Change TabPanel to Visibility.Collapsed in Code-Behind

Question

I am currently experiencing the exact following issue: WPF TabControl collapsed tab headers are not completely hidden (when I collapse the TabItems, I still see a gray line of a few pixels where the TabControl header is located)

But I cannot do it in XAML (I think), because I need to hide the TabPanel only when the application goes into full screen, so when the application exits full screen, the TabPanel should go back to visible.

I am less experienced in styles, how would I set the TabPanel of my TabControl to Visibility.Collapsed in code please?

Thank you for your time and help, it is greatly appreciated!

Answer 1

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

public partial class MainWindow : Window
{
    TabControl tabControl;
    Style styleTabPanel;

    public MainWindow()
    {
        InitializeComponent();

        CheckBox chk = new CheckBox();
        {
            chk.Margin = new Thickness(5);
            chk.Content = "Test";
            chk.Checked += Chk_Checked;
            chk.Unchecked += Chk_Checked;
        }

        TabItem item = new TabItem() { Header = "Tab", Content = chk };

        tabControl = new TabControl();
        tabControl.RenderTransform = new ScaleTransform(5, 5);
        tabControl.Items.Add(item);

        this.Content = tabControl;
    }

    private void Chk_Checked(object sender, RoutedEventArgs e)
    {
        var chk = (CheckBox)sender;
        if (chk.IsChecked == true)
        {
            if (styleTabPanel == null)
            {
                styleTabPanel = new Style(typeof(System.Windows.Controls.Primitives.TabPanel));
                styleTabPanel.Setters.Add(new Setter(UIElement.VisibilityProperty, Visibility.Collapsed));
            }
            tabControl.Resources.Add(styleTabPanel.TargetType, styleTabPanel);
        }
        else
        {
            tabControl.Resources.Remove(styleTabPanel.TargetType);
        }
    }
}

Answer 2

Hi,@Dyr Fenrir . Welcome to Microsoft Q&A .

In that case, you could use the Window_StateChanged event in the code-behind to handle the state changes and update the visibility of your TabPanel. Xaml:

<Window x:Class="TabPanelDemo.MainWindow"
       ...        Name="window"       StateChanged="Window_StateChanged">
   <TabControl x:Name="tabControl" Style="{DynamicResource TabControlStyle1}" >
            <TabItem >tab1</TabItem>
        </TabControl>
</Window>

Codebehind:

 private void Window_StateChanged(object sender, EventArgs e)
    {
      if (WindowState == WindowState.Maximized)
      {
        SetTabPanelVisibility(false);
      }
      else
      {
        SetTabPanelVisibility(true);
      }
    }
      private void SetTabPanelVisibility(bool isVisible)
      {
        var tabPanel = FindVisualChild<TabPanel>(tabControl);
        if (tabPanel != null)
        {
          tabPanel.Visibility = isVisible ? Visibility.Visible : Visibility.Collapsed;
        }
      }

      private T FindVisualChild<T>(DependencyObject parent) where T : DependencyObject
      {
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        {
          DependencyObject child = VisualTreeHelper.GetChild(parent, i);

          if (child is T result)
          {
            return result;
          }

          T childResult = FindVisualChild<T>(child);
          if (childResult != null)
          {
            return childResult;
          }
        }
        return null;
      }

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