无法设置AccordionItem.IsSelected的值

Question

有没有什么方法可以设置WPF手风琴，以便默认情况下折叠它的所有项目，只有当我点击扩展器按钮时它应该展开？

更新 据我意识到模板什么选择项目是AccordionItem的IsSelected财产，问题是，当我尝试设置该属性（从代码按钮单击处理程序），我得到的以下InvalidOperationException：

Cannot modify the IsSelected property while item is locked. 

堆栈跟踪：

at System.Windows.Controls.AccordionItem.OnIsSelectedPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) in C:\dd\WPF_1\src\wpf\src\ControlsPack\WPFToolkit\Layout\Accordion\System\Windows\Controls\AccordionItem.cs:line 315 
    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.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal) 
    at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value) 
    at System.Windows.Controls.AccordionItem.set_IsSelected(Boolean value) in C:\dd\WPF_1\src\wpf\src\ControlsPack\WPFToolkit\Layout\Accordion\System\Windows\Controls\AccordionItem.cs:line 284 
    at WpfSampleApplication.MainWindow.btn_Click(Object sender, RoutedEventArgs e) in d:\users\shimmy\documents\visual studio 2010\Projects\WpfSampleApplication\MainWindow.xaml.vb:line 9 
    at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) 
    at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) 
    at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args) 
    at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e) 
    at System.Windows.Controls.Primitives.ButtonBase.OnClick() 
    at System.Windows.Controls.Button.OnClick() 
    at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e) 
    at System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e) 
    at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget) 
    at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) 
    at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) 
    at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) 
    at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent) 
    at System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e) 
    at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget) 
    at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) 
    at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) 
    at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) 
    at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args) 
    at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args) 
    at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted) 
    at System.Windows.Input.InputManager.ProcessStagingArea() 
    at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input) 
    at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport) 
    at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel) 
    at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled) 
    at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) 
    at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) 
    at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) 
    at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) 
    at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) 
    at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs) 
    at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) 
    at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) 
    at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) 
    at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) 
    at System.Windows.Threading.Dispatcher.Run() 
    at System.Windows.Application.RunDispatcher(Object ignore) 
    at System.Windows.Application.RunInternal(Window window) 
    at System.Windows.Application.Run(Window window) 
    at System.Windows.Application.Run() 
    at WpfSampleApplication.Application.Main() in d:\users\shimmy\documents\visual studio 2010\Projects\WpfSampleApplication\obj\x86\Debug\Application.g.vb:line 64 
    at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) 
    at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) 
    at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() 
    at System.Threading.ThreadHelper.ThreadStart_Context(Object state) 
    at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) 
    at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) 
    at System.Threading.ThreadHelper.ThreadStart() 

Answer 1

可以控制哪些项目与所选择吨他SelectedIndex和SelectedItem控制自己Accordion的属性。

你可以把不可见AccordionItem作为第一个项目最初显示所有项目的崩溃：

<toolkit:AccordionItem Visibility="Collapsed"/> 

要打开一个特定的项目，设置在Loaded处理程序SelectedIndex财产。或者，你可以，如果你使用的行为尽一切XAML：

<toolkit:Accordion> 
    <i:Interaction.Triggers> 
     <i:EventTrigger EventName="Loaded"> 
      <ei:ChangePropertyAction PropertyName="SelectedIndex" Value="2"/> 
     </i:EventTrigger> 
    </i:Interaction.Triggers> 

编辑：

的“的xmlns：我”的命名空间是指System.Windows.Interactivity这是WPF4的一部分。该“的xmlns：EI”命名空间是指Microsoft.Expression.Interactions这是部分：

• Microsoft Expression Blend Software Development Kit (SDK) for .NET 4

已添加到您的项目中引用后，您可以使用此设置的命名空间：

<Window ... 
    xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" 
    xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions" 
    ...>