如何在MAUI结合CommunityToolkit中捕获Windows/Mac平台键盘事件

方案一：修正EventToCommandBehavior的使用 #

之前绑定无效的核心原因可能是命名空间引用错误或未对按键进行判断，调整如下：

1. 确保页面能捕获键盘事件，给ContentPage设置Focusable="True"
2. 正确引用MAUI官方的EventToCommandBehavior命名空间，而非MVVM组件的命名空间
3. 传递键盘事件参数，在ViewModel中判断是否为右键

修改后的XAML代码：

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:behaviors="clr-namespace:Microsoft.Maui.Controls.Behaviors;assembly=Microsoft.Maui.Controls"
             x:Class="YourNamespace.YourPage"
             Focusable="True">

    <ContentPage.Behaviors>
        <behaviors:EventToCommandBehavior 
            EventName="KeyUp"
            Command="{Binding ForwardCommand}"
            CommandParameter="{Binding Source={RelativeSource Self}, Path=EventArgs}" />
    </ContentPage.Behaviors>

    <!-- 原有按钮 -->
    <Button x:Name="ForwardButton" Text="&gt;" Command="{Binding ForwardCommand}" />
</ContentPage>

ViewModel中修改Command以支持参数判断：

using CommunityToolkit.Mvvm.Input;
using Microsoft.Maui.Controls;

public partial class YourViewModel : ObservableObject
{
    [RelayCommand]
    private void Forward(object parameter)
    {
        // 处理右键触发的情况
        if (parameter is KeyEventArgs args && args.Key == Key.Right)
        {
            ExecuteForwardLogic();
            return;
        }
        // 处理原有按钮点击的情况
        ExecuteForwardLogic();
    }

    private void ExecuteForwardLogic()
    {
        // 这里写你原来的ForwardCommand业务逻辑
    }
}

方案二：自定义右键捕获行为（更灵活） #

如果方案一仍有问题，可自定义行为专门捕获右键事件：

using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.Behaviors;

public class RightKeyToCommandBehavior : Behavior<ContentPage>
{
    public static readonly BindableProperty CommandProperty =
        BindableProperty.Create(nameof(Command), typeof(ICommand), typeof(RightKeyToCommandBehavior));

    public ICommand Command
    {
        get => (ICommand)GetValue(CommandProperty);
        set => SetValue(CommandProperty, value);
    }

    protected override void OnAttachedTo(ContentPage page)
    {
        base.OnAttachedTo(page);
        page.KeyUp += OnPageKeyUp;
        page.Focusable = true;
    }

    protected override void OnDetachingFrom(ContentPage page)
    {
        base.OnDetachingFrom(page);
        page.KeyUp -= OnPageKeyUp;
    }

    private void OnPageKeyUp(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Right && Command?.CanExecute(null) == true)
        {
            Command.Execute(null);
        }
    }
}

XAML中使用自定义行为：

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:YourNamespace"
             x:Class="YourNamespace.YourPage">

    <ContentPage.Behaviors>
        <local:RightKeyToCommandBehavior Command="{Binding ForwardCommand}" />
    </ContentPage.Behaviors>

    <!-- 页面内容 -->
</ContentPage>

方案三：Mac平台特殊处理 #

如果Mac上键盘事件捕获仍异常，可在MacCatalyst平台的渲染器中处理：

using Microsoft.Maui.Platform;
using AppKit;
using Foundation;

[assembly: ExportRenderer(typeof(YourPage), typeof(YourPageRenderer))]
namespace YourNamespace.Platforms.MacCatalyst
{
    public class YourPageRenderer : PageRenderer
    {
        protected override void OnElementChanged(VisualElementChangedEventArgs e)
        {
            base.OnElementChanged(e);
            if (e.NewElement is YourPage)
            {
                Window?.MakeFirstResponder(this);
                KeyUp += OnKeyUp;
            }
        }

        private void OnKeyUp(object sender, NSEventEventArgs e)
        {
            // Mac平台右键箭头的键码为124
            if (e.Event.KeyCode == 124)
            {
                var viewModel = (YourViewModel)Element.BindingContext;
                viewModel.ForwardCommand.Execute(null);
            }
        }

        protected override void Dispose(bool disposing)
        {
            KeyUp -= OnKeyUp;
            base.Dispose(disposing);
        }
    }
}

内容的提问来源于stack exchange，提问作者jie xiao