Add an app bar to a DirectX game

[アーティクル]
10/13/2015

[This article is for Windows 8.x and Windows Phone 8.x developers writing Windows Runtime apps. If you’re developing for Windows 10, see the latest documentation]

In this topic, you will learn about adding an app bar to a DirectX 11 game for the Windows Store using C++.

Note If your game does not use XAML, see Creating an app bar or Setting (DirectX and C++) for information about detecting when the app bar is invoked by the user.

This topic uses the DirectX game (XAML) template as a starting point. See the Create a DirectX game project from a template topic for more information.

What is an app bar?

In a game, the main interaction the player has with the app is through the game controls. The app bar provides an interface in addition to your game controls. Use the app bar to present menu navigation, commands, and tools to users. The app bar is hidden by default and appears when users swipe a finger from the top or bottom edge of the screen. It covers the content of the app and can be dismissed by the user with an edge swipe, or by interacting with the game.

Here is an image of the app bar.

You determine the commands to be displayed on the app bar. The example in this topic uses XAML and C++ to display the app bar.

Why use an app bar in a game?

An app bar allows you to give players additional commands on demand and in context to the current state of the game. The app bar is a standard control across all apps, so users do not have to learn a new UI on top of your game controls.

Here are some examples of why you might want to use app bar commands in your game:

Restart the level.
Save the game.
Load a game.
Return to the main menu.
View high scores.
In-game purchases.

You might want different commands depending on your game category. For example, a roleplaying game might have app bar commands to open the inventory or display the map. Or, a strategy game might have an app bar command to create a unit.

Adding an app bar using XAML and C++

Adding an app bar involves a code in a .xaml file and its associated .h and .cpp files.

Design the app bar in XAML

The code here shows how to add a bottom app bar to a XAML file.

<Page.BottomAppBar>
    <AppBar x:Name="bottomAppBar" Padding="10,0,10,0" 
            Opened="AppBar_Opened" Closed="AppBar_Closed">
        <Grid>
            <StackPanel Orientation="Horizontal" HorizontalAlignment="Left">
                <Button Style="{StaticResource EditAppBarButtonStyle}" Click="EditButton_Click"/>
            </StackPanel>
        </Grid>
    </AppBar>
</Page.BottomAppBar>

You add an app bar to your game by assigning an AppBar control to the TopAppBar or BottomAppBar property of a Page.

Your game might need to pause when the app bar opens and resume when it closes. The Opened and Closed attributes of the AppBar specify the methods that handle the app bar state changes.

Note The app bar button style that is used in the preceding example is located in the StandardStyles.xaml file. However in Microsoft Visual Studio project templates, the app bar button styles are commented out in StandardStyles.xaml. For more info, see Quickstart: Styling app bar buttons.

Handle the app bar events

The code here declares the handlers that were specified for the app bar control in the previous XAML code.

void EditButton_Click( Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e );
void AppBar_Opened( Platform::Object^ sender, Platform::Object^ e );
void AppBar_Closed( Platform::Object^ sender, Platform::Object^ e );

The code here defines the event handlers for the app bar open, close, and button events.

// Handles the edit button event.
void Direct3DPage::EditButton_Click
    (Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
{
    // Use the app bar if it is appropriate for your app. Design the app bar, 
    // then fill in event handlers (like this one).
}

// Handles the AppBar open event.
void Direct3DPage::AppBar_Opened(Platform::Object^ sender, Platform::Object^ e)
{
    // If you need something to happen when the app bar opens, do it here.
    m_paused = true;
}

// Handles the AppBar close event.
void Direct3DPage::AppBar_Closed(Platform::Object^ sender, Platform::Object^ e)
{
    // If you need something to happen when the app bar closes, do it here.
    m_paused = false;
}

The AppBar_Opened and AppBar_Closed methods show in these examples pause and resume the game when they are triggered. You should also put any other game code that you want to run when the app bar opens or closes.

Further resources

For additional information on adding an app bar with XAML, see Adding app bars (Windows Store apps using C#/VB/C++ and XAML).

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