當ScrollBar可見時，WPF ScrollViewer顯示邊框

Question

我想向我的scrollviewer添加邊框。此訂單隻應在ScrollViewer的ScrollBar可見時顯示（VerticalScrollBarVisibility設置爲「Auto」）時才顯示。

Thanky you！

Answer 1

使用Binding和Converter。

public sealed class VisibilityToBorderThicknessConverter : IValueConverter 
{ 
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) 
    { 
     try 
     { 
      var flag = (Visibility)value; 
      if (flag == Visibility.Visible) 
       return new Thickness(0); 
      else 
       return new Thickness(1); 
     } 
     catch 
     { 
      return new Thickness(0); 
     } 
    } 
    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) 
    { 
      throw new NotImplementedException(); 
    } 
} 

，比你的XAML：

<ScrollViewer Name="blah"> 
     <Border BorderThickness="{Binding ElementName=blah, Path=VerticalScrollBarVisibility , Converter={StaticResources VisibilityToBorder}}"> 
</ScrollViewer> 

不要忘了你的轉換器添加到資源！

GL HF &

Answer 2

爲此，您可以使用樣式和觸發器，像這樣：

<Border BorderBrush="Black"> 
    <Border.Style> 
     <Style> 
      <Setter Property="Border.Visibility" Value="Visible" /> 
      <Style.Triggers> 
       <DataTrigger Binding="{Binding ElementName=theScrollViewer, Path=ComputedVerticalScrollBarVisibility}" Value="Collapsed"> 
        <Setter Property="Border.Visibility" Value="Collapsed" /> 
       </DataTrigger> 
      </Style.Triggers> 
     </Style> 
    </Border.Style> 
    <ScrollViewer Name="theScrollViewer"> 
    </ScrollViewer> 
</Border>