Listbox IsSynchronizedWithCurrentItem causa la selezione del primo elemento anche se nulla gli dice di farlo

Question

Mi sono imbattuto in qualcosa che potrebbe essere un bug nella casella di riepilogo wpf. Si prega di vedere il codice e poi spiego cosa succede

Finestra

<Window > 
<Grid> 
    <local:MultiSelectionComboBox Width="200" 
            MinHeight="25" 
            HorizontalAlignment="Center" 
            VerticalAlignment="Center" 
            ASLDisplayMemberPath="FirstName" 
            ASLSelectedItems="{Binding SelectedModels}" 
            ItemsSource="{Binding Models}" /> 
    <ListBox HorizontalAlignment="Right" 
      VerticalAlignment="Top" 
      DisplayMemberPath="FirstName" 
      ItemsSource="{Binding SelectedModels}" /> 
</Grid> 
</Window> 

controllo utente

<ComboBox> 
<ComboBox.Style> 
    <Style TargetType="{x:Type ComboBox}"> 
     <Setter Property="Template"> 
      <Setter.Value> 
       <ControlTemplate TargetType="{x:Type ComboBox}"> 
        <Grid x:Name="MainGrid" 
          Width="Auto" 
          Height="Auto" 
          SnapsToDevicePixels="true"> 
         <Grid.ColumnDefinitions> 
          <ColumnDefinition Width="*" /> 
          <ColumnDefinition Width="0" /> 
         </Grid.ColumnDefinitions> 
         <Popup x:Name="PART_Popup" 
           Grid.ColumnSpan="2" 
           Margin="1" 
           AllowsTransparency="true" 
           IsOpen="{Binding Path=IsDropDownOpen, 
               RelativeSource={RelativeSource TemplatedParent}}" 
           Placement="Center" 
           PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}"> 
          <Border x:Name="DropDownBorder" 
            MinWidth="{Binding Path=ActualWidth, 
                 ElementName=MainGrid}" 
            MaxHeight="{TemplateBinding MaxDropDownHeight}"> 
           <ScrollViewer CanContentScroll="true"> 
            <StackPanel> 
             <CheckBox x:Name="checkBox" 
Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ComboBox}, Path=CheckAllCommand}">select all</CheckBox> 
             <ListBox x:Name="lstBox" 
here lies the problem without the line below I dont get to see the result on start up, 
with the it selects the first item even if nothing is triggering it 
               IsSynchronizedWithCurrentItem="True" 
               ItemsSource="{TemplateBinding ItemsSource}" 
               KeyboardNavigation.DirectionalNavigation="Contained" 
               SelectionChanged="ListBoxOnSelectionChanged" 
               SelectionMode="Multiple" 
               SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" /> 
            </StackPanel> 
           </ScrollViewer> 
          </Border> 
         </Popup> 
         <ToggleButton Grid.ColumnSpan="2" 
             MinWidth="20" 
             HorizontalAlignment="Right" 
             Background="{TemplateBinding Background}" 
             BorderBrush="{TemplateBinding BorderBrush}" 
             IsChecked="{Binding Path=IsDropDownOpen, 
                  Mode=TwoWay, 
                  RelativeSource={RelativeSource TemplatedParent}}" 
             Style="{DynamicResource ToggleButtonStyle1}" /> 
         <ItemsControl x:Name="itemsControl" 
             Margin="4,2,0,2" 
             ItemsSource="{Binding Path=SelectedItems, 
                  ElementName=lstBox}"> 
          <ItemsControl.ItemsPanel> 
           <ItemsPanelTemplate> 
            <WrapPanel IsItemsHost="True" Orientation="Horizontal" /> 
           </ItemsPanelTemplate> 
          </ItemsControl.ItemsPanel> 
          <ItemsControl.ItemTemplate> 
           <DataTemplate> 
            <Border Margin="1" 
              HorizontalAlignment="Left" 
              VerticalAlignment="Top" 
              Background="#383838" 
              CornerRadius="2" 
              Padding="5,2,3,2"> 
             <StackPanel Orientation="Horizontal"> 
              <TextBlock x:Name="Test" 
                 Foreground="White" 
                 Loaded="Test_OnLoaded" 
                 Text="{Binding RelativeSource={RelativeSource Mode=FindAncestor, 
                            AncestorType={x:Type ComboBox}}, 
                     Path=ASLDisplayMemberPathActualValue}" /> 
              <Button Width="12" 
                Height="12" 
                Margin="5,0,0,0" 
                Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, 
                            AncestorType=ComboBox}, 
                     Path=UnselectCommand}" 
                CommandParameter="{Binding}"> 
               <Button.Template> 
                <ControlTemplate TargetType="{x:Type Button}"> 
                 <Grid> 
                  <Ellipse x:Name="PART_ButtonBackground" 
                    Fill="White" 
                    Opacity="0" /> 
                  <TextBlock x:Name="PART_Text" 
                     Margin="0,0,0,1" 
                     HorizontalAlignment="Center" 
                     VerticalAlignment="Center" 
                     FontSize="10" 
                     Foreground="White" 
                     Text="X" /> 
                 </Grid> 
                 <ControlTemplate.Triggers> 
                  <Trigger Property="IsMouseOver" Value="True"> 
                   <Setter TargetName="PART_ButtonBackground" Property="Opacity" Value="0.8" /> 
                   <Setter TargetName="PART_Text" Property="Foreground" Value="Black" /> 
                  </Trigger> 
                 </ControlTemplate.Triggers> 
                </ControlTemplate> 
               </Button.Template> 
              </Button> 
             </StackPanel> 
            </Border> 
           </DataTemplate> 
          </ItemsControl.ItemTemplate> 
         </ItemsControl> 
        </Grid> 
       </ControlTemplate> 
      </Setter.Value> 
     </Setter> 
    </Style> 
</ComboBox.Style> 
</ComboBox> 

codice dietro il controllo dell'utente

public partial class MultiSelectionComboBox : ComboBox 
{ 
    #region fields, dependencies, command and constructor 
    private ListBox listBox; 
    private ItemsControl itemsControl; 
    private CheckBox checkBox; 

    public static readonly DependencyProperty ASLSelectedItemsProperty = DependencyProperty.Register("ASLSelectedItems", typeof(ObservableCollection<object>), typeof(MultiSelectionComboBox), new PropertyMetadata(null)); 
    public static readonly DependencyProperty ASLDisplayMemberPathProperty = DependencyProperty.Register("ASLDisplayMemberPath", typeof(string), typeof(MultiSelectionComboBox), new PropertyMetadata("Description")); 

    public MultiSelectionComboBox() 
    { 
     InitializeComponent(); 
    } 

    public DelegateCommand<object> UnselectCommand { get; private set; } 
    public DelegateCommand CheckAllCommand { get; private set; } 

    public ObservableCollection<object> ASLSelectedItems 
    { 
     get { return (ObservableCollection<object>)GetValue(ASLSelectedItemsProperty); } 
     set { SetValue(ASLSelectedItemsProperty, value); } 
    } 

    public string ASLDisplayMemberPath 
    { 
     get { return (string)GetValue(ASLDisplayMemberPathProperty); } 
     set { SetValue(ASLDisplayMemberPathProperty, value); } 
    } 
    #endregion 

    private void CheckAll() 
    { 
     if (checkBox.IsChecked == true) 
     { 
      listBox.SelectAll(); 

     } 
     else 
     { 
      listBox.UnselectAll(); 
     } 
    } 

    private void GetControls() 
    { 
     checkBox = Template.FindName("checkBox", this) as CheckBox; 
     listBox = Template.FindName("lstBox", this) as ListBox; 
     itemsControl = Template.FindName("itemsControl", this) as ItemsControl; 
    } 

    private bool bug = true; 
    private void ListBoxOnSelectionChanged(object sender, SelectionChangedEventArgs e) 
    { 
     e.AddedItems.Cast<object>().Where(item => !ASLSelectedItems.Contains(item)).ForEach(p => ASLSelectedItems.Add(p)); 
     e.RemovedItems.Cast<object>().Where(item => ASLSelectedItems.Contains(item)).ForEach(p => ASLSelectedItems.Remove(p)); 
     checkBox.IsChecked = (listBox.ItemsSource as IList).Count == listBox.SelectedItems.Count; 
    } 

    public override void OnApplyTemplate() 
    { 
     base.OnApplyTemplate(); 
     GetControls(); 
     SetControls(); 
     UnselectCommand = new DelegateCommand<object>(p => listBox?.SelectedItems.Remove(p)); 
     CheckAllCommand = new DelegateCommand(CheckAll); 
    } 

    private void SetControls() 
    { 
     listBox.DisplayMemberPath = ASLDisplayMemberPath; 
     itemsControl.DisplayMemberPath = ASLDisplayMemberPath; 
    } 

    private void Test_OnLoaded(object sender, RoutedEventArgs e) 
    { 
     (sender as TextBlock)?.SetBinding(TextBlock.TextProperty, ASLDisplayMemberPath); 
    } 
} 

vista del modello

public class MainWindowViewModel 
{ 
    public ObservableCollection<Model> Models { get; set; } 
    public ObservableCollection<object> SelectedModels { get; set; } 

    public MainWindowViewModel() 
    { 
     Models = new ObservableCollection<Model>() 
     { 
      new Model() {FirstName = "Amelia", Age = 0}, 
      new Model() {FirstName = "Bruno", Age = 5}, 
      new Model() {FirstName = "Colin", Age = 47}, 
      new Model() {FirstName = "Daniel", Age = 32}, 
      new Model() {FirstName = "Iza", Age = 28}, 
      new Model() {FirstName = "James", Age = 23}, 
      new Model() {FirstName = "Simon", Age = 23} 
     }; 
     SelectedModels = new ObservableCollection<object> {Models.FirstOrDefault() }; 
    } 
} 

Ora il problema è che se all'interno del controllo utente (dove è la casella di riepilogo) se non si imposta la sincronizzazione su true, allora non vedrà il primo elemento all'avvio, se lo imposto, quindi qualcosa costringe un add alla raccolta. E poi, anche se all'interno dei bambini selezionati non imposto un valore, imposta comunque il valore del primo figlio.

Questo è in realtà una casella combinata multiselect, è arrivato così lontano e questa cosa semplice mi ha fermato per metà giornata. E non riesco a trovare cosa lo sta causando.

Qualsiasi aiuto sarebbe apprezzato

Answer 1

Questo ci aiuterà su come capire come si comporta quando listbox IsSynchronizedWithCurrentItem è impostata su true. Link

Dato il tuo requisito, questo dovrebbe essere falso.

Il gestore di eventi LisBox.SelectionChanged verrà richiamato ogni volta che si impostano i valori su ASLSelectedItems.

penso che funzionerà da:

1. Rimuovere vostro gestore dal ListBox (lstBox).

2. Poi modificare il DP

   public static readonly DependencyProperty ASLSelectedItemsProperty = DependencyProperty.Register("ASLSelectedItems", typeof(ObservableCollection<object>), typeof(MultiSelectionComboBox), new PropertyMetadata(null, OnSelectedItemsChanged));

   private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { // Add your logic from your handler }