how do I collapse parent content if all children are collapsed - wpf

Question

I would like to show/collapse a panel (Stakpanel, Grid etc) if every children is collapsed and show it back if at least one if its children is visible again.
Which would be the best way to achive this? (converter, triggers, other thing?)
Thanks!!
I did a converter but it doesn´t fire when I change the visibility of children
public class HasChildrenVisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
Panel parent = value as Panel;
foreach (var child in parent.Children.OfType<UIElement>())
{
if (child.IsVisible)
return Visibility.Visible;
}
return Visibility.Collapsed;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return value;//no implementado
}
}
this is the xaml example
<Window.Resources>
<local:HasChildrenVisibilityConverter x:Key="converter" />
</Window.Resources>
<StackPanel Visibility="{Binding RelativeSource={RelativeSource Self}, Converter={StaticResource converter}}">
<TextBlock x:Name="text1"> Text 1</TextBlock>
<TextBlock x:Name="text2"> Text 2</TextBlock>
</StackPanel>

Answer 1

A MultiDataTrigger would work quite well here. Here's a simple example with a StackPanel and a couple of TextBlock
I declare the Triggers in the Style and apply that Style to the relevant StackPanel
MainWindow.xaml
<Window.Resources>
<Style x:Key="ShowHideStyle" TargetType="StackPanel">
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding ElementName=txtName, Path=Visibility}" Value="Collapsed" />
<Condition Binding="{Binding ElementName=txtDescription, Path=Visibility}" Value="Collapsed" />
</MultiDataTrigger.Conditions>
<Setter Property="Visibility" Value="Collapsed"/>
</MultiDataTrigger>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding ElementName=txtName, Path=Visibility}" Value="Visible" />
<Condition Binding="{Binding ElementName=txtDescription, Path=Visibility}" Value="Visible" />
</MultiDataTrigger.Conditions>
<Setter Property="Visibility" Value="Visible"/>
</MultiDataTrigger>
</Style.Triggers>
</Style>
</Window.Resources>
<StackPanel>
<StackPanel Style="{StaticResource ShowHideStyle}" Height="300" Width="300" Background="Red">
<TextBlock x:Name="txtName" Text="name" />
<TextBlock x:Name="txtDescription" Text="description" />
</StackPanel>
<Button x:Name="btnHide" Width="100" Height="30" Content="hide" Click="btnHide_Click"/>
<Button x:Name="btnShow" Width="100" Height="30" Content="show" Click="btnShow_Click"/>
</StackPanel>
Mainwindow.xaml.cs
I just add the button click events to hide/show child elements
private void btnHide_Click(object sender, RoutedEventArgs e)
{
txtDescription.Visibility = System.Windows.Visibility.Collapsed;
txtName.Visibility = System.Windows.Visibility.Collapsed;
}
private void btnShow_Click(object sender, RoutedEventArgs e)
{
txtDescription.Visibility = System.Windows.Visibility.Visible;
txtName.Visibility = System.Windows.Visibility.Visible;
}