Content="Press me" Command="{TemplateBinding PressedCommand}"/>
                        </StackPanel>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

当我按下 "Press me" 按钮时，PressedCommand 被触发（单词 "Pressed" 出现在输出 window 中 - 但是，当我在 TextBox 中键入并按下向下键时, 没有任何反应。

我需要做什么才能触发 DownCommand？

Answer 1

所以我找到了答案：我需要常规绑定而不是模板绑定：我替换了

<KeyBinding Key="Down" Command="{TemplateBinding DownCommand}"/>

和

<KeyBinding Key="Down"
    Command="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=DownCommand}"/>

我仍然想知道为什么 Button 绑定与 TemplateBinding 一起使用，而 TextBox KeyBinding 却不行！！！

Answer 2

正如您已经发现的那样，您应该将 TemplateBinding 替换为通常的绑定标记并使用 {RelativeSource TemplatedParent}

<KeyBinding Key="Down"
    Command="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=DownCommand}"/>

I would still like to know why the Button binding works with TemplateBinding but the TextBox KeyBinding does not?

因为TemplateBinding经过优化，与使用普通的Binding相比有一些限制。例如，它只直接在 ControlTemplates 的可视化树中起作用，但在 DataTrigger 和 KeyBinding 中不起作用。

您可以在此处找到更多相关信息：

WPF TemplateBinding vs RelativeSource TemplatedParent

WPF KeyBinding 命令未在自定义控件中触发

WPF KeyBinding Command not triggering in Custom Control

c#

wpf

xaml

custom-controls

mvvm