Silverlight的TabItem的能見度不改變

Question

我有很多的TabItems結合到針對每個TabItem的可見性特性的視圖模型一個TabControl。

<sdk:TabControl> 
    <sdk:TabItem Name="Inventory" Header="Inventory" 
     Style="{StaticResource TabItemStyle}" 
     Visibility="{Binding Permissions.Inventory, 
     Converter={StaticResource PermissiveVisibilityConverter}, 
      ConverterParameter='Viewer'}" 
     DataContext="{Binding VM}" /> 

</sdk:TabControl> 

所有TabItem默認爲摺疊的可見性。但是，當VM改變的TabItem到可見它不工作，直到你將鼠標移到控制...

即使我有一個按鈕，它的工作方式設置的知名度編程！

我已檢查，看看虛擬機的性能通知UI，以及它們與NotifyOnPropertyChanged。如果我將數據綁定到按鈕的可見性，它的工作原理就好了......這只是TabItems，似乎有一個錯誤。

有沒有辦法讓TabItem UI刷新？或者爲此做一個解決方法？

謝謝！

Answer 1

如果你改變了XAML讓你第一次設置的DataContext：

<sdk:TabItem Name="Inventory" Header="Inventory" 
    Style="{StaticResource TabItemStyle}" 
    DataContext="{Binding VM}" 
    Visibility="{Binding Permissions.Inventory, 
    Converter={StaticResource PermissiveVisibilityConverter}, 
     ConverterParameter='Viewer'}" /> 

我假設Permissions.Inventory是您的視圖模型中的財產，但因爲你還沒有設置在這一點上下文看起來像綁定不應該工作。

此外，如果您設置一個斷點，如果在Permissions.Inventory吸氣劑被稱爲正在熱播的轉換？

Answer 2

我面臨同樣的問題，我用所附的「可見性」屬性，而不是原來的人能夠戰勝它。在這個新屬性中，我可以將值傳遞給原始的「可見性」屬性，並且如果正在摺疊父標籤控件的「SelectedItem」，請選擇下一個可見的tabItem。

然而，如上所述here，只是可能沒有，如果第一項是TabControl的負載時暈倒是不夠的。這種情況必須在TabControl本身中解決，因爲當第一次設置虛假的「Visility」時，測試顯示TabItem還沒有訪問它的TabControl。正因爲如此，我還使用TabControl的附加屬性來糾正此問題。

完整的解決方案：

public static class TabControlExtensions 
{ 
    /// <summary> 
    /// Use this property on a TabControl to correct the behavior 
    /// of selecting Collapsed TabItems. 
    /// </summary> 
    /// <param name="obj"></param> 
    /// <returns></returns> 
    public static bool GetSelectOnlyVisibleTabs(DependencyObject obj) 
    { 
     return (bool)obj.GetValue(SelectOnlyVisibleTabsProperty); 
    } 
    public static void SetSelectOnlyVisibleTabs(DependencyObject obj, bool value) 
    { 
     obj.SetValue(SelectOnlyVisibleTabsProperty, value); 
    } 
    public static readonly DependencyProperty SelectOnlyVisibleTabsProperty = 
     DependencyProperty.RegisterAttached("SelectOnlyVisibleTabs", typeof(bool), typeof(TabControlExtensions), new PropertyMetadata(false, SelectOnlyVisibleTabsChanged)); 
    public static void SelectOnlyVisibleTabsChanged(object sender, DependencyPropertyChangedEventArgs args) 
    { 
     var tabControl = sender as TabControl; 
     if (tabControl == null) return; 

     if ((bool)args.NewValue) 
     { 
      tabControl.SelectionChanged += TabControl_SelectionChanged; 
      CorrectSelection(tabControl); 
     } 
     else 
     { 
      tabControl.SelectionChanged -= TabControl_SelectionChanged; 
     } 
    } 

    private static void TabControl_SelectionChanged(object sender, SelectionChangedEventArgs args) 
    { 
     var tabControl = sender as TabControl; 
     if (tabControl == null) return; 

     CorrectSelection(tabControl); 
    } 

    public static void CorrectSelection(TabControl tabControl) 
    { 
     var selected = tabControl.SelectedItem as UIElement; 
     if (selected == null) return; 

     // If the selected element is not suposed to be visible, 
     // selects the next visible element 
     if (selected.Visibility == System.Windows.Visibility.Collapsed) 
      tabControl.SelectedItem = tabControl.Items.OfType<UIElement>() 
       .Where(e => e.Visibility == System.Windows.Visibility.Visible) 
       .FirstOrDefault(); 
    } 
} 

public static class TabItemExtensions 
{ 
    /// <summary> 
    /// Use this property in a TabItem instead of the original "Visibility" to 
    /// correct the behavior of a TabControl when a TabItem's Visibility changes. 
    /// </summary> 
    /// <param name="obj"></param> 
    /// <returns></returns> 
    public static Visibility GetVisibility(DependencyObject obj) 
    { 
     return (Visibility)obj.GetValue(VisibilityProperty); 
    } 
    public static void SetVisibility(DependencyObject obj, Visibility value) 
    { 
     obj.SetValue(VisibilityProperty, value); 
    } 
    public static readonly DependencyProperty VisibilityProperty = 
     DependencyProperty.RegisterAttached("Visibility", typeof(Visibility), typeof(TabItemExtensions), new PropertyMetadata(Visibility.Visible, VisibilityChanged)); 

    public static void VisibilityChanged(object sender, DependencyPropertyChangedEventArgs args) 
    { 
     var tabItem = sender as TabItem; 
     if (tabItem == null) return; 

     var visibility = (Visibility)args.NewValue; 
     if (tabItem.Visibility == visibility) return; 

     tabItem.Visibility = visibility; 
     if (visibility == Visibility.Visible) return; 

     // Finds the tab's parent tabcontrol and corrects the selected item, 
     // if necessary. 
     var tabControl = tabItem.Ancestors().OfType<TabControl>().FirstOrDefault(); 
     if (tabControl == null) return; 

     TabControlExtensions.CorrectSelection(tabControl); 
    } 
} 

用法：

<sdk:TabControl local:TabControlExtensions.SelectOnlyVisibleTabs="True"> 
     <sdk:TabItem Header="tabItem1" Visibility="Collapsed"> 
      <TextBlock HorizontalAlignment="Center" 
         VerticalAlignment="Center" 
         Text="TabItem1 which should not be visible (1)" /> 
     </sdk:TabItem> 
     <sdk:TabItem Header="tabItem2"> 
      <TextBlock HorizontalAlignment="Center" 
         VerticalAlignment="Center" 
         Text="TabItem2 which should be visible (2)" /> 
     </sdk:TabItem> 
     <sdk:TabItem DataContext="{Binding ViewModel}" 
        Header="tabItem3" 
        local:TabItemExtensions.Visibility="{Binding MyProperty, 
                   Converter={StaticResource BoolToVisibilityConverter}}"> 
      <TextBlock HorizontalAlignment="Center" 
         VerticalAlignment="Center" 
         Text="TabItem with binded Visibility (3)" /> 
     </sdk:TabItem> 
    </sdk:TabControl>