ObserveableCollection 的 ICollectionView 上的混合 static/dynamic ContextMenu (MCVE)
Mixed static/dynamic ContextMenu on ICollectionView of ObserveableCollection (MCVE)
我正在构建上下文菜单，使用 XAML MenuItems（又名 static）与动态创建的 MenuItems 混合，然后是更多静态。有的没动态显示就隐藏，有动态显示才显示。
（我将 Bindings 和 ValueConverters 留给了 hide/show mcve 之外的东西）
上下文菜单：
Static entry 1 // this one is hidden if any dynamic entries are visible
Static entry 2 // always visible
-------------- // seperator, hidden if no dynamic entry is shown
dynamic entries // \_
dynamic entries // \___ shown sorted if any in collection
dynamic entries // _/ and then only those with filter == ok
dynamic entries // /
--------------- // seperator - always visible
Static entry 3 //
Static entry 4 // \ three more static entries,
Static entry 5 // / always visble
2 问题：内存不断增加 - 以及几个红色 XAML 错误
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')
我无法以自动更新 ObersveableCollection 的方式将 ICollecionView 直接绑定到 ContextMenue.ItemSource.CompositeCollection.CollectionContainer.Collection - 视图用作其源的更改。
这就是为什么我使用 ObersveableCollection-Items 中的 INotifyPropertyChanged 来规避它的原因 - 我的猜测是我通过重置 CollectionContainer 的Collection 到重新创建的 ICollectionView。
如何在不报错且不断增加内存的情况下正确解决？
"Minimal" 示例代码：（来自 WPF App (.NET Framework) 模板）
MainWindow.xaml:
<Window x:Class="DarnContextMenu.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:DarnContextMenu"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<ResourceDictionary>
<!-- Vm to MenuItem -->
<local:VmToMenuItemConverter x:Key="VmToMenuItem"/>
<!-- display template -->
<DataTemplate x:Key="vmTemplate">
<StackPanel Margin="5">
<TextBlock Text="{Binding ConName}"/>
</StackPanel>
</DataTemplate>
</ResourceDictionary>
</Window.Resources>
<Window.ContextMenu>
<ContextMenu>
<ContextMenu.ItemsSource>
<CompositeCollection >
<!-- Connectoptions -->
<MenuItem Header="Connect to last used"/>
<MenuItem Header="Connect to ..."/>
<Separator/>
<!-- List of not disabled connections -->
<CollectionContainer x:Name="cc" Collection="{Binding ConsView, Converter={StaticResource VmToMenuItem}}"/>
<Separator/>
<!-- Others -->
<MenuItem Header="Settings ..."/>
<MenuItem Header="Do Something ..."/>
<MenuItem Header="Exit ..."/>
</CompositeCollection>
</ContextMenu.ItemsSource>
</ContextMenu>
</Window.ContextMenu>
<DockPanel>
<Label DockPanel.Dock="Bottom" x:Name="msgBlock" Height="28" VerticalAlignment="Center" HorizontalAlignment="Right"/>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="5"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<DockPanel>
<TextBlock DockPanel.Dock="Top" Margin="0,5" HorizontalAlignment="Center">Listview with ICollectionView</TextBlock>
<ListView Grid.Column="0" ItemsSource="{Binding ConsView}" ItemTemplate="{StaticResource vmTemplate}" Background="LightGray"/>
</DockPanel>
<DockPanel Grid.Column="2">
<TextBlock DockPanel.Dock="Top" Margin="0,5" HorizontalAlignment="Center">Listview with ObservableCollection:</TextBlock>
<ListView ItemsSource="{Binding Cons}" ItemTemplate="{StaticResource vmTemplate}"/>
</DockPanel>
</Grid>
</DockPanel>
</Window>
MainWindow.xaml.cs（MCVE 全部压在一起）：
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Threading;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Threading;
namespace DarnContextMenu
{
// States used for filtering what is displayed via ICollectionView
public enum EConState { Disabled, LoggedIn, LoggedOff };
// Stripped down model
public class Connection
{
public Connection (string name)
{
Name = name;
}
public EConState State { get; set; } = EConState.Disabled;
public string Name { get; set; } = string.Empty;
}
// Viewmodel
public class ConnectionVM : DependencyObject, INotifyPropertyChanged
{
// Simulation of changing States
static List<EConState> allStates = new List<EConState> { EConState.Disabled, EConState.LoggedIn, EConState.LoggedOff };
Timer t;
void changeMe (object state)
{
if (state is ConnectionVM c)
MainWindow.UIDispatcher
.Invoke (() => c.State =
allStates
.Where (s => s != c.State)
.OrderBy (_ => Guid.NewGuid ().GetHashCode ())
.First ());
}
// End of simulation of changing States
public static readonly DependencyProperty StateProperty = DependencyProperty.Register ("State", typeof (EConState), typeof (ConnectionVM),
new PropertyMetadata (EConState.Disabled, (DependencyObject d, DependencyPropertyChangedEventArgs e) =>
{
if (d is ConnectionVM vm)
{
vm.ConName = $"{vm.Connection.Name} [{(EConState)e.NewValue}]";
vm.PropertyChanged?.Invoke (vm, new PropertyChangedEventArgs (nameof (vm.State)));
}
}));
// The state of the connection: influences if the connection is shown at all and used in sorting
public EConState State
{
get { return (EConState)GetValue (StateProperty); }
set { SetValue (StateProperty, value); }
}
// name created by models basename and state - changes via callback from StateProperty
protected static readonly DependencyPropertyKey ConNamePropertyKey = DependencyProperty.RegisterReadOnly ("ConName", typeof (string), typeof (ConnectionVM), new PropertyMetadata (""));
public static readonly DependencyProperty ConNameProperty = ConNamePropertyKey.DependencyProperty;
public string ConName
{
get { return (string)GetValue (ConNameProperty); }
protected set { SetValue (ConNamePropertyKey, value); }
}
Connection Connection { get; }
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
///
/// </summary>
/// <param name="connection">The connection - used for name and initial state</param>
/// <param name="delay">a delay for the timer until the state-changes start</param>
/// <param name="period">a delay between state changes </param>
public ConnectionVM (Connection connection, TimeSpan delay, TimeSpan period)
{
t = new Timer (changeMe, this, (int)delay.TotalMilliseconds, (int)period.TotalMilliseconds);
Connection = connection;
State = Connection.State; // changing, simulated by timer inside VM
}
}
public class MainViewModel
{
// all connections - in RL: occasionally new ones will be added by the user
public ObservableCollection<ConnectionVM> Cons { get; set; }
// filtered and sorted view on Cons - Collection
public ICollectionView ConsView { get; set; }
public MainViewModel (CollectionContainer cc)
{
// demodata - normally connections are created by userinteractions
// this simulates 9 connections that change status every 4s to 10s
Cons = new ObservableCollection<ConnectionVM> (
Enumerable.Range (1, 9)
.Select (n => new ConnectionVM (new Connection ($"Connection #{n}")
, TimeSpan.FromMilliseconds (300 * n)
, TimeSpan.FromMilliseconds (700 * (n + 5))))
);
// create a sorted and filtered view
// - sort by Status and then by Name
// - show only Connecitons that are not Disabled
ConsView = new CollectionViewSource { Source = Cons }.View;
using (var def = ConsView.DeferRefresh ())
{
ConsView.SortDescriptions.Add (new SortDescription ("State", ListSortDirection.Ascending));
ConsView.SortDescriptions.Add (new SortDescription ("ConName", ListSortDirection.Ascending));
ConsView.Filter = obj => (obj is ConnectionVM vm) && vm.State != EConState.Disabled;
}
// attach a Refresh-Action of MVM to each ConnectionVMs PropertyChanged which is fired by
// ConnectionVM.StateProperty.Callback notifies each listener on StateProperty-Change
foreach (var vm in Cons)
{
vm.PropertyChanged += (s, e) => // object s, PropertyChangedEventArgs e
{
cc.Collection = ConsView;
RefreshViewModels ();
};
}
// in case the whole collection is added or removed to/from
Cons.CollectionChanged += (s, e) =>
{
cc.Collection = ConsView;
RefreshViewModels ();
};
}
void RefreshViewModels ()
{
ConsView.Refresh ();
MainWindow.logger.Content = $"Valid: {Cons.Count (c => c.State != EConState.Disabled)}/{Cons.Count ()} (In/Off/Disabled: {Cons.Count (c => c.State == EConState.LoggedIn)} / {Cons.Count (c => c.State == EConState.LoggedOff)} / {Cons.Count (c => c.State == EConState.Disabled)})";
}
}
// create a MenuItem from the ConnectionVM - in real theres a bit more code inside due to Icons, Commands, etc.
public class VmToMenuItemConverter : IValueConverter
{
public object Convert (object value, Type targetType, object parameter, CultureInfo culture)
=> new MenuItem { Header = (value as ConnectionVM).ConName ?? $"Invalid '{value.GetType ()}'" };
public object ConvertBack (object value, Type targetType, object parameter, CultureInfo culture) => null;
}
public partial class MainWindow : Window
{
public static Dispatcher UIDispatcher = null;
public static Label logger = null;
public MainWindow ()
{
UIDispatcher = Application.Current.Dispatcher;
InitializeComponent ();
logger = msgBlock;
DataContext = new MainViewModel (cc);
}
}
}
I was unable to directly bind the ICollecionView to the ContextMenue.ItemSource.CompositeCollection.CollectionContainer.Collection in a way that it autoupdated on ObersveableCollection-changes that the view uses as its source.
见CompositeCollection + CollectionContainer: Bind CollectionContainer.Collection to property of ViewModel that is used as DataTemplates DataType
简单答案：
<CollectionViewSource x:Key="testing" Source="{Binding items}"></CollectionViewSource>
<ContextMenu.ItemsSource>
<CompositeCollection>
<MenuItem Header="Standard MenuItem 3" />
<CollectionContainer Collection="{Binding Source={StaticResource testing}}" />
<MenuItem Header="Standard MenuItem 6" />
</CompositeCollection>
</ContextMenu.ItemsSource>
像这样，您可以将一个项目添加到 datacontext.items，它会立即出现在菜单中
我正在构建上下文菜单，使用 XAML MenuItems（又名 static）与动态创建的 MenuItems 混合，然后是更多静态。有的没动态显示就隐藏，有动态显示才显示。
（我将 Bindings 和 ValueConverters 留给了 hide/show mcve 之外的东西）
上下文菜单：
Static entry 1 // this one is hidden if any dynamic entries are visible
Static entry 2 // always visible
-------------- // seperator, hidden if no dynamic entry is shown
dynamic entries // \_
dynamic entries // \___ shown sorted if any in collection
dynamic entries // _/ and then only those with filter == ok
dynamic entries // /
--------------- // seperator - always visible
Static entry 3 //
Static entry 4 // \ three more static entries,
Static entry 5 // / always visble
2 问题：内存不断增加 - 以及几个红色 XAML 错误
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')
我无法以自动更新 ObersveableCollection 的方式将 ICollecionView 直接绑定到 ContextMenue.ItemSource.CompositeCollection.CollectionContainer.Collection - 视图用作其源的更改。
这就是为什么我使用 ObersveableCollection-Items 中的 INotifyPropertyChanged 来规避它的原因 - 我的猜测是我通过重置 CollectionContainer 的Collection 到重新创建的 ICollectionView。
如何在不报错且不断增加内存的情况下正确解决？
"Minimal" 示例代码：（来自 WPF App (.NET Framework) 模板）
MainWindow.xaml:
<Window x:Class="DarnContextMenu.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:DarnContextMenu"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<ResourceDictionary>
<!-- Vm to MenuItem -->
<local:VmToMenuItemConverter x:Key="VmToMenuItem"/>
<!-- display template -->
<DataTemplate x:Key="vmTemplate">
<StackPanel Margin="5">
<TextBlock Text="{Binding ConName}"/>
</StackPanel>
</DataTemplate>
</ResourceDictionary>
</Window.Resources>
<Window.ContextMenu>
<ContextMenu>
<ContextMenu.ItemsSource>
<CompositeCollection >
<!-- Connectoptions -->
<MenuItem Header="Connect to last used"/>
<MenuItem Header="Connect to ..."/>
<Separator/>
<!-- List of not disabled connections -->
<CollectionContainer x:Name="cc" Collection="{Binding ConsView, Converter={StaticResource VmToMenuItem}}"/>
<Separator/>
<!-- Others -->
<MenuItem Header="Settings ..."/>
<MenuItem Header="Do Something ..."/>
<MenuItem Header="Exit ..."/>
</CompositeCollection>
</ContextMenu.ItemsSource>
</ContextMenu>
</Window.ContextMenu>
<DockPanel>
<Label DockPanel.Dock="Bottom" x:Name="msgBlock" Height="28" VerticalAlignment="Center" HorizontalAlignment="Right"/>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="5"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<DockPanel>
<TextBlock DockPanel.Dock="Top" Margin="0,5" HorizontalAlignment="Center">Listview with ICollectionView</TextBlock>
<ListView Grid.Column="0" ItemsSource="{Binding ConsView}" ItemTemplate="{StaticResource vmTemplate}" Background="LightGray"/>
</DockPanel>
<DockPanel Grid.Column="2">
<TextBlock DockPanel.Dock="Top" Margin="0,5" HorizontalAlignment="Center">Listview with ObservableCollection:</TextBlock>
<ListView ItemsSource="{Binding Cons}" ItemTemplate="{StaticResource vmTemplate}"/>
</DockPanel>
</Grid>
</DockPanel>
</Window>
MainWindow.xaml.cs（MCVE 全部压在一起）：
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Threading;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Threading;
namespace DarnContextMenu
{
// States used for filtering what is displayed via ICollectionView
public enum EConState { Disabled, LoggedIn, LoggedOff };
// Stripped down model
public class Connection
{
public Connection (string name)
{
Name = name;
}
public EConState State { get; set; } = EConState.Disabled;
public string Name { get; set; } = string.Empty;
}
// Viewmodel
public class ConnectionVM : DependencyObject, INotifyPropertyChanged
{
// Simulation of changing States
static List<EConState> allStates = new List<EConState> { EConState.Disabled, EConState.LoggedIn, EConState.LoggedOff };
Timer t;
void changeMe (object state)
{
if (state is ConnectionVM c)
MainWindow.UIDispatcher
.Invoke (() => c.State =
allStates
.Where (s => s != c.State)
.OrderBy (_ => Guid.NewGuid ().GetHashCode ())
.First ());
}
// End of simulation of changing States
public static readonly DependencyProperty StateProperty = DependencyProperty.Register ("State", typeof (EConState), typeof (ConnectionVM),
new PropertyMetadata (EConState.Disabled, (DependencyObject d, DependencyPropertyChangedEventArgs e) =>
{
if (d is ConnectionVM vm)
{
vm.ConName = $"{vm.Connection.Name} [{(EConState)e.NewValue}]";
vm.PropertyChanged?.Invoke (vm, new PropertyChangedEventArgs (nameof (vm.State)));
}
}));
// The state of the connection: influences if the connection is shown at all and used in sorting
public EConState State
{
get { return (EConState)GetValue (StateProperty); }
set { SetValue (StateProperty, value); }
}
// name created by models basename and state - changes via callback from StateProperty
protected static readonly DependencyPropertyKey ConNamePropertyKey = DependencyProperty.RegisterReadOnly ("ConName", typeof (string), typeof (ConnectionVM), new PropertyMetadata (""));
public static readonly DependencyProperty ConNameProperty = ConNamePropertyKey.DependencyProperty;
public string ConName
{
get { return (string)GetValue (ConNameProperty); }
protected set { SetValue (ConNamePropertyKey, value); }
}
Connection Connection { get; }
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
///
/// </summary>
/// <param name="connection">The connection - used for name and initial state</param>
/// <param name="delay">a delay for the timer until the state-changes start</param>
/// <param name="period">a delay between state changes </param>
public ConnectionVM (Connection connection, TimeSpan delay, TimeSpan period)
{
t = new Timer (changeMe, this, (int)delay.TotalMilliseconds, (int)period.TotalMilliseconds);
Connection = connection;
State = Connection.State; // changing, simulated by timer inside VM
}
}
public class MainViewModel
{
// all connections - in RL: occasionally new ones will be added by the user
public ObservableCollection<ConnectionVM> Cons { get; set; }
// filtered and sorted view on Cons - Collection
public ICollectionView ConsView { get; set; }
public MainViewModel (CollectionContainer cc)
{
// demodata - normally connections are created by userinteractions
// this simulates 9 connections that change status every 4s to 10s
Cons = new ObservableCollection<ConnectionVM> (
Enumerable.Range (1, 9)
.Select (n => new ConnectionVM (new Connection ($"Connection #{n}")
, TimeSpan.FromMilliseconds (300 * n)
, TimeSpan.FromMilliseconds (700 * (n + 5))))
);
// create a sorted and filtered view
// - sort by Status and then by Name
// - show only Connecitons that are not Disabled
ConsView = new CollectionViewSource { Source = Cons }.View;
using (var def = ConsView.DeferRefresh ())
{
ConsView.SortDescriptions.Add (new SortDescription ("State", ListSortDirection.Ascending));
ConsView.SortDescriptions.Add (new SortDescription ("ConName", ListSortDirection.Ascending));
ConsView.Filter = obj => (obj is ConnectionVM vm) && vm.State != EConState.Disabled;
}
// attach a Refresh-Action of MVM to each ConnectionVMs PropertyChanged which is fired by
// ConnectionVM.StateProperty.Callback notifies each listener on StateProperty-Change
foreach (var vm in Cons)
{
vm.PropertyChanged += (s, e) => // object s, PropertyChangedEventArgs e
{
cc.Collection = ConsView;
RefreshViewModels ();
};
}
// in case the whole collection is added or removed to/from
Cons.CollectionChanged += (s, e) =>
{
cc.Collection = ConsView;
RefreshViewModels ();
};
}
void RefreshViewModels ()
{
ConsView.Refresh ();
MainWindow.logger.Content = $"Valid: {Cons.Count (c => c.State != EConState.Disabled)}/{Cons.Count ()} (In/Off/Disabled: {Cons.Count (c => c.State == EConState.LoggedIn)} / {Cons.Count (c => c.State == EConState.LoggedOff)} / {Cons.Count (c => c.State == EConState.Disabled)})";
}
}
// create a MenuItem from the ConnectionVM - in real theres a bit more code inside due to Icons, Commands, etc.
public class VmToMenuItemConverter : IValueConverter
{
public object Convert (object value, Type targetType, object parameter, CultureInfo culture)
=> new MenuItem { Header = (value as ConnectionVM).ConName ?? $"Invalid '{value.GetType ()}'" };
public object ConvertBack (object value, Type targetType, object parameter, CultureInfo culture) => null;
}
public partial class MainWindow : Window
{
public static Dispatcher UIDispatcher = null;
public static Label logger = null;
public MainWindow ()
{
UIDispatcher = Application.Current.Dispatcher;
InitializeComponent ();
logger = msgBlock;
DataContext = new MainViewModel (cc);
}
}
}
I was unable to directly bind the ICollecionView to the ContextMenue.ItemSource.CompositeCollection.CollectionContainer.Collection in a way that it autoupdated on ObersveableCollection-changes that the view uses as its source.
见CompositeCollection + CollectionContainer: Bind CollectionContainer.Collection to property of ViewModel that is used as DataTemplates DataType
简单答案：
<CollectionViewSource x:Key="testing" Source="{Binding items}"></CollectionViewSource>
<ContextMenu.ItemsSource>
<CompositeCollection>
<MenuItem Header="Standard MenuItem 3" />
<CollectionContainer Collection="{Binding Source={StaticResource testing}}" />
<MenuItem Header="Standard MenuItem 6" />
</CompositeCollection>
</ContextMenu.ItemsSource>
像这样，您可以将一个项目添加到 datacontext.items，它会立即出现在菜单中