Csharp 不仅仅是一个简单的自定义按钮

你可以用Style和DataTrigger来实现你的行为.您可以将此Style定义为应用程序资源或自定义Button的默认Style的一部分.

下面的示例显示如何切换Button.Content值.您可以修改触发器来切换任何其他依赖项属性，如图像源.目前还不清楚你的按钮是什么样子的，所以我决定显示针对Content属性的触发器:

<Button Command="{Binding SomeCommand}">
  <Button.Style>
    <Style TargetType="Button">
      <Setter Property="Content"
              Value="Not running" />

      <Style.Triggers>
        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Command.IsExecuting}"
                     Value="True">
          <Setter Property="Content"
                  Value="Command is Running..." />
        </DataTrigger>
      </Style.Triggers>
    </Style>
  </Button.Style>
</Button>

关于ICommand实现的注意事项:您的命令既没有将ICommand.CanExecuteChanged事件链接到CommandManager.RequerySuggested事件，也没有使客户端能够手动引发它.事件当前只在命令执行后引发，这是非常没有意义的.

当你不公开它并将它添加到命令API时，它的意义是什么？

如果你想使ExecuteAsync虚拟化，允许继承者重写它，你应该考虑在这个虚拟方法中添加执行逻辑，使继承者能够改变行为，而不是只添加行为.或者，也可以将Icommand.Execute实现定义为虚拟.

通过添加IsExecuting条件在内部修改CanExecute条件也是有问题的，因为它会减少使用类型的一些灵活性.

您的代码包含一个拼写错误:R100sePropertyChanged，而不是R101sePropertyChanged.

建议改进你的AsyncCommand个版本:

public class AsyncCommand : ViewModelBase, ICommand
{
  protected readonly Func<Task> _execute;
  protected readonly Func<bool>? _canExecute;

  private bool _isExecuting;
  public bool IsExecuting
  {
    get => _isExecuting;
    set => RisePropertyChanged(ref _isExecuting, value);
  }

  public bool IsCommandMangerRequerySuggestedEnabled { get; set; }

  public AsyncCommand(Func<Task> execute, Func<bool>? canExecute = null)
  {
    _execute = execute ?? throw new ArgumentNullException(nameof(execute));
    _canExecute = canExecute;

    this.IsCommandMangerRequerySuggestedEnabled = true;
    CommandManager.RequerySuggested += OnCommandManagerRequerySuggested;
  }

  private void OnCommandManagerRequerySuggested(object? sender, EventArgs e)
  {
    if (this.IsCommandMangerRequerySuggestedEnabled)
    {
      this.CanExecuteChanged?.Invoke(sender, e);
    }
  }

  // Manually raise the CanExecuteChanged event
  public void InvalidateCommand()
    => this.CanExecuteChanged?.Invoke(this, EventArgs.Empty);

  public event EventHandler? CanExecuteChanged;

  public bool CanExecute(object? parameter) => !_isExecuting && (_canExecute?.Invoke() ?? true);

  public async virtual void Execute(object? parameter)
  {
    if (CanExecute(parameter))
    {
      try
      {
        IsExecuting = true;
        await ExecuteAsync(parameter);
      }
      finally
      {
        IsExecuting = false;
      }
    }
  }

  public virtual async Task ExecuteAsync(object? parameter) => await _execute();

  protected virtual void OnCanExecuteChanged() => CanExecuteChanged?.Invoke(this, EventArgs.Empty);
}