Display_D_HP/TeamAAS-VM/Behaviors/ComboBoxSelectionBehavior.cs

using Microsoft.Xaml.Behaviors;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace TeamAAS_VP.Behaviors
{
    public class ComboBoxSelectionBehavior : Behavior<ComboBox>
    {

        // 定义一个依赖属性，用于绑定命令
        public static readonly DependencyProperty UserSelectionCommandProperty =
            DependencyProperty.Register(
                nameof(UserSelectionCommand),
                typeof(ICommand),
                typeof(ComboBoxSelectionBehavior));

        public ICommand UserSelectionCommand
        {
            get => (ICommand)GetValue(UserSelectionCommandProperty);
            set => SetValue(UserSelectionCommandProperty, value);
        }

        // 定义 CommandParameter 依赖属性
        public static readonly DependencyProperty CommandParameterProperty =
            DependencyProperty.Register(
                nameof(CommandParameter),
                typeof(object),
                typeof(ComboBoxSelectionBehavior));

        public object CommandParameter
        {
            get => GetValue(CommandParameterProperty);
            set => SetValue(CommandParameterProperty, value);
        }

        protected override void OnAttached()
        {
            base.OnAttached();
            AssociatedObject.SelectionChanged += OnSelectionChanged;
            AssociatedObject.PreviewMouseDown += OnPreviewMouseDown;
            AssociatedObject.PreviewMouseWheel += OnPreviewMouseWheel;// 处理鼠标滚轮事件
        }

        protected override void OnDetaching()
        {
            base.OnDetaching();
            AssociatedObject.SelectionChanged -= OnSelectionChanged;
            AssociatedObject.PreviewMouseDown -= OnPreviewMouseDown;
            AssociatedObject.PreviewMouseWheel -= OnPreviewMouseWheel; // 处理鼠标滚轮事件
        }

        private void OnPreviewMouseWheel(object sender, MouseWheelEventArgs e)
        {
            if (sender is ComboBox comboBox)
            {
                if (!comboBox.IsDropDownOpen)
                {
                    // 吞掉滚轮事件，禁止它改变选项
                    e.Handled = true;
                }
            }

        }

        private void OnPreviewMouseDown(object sender, MouseButtonEventArgs e)
        {
            
        }

        private void OnSelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (sender is ComboBox comboBox && comboBox.IsDropDownOpen)
            {
                if (UserSelectionCommand?.CanExecute(CommandParameter) == true)
                {
                    // 用户手动选择
                    var selectedItem = AssociatedObject.SelectedItem;
                    var parameter = new Tuple<object, object>(CommandParameter, comboBox.SelectedItem);
                    UserSelectionCommand.Execute(parameter);
                }
            }
        }
    }
}