WPF MVVM：GridViewColumnをViewModel-Collectionにバインドする方法は？
私のビューでは、たとえば次のように、ViewModelのCollectionViewにバインドされたListViewを取得しました。
<ListView ItemsSource="{Binding MyCollection}" IsSynchronizedWithCurrentItem="true">
<ListView.View>
<GridView>
<GridViewColumn Header="Title" DisplayMemberBinding="{Binding Path=Title}"/>
<GridViewColumn Header="Name" DisplayMemberBinding="{Binding Path=Name}"/>
<GridViewColumn Header="Phone" DisplayMemberBinding="{Binding Path=Phone}"/>
<GridViewColumn Header="E-mail" DisplayMemberBinding="{Binding Path=EMail}"/>
</GridView>
</ListView.View>
</ListView>
現在、これらのGridViewColumnsは修正されていますが、ViewModelから変更できるようにしたいと思います。 GridViewColumnコレクションをViewModel内の何かにバインドする必要があると思いますが、何をどのように行うのでしょうか。
ViewModelはWPFについて何も知らないので、MVVMでこれを実現する方法がわかりませんでした。
ここで何か助けはありますか？
Columnsプロパティは依存関係プロパティではないため、バインドすることはできません。ただし、ViewModelのコレクションにバインドできる添付プロパティを作成できる場合があります。この添付プロパティにより、列が作成されます。
更新
OK、これが基本的な実装です...
添付プロパティ
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Reflection;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
namespace TestPadWPF
{
public static class GridViewColumns
{
[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;
}
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);
}
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];
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;
}
}
}
ViewModel
class PersonsViewModel
{
public PersonsViewModel()
{
this.Persons = new ObservableCollection<Person>
{
new Person
{
Name = "Doe",
FirstName = "John",
DateOfBirth = new DateTime(1981, 9, 12)
},
new Person
{
Name = "Black",
FirstName = "Jack",
DateOfBirth = new DateTime(1950, 1, 15)
},
new Person
{
Name = "Smith",
FirstName = "Jane",
DateOfBirth = new DateTime(1987, 7, 23)
}
};
this.Columns = new ObservableCollection<ColumnDescriptor>
{
new ColumnDescriptor { HeaderText = "Last name", DisplayMember = "Name" },
new ColumnDescriptor { HeaderText = "First name", DisplayMember = "FirstName" },
new ColumnDescriptor { HeaderText = "Date of birth", DisplayMember = "DateOfBirth" }
};
}
public ObservableCollection<Person> Persons { get; private set; }
public ObservableCollection<ColumnDescriptor> Columns { get; private set; }
private ICommand _addColumnCommand;
public ICommand AddColumnCommand
{
get
{
if (_addColumnCommand == null)
{
_addColumnCommand = new DelegateCommand<string>(
s =>
{
this.Columns.Add(new ColumnDescriptor { HeaderText = s, DisplayMember = s });
});
}
return _addColumnCommand;
}
}
private ICommand _removeColumnCommand;
public ICommand RemoveColumnCommand
{
get
{
if (_removeColumnCommand == null)
{
_removeColumnCommand = new DelegateCommand<string>(
s =>
{
this.Columns.Remove(this.Columns.FirstOrDefault(d => d.DisplayMember == s));
});
}
return _removeColumnCommand;
}
}
}
XAML：
<ListView ItemsSource="{Binding Persons}" Grid.Row="0">
<ListView.View>
<GridView local:GridViewColumns.HeaderTextMember="HeaderText"
local:GridViewColumns.DisplayMemberMember="DisplayMember"
local:GridViewColumns.ColumnsSource="{Binding Columns}"/>
</ListView.View>
</ListView>
ColumnDescriptorクラスは実際には必要ないことに注意してください。わかりやすくするために追加しただけですが、どのタイプでもかまいません（匿名タイプを含む）。ヘッダーテキストと表示メンバー名を保持するプロパティを指定するだけです。
また、まだ完全にはテストされていないため、修正すべき問題がいくつかある可能性があることに注意してください...
Thomas Levesqueの優れたソリューションを採用し、GridViewの静的コレクションを削除し、列幅と文字列形式を設定する機能を追加するように変更したので、コードを共有したいと思いました。
変更された添付プロパティクラス：
public static class GridViewColumnCollection
{
public static readonly DependencyProperty ColumnCollectionBehaviourProperty =
DependencyProperty.RegisterAttached("ColumnCollectionBehaviour", typeof(GridViewColumnCollectionBehaviour), typeof(GridViewColumnCollection), new UIPropertyMetadata(null));
public static readonly DependencyProperty ColumnsSourceProperty =
DependencyProperty.RegisterAttached("ColumnsSource", typeof(object), typeof(GridViewColumnCollection), new UIPropertyMetadata(null, GridViewColumnCollection.ColumnsSourceChanged));
public static readonly DependencyProperty DisplayMemberFormatMemberProperty =
DependencyProperty.RegisterAttached("DisplayMemberFormatMember", typeof(string), typeof(GridViewColumnCollection), new UIPropertyMetadata(null, GridViewColumnCollection.DisplayMemberFormatMemberChanged));
public static readonly DependencyProperty DisplayMemberMemberProperty =
DependencyProperty.RegisterAttached("DisplayMemberMember", typeof(string), typeof(GridViewColumnCollection), new UIPropertyMetadata(null, GridViewColumnCollection.DisplayMemberMemberChanged));
public static readonly DependencyProperty HeaderTextMemberProperty =
DependencyProperty.RegisterAttached("HeaderTextMember", typeof(string), typeof(GridViewColumnCollection), new UIPropertyMetadata(null, GridViewColumnCollection.HeaderTextMemberChanged));
public static readonly DependencyProperty WidthMemberProperty =
DependencyProperty.RegisterAttached("WidthMember", typeof(string), typeof(GridViewColumnCollection), new UIPropertyMetadata(null, GridViewColumnCollection.WidthMemberChanged));
[AttachedPropertyBrowsableForType(typeof(GridView))]
public static GridViewColumnCollectionBehaviour GetColumnCollectionBehaviour(DependencyObject obj)
{
return (GridViewColumnCollectionBehaviour)obj.GetValue(ColumnCollectionBehaviourProperty);
}
public static void SetColumnCollectionBehaviour(DependencyObject obj, GridViewColumnCollectionBehaviour value)
{
obj.SetValue(ColumnCollectionBehaviourProperty, value);
}
[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);
}
[AttachedPropertyBrowsableForType(typeof(GridView))]
public static string GetDisplayMemberFormatMember(DependencyObject obj)
{
return (string)obj.GetValue(DisplayMemberFormatMemberProperty);
}
public static void SetDisplayMemberFormatMember(DependencyObject obj, string value)
{
obj.SetValue(DisplayMemberFormatMemberProperty, value);
}
[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);
}
[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);
}
[AttachedPropertyBrowsableForType(typeof(GridView))]
public static string GetWidthMember(DependencyObject obj)
{
return (string)obj.GetValue(WidthMemberProperty);
}
public static void SetWidthMember(DependencyObject obj, string value)
{
obj.SetValue(WidthMemberProperty, value);
}
private static void ColumnsSourceChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
GridViewColumnCollection.GetOrCreateColumnCollectionBehaviour(sender).ColumnsSource = e.NewValue;
}
private static void DisplayMemberFormatMemberChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
GridViewColumnCollection.GetOrCreateColumnCollectionBehaviour(sender).DisplayMemberFormatMember = e.NewValue as string;
}
private static void DisplayMemberMemberChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
GridViewColumnCollection.GetOrCreateColumnCollectionBehaviour(sender).DisplayMemberMember = e.NewValue as string;
}
private static void HeaderTextMemberChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
GridViewColumnCollection.GetOrCreateColumnCollectionBehaviour(sender).HeaderTextMember = e.NewValue as string;
}
private static void WidthMemberChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
GridViewColumnCollection.GetOrCreateColumnCollectionBehaviour(sender).WidthMember = e.NewValue as string;
}
private static GridViewColumnCollectionBehaviour GetOrCreateColumnCollectionBehaviour(DependencyObject source)
{
GridViewColumnCollectionBehaviour behaviour = GetColumnCollectionBehaviour(source);
if (behaviour == null)
{
GridView typedSource = source as GridView;
if (typedSource == null)
{
throw new Exception("This property can only be set on controls deriving GridView");
}
behaviour = new GridViewColumnCollectionBehaviour(typedSource);
SetColumnCollectionBehaviour(typedSource, behaviour);
}
return behaviour;
}
}
動作（これは各GridViewに対して保存され、コレクションを保存する必要がなくなります-GridViewマッピングを一元的に）：
public class GridViewColumnCollectionBehaviour
{
private object columnsSource;
private GridView gridView;
public GridViewColumnCollectionBehaviour(GridView gridView)
{
this.gridView = gridView;
}
public object ColumnsSource
{
get { return this.columnsSource; }
set
{
object oldValue = this.columnsSource;
this.columnsSource = value;
this.ColumnsSourceChanged(oldValue, this.columnsSource);
}
}
public string DisplayMemberFormatMember { get; set; }
public string DisplayMemberMember { get; set; }
public string HeaderTextMember { get; set; }
public string WidthMember { get; set; }
private void AddHandlers(ICollectionView collectionView)
{
collectionView.CollectionChanged += this.ColumnsSource_CollectionChanged;
}
private void ColumnsSource_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
ICollectionView view = sender as ICollectionView;
if (this.gridView == null)
{
return;
}
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
for (int i = 0; i < e.NewItems.Count; i++)
{
GridViewColumn column = CreateColumn(e.NewItems[i]);
gridView.Columns.Insert(e.NewStartingIndex + i, column);
}
break;
case NotifyCollectionChangedAction.Move:
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];
gridView.Columns.Insert(e.NewStartingIndex + i, column);
}
break;
case NotifyCollectionChangedAction.Remove:
for (int i = 0; i < e.OldItems.Count; i++)
{
gridView.Columns.RemoveAt(e.OldStartingIndex);
}
break;
case NotifyCollectionChangedAction.Replace:
for (int i = 0; i < e.NewItems.Count; i++)
{
GridViewColumn column = CreateColumn(e.NewItems[i]);
gridView.Columns[e.NewStartingIndex + i] = column;
}
break;
case NotifyCollectionChangedAction.Reset:
gridView.Columns.Clear();
CreateColumns(sender as ICollectionView);
break;
default:
break;
}
}
private void ColumnsSourceChanged(object oldValue, object newValue)
{
if (this.gridView != null)
{
gridView.Columns.Clear();
if (oldValue != null)
{
ICollectionView view = CollectionViewSource.GetDefaultView(oldValue);
if (view != null)
{
this.RemoveHandlers(view);
}
}
if (newValue != null)
{
ICollectionView view = CollectionViewSource.GetDefaultView(newValue);
if (view != null)
{
this.AddHandlers(view);
this.CreateColumns(view);
}
}
}
}
private GridViewColumn CreateColumn(object columnSource)
{
GridViewColumn column = new GridViewColumn();
if (!string.IsNullOrEmpty(this.HeaderTextMember))
{
column.Header = GetPropertyValue(columnSource, this.HeaderTextMember);
}
if (!string.IsNullOrEmpty(this.DisplayMemberMember))
{
string propertyName = GetPropertyValue(columnSource, this.DisplayMemberMember) as string;
string format = null;
if (!string.IsNullOrEmpty(this.DisplayMemberFormatMember))
{
format = GetPropertyValue(columnSource, this.DisplayMemberFormatMember) as string;
}
if (string.IsNullOrEmpty(format))
{
format = "{0}";
}
column.DisplayMemberBinding = new Binding(propertyName) { StringFormat = format };
}
if (!string.IsNullOrEmpty(this.WidthMember))
{
double width = (double)GetPropertyValue(columnSource, this.WidthMember);
column.Width = width;
}
return column;
}
private void CreateColumns(ICollectionView collectionView)
{
foreach (object item in collectionView)
{
GridViewColumn column = this.CreateColumn(item);
this.gridView.Columns.Add(column);
}
}
private object GetPropertyValue(object obj, string propertyName)
{
object returnVal = null;
if (obj != null)
{
PropertyInfo prop = obj.GetType().GetProperty(propertyName);
if (prop != null)
{
returnVal = prop.GetValue(obj, null);
}
}
return returnVal;
}
private void RemoveHandlers(ICollectionView collectionView)
{
collectionView.CollectionChanged -= this.ColumnsSource_CollectionChanged;
}
}
このコードはメモリリークの問題を引き起こすと思います。クラスGridViewColumnsで説明されているように、グリッドビューとその列のソース参照を含む静的ディクショナリ「_gridViewsByColumnsSource」を定義しました。したがって、これは追加されたグリッドビューと列のソースへの強力な参照です。このディクショナリは静的であるため、グリッドビューと列のソースデータへの静的参照「ポイント」が常に存在するようです。グリッドビューが定義された画面が閉じている場合、GCが開始されるとグリッドビューをGCで収集できません。ますます多くの同様の画面が開かれ、ますます多くのグリッドビューとその列のソースデータを収集できなくなるため、最後にメモリリークが発生します。