Question

我有一个Window元素，其中包含RibbonMenue。在此Window中，有一些UserControls。其中一个UserControl是DataGrid。我创建了一个ICommand，可以添加和删除DataGrid中的行。

问题在于我需要从ICommands访问这些RibbonMenu，但我只能在更高级别访问它们＆＃34; （窗口），因为它们被声明并绑定到绑定到ViewModel的{{1}}。

如何创建可以全局调用的UserControl？请注意，ICommands需要对ICommand后面的ViewModel的引用，因为我需要从中删除行等等。

Image makes it a bit clearer I hope

Answer 1

传统的MVVM方式＆＃34;全局命令＆＃34;是使用CompositeCommand。您将拥有一个GlobalCommands.cs文件，其中包含一个名为GlobalCommands的静态类。

在其中，您将拥有返回CompositeCommand实例的ICommand属性。然后，任何对该命令感兴趣的VM都可以在其构造函数中附加到它：GlobalCommands.SomeCommand.RegisterCommand（...）。您的UI将附加到GlobalCommands命令。

因此GlobalCommands将保存CompositeCommand，它只是一个空的shell / holder命令，VM将使用复合命令注册一个正常的RelayCommand并处理该命令。多个VM可以使用相同的命令注册，所有VM都将被调用。

更高级的CompositeCommand实现还包括一个IActiveAware功能，可以使CompositeCommand只将canexecute / execute发送给＆＃34; active＆＃34; VM＆＃39; S

我相信CompositeCommand最初来自Prism，但许多人（包括我自己）刚刚将其用于非Prism应用程序。

Answer 2

我设法得到了你需要的东西，我在这里做了一个单独的命令是完整的例子（对不起长篇文章只是想确保你能正确地工作）：

using System;
using System.Windows.Input;

namespace WpfApplication
{
    public class GlobalCommand<T> : ICommand
    {
        #region Fields
        private readonly Action<T> _execute = null;
        private readonly Predicate<T> _canExecute = null;
        private static GlobalCommand<T> _globalCommand; 
        private static readonly object locker = new object();
        #endregion

        #region Constructors

        public static GlobalCommand<T> GetInstance(Action<T> execute)
        {
            return GetInstance(execute, null);
        }
        public static GlobalCommand<T> GetInstance(Action<T> execute, Predicate<T> canExecute)
        {
            lock (locker)
            {
                if (_globalCommand == null)
                {
                    _globalCommand = new GlobalCommand<T>(execute, canExecute);
                }
            }
            return _globalCommand;
        }

        private GlobalCommand(Action<T> execute, Predicate<T> canExecute)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");

            _execute = execute;
            _canExecute = canExecute;
        }

        #endregion

        #region ICommand Members

        public bool CanExecute(object parameter)
        {
            return _canExecute == null || _canExecute((T)parameter);
        }

        public event EventHandler CanExecuteChanged
        {
            add
            {
                if (_canExecute != null)
                    CommandManager.RequerySuggested += value;
            }
            remove
            {
                if (_canExecute != null)
                    CommandManager.RequerySuggested -= value;
            }
        }

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

        #endregion
    }
}

的视图模型

using System; using System.Collections.Generic; using System.Collections.ObjectModel; using System.ComponentModel; using System.Windows.Input; namespace WpfApplication { public class ViewModel : INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged; public ObservableCollection<Category> Categories { get; set; } public ICommand AddRowCommand { get; set; } public ViewModel() { Categories = new ObservableCollection<Category>() { new Category(){ Id = 1, Name = "Cat1", Description = "This is Cat1 Desc"}, new Category(){ Id = 1, Name = "Cat2", Description = "This is Cat2 Desc"}, new Category(){ Id = 1, Name = "Cat3", Description = "This is Cat3 Desc"}, new Category(){ Id = 1, Name = "Cat4", Description = "This is Cat4 Desc"} }; this.AddRowCommand = GlobalCommand<object>.GetInstance(ExecuteAddRowCommand, CanExecuteAddRowCommand); } private bool CanExecuteAddRowCommand(object parameter) { if (Categories.Count <= 15) return true; return false; } private void ExecuteAddRowCommand(object parameter) { Categories.Add(new Category() { Id = 1, Name = "Cat"+(Categories.Count+1), Description = "This is Cat" + (Categories.Count + 1) + " Desc" }); } } }

的模型

namespace WpfApplication { public class Category { public int Id { get; set; } public string Name { get; set; } public string Description { get; set; } } }

的 MainWindow.Xaml

<Window x:Class="WpfApplication.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:WpfApplication" Title="MainWindow" Height="500" Width="525"> <Window.Resources> <local:ViewModel x:Key="ViewModel" /> </Window.Resources> <Grid> <Grid.RowDefinitions> <RowDefinition Height="Auto"/> <RowDefinition/> </Grid.RowDefinitions> <Ribbon x:Name="RibbonWin" SelectedIndex="0" Grid.Row="0"> <Ribbon.QuickAccessToolBar> <RibbonQuickAccessToolBar> <RibbonButton x:Name ="Delete" Content="Delete a row" Click="Delete_Click"/> </RibbonQuickAccessToolBar> </Ribbon.QuickAccessToolBar> </Ribbon> <UserControl Grid.Row="1" x:Name="UserControl" DataContext="{StaticResource ViewModel}"> <Grid> <Grid.RowDefinitions> <RowDefinition Height="*"/> <RowDefinition Height="Auto"/> </Grid.RowDefinitions> <DataGrid ItemsSource="{Binding Path=Categories}" AutoGenerateColumns="False" CanUserAddRows="False" Margin="0,10,0,100" Name="DataGrid1" Grid.Row="0" > <DataGrid.Columns> <DataGridTextColumn Header="Id" IsReadOnly="True" Binding="{Binding Id}"/> <DataGridTextColumn Header="Name" IsReadOnly="True" Binding="{Binding Name}"/> <DataGridTextColumn Header="Description" IsReadOnly="True" Binding="{Binding Description}"/> </DataGrid.Columns> </DataGrid> <Button Content="Add new row" Command="{Binding Path=AddRowCommand}" HorizontalAlignment="Center" Width="75" Grid.Row="1"/> </Grid> </UserControl> </Grid> </Window>

代码隐藏

using System.Windows; namespace WpfApplication { public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void Delete_Click(object sender, RoutedEventArgs e) { GlobalCommand<object>.GetInstance(null).Execute(null);// I'm not quite happy with this but it works } } }

WPF命令全局可用

2 个答案: