向 EventToCommand 添加确认对话框

Question

Laurent 表示，

当用户选择按钮来执行操作时，常见的期望行为是在执行该操作之前显示确认对话框。当这种行为与视图模型结合处理时，需要大量的管道来实现这一点。由于这种行为严格地可以被视为 GUI 问题，因此我想设计一种允许视图处理确认对话框的方法。

因此，我继承了您的 EventToCommand 类并创建了 EventToCommandWithConfirm。此类调用一个自定义消息框视图，我不会包含该视图，但我想获得您对这个概念的反馈以及它是否可以考虑包含在您的工具包中。

using System;
using System.Windows;
using System.Windows.Input;
using System.Windows.Interactivity;

namespace GalaSoft.MvvmLight.Command
{
    public partial class EventToCommandWithConfirm : EventToCommand
    {

        protected override void Invoke(object parameter)
        {
            // if confirmation is not required, the command can be run immediately
            if (!IsConfirm)
            {
                base.Invoke(parameter);
            }
            else
            {
                switch (ConfirmButtons)
                {
                    case MessageBoxPopUp.Buttons.YesNo:
                    case MessageBoxPopUp.Buttons.YesNoCancel:
                        MessageBoxPopUp.Show(ConfirmMessage, ConfirmCaption , ConfirmButtons, YesAction: () => base.Invoke(parameter));
                        break;
                    case MessageBoxPopUp.Buttons.Ok:
                    case MessageBoxPopUp.Buttons.OkCancel:
                    case MessageBoxPopUp.Buttons.None:
                    default:
                        MessageBoxPopUp.Show(ConfirmMessage, ConfirmCaption, ConfirmButtons, OKAction: () => base.Invoke(parameter));
                        break;
                }

            }            
        }

        public static readonly DependencyProperty IsConfirmProperty = DependencyProperty.Register("Confirm", typeof(bool), typeof(EventToCommandWithConfirm), null);
        public bool IsConfirm
        {
            get { return (bool)GetValue(IsConfirmProperty); }
            set { SetValue(IsConfirmProperty, value); }
        }

        public static readonly DependencyProperty ConfirmCaptionProperty = DependencyProperty.Register("ConfirmCaption", typeof(string), typeof(EventToCommandWithConfirm), null);
        public string ConfirmCaption
        {
            get { return (string)GetValue(ConfirmCaptionProperty); }
            set { SetValue(ConfirmCaptionProperty, value); }
        }

        public static readonly DependencyProperty ConfirmMessageProperty = DependencyProperty.Register("ConfirmMessage", typeof(string), typeof(EventToCommandWithConfirm), null);
        public string ConfirmMessage
        {
            get { return (string)GetValue(ConfirmMessageProperty); }
            set { SetValue(ConfirmMessageProperty, value); }
        }

        public static readonly DependencyProperty ConfirmButtonsProperty = DependencyProperty.Register("ConfirmButtons", typeof(MessageBoxPopUp.Buttons), typeof(EventToCommandWithConfirm), null);
        public MessageBoxPopUp.Buttons ConfirmButtons
        {
            get { return (MessageBoxPopUp.Buttons)GetValue(ConfirmButtonsProperty); }
            set { SetValue(ConfirmButtonsProperty, value); }
        }
    }
}

使用示例：

<Button Content="Delete Room..." Height="36" HorizontalAlignment="Left" Margin="279.838,237,0,0" Name="DeleteRoomButton" VerticalAlignment="Top" Width="92" Grid.Column="2">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="Click">
                    <confirm:EventToCommandWithConfirm Command="{Binding DeleteRoomClick}" MustToggleIsEnabled="True" ConfirmMessage="{Binding cvsRooms.View.CurrentItem.Description}" ConfirmCaption="Delete Room?" IsConfirm="True"  ConfirmButtons="YesNoCancel"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
</Button>

MessageBoxPopUp.xaml.cs

using System;
using System.Windows;
using System.Windows.Controls;
using System.Collections.Generic;

namespace GalaSoft.MvvmLight.Command
{

    public partial class MessageBoxPopUp : ChildWindow
    {

        public enum Buttons
        {
            Ok,
            YesNo,
            OkCancel,
            YesNoCancel,
            None,
        }

        public enum ButtonTypes
        {
            Ok,
            Yes,
            No,
            Cancel,
            Custom,
        }


        private int _buttonCount = 0;
        private Dictionary<int, Button> _buttons = new Dictionary<int, Button>();
        private int _defaultButtonIdx = Int32.MinValue;
        private Action _defaultAction = null;
        private Button _defaultButton = null;

        public string Message
        {
            get { return MessageTextBlock.Text; }
            set { MessageTextBlock.Text = value; }
        }

        public ButtonTypes DefaultButton {get;set;}
        public ButtonTypes ResultButton {get; private set;}
        public int ButtonSelectedIdx { get; private set; }


        public MessageBoxPopUp()
        {  
            InitializeComponent(); 
        }

        /// <summary>
        /// Displays a message box with the specified text, caption, buttons
        /// </summary>
        /// <param name="Message">The text to display in the message box.</param>
        /// <param name="Caption">he text to display in the title bar of the message box.</param>
        /// <param name="Buttons">The set of buttons to display</param>
        /// <param name="DefaultButton">Which button is the default</param>
        /// <param name="Width">Width of the message box</param>
        /// <param name="Height">Height of the message box</param>
        /// <param name="Opacity">Opacity of the message box</param>
        /// <param name="OKAction">Action to perform when the OK button is selected</param>
        /// <param name="CancelAction">Action to perform when the Cancel button is selected</param>
        /// <param name="YesAction">Action to perform when the Yes button is selected</param>
        /// <param name="NoAction">Action to perform when the No button is selected</param>
        /// <param name="MessageBoxToUse">Optional pre-configured instance of window to use.  Use only if custom results are required.</param>
        /// <param name="CustomButton">Any number of custom pairs of button names and associated actions if selected</param>
        public static void Show(String Message, String Caption = "", Buttons Buttons = Buttons.None, ButtonTypes DefaultButton = ButtonTypes.Ok, double Width = Int32.MinValue, double Height = Int32.MinValue, double Opacity = Int32.MinValue, Action OKAction = null, Action CancelAction = null, Action YesAction = null, Action NoAction = null, MessageBoxPopUp MessageBoxToUse = null, params Tuple<string, Action>[] CustomButton)
        {
            MessageBoxPopUp msgBox = MessageBoxToUse != null ? MessageBoxToUse : new MessageBoxPopUp();
            msgBox.ResultButton = ButtonTypes.Cancel;
            if (Width != Int32.MinValue)
                msgBox.Width = Width;
            if (Width != Int32.MinValue)
                msgBox.Height = Height;
            if (Width != Int32.MinValue)
                msgBox.Opacity = Opacity;
            msgBox.Title = Caption;
            msgBox.Message = Message;
            msgBox.ButtonSelectedIdx = -1;


            // create the stock buttons
            if (Buttons == Buttons.Ok || Buttons == Buttons.OkCancel)
                msgBox.CreateButton("Ok", () => { msgBox.ResultButton = ButtonTypes.Ok; if (OKAction != null) msgBox.Closed += (s, e) => OKAction.Invoke(); msgBox.DialogResult = true; }, DefaultButton == ButtonTypes.Ok);
            if (Buttons == Buttons.YesNo || Buttons == Buttons.YesNoCancel)
                msgBox.CreateButton("Yes", () => { msgBox.ResultButton = ButtonTypes.Yes; if (YesAction != null) msgBox.Closed += (s, e) => YesAction.Invoke(); msgBox.DialogResult = true; }, DefaultButton == ButtonTypes.Yes);
            if (Buttons == Buttons.YesNo || Buttons == Buttons.YesNoCancel)
                msgBox.CreateButton("No", () => { msgBox.ResultButton = ButtonTypes.No; if (NoAction != null) msgBox.Closed += (s, e) => NoAction.Invoke(); msgBox.DialogResult = false; }, DefaultButton == ButtonTypes.No);
            if (Buttons == Buttons.YesNoCancel || Buttons == Buttons.OkCancel)
                msgBox.CreateButton("Cancel", () => { msgBox.ResultButton = ButtonTypes.Cancel; if (CancelAction != null) msgBox.Closed += (s, e) => CancelAction.Invoke(); msgBox.DialogResult = false; }, DefaultButton == ButtonTypes.Cancel);
            if (CustomButton != null)
            {
                foreach (Tuple<string, Action> custom in CustomButton)
                {
                    msgBox.CreateButton(custom.Item1, () => { msgBox.ResultButton = ButtonTypes.Custom; if (custom.Item2 != null) msgBox.Closed += (s, e) => custom.Item2.Invoke(); msgBox.DialogResult = true; }, msgBox._buttons.Count == 0);
                }
            }

            // add the buttons to the grid
            resetAndClearGrid(msgBox.ButtonsGrid);
            addColumnDefinitionsToGrid(msgBox.ButtonsGrid, msgBox._buttons.Count);
            for (int i = 0; i < msgBox._buttons.Count; i++)
            {
                addButtonToGrid(msgBox.ButtonsGrid, msgBox._buttons[i], i);
            }
            if (msgBox._defaultButton != null)
                msgBox._defaultButton.Focus();

            msgBox.Show();
        }


        private static void resetAndClearGrid(Grid grid)
        {
            grid.Children.Clear();
            grid.ColumnDefinitions.Clear();
        }

        private static void addColumnDefinitionsToGrid(Grid grid, int columns)
        {
            for (var i = 0; i < columns; i++)
            { grid.ColumnDefinitions.Add(new ColumnDefinition()); }
        }

        private static void addButtonToGrid(Panel grid, UIElement button, int columnIndex)
        {
            grid.Children.Add(button);
            button.SetValue(Grid.ColumnProperty, columnIndex);
        }

        private void CreateButton(String ButtonText, Action ButtonAction, bool IsDefaultButton)
        {
            Button _newButton = new Button
            {
                Content = ButtonText,
                Margin = new Thickness(2)
            };
            int thisButtonIdx = _buttons.Count;
            Action doAction = () => { ButtonSelectedIdx = thisButtonIdx; ButtonAction.Invoke(); };

            _newButton.Click += (sender, args) => 
                doAction.Invoke();
            _buttons.Add(_buttonCount++, _newButton);
            if (IsDefaultButton)
            {
                _defaultButton = _newButton;
                _defaultAction = doAction;
            }
        }

    }
}

Answer 1

我在你的想法中看到了一些积极的一面和一些消极的一面。积极的一面是需要更少的“管道”。缺点是 MessageBoxPopUp 不可配置。

在MIX11中，我将提出一种我认为更灵活的显示对话框的方式。我已经在多个 WP7 应用程序和 Silverlight 应用程序中使用它，并且效果非常好。它确实有点“管道”，但它很灵活，易于测试（我将在 MIX 中展示如何进行）并且可以打包在组件中以供重用。

干杯，
洛朗