Ermitteln aller UIElements in einem bestimmten Punkt

Question

Wie kann ich alle UIElements an einem bestimmten Punkt in UWP abrufen? Ich möchte alle UIElements erhalten, wenn der Benutzer den Zeiger freigibt (im PointerReleased-Ereignis). Ich habe die VisualTreeHelper.FindElementsInHostCoordinates Methode verwendet, aber es gibt Nullwert zurück.

CS DATEI:

private void drawingPanel_PointerReleased(object sender, PointerRoutedEventArgs e) 

      PointerPoint endPoint = e.GetCurrentPoint(this.drawingPanel);    
      List<UIElement> list = VisualTreeHelper.FindElementsInHostCoordinates(endPoint.Position, this) as List<UIElement>;    

     } 

UI XAML:

<UserControl ***** bla bla *****>  

     <UserControl.Resources> 


      <DataTemplate x:Key="ImageTemplate"> 
       <Viewbox Stretch="UniformToFill" StretchDirection="Both" > 
        <Grid> 
         <ScrollViewer MinZoomFactor="1" MaxZoomFactor="3" ZoomMode="Disabled" 
            HorizontalAlignment="Center" VerticalAlignment="Center" 
            HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"> 
          <Image Source="{Binding BlockData}" Height="{Binding ScreenHeight, Mode=TwoWay}" Width="{Binding ScreenWidth, Mode=TwoWay}" 
            Holding="Image_Holding" 
            PointerPressed="Image_PointerPressed" /> 
         </ScrollViewer> 
        </Grid> 
       </Viewbox> 
      </DataTemplate> 


      <DataTemplate x:Key="TextTemplate" ScrollViewer.VerticalScrollMode="Disabled" ScrollViewer.HorizontalScrollMode="Disabled"> 

       <Viewbox Stretch="Uniform" StretchDirection="Both" VerticalAlignment="Top" Grid.Row="1"> 
        <RichEditBox Width="{Binding ScreenWidth, Mode=TwoWay}" Name="richEditor" l:RtfText.RichText="{Binding BlockData}" Margin="0" BorderThickness="0" IsHitTestVisible="True" IsTapEnabled="True" GotFocus="richEditor_GotFocus" > 
        </RichEditBox> 
       </Viewbox> 

      </DataTemplate> 
      <DataTemplate x:Key="GapTemplate"> 
       <Grid Height="20" > 
       </Grid> 
      </DataTemplate> 

      <l:NoteTypeTemplateSelector x:Key="NoteTypeTemplateSelector" 
      TextTemplate="{StaticResource TextTemplate}" 
      ImageTemplate="{StaticResource ImageTemplate}" 
      GapTemplate="{StaticResource GapTemplate}"> 
      </l:NoteTypeTemplateSelector> 

     </UserControl.Resources> 

     <Grid Name="ContainerGrid" Background="White" PointerPressed="ContainerGrid_PointerPressed" > 
      <Grid.RowDefinitions> 

       <RowDefinition Height="Auto"></RowDefinition> 
       <RowDefinition Height="*"></RowDefinition> 
       <RowDefinition Height="30"></RowDefinition> 
      </Grid.RowDefinitions> 
      <ListView x:Name="NoteList" Background="Transparent" 
         Grid.Row="1"      
         Style="{StaticResource ListViewStyle1}" 
         ItemsSource="{Binding Data}"     
         ItemTemplateSelector="{StaticResource NoteTypeTemplateSelector}"> 
       <ListView.ItemContainerStyle> 
        <Style TargetType="ListViewItem"> 
         <Setter Property="Template"> 
          <Setter.Value> 
           <ControlTemplate> 
            <ContentPresenter/> 
           </ControlTemplate> 
          </Setter.Value> 
         </Setter> 
        </Style> 
       </ListView.ItemContainerStyle> 
      </ListView> 
      <SwapChainPanel Name="DxPanel" Grid.Row="1" Visibility="Collapsed"></SwapChainPanel> 
      <c:DrawingControl x:Name="drawingPanel" Grid.Row="1" 
           Holding="drawingPanel_Holding" 
           PointerPressed="drawingPanel_PointerPressed" 
           PointerMoved="drawingPanel_PointerMoved" 
           PointerReleased="drawingPanel_PointerReleased" 
           PointerWheelChanged="drawingPanel_PointerWheelChanged" 
           PointerExited="drawingPanel_PointerExited" 

           ManipulationStarted="drawingPanel_ManipulationStarted" 
           ManipulationDelta="drawingPanel_ManipulationDelta" 
           ManipulationCompleted="drawingPanel_ManipulationCompleted"></c:DrawingControl> 
      <c:ReadModeToolbar x:Name="ReadModeToolbar" Grid.Row="0"></c:ReadModeToolbar> 
      <c:EditModeToolbar x:Name="EditModeToolbar" Grid.Row="0" Visibility="Collapsed"></c:EditModeToolbar> 
      <TextBlock Grid.Row="2" x:Name="InfoText" Text="Offset"></TextBlock> 
     </Grid> 
    </UserControl> 

Vielen Dank für Ihre Hilfe.

Answer 1

VisualTreeHelper.FindElementsInHostCoordinates gibt eine Aufzählung aller Elemente an einem bestimmten Punkt zurück.

Das PointerReleased-Ereignis enthält die Zeigerposition in seiner PointerRoutedEventArgs. GetCurrentPoint() Methode.

Übergeben Sie das gleiche UIElement (wahrscheinlich Ihre Seite) an GetCurrentPoint und FindElementsInHostCoordinates, damit die Koordinatensysteme übereinstimmen.