c# - 更改 ListView 中列的显示顺序

Question

我必须根据某些显示更改列表 View 列的显示顺序
从xml文件中进行设置。有没有一种方法可以在xaml中仅在没有任何代码的情况下实现此目的。我正在使用MVVM。

这是代码，我想根据我从xml读取的设置来更改列的顺序(基本上是列名称的序列)。

<ListView ItemsSource="{Binding MyList}" >
 <ListView.View >
        <GridView>

       <GridViewColumn Header="column1" />
       <GridViewColumn Header="column2"/>
       <GridViewColumn Header="column3" />
       <GridViewColumn Header="column4" />
       <GridViewColumn Header="column5" />
       </GridView>
   </ListView.View>
  </ListView>

Answer 1

这可以通过MVVM方式完成。由于GridView.Columns不是依赖项属性，因此您已定义了自己的附加属性。请引用此问题以定义附加属性。

WPF MVVM: how to bind GridViewColumn to ViewModel-Collection?

在下面，我分享了我创建的示例代码。注意:为简单起见，我使用了后面的代码，但是可以将代码很好地移动到您的 View 模型中。

GridViewColumns.cs -附加属性

using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.ComponentModel;
using System.Windows.Data;
using System.Collections.Specialized;
using System.Reflection;
using System.Collections.ObjectModel;

namespace WpfApplication1
{
    public static class GridViewColumns
    {
        private static NotifyCollectionChangedEventHandler _CollectionChangedEventHandler = null;

        [AttachedPropertyBrowsableForType(typeof(GridView))]
        public static object GetColumnsSource(DependencyObject obj)
        {
            return (object)obj.GetValue(ColumnsSourceProperty);
        }

        public static void SetColumnsSource(DependencyObject obj, object value)
        {
            obj.SetValue(ColumnsSourceProperty, value);
        }

        // Using a DependencyProperty as the backing store for ColumnsSource.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty ColumnsSourceProperty =
            DependencyProperty.RegisterAttached(
                "ColumnsSource",
                typeof(object),
                typeof(GridViewColumns),
                new UIPropertyMetadata(
                    null,
                    ColumnsSourceChanged));


        [AttachedPropertyBrowsableForType(typeof(GridView))]
        public static string GetHeaderTextMember(DependencyObject obj)
        {
            return (string)obj.GetValue(HeaderTextMemberProperty);
        }

        public static void SetHeaderTextMember(DependencyObject obj, string value)
        {
            obj.SetValue(HeaderTextMemberProperty, value);
        }

        // Using a DependencyProperty as the backing store for HeaderTextMember.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty HeaderTextMemberProperty =
            DependencyProperty.RegisterAttached("HeaderTextMember", typeof(string), typeof(GridViewColumns), new UIPropertyMetadata(null));


        [AttachedPropertyBrowsableForType(typeof(GridView))]
        public static string GetDisplayMemberMember(DependencyObject obj)
        {
            return (string)obj.GetValue(DisplayMemberMemberProperty);
        }

        public static void SetDisplayMemberMember(DependencyObject obj, string value)
        {
            obj.SetValue(DisplayMemberMemberProperty, value);
        }

        // Using a DependencyProperty as the backing store for DisplayMember.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty DisplayMemberMemberProperty =
            DependencyProperty.RegisterAttached("DisplayMemberMember", typeof(string), typeof(GridViewColumns), new UIPropertyMetadata(null));


        private static void ColumnsSourceChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
        {
            GridView gridView = obj as GridView;
            if (gridView != null)
            {
                gridView.Columns.Clear();

                if (e.OldValue != null)
                {
                    ICollectionView view = CollectionViewSource.GetDefaultView(e.OldValue);
                    if (view != null)
                        RemoveHandlers(gridView, view);
                }

                if (e.NewValue != null)
                {
                    ICollectionView view = CollectionViewSource.GetDefaultView(e.NewValue);
                    if (view != null)
                    {
                        AddHandlers(gridView, view);
                        CreateColumns(gridView, view);
                    }
                }
            }
        }

        private static IDictionary<ICollectionView, List<GridView>> _gridViewsByColumnsSource =
            new Dictionary<ICollectionView, List<GridView>>();

        private static List<GridView> GetGridViewsForColumnSource(ICollectionView columnSource)
        {
            List<GridView> gridViews;
            if (!_gridViewsByColumnsSource.TryGetValue(columnSource, out gridViews))
            {
                gridViews = new List<GridView>();
                _gridViewsByColumnsSource.Add(columnSource, gridViews);
            }
            return gridViews;
        }

        private static void AddHandlers(GridView gridView, ICollectionView view)
        {
            GetGridViewsForColumnSource(view).Add(gridView);
            view.CollectionChanged += ColumnsSource_CollectionChanged;

            _CollectionChangedEventHandler = delegate(object sender, NotifyCollectionChangedEventArgs e)
            {
                var source = view.SourceCollection as ObservableCollection<ColumnDescriptor>;
                if (source != null && e.Action == NotifyCollectionChangedAction.Move)
                        source.Move(e.OldStartingIndex, e.NewStartingIndex);
            };
            gridView.Columns.CollectionChanged += _CollectionChangedEventHandler;
        }

        private static void CreateColumns(GridView gridView, ICollectionView view)
        {
            foreach (var item in view)
            {
                GridViewColumn column = CreateColumn(gridView, item);
                gridView.Columns.Add(column);
            }
        }

        private static void RemoveHandlers(GridView gridView, ICollectionView view)
        {
            view.CollectionChanged -= ColumnsSource_CollectionChanged;
            GetGridViewsForColumnSource(view).Remove(gridView);
            gridView.Columns.CollectionChanged -= _CollectionChangedEventHandler;
        }

        private static void ColumnsSource_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            ICollectionView view = sender as ICollectionView;
            var gridViews = GetGridViewsForColumnSource(view);
            if (gridViews == null || gridViews.Count == 0)
                return;

            switch (e.Action)
            {
                case NotifyCollectionChangedAction.Add:
                    foreach (var gridView in gridViews)
                    {
                        for (int i = 0; i < e.NewItems.Count; i++)
                        {
                            GridViewColumn column = CreateColumn(gridView, e.NewItems[i]);
                            gridView.Columns.Insert(e.NewStartingIndex + i, column);
                        }
                    }
                    break;
                case NotifyCollectionChangedAction.Move:
                    foreach (var gridView in gridViews)
                    {
                        List<GridViewColumn> columns = new List<GridViewColumn>();
                        for (int i = 0; i < e.OldItems.Count; i++)
                        {
                            GridViewColumn column = gridView.Columns[e.OldStartingIndex + i];
                            columns.Add(column);
                        }
                        for (int i = 0; i < e.NewItems.Count; i++)
                        {
                            GridViewColumn column = columns[i];

                            // Check if column exists
                            if (gridView.Columns.Contains(columns[i]) == false)
                            gridView.Columns.Insert(e.NewStartingIndex + i, column);
                        }
                    }
                    break;
                case NotifyCollectionChangedAction.Remove:
                    foreach (var gridView in gridViews)
                    {
                        for (int i = 0; i < e.OldItems.Count; i++)
                        {
                            gridView.Columns.RemoveAt(e.OldStartingIndex);
                        }
                    }
                    break;
                case NotifyCollectionChangedAction.Replace:
                    foreach (var gridView in gridViews)
                    {
                        for (int i = 0; i < e.NewItems.Count; i++)
                        {
                            GridViewColumn column = CreateColumn(gridView, e.NewItems[i]);
                            gridView.Columns[e.NewStartingIndex + i] = column;
                        }
                    }
                    break;
                case NotifyCollectionChangedAction.Reset:
                    foreach (var gridView in gridViews)
                    {
                        gridView.Columns.Clear();
                        CreateColumns(gridView, sender as ICollectionView);
                    }
                    break;
                default:
                    break;
            }
        }

        private static GridViewColumn CreateColumn(GridView gridView, object columnSource)
        {
            GridViewColumn column = new GridViewColumn();
            string headerTextMember = GetHeaderTextMember(gridView);
            string displayMemberMember = GetDisplayMemberMember(gridView);
            if (!string.IsNullOrEmpty(headerTextMember))
            {
                column.Header = GetPropertyValue(columnSource, headerTextMember);
            }
            if (!string.IsNullOrEmpty(displayMemberMember))
            {
                string propertyName = GetPropertyValue(columnSource, displayMemberMember) as string;
                column.DisplayMemberBinding = new Binding(propertyName);
            }
            return column;
        }

        private static object GetPropertyValue(object obj, string propertyName)
        {
            if (obj != null)
            {
                PropertyInfo prop = obj.GetType().GetProperty(propertyName);
                if (prop != null)
                    return prop.GetValue(obj, null);
            }
            return null;
        }
    }
}

XAML:

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication1"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Button Content="Change Order" Click="Button_Click" Width="120" Margin="5"/>
        <ListView Grid.Row="1" ItemsSource="{Binding MyList}" >
            <ListView.View >
                <GridView  local:GridViewColumns.HeaderTextMember="HeaderText"
                      local:GridViewColumns.DisplayMemberMember="DisplayMember"
                      local:GridViewColumns.ColumnsSource="{Binding OrderedColumns}">
                </GridView>
            </ListView.View>
        </ListView>
    </Grid>
</Window>

背后的代码:

using System.Collections.Generic;
using System.Windows;
using System.Collections.ObjectModel;

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private ViewModel _ViewModel = null;
        public MainWindow()
        {
            InitializeComponent();

            _ViewModel = new ViewModel();
            this.DataContext = _ViewModel;
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            // Moves the first column to the last
            var temp = _ViewModel.OrderedColumns[0];
            _ViewModel.OrderedColumns.Remove(temp);
            _ViewModel.OrderedColumns.Add(temp);

        }
    }

    public class ViewModel
    {
        private ObservableCollection<ColumnDescriptor> _OrderedColumns;

        public ObservableCollection<ColumnDescriptor> OrderedColumns
        {
            get { return _OrderedColumns; }
            set { _OrderedColumns = value; }
        }

        private List<Customer> _MyList;

        public List<Customer> MyList
        {
            get { return _MyList; }
            set { _MyList = value; }
        }


        public ViewModel()
        {
            OrderedColumns = new ObservableCollection<ColumnDescriptor>();
            OrderedColumns.Add(new ColumnDescriptor() { HeaderText = "Column1", DisplayMember = "Column1" });
            OrderedColumns.Add(new ColumnDescriptor() { HeaderText = "Column2", DisplayMember = "Column2" });
            OrderedColumns.Add(new ColumnDescriptor() { HeaderText = "Column3", DisplayMember = "Column3" });
            OrderedColumns.Add(new ColumnDescriptor() { HeaderText = "Column4", DisplayMember = "Column4" });

            MyList = new List<Customer>();

            MyList.Add(new Customer() { Column1 = "Data_Col1", Column2 = "Data_Col2", Column3 = "Data_Col3", Column4 = "Data_Col4" });
            MyList.Add(new Customer() { Column1 = "2Data_Col1", Column2 = "2Data_Col2", Column3 = "2Data_Col3", Column4 = "2Data_Col4" });
        }
    }

    public class ColumnDescriptor
    {
        public string HeaderText { get; set; }
        public string DisplayMember { get; set; }
    }

    public class Customer
    {
        public string Column1 { get; set; }
        public string Column2 { get; set; }
        public string Column3 { get; set; }
        public string Column4 { get; set; }
    }
}