Theme Transition

Learn to use a Theme Transition using Windows App SDK with this Tutorial

Theme Transition

Theme Transition shows how you can create Transitions that apply to elements within an application using the Windows App SDK.

Step 1

Follow Setup and Start on how to get Setup and Install what you need for Visual Studio 2022 and Windows App SDK.

In Windows 11 choose Start and then find or search for Visual Studio 2022 and then select it.
Visual Studio 2022
Once Visual Studio 2022 has started select Create a new project.
Create a new project
Then choose the Blank App, Packages (WinUI in Desktop) and then select Next.
Blank App, Packages (WinUI in Desktop)
After that in Configure your new project type in the Project name as ThemeTransition, then select a Location and then select Create to start a new Solution.
Configure project

Step 2

Then in Visual Studio within Solution Explorer for the Solution, right click on the Project shown below the Solution and then select Add then New Item…

Add New Item

Step 3

Then in Add New Item from the C# Items list, select Code and then select Code File from the list next to this, then type in the name of Library.cs and then Click on Add.

Add New Code File

Step 4

You will now be in the View for the Code of Library.cs, within this type the following Code:

using Microsoft.UI;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Media;
using Microsoft.UI.Xaml.Shapes;
using System.Collections.Generic;
using System.Linq;
using Windows.UI;

internal class Library
    private static readonly List<Color> _colours = new()
        Colors.Black, Colors.Gray, Colors.Red, Colors.Orange, Colors.Yellow,
        Colors.Green, Colors.Cyan, Colors.Blue, Colors.Magenta, Colors.Purple

    private static int _index = 0;

    public static void Add(StackPanel panel)
        Rectangle previous = panel.Children.LastOrDefault() as Rectangle;
        if(previous == null || _index == _colours.Count)
            _index = 0;
        panel.Children.Add(new Rectangle()
            Width = 50,
            Height = 50,
            Fill = new SolidColorBrush(_colours[_index])

    public static void Remove(StackPanel panel)
        int count = panel.Children.Count;
        if (count > 0)
            panel.Children.RemoveAt(count - 1);

The Class that has been defined in Library.cs has List of Color for the colours to use for elements along with an int value for keeping track of which one will be used. Then there is a Method of Add, which will add a Rectangle to a StackPanel with the given next colour to use and the Method of Remove, which will remove added Rectangle elements from a StackPanel.

Step 5

Within Solution Explorer for the Solution double-click on MainWindow.xaml to see the XAML for the Main Window.
Solution Explorer MainWindow.xaml

Step 6

In the XAML for MainWindow.xaml there will be some XAML for a StackPanel, this should be Removed:

<StackPanel Orientation="Horizontal" 
HorizontalAlignment="Center" VerticalAlignment="Center">
    <Button x:Name="myButton" Click="myButton_Click">Click Me</Button>

Step 7

While still in the XAML for MainWindow.xaml above </Window>, type in the following XAML:

    <Viewbox Margin="25">
        <StackPanel Name="Display" Spacing="5" 
            Orientation="Horizontal" HorizontalAlignment="Center">
                    <EntranceThemeTransition IsStaggeringEnabled="True" />
    <CommandBar VerticalAlignment="Bottom" HorizontalAlignment="Stretch" >
        <AppBarButton Icon="Add" Label="Add" Click="Add_Click"/>
        <AppBarButton Icon="Remove" Label="Remove" Click="Remove_Click"/>

This XAML features a Grid with a ViewBox to Scale elements and in this is a StackPanel which has the Theme Transition set for the ChildrenTransitions of EntranceThemeTransition with an AppBarButton to Add and Remove elements.

Step 8

Within Solution Explorer for the Solution select the arrow next to MainWindow.xaml then double-click on MainWindow.xaml.cs to see the Code for the Main Window.
Solution Explorer MainWindow.xaml.cs

Step 9

In the Code for MainWindow.xaml.cs there be a Method of myButton_Click(...) this should be Removed by removing the following:

private void myButton_Click(object sender, RoutedEventArgs e)
    myButton.Content = "Clicked";

Step 10

Once myButton_Click(...) has been removed, type the following Code below the end of the Constructor of public MainWindow() { ... }:

private void Add_Click(object sender, RoutedEventArgs e)

private void Remove_Click(object sender, RoutedEventArgs e)

The Methods of Add_Click and Remove_Click will when Clicked will call the Methods within Library.cs of Add and Remove from Library passing in the StackPanel.

Step 11

That completes the Windows App SDK application. In Visual Studio 2022 from the Toolbar select ThemeTransition (Package) to Start the application.
ThemeTransition (Package)

Step 12

Once running you should see the AppBarButton for Add and Remove.

Theme Transition Running

Step 13

You can select the AppBarButton for Add to add some elements and they should appear with a Theme Transition.

Theme Transition Output

Step 14

To Exit the Windows App SDK application, select the Close button from the top right of the application as that concludes this Tutorial for Windows App SDK from!
Close application