如何使溢出的內容像DatePicker一樣可見？

Question

我想顯示整個列表框，當它的界限從主窗口溢出時。 DatePicker的行爲只是我想要做的（見附圖）。我該如何執行此操作？

Screen capture describing what DatePicker can do and I can't do

<!-- MainWindow.xaml --> 
<Window x:Class="OverflowSample.MainWindow" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
     xmlns:local="clr-namespace:OverflowSample" 
     mc:Ignorable="d" 
     Title="MainWindow" Height="130" Width="500"> 
    <Grid> 
     <DatePicker HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top"/> 
     <Button x:Name="buttonShowListBox" Content="Show" HorizontalAlignment="Left" Margin="240,10,0,0" VerticalAlignment="Top" Width="75" Click="buttonShowListBox_Click"/> 
     <ListBox x:Name="listBox" HorizontalAlignment="Left" Height="160" Margin="250,40,0,-90" VerticalAlignment="Top" Width="200" FontSize="24" Visibility="Collapsed"> 
      <ListBoxItem Content="Three"/> 
      <ListBoxItem Content="Two"/> 
      <ListBoxItem Content="One"/> 
      <ListBoxItem Content="Zero"/> 
     </ListBox> 
    </Grid> 
</Window> 

 

// MainWindow.xaml.cs 
using System.Windows; 

namespace OverflowSample 
{ 
    public partial class MainWindow : Window 
    { 
     public MainWindow() 
     { 
      InitializeComponent(); 
     } 

     private void buttonShowListBox_Click(object sender, RoutedEventArgs e) 
     { 
      listBox.Visibility = (listBox.Visibility == Visibility.Visible) ? 
       Visibility.Collapsed : 
       Visibility.Visible; 
     } 
    } 
} 

Answer 1

DatePicker使用Popup和往裏面的日曆。

在.NET Framework源代碼可以看到自己： http://referencesource.microsoft.com/#PresentationFramework/src/Framework/System/Windows/Controls/DatePicker.cs,c20427230c18ba13