利用wpf做一个加载等待界面，当上位机发出命令后触发，接收到命令截止，写出代码

以下是一个简单的加载等待界面，当上位机发出命令后触发，接收到命令截止的WPF代码：

// XAML代码
<Window x:Class="LoadWaitWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="LoadWaitWindow" Height="150" Width="350">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <StackPanel Grid.Row="0" VerticalAlignment="Center" HorizontalAlignment="Center">
            <TextBlock Text="正在加载，请稍等..." FontSize="16" FontWeight="Bold"/>
            <ProgressBar Width="200" Height="20" Margin="0,20,0,0"/>
        </StackPanel>
        <Button Grid.Row="1" Margin="0,10,0,10" Width="100" Height="30" Content="取消" Click="CancelButton_Click"/>
    </Grid>
</Window>

// C#代码
public partial class LoadWaitWindow : Window
{
    private CancellationTokenSource _cancellationTokenSource;

    public LoadWaitWindow()
    {
        InitializeComponent();
    }

    public async Task ShowAndWait(CancellationTokenSource cancellationTokenSource)
    {
        _cancellationTokenSource = cancellationTokenSource;
        Show();

        try
        {
            await Task.Delay(1000, cancellationTokenSource.Token); // 模拟加载过程
        }
        catch (TaskCanceledException)
        {
            Close();
        }
    }

    private void CancelButton_Click(object sender, RoutedEventArgs e)
    {
        _cancellationTokenSource.Cancel();
    }
}

在使用时，可以先创建一个 `CancellationTokenSource` 对象，当需要显示加载等待界面时，调用 `ShowAndWait` 方法并传入 `CancellationTokenSource` 对象，当需要结束加载等待界面时，调用 `CancellationTokenSource` 的 `Cancel` 方法即可。例如：

private CancellationTokenSource _cancellationTokenSource;

private async Task ExecuteCommand()
{
    _cancellationTokenSource = new CancellationTokenSource();

    var loadWaitWindow = new LoadWaitWindow();
    await loadWaitWindow.ShowAndWait(_cancellationTokenSource);

    // 执行命令
    // ...

    loadWaitWindow.Close();
}