C# WPF ListView SelectedItems数据绑定MVVM
以下是我认为的源代码C# WPF ListView SelectedItems数据绑定MVVM,c#,wpf,mvvm,data-binding,C#,Wpf,Mvvm,Data Binding,以下是我认为的源代码 <ListView SelectionMode="Multiple" ItemsSource="{Binding Items, Mode=OneWay}" SelectedItems="{Binding SelectedItems}"> <ListView.ItemTemplate> <DataTemplate> <Grid Height="
<ListView SelectionMode="Multiple"
ItemsSource="{Binding Items, Mode=OneWay}"
SelectedItems="{Binding SelectedItems}">
<ListView.ItemTemplate>
<DataTemplate>
<Grid Height="55" Margin="-3,0,-3,0">
<TextBlock Text="{Binding Name}"/>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
SelectedItems属性（ViewModel）我怎么去那里 我们用一个附加属性解决了它，该属性如下所示：
public class MultiSelectorExtension
{
public static readonly DependencyProperty SelectedItemsProperty =
DependencyProperty.RegisterAttached("SelectedItems", typeof(INotifyCollectionChanged), typeof(MultiSelectorExtension),
new PropertyMetadata(default(INotifyCollectionChanged), OnSelectedItemsChanged));
public static void SetSelectedItems(DependencyObject element, INotifyCollectionChanged value)
{
element.SetValue(SelectedItemsProperty, value);
}
public static INotifyCollectionChanged GetSelectedItems(DependencyObject element)
{
return (INotifyCollectionChanged)element.GetValue(SelectedItemsProperty);
}
private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
MultiSelector multiSelectorControl = d as MultiSelector;
NotifyCollectionChangedEventHandler handler = (sender,
args) =>
{
if (multiSelectorControl != null)
{
IList listSelectedItems = multiSelectorControl.SelectedItems;
if (args.OldItems != null)
{
foreach (var item in args.OldItems)
{
if (listSelectedItems.Contains(item))
{
listSelectedItems.Remove(item);
}
}
}
if (args.NewItems != null)
{
foreach (var item in args.NewItems)
{
if (!listSelectedItems.Contains(item))
{
listSelectedItems.Add(item);
}
}
}
}
};
if (e.OldValue == null && multiSelectorControl != null)
{
multiSelectorControl.SelectionChanged += OnSelectionChanged;
}
if (e.OldValue is INotifyCollectionChanged)
{
(e.OldValue as INotifyCollectionChanged).CollectionChanged -= handler;
}
if (e.NewValue is INotifyCollectionChanged)
{
(e.NewValue as INotifyCollectionChanged).CollectionChanged += handler;
}
}
private static void OnSelectionChanged(object sender, SelectionChangedEventArgs e)
{
DependencyObject d = sender as DependencyObject;
if (GetSelectionChangedInProgress(d))
return;
// Internal Flag to avoid infinite loop
SetSelectionChangedInProgress(d, true);
dynamic selectedItems = GetSelectedItems(d);
try
{
foreach (var item in e.RemovedItems.Cast<dynamic>().Where(item => selectedItems.Contains(item)))
{
selectedItems.Remove(item);
}
}
catch (Exception)
{
}
try
{
foreach (var item in e.AddedItems.Cast<dynamic>().Where(item => !selectedItems.Contains(item)))
{
selectedItems.Add(item);
}
}
catch (Exception)
{
}
SetSelectionChangedInProgress(d, false);
}
private static readonly DependencyProperty SelectionChangedInProgressProperty =
DependencyProperty.RegisterAttached("SelectionChangedInProgress", typeof(bool), typeof(MultiSelectorExtension), new PropertyMetadata(default(bool)));
private static void SetSelectionChangedInProgress(DependencyObject element,
bool value)
{
element.SetValue(SelectionChangedInProgressProperty, value);
}
private static bool GetSelectionChangedInProgress(DependencyObject element)
{
return (bool)element.GetValue(SelectionChangedInProgressProperty);
}
}
AttachedProperties:MultiSelectorExtension.SelectedItems="{Binding SelectedPersonss, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
我们用一个附加属性解决了它，该属性如下所示：
public class MultiSelectorExtension
{
public static readonly DependencyProperty SelectedItemsProperty =
DependencyProperty.RegisterAttached("SelectedItems", typeof(INotifyCollectionChanged), typeof(MultiSelectorExtension),
new PropertyMetadata(default(INotifyCollectionChanged), OnSelectedItemsChanged));
public static void SetSelectedItems(DependencyObject element, INotifyCollectionChanged value)
{
element.SetValue(SelectedItemsProperty, value);
}
public static INotifyCollectionChanged GetSelectedItems(DependencyObject element)
{
return (INotifyCollectionChanged)element.GetValue(SelectedItemsProperty);
}
private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
MultiSelector multiSelectorControl = d as MultiSelector;
NotifyCollectionChangedEventHandler handler = (sender,
args) =>
{
if (multiSelectorControl != null)
{
IList listSelectedItems = multiSelectorControl.SelectedItems;
if (args.OldItems != null)
{
foreach (var item in args.OldItems)
{
if (listSelectedItems.Contains(item))
{
listSelectedItems.Remove(item);
}
}
}
if (args.NewItems != null)
{
foreach (var item in args.NewItems)
{
if (!listSelectedItems.Contains(item))
{
listSelectedItems.Add(item);
}
}
}
}
};
if (e.OldValue == null && multiSelectorControl != null)
{
multiSelectorControl.SelectionChanged += OnSelectionChanged;
}
if (e.OldValue is INotifyCollectionChanged)
{
(e.OldValue as INotifyCollectionChanged).CollectionChanged -= handler;
}
if (e.NewValue is INotifyCollectionChanged)
{
(e.NewValue as INotifyCollectionChanged).CollectionChanged += handler;
}
}
private static void OnSelectionChanged(object sender, SelectionChangedEventArgs e)
{
DependencyObject d = sender as DependencyObject;
if (GetSelectionChangedInProgress(d))
return;
// Internal Flag to avoid infinite loop
SetSelectionChangedInProgress(d, true);
dynamic selectedItems = GetSelectedItems(d);
try
{
foreach (var item in e.RemovedItems.Cast<dynamic>().Where(item => selectedItems.Contains(item)))
{
selectedItems.Remove(item);
}
}
catch (Exception)
{
}
try
{
foreach (var item in e.AddedItems.Cast<dynamic>().Where(item => !selectedItems.Contains(item)))
{
selectedItems.Add(item);
}
}
catch (Exception)
{
}
SetSelectionChangedInProgress(d, false);
}
private static readonly DependencyProperty SelectionChangedInProgressProperty =
DependencyProperty.RegisterAttached("SelectionChangedInProgress", typeof(bool), typeof(MultiSelectorExtension), new PropertyMetadata(default(bool)));
private static void SetSelectionChangedInProgress(DependencyObject element,
bool value)
{
element.SetValue(SelectionChangedInProgressProperty, value);
}
private static bool GetSelectionChangedInProgress(DependencyObject element)
{
return (bool)element.GetValue(SelectionChangedInProgressProperty);
}
}
AttachedProperties:MultiSelectorExtension.SelectedItems="{Binding SelectedPersonss, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
这并不重要，因为我发布的源代码不是完整的（不是真实的）。实际上，SelectedItems不仅仅是字符串的一个可观察集合，而是某些对象的集合。我需要得到那些东西。即使在setter中设置断点，也不能停止程序。哦，我明白了。那么你的问题是绑定似乎不起作用了？你的问题并不完全清楚。我假设您已经实现了INotifyPropertyChanged（看起来是这样的）？啊，看来SelectedItems是一种方式-您不能从XAML内部设置它。Tomtom的答案应该对您有所帮助。这并不重要，因为我发布的源代码并不完整（不是真正的源代码）。实际上，SelectedItems不仅仅是字符串的一个可观察集合，而是某些对象的集合。我需要得到那些东西。即使在setter中设置断点，也不能停止程序。哦，我明白了。那么你的问题是绑定似乎不起作用了？你的问题并不完全清楚。我假设您已经实现了INotifyPropertyChanged（看起来是这样的）？啊，看来SelectedItems是一种方式-您不能从XAML内部设置它。Tomtom的回答应该对你有帮助。谢谢你——这很有效！如果调试程序，我会看到SelectedItems属性包含ListView中的所有选定项。如果用户选择或取消选择项目，是否有方法引发事件。我需要在ViewModel中处理ListView选择的更改。正如我提到的，如果在我的setter中设置了一个断点，程序就不会停在那里。如果这个答案是您的解决方案的答案，请将其标记为已接受。对于其他疑问和疑问，请问另一个问题！！谢谢你，这很有效！如果调试程序，我会看到SelectedItems属性包含ListView中的所有选定项。如果用户选择或取消选择项目，是否有方法引发事件。我需要在ViewModel中处理ListView选择的更改。正如我提到的，如果在我的setter中设置了一个断点，程序就不会停在那里。如果这个答案是您的解决方案的答案，请将其标记为已接受。对于其他疑问和疑问，请问另一个问题！！