如何从其 Click 事件 WPF 中停止执行按钮命令

Question

有什么方法可以根据点击事件的某些条件停止 Button 命令的执行？

实际上，我希望在我们的应用程序中单击某些按钮时弹出确认消息。为了使其成为通用解决方案，我做了以下工作：

1. 我有 WPF 按钮类调用 AppBarButton 的扩展，它已经包含一些依赖属性。
2. 我还有 2 个属性如下：IsActionConfirmationRequired 和 ConfirmationActionCommand。

如果IsActionConfirmationRequired 然后在左键点击事件中，我将打开确认弹出窗口。

有什么方法可以避免创建新的ConfirmationActionCommand，并使用Button 的相同Command 属性？如果我设置Command，然后在Button 上单击，即使用户未确认操作仍然执行按钮命令，我也会遇到问题。

C#：

public class AppBarButton : Button
{
    public AppBarButton()
    {
        this.Click += AppBarButton_Click;
    }

    private void AppBarButton_Click(object sender, RoutedEventArgs e)
    {
        Button button = sender as Button;
        if (button == null || IsActionConfirmationRequired == false || ConfirmationActionCommand == null)
            return;

        const string defaultMessage = "Do you really want to {0}";

        string confirmationPopUpMessage = string.IsNullOrEmpty(ActionConfirmationMessage)
          ? DebugFormat.Format(defaultMessage, button.Content)
          : ActionConfirmationMessage;

        ConfirmationDailogDetails confirmationDailogDetails = new ConfirmationDailogDetails
        {
            Message = confirmationPopUpMessage,
            ActionName = button.Content.ToString(),
            Template = button.Template,
            ActionCommand = ConfirmationActionCommand
        };

        //instead of ConfirmationActionCommand want to use base.Command
        ConfirmationDailog dialog = new ConfirmationDailog(confirmationDailogDetails)
        {
            PlacementTarget = button,
            IsOpen = true
        };
    }

    public static readonly DependencyProperty IsActionConfirmationRequiredProperty =
        DependencyProperty.Register("IsActionConfirmationRequired", typeof(bool), typeof(AppBarButton));

    public static readonly DependencyProperty ActionConfirmationMessageProperty =
        DependencyProperty.Register("ActionConfirmationMessage", typeof(string), typeof(AppBarButton));

    public static readonly DependencyProperty ConfirmationActionCommandProperty =
       DependencyProperty.Register("ConfirmationActionCommand", typeof(ICommand), typeof(AppBarButton));

    /// <summary>
    /// Gets or sets the flag to show the confirmation popup on before taking any action on App Bar button click.
    /// Also its required to set the command in Tag Property of the App Bar button not in the Command Property, then only required command will fire only when user
    /// confirms and click on the action button on confirmation popup.
    /// </summary>
    public bool IsActionConfirmationRequired
    {
        get { return (bool)GetValue(IsActionConfirmationRequiredProperty); }
        set { SetValue(IsActionConfirmationRequiredProperty, value); }
    }

    /// <summary>
    /// Gets or sets the confirmation message in confirmation popup  before taking any action on App Bar button click.
    /// </summary>
    public ICommand ConfirmationActionCommand
    {
        get { return (ICommand)GetValue(ConfirmationActionCommandProperty); }
        set { SetValue(ConfirmationActionCommandProperty, value); }
    }
}

XAML：

<controls:AppBarButton x:Key="WithdrawAll"
                       AppBarOrder="1"
                       PageIndex="1"
                       AppBarOrientation="Left"
                       Content="Withdraw" IsActionConfirmationRequired="True"
                       ConfirmationActionCommand="{Binding WithdrawAllCommand}"
                       Template="{StaticResource DeleteCircleIcon}" />

请提出一些建议。我什么也找不到。已经尝试将CanExecute 设置为 false，但它的 make 按钮禁用，所以没有用。我只是简单的不想再做一个命令，使用这个AppBarButton的开发者需要设置ConfirmationActionCommand不正常Command。

Answer 1

如果我理解正确，您想确认用户的操作并执行存储在ButtonBase.Command 属性中的命令。

要实现这一点，请删除 ConfirmationActionCommand 属性并使用 OnClick 方法而不是 Click 事件。在覆盖的OnClick 方法中调用基本方法，如果用户确认操作或不需要确认，该方法将从Command 属性执行命令。

public class AppBarButton : Button
{
    public static readonly DependencyProperty IsActionConfirmationRequiredProperty =
        DependencyProperty.Register("IsActionConfirmationRequired", typeof(bool), typeof(AppBarButton));

    public static readonly DependencyProperty ActionConfirmationMessageProperty =
        DependencyProperty.Register("ActionConfirmationMessage", typeof(string), typeof(AppBarButton));

    public bool IsActionConfirmationRequired
    {
        get { return (bool)GetValue(IsActionConfirmationRequiredProperty); }
        set { SetValue(IsActionConfirmationRequiredProperty, value); }
    }

    public string ActionConfirmationMessage
    {
        get { return (string)GetValue(ActionConfirmationMessageProperty ); }
        set { SetValue(ActionConfirmationMessageProperty , value); }
    }

    protected override void OnClick()
    {
        bool confirmed = true;

        if (IsActionConfirmationRequired)
        {
            ConfirmationDailogDetails confirmationDailogDetails = new ConfirmationDailogDetails
            {
                Message = confirmationPopUpMessage,
                ActionName = button.Content.ToString(),
                Template = button.Template,
                ActionCommand = ConfirmationActionCommand
            };

            ConfirmationDailog dialog = new ConfirmationDailog(confirmationDailogDetails)
            {
                PlacementTarget = button,
                IsOpen = true
            };

            // Set confirmed here

            // If you set the DialogResult property in the ConfirmationDailog class then
            // confirmed = dialog.ShowDialog().Value;
        }

        // If there is no confirmation requred or if an user have confirmed an action
        // then call base method which will execute a command if it exists.
        if (confirmed)
        {
            base.OnClick();
        }
    }
}

Answer 2

处理PreviewMouseLeftButtonDown 事件，而不是单击事件。这发生在命令执行之前。在处理程序中要求确认并将event 的Handled 属性设置为true 或false。
如果设置为true，则不会执行该命令。

private void btn_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
    var confirmed = true;   //use your confirmation instead
    e.Handled = confirmed;
}

您的代码如下所示（我不知道具体是因为我没有ConfirmationDailog 的代码：

public class AppBarButton : Button
{
    public AppBarButton()
    {
        this.PreviewMouseLeftButtonDown += AppBarButton_PreviewMouseLeftButtonDown; ;
    }

    private void AppBarButton_PreviewMouseLeftButtonDown(object sender, RoutedEventArgs e)
    {
        Button button = sender as Button;
        if (button == null || IsActionConfirmationRequired == false || ConfirmationActionCommand == null)
            return;

        const string defaultMessage = "Do you really want to {0}";

        string confirmationPopUpMessage = string.IsNullOrEmpty(ActionConfirmationMessage)
          ? DebugFormat.Format(defaultMessage, button.Content)
          : ActionConfirmationMessage;

        ConfirmationDailogDetails confirmationDailogDetails = new ConfirmationDailogDetails
        {
            Message = confirmationPopUpMessage,
            ActionName = button.Content.ToString(),
            Template = button.Template,
            ActionCommand = ConfirmationActionCommand
        };
        **//instead of ConfirmationActionCommand want to use base.Command**
       ConfirmationDailog dialog = new ConfirmationDailog(confirmationDailogDetails)
       {
           PlacementTarget = button,
           IsOpen = true
       };
        //validation here
        dialog.ShowDialog();
        var confirmed = dialog.IsConfirmed;
        e.Handled = confirmed;
    }
    ...