如何在当前焦点旁边的控件旁边放置WPF控件？

Question

我有一个典型的edit form (user control)，有几个输入框。 我需要一个ListBox，它必须显示在当前焦点的TextBox的正下方，所以它需要动态移动。 我尝试了一些具有约束力，但什么也没发生

<local:MyList x:Name="myList" 
     Canvas.Left="{Binding (FocusManager.FocusedElement).Canvas.Left,RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}" 
     Canvas.Top="{Binding (FocusManager.FocusedElement).Canvas.Bottom,RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}" 
/> 

Answer 1

使用Popup因为它给你的设施，以显示它放在你想要的。它的Placement = Bottom将显示它正好在PlacementTarget以下。

处理GotFocus和LostFocus的TextBox。

 <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,19,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" GotFocus="TextBox_GotFocus_1" LostFocus="TextBox_LostFocus_1"/> 
     <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,57,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" GotFocus="TextBox_GotFocus_1" LostFocus="TextBox_LostFocus_1"/> 
     <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,96,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/> 
     <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,136,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" GotFocus="TextBox_GotFocus_1" LostFocus="TextBox_LostFocus_1"/> 
     <TextBox Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="10,174,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/> 

     <Popup Placement="Bottom" x:Name="LsbPopup"> 
      <ListBox> 
       <ListBoxItem>item1</ListBoxItem> 
       <ListBoxItem>item1</ListBoxItem> 
       <ListBoxItem>item1</ListBoxItem> 
       <ListBoxItem>item1</ListBoxItem> 
       <ListBoxItem>item1</ListBoxItem> 
       <ListBoxItem>item1</ListBoxItem> 
       <ListBoxItem>item1</ListBoxItem> 
      </ListBox> 
     </Popup> 

处理程序：

private void TextBox_GotFocus_1(object sender, RoutedEventArgs e) 
{ 
    LsbPopup.PlacementTarget = sender as TextBox; 
    LsbPopup.IsOpen = true; 
} 

private void TextBox_LostFocus_1(object sender, RoutedEventArgs e) 
{ 
    LsbPopup.IsOpen = false; 
}