WPF MVVM:如何将GridViewColumn绑定到视图模型集合？
WPF MVVM:如何将GridViewColumn绑定到视图模型集合？
提问于 2010-04-15 15:52:54
在我的视图中，我将一个ListView绑定到我的ViewModel中的一个CollectionView，例如：
<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>现在这些GridViewColumns是固定的，但我希望能够从ViewModel中更改它们。我猜我必须将GridViewColumn集合绑定到ViewModel中的某个东西，但是绑定的是什么，又是如何绑定的呢？
ViewModel对WPF一无所知，所以我不知道如何在MVVM中实现这一点。
这里有帮助吗？
回答 2
Stack Overflow用户
发布于 2012-07-27 19:45:36
我采用了Thomas Levesque的优秀解决方案，并对其进行了修改，删除了GridViews的静态集合，还添加了设置列宽和字符串格式的功能，所以我想分享一下我的代码。
修改后的附加属性类：
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;
}
}Behaviour (这是针对每个GridView进行存储的，因此无需集中存储集合-GridView映射)：
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;
}
}Stack Overflow用户
发布于 2011-12-08 00:22:26
我认为这段代码会导致一些内存泄漏问题；正如您的类GridViewColumns所描述的，您已经定义了一个静态字典"_gridViewsByColumnsSource“，其中包含了网格视图和它们的列源引用；因此这是对添加的网格视图和列源的强引用；因为这个字典是静态的，所以似乎一直存在对网格视图和列源数据的静态引用”指针“，如果定义网格视图的屏幕关闭，如果启动GC，网格视图就不能被GC收集；随着越来越多的类似屏幕打开，越来越多的网格视图及其列源数据无法收集，最终会出现内存泄漏。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/2643545
复制相关文章
相似问题
腾讯云开发者
