WPF Freezable 错误的解决方法？

Question

我最近遇到了一个非常糟糕的 WPF 错误。 我认为这与 Microsoft Connect 上的此错误相同。

我们的应用程序面向使用 Visual Studio 2010 的 .NET 4.0 Client Profile。

基本上，当 ViewModel 触发对导致项目在 ItemsControl 中移动的任何属性或集合的更改时，有可能会引发以下异常。 它并不总是发生，并且似乎基于不同时间的不同触发而发生。 似乎更有可能在启动应用程序后不久。 如果您可以使用它几分钟而不会遇到异常，那么您可能永远不会在该应用程序实例期间遇到异常。

像 Connect 错误报告一样，我使用{DynamicResource key}从ResourceDictionary加载SolidColorBrush es。 一些词典是手动加载的（用于主题支持）。 我尝试手动冻结这些词典中的所有内容，但似乎没有帮助。

最近，当我向主窗口添加更多UserControl时，异常变得更加频繁，其中的 ItemsControl 绑定到ObservableCollection 。 以前，我只看到 50 次中的 1 次异常，但现在我使用该程序的 5 次中看到了 4 次。

有没有人对解决方法有任何想法？ Connect 错误表明这可能会在下一个 .NET 版本中修复（无论何时），但此错误使我们的应用程序现在基本上无法使用。

System.InvalidOperationException: Specified value of type 'System.Windows.Media.SolidColorBrush' must have IsFrozen set to false to modify.
       at System.Windows.Freezable.WritePreamble()
       at System.Windows.Freezable.remove_Changed(EventHandler value)
       at System.Windows.ResourceReferenceExpression.ResourceReferenceExpressionWeakContainer.RemoveChangedHandler()
       at System.Windows.ResourceReferenceExpression.ResourceReferenceExpressionWeakContainer.InvalidateTargetSubProperty(Object sender, EventArgs args)
       at System.Windows.Freezable.FireChanged()
       at System.Windows.Freezable.Freeze(Boolean isChecking)
       at System.Windows.Freezable.Freeze()
       at System.Windows.Freezable.System.Windows.ISealable.Seal()
       at System.Windows.StyleHelper.SealIfSealable(Object value)
       at System.Windows.StyleHelper.GetChildValueHelper(UncommonField`1 dataField, ItemStructList`1& valueLookupList, DependencyProperty dp, DependencyObject container, FrameworkObject child, Int32 childIndex, Boolean styleLookup, EffectiveValueEntry& entry, ValueLookupType& sourceType, FrameworkElementFactory templateRoot)
       at System.Windows.StyleHelper.GetChildValue(UncommonField`1 dataField, DependencyObject container, Int32 childIndex, FrameworkObject child, DependencyProperty dp, FrugalStructList`1& childRecordFromChildIndex, EffectiveValueEntry& entry, ValueLookupType& sourceType, FrameworkElementFactory templateRoot)
       at System.Windows.StyleHelper.GetValueFromTemplatedParent(DependencyObject container, Int32 childIndex, FrameworkObject child, DependencyProperty dp, FrugalStructList`1& childRecordFromChildIndex, FrameworkElementFactory templateRoot, EffectiveValueEntry& entry)
       at System.Windows.FrameworkElement.GetValueFromTemplatedParent(DependencyProperty dp, EffectiveValueEntry& entry)
       at System.Windows.FrameworkElement.GetRawValue(DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry& entry)
       at System.Windows.FrameworkElement.EvaluateBaseValueCore(DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry& newEntry)
       at System.Windows.DependencyObject.EvaluateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry newEntry, OperationType operationType)
       at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
       at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp)
       at System.Windows.StyleHelper.InvalidateResourceDependentsForChild(DependencyObject container, DependencyObject child, Int32 childIndex, ResourcesChangeInfo info, FrameworkTemplate parentTemplate)
       at System.Windows.TreeWalkHelper.InvalidateStyleAndReferences(DependencyObject d, ResourcesChangeInfo info, Boolean containsTypeOfKey)
       at System.Windows.TreeWalkHelper.OnResourcesChanged(DependencyObject d, ResourcesChangeInfo info, Boolean raiseResourceChangedEvent)
       at System.Windows.FrameworkElement.OnAncestorChangedInternal(TreeChangeInfo parentTreeState)
       at System.Windows.TreeWalkHelper.OnAncestorChanged(DependencyObject d, TreeChangeInfo info)
       at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d)
       at MS.Internal.PrePostDescendentsWalker`1._VisitNode(DependencyObject d)
       at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe)
       at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d)
       at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren)
       at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d)
       at System.Windows.DescendentsWalker`1.StartWalk(DependencyObject startNode, Boolean skipStartNode)
       at MS.Internal.PrePostDescendentsWalker`1.StartWalk(DependencyObject startNode, Boolean skipStartNode)
       at System.Windows.TreeWalkHelper.InvalidateOnTreeChange(FrameworkElement fe, FrameworkContentElement fce, DependencyObject parent, Boolean isAddOperation)
       at System.Windows.FrameworkElement.OnVisualParentChanged(DependencyObject oldParent)
       at System.Windows.Media.Visual.FireOnVisualParentChanged(DependencyObject oldParent)
       at System.Windows.Media.Visual.RemoveVisualChild(Visual child)
       at System.Windows.Media.VisualCollection.DisconnectChild(Int32 index)
       at System.Windows.Media.VisualCollection.Clear()
       at System.Windows.Controls.UIElementCollection.ClearInternal()
       at System.Windows.Controls.Panel.ClearChildren()
       at System.Windows.Controls.Panel.OnItemsChangedInternal(Object sender, ItemsChangedEventArgs args)
       at System.Windows.Controls.Panel.OnItemsChanged(Object sender, ItemsChangedEventArgs args)
       at System.Windows.Controls.ItemContainerGenerator.OnRefresh()
       at System.Windows.Controls.ItemContainerGenerator.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
       at System.Windows.Controls.ItemContainerGenerator.System.Windows.IWeakEventListener.ReceiveWeakEvent(Type managerType, Object sender, EventArgs e)
       at System.Windows.WeakEventManager.DeliverEventToList(Object sender, EventArgs args, ListenerList list)
       at System.Windows.WeakEventManager.DeliverEvent(Object sender, EventArgs args)
       at System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
       at System.Collections.Specialized.NotifyCollectionChangedEventHandler.Invoke(Object sender, NotifyCollectionChangedEventArgs e)
       at System.Windows.Data.CollectionView.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
       at System.Windows.Controls.ItemCollection.System.Windows.IWeakEventListener.ReceiveWeakEvent(Type managerType, Object sender, EventArgs e)
       at System.Windows.WeakEventManager.DeliverEventToList(Object sender, EventArgs args, ListenerList list)
       at System.Windows.WeakEventManager.DeliverEvent(Object sender, EventArgs args)
       at System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
       at System.Windows.Data.CollectionView.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
       at System.Windows.Data.ListCollectionView.RefreshOverride()
       at System.Windows.Data.CollectionView.Refresh()
       at System.Windows.Data.CollectionView.EndDefer()
       at System.Windows.Data.CollectionView.DeferHelper.Dispose()
       at System.Windows.Controls.ItemCollection.SetCollectionView(CollectionView view)
       at System.Windows.Controls.ItemCollection.SetItemsSource(IEnumerable value)
       at System.Windows.Controls.ItemsControl.OnItemsSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
       at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
       at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
       at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
       at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
       at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp)
       at System.Windows.Data.BindingExpressionBase.Invalidate(Boolean isASubPropertyChange)
       at System.Windows.Data.BindingExpression.TransferValue(Object newValue, Boolean isASubPropertyChange)
       at System.Windows.Data.BindingExpression.ScheduleTransfer(Boolean isASubPropertyChange)
       at MS.Internal.Data.ClrBindingWorker.NewValueAvailable(Boolean dependencySourcesChanged, Boolean initialValue, Boolean isASubPropertyChange)
       at MS.Internal.Data.PropertyPathWorker.UpdateSourceValueState(Int32 k, ICollectionView collectionView, Object newValue, Boolean isASubPropertyChange)
       at MS.Internal.Data.ClrBindingWorker.OnSourcePropertyChanged(Object o, String propName)
       at MS.Internal.Data.PropertyPathWorker.System.Windows.IWeakEventListener.ReceiveWeakEvent(Type managerType, Object sender, EventArgs e)
       at System.Windows.WeakEventManager.DeliverEventToList(Object sender, EventArgs args, ListenerList list)
       at System.ComponentModel.PropertyChangedEventManager.OnPropertyChanged(Object sender, PropertyChangedEventArgs args)
       at ***.ViewModelBase.OnPropertyChanged(String name) in c:\***\ViewModelBase.cs:line 17
    .....

编辑：我们还尝试简单地抑制在我们的 ViewModel 基类的 PropertyChanged 事件中抛出的任何InvalidOperationException 。 这似乎在一定程度上减少了异常的数量，但现在我们只是在ObservableCollection的CollectionChanged事件中点击它们。

Answer 1

要解决此 .net 错误，请将代码中的所有纯色画笔更改为可冻结。 例如

<SolidColorBrush x:Key="WindowBackground" Color="Black" />

应改为：

<SolidColorBrush po:Freeze="True" x:Key="WindowBackground" Color="Black" />. 

有关更详细的说明，请参见此处： 如何在 XAML 中冻结从 Freezable 派生的 WPF 对象？ .

Answer 2

我不相信有解决方法。 在不得不自己处理这个问题时，根据我的阅读，WPF 在创建时自动冻结资源。 因此，无论何时您尝试在该资源上使用 DynamicResource，您都会遇到 freezable 异常。

以下是微软基金会团队关于正在发生的事情的引述：

“WPF 将冻结样式或模板中的任何可冻结对象。样式和模板可以在多个线程上使用，除非它们被冻结，否则不能冻结。我们目前正在考虑将其扩展到 Application.Resources 中的任何内容，因为那具有相同的线程问题......冻结的 freezable 上的 DynamicResource 不起作用，因为冻结的 freezable 可能有多个父级——所以我们将搜索资源的父级是不明确的。”

Answer 3

每次谈到关于带有 ItemsControl 和派生控件的 MVVM 的错误行为时，我的第一次尝试是禁用 VirtualizingStackPanel。

<ItemsControl VirtualizingStackPanel.IsVirtualizing="False" />

只是尝试...