c# – 使用CommandParameter在树视图项上进行键绑定

我正在尝试使用带有KeyBinding的TreeViewItem和MenuContext来执行位于我的viewmodel上的命令.

目前,使用上下文菜单,在正确的viewmodel实例上调用该命令.
但是,当我选择TreeViewItem并按“C”键时,将在“根”viewmodel上调用该命令.

我也尝试过扩展KeyBinding类(Keybinding a RelayCommand)而没有运气.

也许我会走错路：我只想显示正确的MessageBox,如果我使用上下文菜单或键.

名为WpfTest的WPF项目的代码示例.

MainWindow.xaml

<Window x:Class="WpfTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="clr-namespace:WpfTest"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <TreeView ItemsSource="{Binding}">
            <TreeView.ItemTemplate>
                <HierarchicalDataTemplate ItemsSource="{Binding Child}" DataType="{x:Type vm:viewmodel}">
                    <TextBlock Text="{Binding Name}" />
                </HierarchicalDataTemplate>
            </TreeView.ItemTemplate>
            <TreeView.ItemContainerStyle>
                <Style targettype="{x:Type TreeViewItem}">
                    <Setter Property="ContextMenu">
                        <Setter.Value>
                            <ContextMenu>
                                <MenuItem Header="{Binding Name}" Command="{Binding SomeCommand}" CommandParameter="{Binding}"/>
                            </ContextMenu>
                        </Setter.Value>
                    </Setter>
                    <Setter Property="vm:MyAttached.InputBindings">
                        <Setter.Value>
                            <InputBindingCollection>
                                <KeyBinding Key="C" Command="{Binding SomeCommand}" CommandParameter="{Binding}"/>
                            </InputBindingCollection>
                        </Setter.Value>
                    </Setter>
                </Style>
            </TreeView.ItemContainerStyle>
        </TreeView>
    </Grid>
</Window>

MainWindow.xaml.cs：

namespace WpfTest
{
    using System;
    using System.Collections.Generic;
    using System.Collections.ObjectModel;
    using System.Windows;
    using System.Windows.Input;

    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            this.DataContext = new List<viewmodel>
            {
                new viewmodel
                {
                    Name = "Parent",Child = new ObservableCollection<viewmodel>
                    {
                        new viewmodel { Name = "Child 1" },new viewmodel { Name = "Child 2" },new viewmodel { Name = "Child 3" }
                    }
                }
            };
        }
    }

    public class viewmodel
    {
        public string Name { get; set; }
        public ObservableCollection<viewmodel> Child { get; set; }
        public ICommand SomeCommand { get; set; }

        public viewmodel()
        {
            this.someCommand = new RelayCommand<viewmodel>(OnCommandExecuted);
        }

        private void OnCommandExecuted(viewmodel parameter)
        {
            MessageBox.Show("CommandExecuted on " + Name + " with parameter " + parameter.Name);
        }
    }

    public class MyAttached
    {
        public static readonly DependencyProperty InputBindingsProperty =
            DependencyProperty.Registerattached("InputBindings",typeof(InputBindingCollection),typeof(MyAttached),new FrameworkPropertyMetadata(new InputBindingCollection(),(sender,e) =>
            {
                var element = sender as UIElement;
                if (element == null) return;
                element.InputBindings.Clear();
                element.InputBindings.AddRange((InputBindingCollection)e.NewValue);
            }));

        public static InputBindingCollection GetInputBindings(UIElement element)
        {
            return (InputBindingCollection)element.GetValue(InputBindingsProperty);
        }

        public static void SetInputBindings(UIElement element,InputBindingCollection inputBindings)
        {
            element.SetValue(InputBindingsProperty,inputBindings);
        }
    }

    public class RelayCommand<T> : ICommand
    {
        readonly Action<T> _execute = null;
        public RelayCommand(Action<T> execute)  { _execute = execute; }
        public bool CanExecute(object parameter) { return true; }
        public void Execute(object parameter) { _execute((T)parameter); }
        public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } }
    }
}

解决方法

问题是：Style只为所有ListViewItem创建一个InputBindingCollection,因此您必须非常小心Setter.Values.

这是修复：

<TreeView ItemsSource="{Binding}">
        <TreeView.Resources>
            <!-- x:Shared="False" forces the new creation of that object whenever referenced -->
            <InputBindingCollection x:Shared="False" x:Key="InputBindings">
                <KeyBinding Key="C" Command="{Binding SomeCommand}" CommandParameter="{Binding}" />
            </InputBindingCollection>
        </TreeView.Resources>
        <!-- ... -->
        <TreeView.ItemContainerStyle>
            <Style targettype="{x:Type TreeViewItem}">
                <!-- ... -->
                <Setter Property="vm:MyAttached.InputBindings" Value="{StaticResource InputBindings}"/>
            </Style>
        </TreeView.ItemContainerStyle>
    </TreeView>