WPF自定义控件-绑定到在后台代码中定义的命令

user4633966 发表于 Dev

463

我正在尝试创建一个名为“ DataTextBox”的WPF自定义控件。除了此控件的上下文菜单之外，其他所有东西都工作正常。确实，我想在DataTextBox的上下文菜单中添加一个项目。为此，我以在generic.xaml中定义的DataTextBox样式添加了一个MenuItem：

<Style TargetType="{x:Type controls:DataTextBox}">
    <Setter Property="ContextMenu">
        <Setter.Value>
            <ContextMenu>
                <MenuItem Header="{DynamicResource Components_TextBoxCut}" Command="ApplicationCommands.Cut" />
                <MenuItem Header="{DynamicResource Components_TextBoxCopy}" Command="ApplicationCommands.Copy" />
                <MenuItem Header="{DynamicResource Components_TextBoxPaste}" Command="ApplicationCommands.Paste" />
                <MenuItem x:Name="menuItemInsertChecksum" Header="{DynamicResource Components_DataTextBoxInsertChecksum}"
                Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type controls:DataTextBox}}, Path=CalculateChecksumCommand}" />
            </ContextMenu>
        </Setter.Value>
    </Setter>
    <Setter Property="Template">
        <Setter.Value>
              ...
        </Setter.Value>
    </Setter>
</Style>

我还在代码背后的DataTextBox中添加了一条命令

    public static DependencyProperty CalculateChecksumCommandProperty = DependencyProperty.Register("CalculateChecksumCommand", typeof(ICommand), typeof(DataTextBox));
    public ICommand CalculateChecksumCommand { get; private set; }

此命令在DataTextBox构造函数中初始化：

    public DataTextBox() : base()
    {
        CalculateChecksumCommand = new RelayCommand(() => CalculateChecksum(), () => CanCalculateChecksum());
    }

我的问题是我的最后一个MenuItem的命令绑定不起作用，因为找不到“ CalculateChecksumCommand”。这意味着从不调用“ CalculateChecksum（）”方法。

我希望在这个问题上有所帮助。谢谢你。

编辑：依赖项属性声明应为：

    public static DependencyProperty CalculateChecksumCommandProperty = DependencyProperty.Register("CalculateChecksumCommand", typeof(ICommand), typeof(DataTextBox));
    public ICommand CalculateChecksumCommand
    {
        get { return (ICommand)GetValue(CalculateChecksumCommandProperty); }
        private set { SetValue(CalculateChecksumCommandProperty, value); }
    }

艾比

承载控件并为其定义样式的窗口，该窗口将其上下文菜单的一个菜单项绑定到其命令：

XAML

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:wpfApplication2="clr-namespace:WpfApplication2"
        Title="MainWindow"
        Width="525"
        Height="350"
        mc:Ignorable="d">
    <Grid>
        <Grid.Resources>
            <Style TargetType="wpfApplication2:UserControl1" x:Shared="False">
                <Style.Setters>
                    <Setter Property="ContextMenu">
                        <Setter.Value>
                            <ContextMenu>
                                <MenuItem Command="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=ContextMenu}, Path=PlacementTarget.(wpfApplication2:UserControl1.MyCommand)}" Header="Hello" />
                            </ContextMenu>
                        </Setter.Value>
                    </Setter>
                </Style.Setters>
            </Style>
        </Grid.Resources>
        <wpfApplication2:UserControl1 />

    </Grid>
</Window>

代码

using System;
using System.Windows;
using System.Windows.Input;

namespace WpfApplication2
{
    /// <summary>
    ///     Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }


    public class DelegateCommand : ICommand
    {
        private readonly Func<object, bool> _canExecute;
        private readonly Action<object> _execute;

        public DelegateCommand(Action<object> execute) : this(execute, s => true)
        {
        }

        public DelegateCommand(Action<object> execute, Func<object, bool> canExecute)
        {
            _execute = execute;
            _canExecute = canExecute;
        }

        public bool CanExecute(object parameter)
        {
            return _canExecute(parameter);
        }

        public void Execute(object parameter)
        {
            _execute(parameter);
        }

        public event EventHandler CanExecuteChanged;
    }
}

控制：

using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;

namespace WpfApplication2
{
    /// <summary>
    ///     Interaction logic for UserControl1.xaml
    /// </summary>
    public partial class UserControl1 : UserControl, INotifyPropertyChanged
    {
        private DelegateCommand _myCommand;

        public UserControl1()
        {
            InitializeComponent();

            MyCommand = new DelegateCommand(Execute);
        }

        public DelegateCommand MyCommand
        {
            get { return _myCommand; }
            set
            {
                _myCommand = value;
                OnPropertyChanged();
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void Execute(object o)
        {
            MessageBox.Show("Hello");
        }

        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            var handler = PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}