feat(controls): Add an “Add Button” and a “Close Button” to the tab control. Additionally, drag-and-drop functionality has been enabled.

src/Wpf.Ui.Gallery/ViewModels/Pages/Navigation/TabControlViewModel.cs

@@ -3,6 +3,164 @@
 // Copyright (C) Leszek Pomianowski and WPF UI Contributors.
 // All Rights Reserved.
 
+using System;
+using System.Collections.ObjectModel;
+using System.Windows;
+using System.Windows.Controls;
+using Wpf.Ui.Controls;
+
 namespace Wpf.Ui.Gallery.ViewModels.Pages.Navigation;
 
-public partial class TabControlViewModel : ViewModel;
+public partial class TabControlViewModel : ViewModel
+{
+    [ObservableProperty]
+    private TabItem? _selectedTab;
+
+    // Stores the tab being dragged during drag-and-drop operation
+    private TabItem? _draggedTab;
+
+    // Stores the starting point of the drag operation
+    private Point _dragStartPoint;
+
+    // Indicates whether a drag operation is currently in progress
+    private bool _isDragging;
+
+    partial void OnSelectedTabChanged(TabItem? value)
+    {
+        // Update IsSelected property only for tabs that need to change
+        foreach (TabItem tab in StandardTabs)
+        {
+            bool shouldBeSelected = tab == value;
+            if (tab.IsSelected != shouldBeSelected)
+            {
+                tab.SetCurrentValue(TabItem.IsSelectedProperty, shouldBeSelected);
+            }
+        }
+    }
+
+    [ObservableProperty]
+    private ObservableCollection<TabItem> _standardTabs =
+    [
+        new TabItem
+        {
+            Header = CreateTabHeader("Hello", SymbolRegular.XboxConsole24),
+            Content = new System.Windows.Controls.TextBlock { Text = "World", Margin = new System.Windows.Thickness(12) },
+            IsSelected = true
+        },
+        new TabItem
+        {
+            Header = CreateTabHeader("The cake", SymbolRegular.StoreMicrosoft16),
+            Content = new System.Windows.Controls.TextBlock { Text = "Is a lie.", Margin = new System.Windows.Thickness(12) }
+        },
+    ];
+
+    /// <summary>
+    /// Selects the specified tab and prepares for potential drag operation.
+    /// </summary>
+    [RelayCommand]
+    private void SelectTabForDrag(object? parameter)
+    {
+        if (parameter is not TabItem tabItem)
+        {
+            return;
+        }
+
+        // Select the clicked tab
+        SelectedTab = tabItem;
+        _draggedTab = tabItem;
+    }
+
+    /// <summary>
+    /// Starts the drag operation if the mouse has moved far enough.
+    /// </summary>
+    /// <param name="currentPoint">The current mouse position.</param>
+    /// <returns>True if drag operation was started, false otherwise.</returns>
+    public bool TryStartDrag(Point currentPoint)
+    {
+        if (_draggedTab == null || _isDragging)
+        {
+            return false;
+        }
+
+        // Check if the mouse has moved far enough to initiate a drag operation
+        double deltaX = currentPoint.X - _dragStartPoint.X;
+        double deltaY = currentPoint.Y - _dragStartPoint.Y;
+        double minDistance = SystemParameters.MinimumHorizontalDragDistance;
+
+        if (Math.Abs(deltaX) > minDistance || Math.Abs(deltaY) > minDistance)
+        {
+            _isDragging = true;
+            return true;
+        }
+
+        return false;
+    }
+
+    /// <summary>
+    /// Gets the tab being dragged.
+    /// </summary>
+    public TabItem? GetDraggedTab() => _draggedTab;
+
+    /// <summary>
+    /// Sets the starting point for drag operation.
+    /// </summary>
+    public void SetDragStartPoint(Point point)
+    {
+        _dragStartPoint = point;
+    }
+
+    /// <summary>
+    /// Ends the drag operation.
+    /// </summary>
+    public void EndDrag()
+    {
+        _draggedTab = null;
+        _isDragging = false;
+    }
+
+    /// <summary>
+    /// Reorders tabs by moving a tab from one position to another.
+    /// </summary>
+    /// <param name="draggedTab">The tab being moved.</param>
+    /// <param name="targetTab">The target tab position.</param>
+    public void ReorderTabs(TabItem draggedTab, TabItem targetTab)
+    {
+        if (draggedTab == targetTab)
+        {
+            return;
+        }
+
+        int draggedIndex = StandardTabs.IndexOf(draggedTab);
+        int targetIndex = StandardTabs.IndexOf(targetTab);
+
+        // Early return if indices are invalid or the same
+        if (draggedIndex < 0 || targetIndex < 0 || draggedIndex == targetIndex)
+        {
+            return;
+        }
+
+        StandardTabs.Move(draggedIndex, targetIndex);
+        SelectedTab = draggedTab;
+    }
+
+    private static System.Windows.Controls.StackPanel CreateTabHeader(string text, SymbolRegular symbol)
+    {
+        return new System.Windows.Controls.StackPanel
+        {
+            Orientation = System.Windows.Controls.Orientation.Horizontal,
+            HorizontalAlignment = System.Windows.HorizontalAlignment.Left,
+            Children =
+            {
+                new SymbolIcon
+                {
+                    Symbol = symbol,
+                    Margin = new System.Windows.Thickness(0, 0, 6, 0)
+                },
+                new System.Windows.Controls.TextBlock
+                {
+                    Text = text
+                }
+            }
+        };
+    }
+}

src/Wpf.Ui.Gallery/Views/Pages/Navigation/TabControlPage.xaml

@@ -6,8 +6,8 @@
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:local="clr-namespace:Wpf.Ui.Gallery.Views.Pages.Navigation"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-    xmlns:system="clr-namespace:System;assembly=System.Runtime"
     xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"
+    xmlns:uiControls="clr-namespace:Wpf.Ui.Controls;assembly=Wpf.Ui"
     Title="TabControlPage"
     d:DataContext="{d:DesignInstance local:TabControlPage,
                                      IsDesignTimeCreatable=False}"
@@ -23,29 +23,19 @@
             Margin="0"
             HeaderText="Standard TabControl."
             XamlCode="<TabControl />">
-            <TabControl Margin="0,8,0,0">
-                <TabItem>
-                    <TabItem.Header>
-                        <StackPanel Orientation="Horizontal">
-                            <ui:SymbolIcon Margin="0,0,6,0" Symbol="XboxConsole24" />
-                            <TextBlock Text="Hello" />
-                        </StackPanel>
-                    </TabItem.Header>
-                    <Grid>
-                        <TextBlock Margin="12" Text="World" />
-                    </Grid>
-                </TabItem>
-                <TabItem IsSelected="True">
-                    <TabItem.Header>
-                        <StackPanel Orientation="Horizontal">
-                            <ui:SymbolIcon Margin="0,0,6,0" Symbol="StoreMicrosoft16" />
-                            <TextBlock Text="The cake" />
-                        </StackPanel>
-                    </TabItem.Header>
-                    <Grid>
-                        <TextBlock Margin="12" Text="Is a lie." />
-                    </Grid>
-                </TabItem>
+            <TabControl
+                Margin="0,8,0,0"
+                uiControls:TabControlExtensions.CanAddTabs="True"
+                uiControls:TabControlExtensions.CanReorderTabs="True"
+                uiControls:TabControlExtensions.TabAdding="OnTabAdding"
+                uiControls:TabControlExtensions.TabClosing="OnTabClosing"
+                ItemsSource="{Binding StandardTabs}"
+                SelectedItem="{Binding SelectedTab, Mode=TwoWay}">
+                <TabControl.ItemContainerStyle>
+                    <Style BasedOn="{StaticResource {x:Type TabItem}}" TargetType="TabItem">
+                        <Setter Property="uiControls:TabControlExtensions.IsClosable" Value="True" />
+                    </Style>
+                </TabControl.ItemContainerStyle>
             </TabControl>
         </controls:ControlExample>
     </Grid>

src/Wpf.Ui.Gallery/Views/Pages/Navigation/TabControlPage.xaml.cs

@@ -1,8 +1,9 @@
-// This Source Code Form is subject to the terms of the MIT License.
+// This Source Code Form is subject to the terms of the MIT License.
 // If a copy of the MIT was not distributed with this file, You can obtain one at https://opensource.org/licenses/MIT.
 // Copyright (C) Leszek Pomianowski and WPF UI Contributors.
 // All Rights Reserved.
 
+using System.Windows.Controls;
 using Wpf.Ui.Controls;
 using Wpf.Ui.Gallery.ControlsLookup;
 using Wpf.Ui.Gallery.ViewModels.Pages.Navigation;
@@ -14,11 +15,104 @@ public partial class TabControlPage : INavigableView<TabControlViewModel>
 {
     public TabControlViewModel ViewModel { get; }
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TabControlPage"/> class.
+    /// The sample ensures the first tab remains selected and prevents it from being closed.
+    /// </summary>
     public TabControlPage(TabControlViewModel viewModel)
     {
         ViewModel = viewModel;
-        DataContext = this;
+        DataContext = viewModel;
 
         InitializeComponent();
+
+        // Ensure the first tab is selected and its content is displayed
+        if (ViewModel.StandardTabs.Count > 0)
+        {
+            ViewModel.SelectedTab = ViewModel.StandardTabs[0];
+
+            // Make the first tab non-closable
+            TabControlExtensions.SetIsClosable(ViewModel.StandardTabs[0], false);
+        }
+    }
+
+    /// <summary>
+    /// Handles the TabClosing event.
+    /// This event is raised when a user attempts to close a tab.
+    /// You can cancel the operation by setting e.Cancel = true.
+    /// </summary>
+    /// <remarks>
+    /// Examples of usage:
+    /// <list type="bullet">
+    /// <item>Prevent closing the last tab (implemented in this method).</item>
+    /// <item>Show confirmation dialog before closing (commented out, can be uncommented if needed).</item>
+    /// </list>
+    /// The tab will be automatically removed from ItemsSource by OnTabCloseRequested.
+    /// ViewModel's CloseTabCommand is not needed here as the removal is handled automatically.
+    /// </remarks>
+    /// <param name="sender">The source of the event.</param>
+    /// <param name="e">The event arguments containing the tab item to close.</param>
+    private void OnTabClosing(object sender, TabClosingEventArgs e)
+    {
+        if (ViewModel.StandardTabs.Count <= 1)
+        {
+            e.Cancel = true;
+            return;
+        }
+    }
+
+    /// <summary>
+    /// Handles the TabAdding event.
+    /// This event is raised when a user clicks the add button to create a new tab.
+    /// You can customize the new tab by setting e.Header, e.Content, or e.TabItem.
+    /// You can cancel the operation by setting e.Cancel = true.
+    /// </summary>
+    /// <remarks>
+    /// This implementation uses Method 1: Setting tab properties using TabAddingEventArgs.
+    /// <list type="number">
+    /// <item>Get the tab number from the current tab count.</item>
+    /// <item>Set the header with an icon using CreateTabHeader.</item>
+    /// <item>Set the content to a TextBlock with the tab number.</item>
+    /// </list>
+    /// Alternative Method 2: You can also create a custom TabItem and assign it to e.TabItem for more control over tab creation.
+    /// Example: Cancel adding if maximum tabs reached (commented out, can be uncommented if needed).
+    /// </remarks>
+    /// <param name="sender">The source of the event.</param>
+    /// <param name="e">The event arguments used to customize the new tab.</param>
+    private void OnTabAdding(object sender, TabAddingEventArgs e)
+    {
+        int tabNumber = ViewModel.StandardTabs.Count + 1;
+
+        e.Header = CreateTabHeader($"New Tab {tabNumber}", SymbolRegular.Document24);
+
+        e.Content = new System.Windows.Controls.TextBlock
+        {
+            Text = $"New Tab {tabNumber} content",
+            Margin = new System.Windows.Thickness(12)
+        };
+    }
+
+    /// <summary>
+    /// Creates a tab header with an icon and text.
+    /// </summary>
+    private static System.Windows.Controls.StackPanel CreateTabHeader(string text, SymbolRegular symbol)
+    {
+        return new System.Windows.Controls.StackPanel
+        {
+            Orientation = System.Windows.Controls.Orientation.Horizontal,
+            HorizontalAlignment = System.Windows.HorizontalAlignment.Left,
+            Children =
+            {
+                new SymbolIcon
+                {
+                    Symbol = symbol,
+                    Margin = new System.Windows.Thickness(0, 0, 6, 0)
+                },
+                new System.Windows.Controls.TextBlock
+                {
+                    Text = text
+                }
+            }
+        };
     }
 }

src/Wpf.Ui/Appearance/ApplicationAccentColorManager.cs

@@ -52,7 +52,7 @@
     /// <summary>
     /// The maximum value of the background HSV brightness after which the text on the accent will be turned dark.
     /// </summary>
     private const double BackgroundBrightnessThresholdValue = 80d;
 
     /// <summary>
     /// Gets the SystemAccentColor.
@@ -356,7 +356,7 @@
         UiApplication.Current.Resources["AccentFillColorSelectedTextBackgroundBrush"] =
             systemAccent.ToBrush();
 
-        var themeAccent = applicationTheme == ApplicationTheme.Dark ? secondaryAccent : primaryAccent;
+        Color themeAccent = applicationTheme == ApplicationTheme.Dark ? secondaryAccent : primaryAccent;
         UiApplication.Current.Resources["AccentFillColorDefault"] = themeAccent;
         UiApplication.Current.Resources["AccentFillColorDefaultBrush"] = themeAccent.ToBrush();
         UiApplication.Current.Resources["AccentFillColorSecondary"] = Color.FromArgb(

src/Wpf.Ui/Controls/TabControl/TabAddingEventArgs.cs

@@ -0,0 +1,45 @@
+// This Source Code Form is subject to the terms of the MIT License.
+// If a copy of the MIT was not distributed with this file, You can obtain one at https://opensource.org/licenses/MIT.
+// Copyright (C) Leszek Pomianowski and WPF UI Contributors.
+// All Rights Reserved.
+
+using System.Windows;
+using System.Windows.Controls;
+
+// ReSharper disable once CheckNamespace
+namespace Wpf.Ui.Controls;
+
+/// <summary>
+/// Provides data for the <see cref="TabControlExtensions.TabAddingEvent"/> event.
+/// </summary>
+public class TabAddingEventArgs : RoutedEventArgs
+{
+    /// <summary>
+    /// Gets or sets the tab item to be added. If null, a new TabItem will be created.
+    /// </summary>
+    public TabItem? TabItem { get; set; }
+
+    /// <summary>
+    /// Gets or sets the content for the new tab.
+    /// </summary>
+    public object? Content { get; set; }
+
+    /// <summary>
+    /// Gets or sets the header for the new tab.
+    /// </summary>
+    public object? Header { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether the add operation should be canceled.
+    /// </summary>
+    public bool Cancel { get; set; }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TabAddingEventArgs"/> class.
+    /// </summary>
+    public TabAddingEventArgs(RoutedEvent routedEvent)
+        : base(routedEvent)
+    {
+    }
+}
+