WPF用户控件，带有按钮和键绑定

我正在尝试在WPF中实现一个拨号器。我有一个窗口，里面有一个用户控件。用户控件有很多按钮，但用户也可以使用数字键输入数字。

我创建了一个小的示例项目来显示我在哪里:

MainWindow.xaml

<Window x:Class="wpf_dialer.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:wpf_dialer"
        Title="MainWindow" Height="200" Width="525">
  <Window.Resources>
    <local:DialerViewModel x:Key="myViewModel" />
  </Window.Resources>
  <Grid DataContext="{StaticResource myViewModel}">
    <local:Dialer />
  </Grid>
</Window>

Dialer.xaml

<UserControl x:Class="wpf_dialer.Dialer"
             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:local="clr-namespace:wpf_dialer"
             mc:Ignorable="d" 
             d:DesignHeight="200" d:DesignWidth="300"
             d:DataContext="{d:DesignInstance local:DialerViewModel}"
             Loaded="UserControl_Loaded">
  <UserControl.InputBindings>
    <KeyBinding Key="A" Command="{Binding CommandDialValue, Mode=OneTime}" CommandParameter="." />
    <KeyBinding Key="Back" Command="{Binding CommandDialValue, Mode=OneTime}" CommandParameter="Back" />
    <KeyBinding Key="Enter" Command="{Binding  CommandAcceptValue, Mode=OneTime}" CommandParameter="KeyBinding" />
  </UserControl.InputBindings>
  <UniformGrid Columns="1">
    <TextBox IsEnabled="False" Text="{Binding DialedValue, Mode=OneWay}" MinWidth="200" FontSize="20" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="10"/>
    <Button Content="OK" Margin="60,30" Command="{Binding CommandAcceptValue, Mode=OneTime}" CommandParameter="Button" />
  </UniformGrid>
</UserControl>

DialerViewModel.cs

using System;
using System.ComponentModel;
using System.Windows.Input;
namespace wpf_dialer
{
    class DialerViewModel : INotifyPropertyChanged
    {
        private Random RAND = new Random();
        private string _dialed_value = "00";
        public string DialedValue
        {
            get { return _dialed_value; }
            set
            {
                if (_dialed_value == value) return;
                _dialed_value = value;
                RaisePropertyChanged("DialedValue");
            }
        }
        public ICommand CommandDialValue { get { return new CommandImpl(DialValue); } }
        public ICommand CommandAcceptValue { get { return new CommandImpl(Alert); } }
        private void DialValue(object parameter)
        {
            if (parameter.ToString() == "Back")
            {
                if (DialedValue.Length > 0)
                {
                    DialedValue = DialedValue.Substring(0, DialedValue.Length - 1);
                }
            }
            else
            {
                DialedValue += RAND.Next(0, 10).ToString();
            }
        }
        private void Alert(object parameter)
        {
            System.Windows.MessageBox.Show(parameter.ToString());
        }
        #region INotifyPropertyChanged
        protected void RaisePropertyChanged(string property_name)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(property_name));
            }
        }
        public event PropertyChangedEventHandler PropertyChanged;
        #endregion
        private class CommandImpl : ICommand
        {
            private readonly Action<object> _action = null;
            public CommandImpl(Action<object> action)
            {
                _action = action;
            }
            public event EventHandler CanExecuteChanged;
            public bool CanExecute(object parameter) { return true; }
            public void Execute(object parameter) { _action(parameter); }
        }
    }
}

目的:

• 一旦加载窗口，当用户按下A键时，执行CommandDialValue;
• 当用户按输入时，弹出提示框，提示"KeyBinding"字样。CommandAcceptValue必须从KeyBinding调用，而不是从按钮调用;

问题:

• 当窗口加载时，KeyBindings不会执行。当我点击UserControl中的某个按钮时，它们被执行;

• 当我按Enter时，按钮的命令被执行，但我希望用户控件的KeyBinding被执行;

• 这个拨号器必须保存在UserControl(或ControlTemplate，或DataTemplate)中，因为它包含在一个非常精细的窗口中。

• 我不想把KeyBindings放在窗口上，因为这样UserControl是不可重用的，因为它的DataContext与用户控件不一样。

更新:

我通过在所有按钮上设置Focusable="False"来解决第二个问题。

             d:DataContext="{d:DesignInstance local:DialerViewModel}"
             Loaded="UserControl_Loaded" Focusable="True">
  <UserControl.InputBindings>

private void UserControl_Loaded(object sender, RoutedEventArgs e) {
    Focus();
}