ListBox实现拖拽排序功能

1、拖拽需要实现的事件包括：

PreviewMouseLeftButtonDown

LBoxSort_OnDrop

具体实现如下：

 private void LBoxSort_OnPreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            var pos = e.GetPosition(LBoxSort);
            HitTestResult result = VisualTreeHelper.HitTest(LBoxSort, pos);
            if (result == null)
            {
                return;
            }
            var listBoxItem = Utils.FindVisualParent<ListBoxItem>(result.VisualHit);
            if (listBoxItem == null || listBoxItem.Content != LBoxSort.SelectedItem)
            {
                return;
            }
            DataObject dataObj = new DataObject(listBoxItem.Content as Person);
            DragDrop.DoDragDrop(LBoxSort, dataObj, DragDropEffects.Move);

        }

        private void LBoxSort_OnDrop(object sender, DragEventArgs e)
        {
            var pos = e.GetPosition(LBoxSort);
            var result = VisualTreeHelper.HitTest(LBoxSort, pos);
            if (result == null)
            {
                return;
            }
            //查找元数据
            var sourcePerson = e.Data.GetData(typeof (Person)) as Person;
            if (sourcePerson == null)
            {
                return;
            }
            //查找目标数据
            var listBoxItem = Utils.FindVisualParent<ListBoxItem>(result.VisualHit);
            if (listBoxItem == null)
            {
                return;
            }
            var targetPerson = listBoxItem.Content as Person;
            if (ReferenceEquals(targetPerson, sourcePerson))
            {
                return;
            }
            _persons.Remove(sourcePerson);
            _persons.Insert(_persons.IndexOf(targetPerson), sourcePerson);
        }
    }

事件实现

2、排序功能实现：
数据源：

private ObservableCollection<Person> _persons = new ObservableCollection<Person>();
 private void InitData()
        {
            _persons.Add(new Person{Name = "test1", Order = "1"});
            _persons.Add(new Person { Name = "test2", Order = "2" });
            _persons.Add(new Person { Name = "test3", Order = "3" });
            _persons.Add(new Person { Name = "test4", Order = "4" });
            _persons.Add(new Person { Name = "test5", Order = "5" });
        }

数据源

3、排序功能实现：
为数据集合实现CollectionChanged事件，当数据集合发生变化时执行：

  private void PersonsOnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            if (e.Action == NotifyCollectionChangedAction.Remove)
            {
                for (int i = e.OldStartingIndex; i < _persons.Count; i++)
                {
                    _persons[i].Order = i.ToString();
                }
            }
            else if (e.Action == NotifyCollectionChangedAction.Add)
            {
                for (int i = e.NewStartingIndex; i < _persons.Count; i++)
                {
                    _persons[i].Order = i.ToString();
                }
            }
        }

排序

4、相关代码附加：

 public class Person : INotifyPropertyChanged
    {
        public string Name { get; set; }

        private string _order;
        public string Order
        {
            get { return _order; }
            set { _order = value; OnPropertyChanged("Order"); }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        [NotifyPropertyChangedInvocator]
        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }

      internal static class Utils
     {
         //根据子元素查找父元素
         public static T FindVisualParent<T>(DependencyObject obj) where T : class
         {
             while (obj != null)
             {
                 if (obj is T)
                     return obj as T;
 
                 obj = VisualTreeHelper.GetParent(obj);
             }
             return null;
         }
     }