Game development with SharpDX Toolkit: Creating a base project

Since the announcement that Microsoft wasn’t going to update XNA anymore, lots of frameworks have tried to fill the void it left as a friendly way of being introduced to game development. Perhaps the most well known of them is MonoGame, which started as a way to expand XNA compatibility to non-Windows platforms by using managed OpenGL and the Xamarin products. Other alternatives based on C# are Unity, OpenTK and SharpDX, but they have totally different APIs or are just graphical libraries with a more low level approach.

But time passed and the people behind SharpDX launched their own solution: SharpDX Toolkit, a higher-level library that mimicked XNA. While the namespaces are named differently, almost all classes have matching names and even their structure is identical. With this, you can bring the power of DirectX 11 to desktop, Windows Store and Windows Phone games while maintaining the philosophy that XNA introduced.

Starting with this post, there will be a (hopefully regular!) series of tutorials on how to use SharpDX Toolkit for game development. They will be intertwined with the regular, more low level Direct2D and Direct3D posts using bare SharpDX.

Creating a new Windows desktop project

This time we are going to focus on game development for the desktop platform, and in future tutorials we will be porting the existing code to Windows Store and Windows Phone Universal Apps. So, open Visual Studio and go to select the New > Project… menu option. Inside the New Project window, select the template Templates > Visual C# > Windows Desktop > Empty Project. Give it a name and a location and click OK.

Create new project window

This will give us an empty project that by default is meant for console applications; this means that a console window will pop up when our app runs! You can change this by right clicking your project file from the Solution Explorer window and selecting Properties > Application > Output Type: Windows Application. However, you can keep it this way if you want to print debug messages via Console.Write.

Now, let’s add the references to the SharpDX Toolkit assemblies that we are going to need. Instead of downloading the package and manually adding it (which you can do if you want), we are going to take advantage of NuGet to download and reference the latest version of the libraries. So right click again your project file and select Manage NuGet Packages…. In this new window search for SharpDX.Toolkit and install only the SharpDX.Toolkit.Game package; every other library (including vanilla SharpDX) will be automatically added since it’s marked as a dependency.

Installing SharpDX Toolkig packages from NuGet window

Adding the game class

Let’s get started with the Game class. Add a new source file and define a class inside it (we will call it CrazyPlanesGame) that inherits from SharpDX.Toolkit.Game. Like in XNA, this class will be used to abstract the game loop and run the update and draw logic when it is needed.

Next, we need to perform a little initialization before the game class runs properly. Add a private member field of type GraphicsDeviceManager and instantiate it inside the constructor of CrazyPlanesGame. This will take care of initializing the graphics device (Direct3D device, context and application window) and will raise the proper events during the application life cycle. For now we will only modify its PreferredBackBufferWidth and PreferredBackBufferHeight properties because we want a portrait window for our game, although you can change other properties, like running the window in full screen mode or specifying a custom colour format for the back buffer.

internal class CrazyPlanesGame : Game
{
    private GraphicsDeviceManager deviceManager;

    public CrazyPlanesGame()
    {
        deviceManager = new GraphicsDeviceManager(this);
        deviceManager.PreferredBackBufferWidth = 480;
        deviceManager.PreferredBackBufferHeight = 800;
    }
}

Creating our GraphicsDeviceManager is mandatory; not doing so will throw an InvalidOperationException with the error message No GraphicsDeviceManager found when the game starts running.

Now, and to properly run, our game needs an entry point so the operating system knows what code should be called first. In C# this is achieved by declaring a class with a static function named Main of type void. Inside it, we will need to instantiate a copy of our CrazyPlanesGame and call its Run method. In addition, the Main function must be marked with the STAThread attribute because internally SharpDX uses Windows Forms to create the game window and this is one of its requisites.

public static class Program
{
    [STAThread]
    public static void Main()
    {
        using (CrazyPlanesGame game = new CrazyPlanesGame())
        {
            game.Run();
        }
    }
}

At last, go back to the CrazyPlanesGame class and override the Draw method. This will allow us to insert our own drawing code, which for now will be just clearing the screen to a cornflower blue colour:

protected override void Draw(GameTime gameTime)
{
    GraphicsDevice.Clear(Color.CornflowerBlue);

    base.Draw(gameTime);
}

Now you can run the project and take a look at the results of our coding session.

Our first SharpDX Toolkit game window

Source code

Unlike previously, the code for this series of tutorials will be all hosted in the same repository, with each solution inside its own folder. Here it is on GitHub, and you can find the one for this article inside the folder named Chapter1.

Styling the CheckBox control with Segoe UI Symbol glyphs

With Windows 8.1 Microsoft updated the Segoe UI Symbol font and added a nice amount of icons for the most commonly actions used in application bar buttons. The reason behind this was to replace the old method of creating small PNG images to use as the content of the buttons and directly use font glyphs that would scale nicely across all target resolutions.

Character Map tool showing Segoe UI Symbol

This font also introduces some other symbols like back/forward arrows, hearts for favourited items and even the tick parts of CheckBox and RadioButton controls. However, the standard XAML controls still don’t use it so I’m assuming they were thought for using inside HTML/WinJS apps.

Today, we are going to dissect the CheckBox control to see what parts it is composed of, and will be switching standard XAML shapes and paths for glyphs when applicable.

Understanding the parts of the CheckBox control

Let’s start by creating a new Universal App project and adding a CheckBox control to both the MainPage of the Windows 8.1 and Windows Phone projects. We have to do it this way since the styles for both platforms are a little different, and we want to make them as accurate to the original version as possible.

Now, to better work with control styles, open the project in Blend. Right click the CheckBox control and select Edit Template > Edit a Copy… . Set a name in the new dialog (we will be using CheckBoxGlyphStyle) and make sure it’s defined at the document level so there aren’t any duplicate names in App.xaml. Now, if you have never customized control templates or styles, what it does is copy all the default XAML for the control so you can edit it and override whatever you want, including animations and visual states.

If you examine the generated templates for both controls, you will see that they have some things in common:

  • Both have a grid that encompasses the ContentPresenter (where the text or custom content will be displayed) and another grid for holding the tick/check part.
  • Inside that grid, both have a Path named CheckGlyph to the represent the tick mark.

However, other parts are platform specific.

Windows Phone
  • The indeterminate mark is a Rectangle called NormalRectangle.
  • A Border named CheckBackground is used as the background of the tick. Its BorderThickness is directly bound to the same property of the CheckBox control.
  • The root container of the control is a Grid.
  • Display of parts depending on the visual state is controlled through the Visibility property.
Windows 8.1
  • The indeterminate mark is a Rectangle too, but this time it’s called IndeterminateGlyph.
  • The NormalRectangle exists, too, but in this case is a Rectangle that acts as the background of the tick part.
  • The root container of the control is a Border, whose BorderThickness is bound to the same property of the CheckBox control.
  • Display of parts depending on the visual state is controlled through the Opacity property.
  • There are two other rectangles, FocusVisualWhite and FocusVisualBlack, for displaying that the control has focus while tab navigating.

Take a deep look at the default templates generated for both controls and make you comfortable with them. When you are ready, let’s start customizing them.

Switching from shapes to glyphs

To achieve our goal we must replace some of the existing XAML shapes with TextBlock controls containing a single glyph. Since the process has some differences depending on the target platform, we are going to detail them separately:

Windows Phone
  • Give a name to the Grid that contains the tick parts, since we will set some of its properties via a visual state later. We will be using CheckGrid.
  • Create three TextBlock controls inside this grid and name them as the existing control parts.
  • Set their font family to Segoe UI Symbol and size to the system resource called TextStyleLargeFontSize.
  • Match the HorizontalAlignment and VerticalAlignment with those of the old controls; in some instances the glyphs will appear cut off due to font padding/kerning. You can try fixing this for perfection or leave it as is.
  • Set their Text values to the matchings glyphs (this is more easily achieved by writing the escaped value in XAML code). The escaped values for each one are as follows:
Usage Escaped Unicode Glyph
Border 
Tick 
Indeterminate 
  • Match the IsHitTestVisible and Visibility properties with those of the old controls.
  • Now, since the brush properties of the old and new controls are different, we have to try and match the bindings as closely as possible:
Control and property Binding value
CheckBackground Foreground TemplateBinding BorderBrush
Parent Grid Background TemplateBinding Background
NormalRectangle Foreground ThemeResource CheckBoxForegroundThemeBrush
CheckGlyph Foreground ThemeResource CheckBoxForegroundThemeBrush

WARNING: by default, the indeterminate state of the CheckBox is broken! The theme background brush is incorrectly assigned to NormalRectangle instead of the foreground one, so if you declare the control as IsThreeState you can see it behave erroneously.

<Grid x:Name=”CheckGrid” Grid.Column=”0″ VerticalAlignment=”Top” Background=”{TemplateBinding Background}“>

    <TextBlock x:Name=”CheckBackground” HorizontalAlignment=”Center” Text=”&#xE003;” VerticalAlignment=”Top” FontFamily=”Segoe UI Symbol” IsHitTestVisible=”False” Foreground=”{TemplateBinding BorderBrush} FontSize=”{StaticResource TextStyleLargeFontSize}“/>

    <TextBlock x:Name=”NormalRectangle” HorizontalAlignment=”Center” Text=”&#xE004;” VerticalAlignment=”Top” FontFamily=”Segoe UI Symbol” IsHitTestVisible=”False” Visibility=”Collapsed” Foreground=”{ThemeResource CheckBoxForegroundThemeBrush} FontSize=”{StaticResource TextStyleLargeFontSize}” />

    <TextBlock x:Name=”CheckGlyph” HorizontalAlignment=”Center” Text=”&#xE001;” VerticalAlignment=”Top” FontFamily=”Segoe UI Symbol” IsHitTestVisible=”False” Visibility=”Collapsed” Foreground=”{ThemeResource CheckBoxForegroundThemeBrush} FontSize=”{StaticResource TextStyleLargeFontSize}” />

</Grid>

Windows 8.1
  • Create three TextBlock controls inside this grid and name them as the existing control parts that aren’t focus visuals.
  • Set their font family to Segoe UI Symbol and size to 11 points.
  • Again, match the HorizontalAlignment and VerticalAlignment with those of the old controls. Fix the small displacements adjusting margins if you want.
  • Set their Text values to the matchings glyphs. They are almost the same, except that in this instance the tick has a solid background instead of a border:
Usage Escaped Unicode Glyph
Background &#xE002;
Tick &#xE001;
Indeterminate &#xE004;
  • Match the Opacity properties with those of the old controls.
  • Again, match the brush properties using the following table:
Control and property Binding value
NormalRectangle Foreground ThemeResource CheckBoxBackgroundThemeBrush
CheckGlyph Foreground ThemeResource ComboBoxForegroundThemeBrush
IndeterminateGlyph Foreground TemplateBinding ComboBoxForegroundThemeBrush

<Grid VerticalAlignment=”Top”>

    <TextBlock x:Name=”NormalRectangle” HorizontalAlignment=”Center” Text=”&#xE002;” VerticalAlignment=”Center” FontFamily=”Segoe UI Symbol” Foreground=”{ThemeResource CheckBoxBackgroundThemeBrush}“/>

    <TextBlock x:Name=”CheckGlyph” HorizontalAlignment=”Center” Text=”&#xE001;” VerticalAlignment=”Center” FontFamily=”Segoe UI Symbol” Foreground=”{ThemeResource ComboBoxForegroundThemeBrush} Opacity=”0″/>

    <TextBlock x:Name=”IndeterminateGlyph” HorizontalAlignment=”Center” Text=”&#xE004;” VerticalAlignment=”Center” FontFamily=”Segoe UI Symbol” Foreground=”{ThemeResource ComboBoxForegroundThemeBrush} Opacity=”0″/>

    <Rectangle x:Name=”FocusVisualWhite” Height=”27″ Opacity=”0″ StrokeDashOffset=”0.5″ StrokeEndLineCap=”Square” Stroke=”{ThemeResource FocusVisualWhiteStrokeThemeBrush} StrokeDashArray=”1,1″ Width=”27″/>

    <Rectangle x:Name=”FocusVisualBlack” Height=”27″ Opacity=”0″ StrokeDashOffset=”1.5″ StrokeEndLineCap=”Square” Stroke=”{ThemeResource FocusVisualBlackStrokeThemeBrush} StrokeDashArray=”1,1″ Width=”27″/>

</Grid>

Fixing the visual states

Now you could run the project in both platforms and check that it displays correctly. However, interacting with the CheckBox controls in any way will crash the application. This is due to changing the parts that compose the control, so when a new visual state tries to change a property that doesn’t exist an exception is thrown. We are going to fix this by modifying the default visual states so they match our new layout.

Windows Phone

In this case we only need to modify the Pressed and Disabled visual states, since they are the ones that change the conflicting values. We need to match the Storyboard.TargetProperty and Storyboard.TargetName accordingly to the names and properties of the new control parts.

<VisualState x:Name=”Pressed”>

    <Storyboard>

        <PointerDownThemeAnimation Storyboard.TargetName=”Grid”/>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Background” Storyboard.TargetName=”CheckGrid”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxPressedBackgroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”CheckGlyph”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxPressedForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”NormalRectangle”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxPressedBackgroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

    </Storyboard>

</VisualState>

<VisualState x:Name=”Disabled”>

    <Storyboard>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”CheckBackground”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxDisabledBorderThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”CheckGlyph”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxDisabledForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”NormalRectangle”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxDisabledBackgroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”ContentPresenter”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxDisabledForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

    </Storyboard>

</VisualState>

Windows 8.1

As before, but this time the visual states to be modified are PointerOver, Pressed and Disabled. Also, setting the Stroke property of NormalRectangle should be deleted since we don’t have an equivalent for it.

<VisualState x:Name=”PointerOver”>

    <Storyboard>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”NormalRectangle”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxPointerOverBackgroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”CheckGlyph”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxPointerOverForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”IndeterminateGlyph”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxPointerOverForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

    </Storyboard>

</VisualState>

<VisualState x:Name=”Pressed”>

    <Storyboard>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”NormalRectangle”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxPressedBackgroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”CheckGlyph”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxPressedForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”IndeterminateGlyph”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxPressedForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

    </Storyboard>

</VisualState>

<VisualState x:Name=”Disabled”>

    <Storyboard>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”NormalRectangle”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxDisabledBackgroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”CheckGlyph”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxDisabledForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”IndeterminateGlyph”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxDisabledForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty=”Foreground” Storyboard.TargetName=”ContentPresenter”>

            <DiscreteObjectKeyFrame KeyTime=”0″ Value=”{ThemeResource CheckBoxContentDisabledForegroundThemeBrush}“/>

        </ObjectAnimationUsingKeyFrames>

    </Storyboard>

</VisualState>

And that’s it. Now you can run both projects and test that they work.

Custom CheckBox styles on Windows 8.1 and Windows Phone

Further customization

While you can leave the controls as they are right now, the purpose of this article is to give an entry point so you can customize them further. What about styling the RadioButton in a similar way, too? Or using the CheckBox to mark favourite items with a heart icon? Now you can use whatever glyphs you like to give your app a more personalized look. This is just the entry point.

Showing the CheckBox using glyphs and with a new custom style with hearts

Source code

You can download the source code as a Visual Studio 2013 C#/XAML Universal App project from the GitHub repository. Feel free to use in any way you like since it’s MIT licensed, and if you have any questions or improvements contact me via the contact page or the repository’s issues page.

Proper lifecycle management of SharpDX resources in C#/XAML Universal Apps

In the last tutorial we learned how to properly use SharpDX in our XAML apps so we can get the power of DirectX without having to touch native C++ code. However, it was a very superficial introduction for demonstrative purposes that didn’t take into account anything more than single page applications. Using that code in real-world applications would introduce lots of problems (memory leaks, bad performance, crashes) that we are going to learn how to fix in this article. So, we are going to learn how to extend that code so it behaves better when our application has page navigation, gets snapped or is suspended/reactivated.

Now that we are focusing on integrating SharpDX with XAML applications, we have to take into account proper finalization of the created resources when navigating away from pages that contain SwapChainPanel/SwapChainBackgroundPanel controls.

Start by adding a new Page to the shared project. Add a button in MainPage to navigate to the new page, and another one there to make the frame go back in the navigation stack so we don’t end with an infinite navigation loop. If you run the project you will see that it works correctly; however, there is a small problem that can only be spotted by running the Performance and Diagnostics tool with the Memory Usage option selected:

leak


There is a memory leak in the application, because when we are navigating away from the page, we aren’t disposing any of the SharpDX resources we have created for rendering. And since they are wrappers over native objects, they will hardly be automatically reclaimed by the garbage collector.

But this has a very easy solution. Since we subscribed to the Loaded event of the SwapChainPanel for creating everything, we can subscribe to the Unloaded one and perform the opposite operations:

private void SwapChainPanel_Unloaded(object sender, RoutedEventArgs e)
{
    CompositionTarget.Rendering -= CompositionTarget_Rendering;    using (DXGI.ISwapChainPanelNative nativeObject = ComObject.As<DXGI.ISwapChainPanelNative>(this.SwapChainPanel))
    {
        nativeObject.SwapChain = null;
    }

    Utilities.Dispose(ref this.backBufferView);
    Utilities.Dispose(ref this.backBufferTexture);
    Utilities.Dispose(ref this.swapChain);
    Utilities.Dispose(ref this.deviceContext);
    Utilities.Dispose(ref this.device);
}


If we run again the memory diagnostics tool, we can verify that all allocated memory is properly being released when navigating away from the page:

leak_fixed


Window resizing

UPDATE: SourceSize isn’t the most appropriate approach to use when the application is being snapped, since it’s thought for uniformly scaling the swap chain to smaller sizes in less powerful hardware; using it this way will stretch the output image when drawing with Direct 3D. In this case, setting a different viewport will be enough.

Now we take into account when resizing happens so the swap chain dimensions match those of the control it is associated with. DirectX 11.2 introduced the new SourceSize property for DXGI.SwapChain2 objects, which lets you specify a region equal or smaller than the swap chain’s total size so you don’t have to always destroy and recreate it, only in the cases that a bigger one is needed.

Let’s subscribe to the SizeChanged event of the SwapChainPanel to accomplish this. But, this event can fire before the Loaded one if we don’t specify a default size for the control. To check that our swap chain is initialized and ready for resizing, we must declare a boolean flag (in our case it’s named isDXInitialized) and set it to true at the end of the SwapChainPanel_Loaded function. Now we can safely resize set the SourceSize property:

private void SwapChainPanel_SizeChanged(object sender, SizeChangedEventArgs e)
{
    if (isDXInitialized)
    {
        Size2 newSize = RenderSizeToPixelSize(e.NewSize);
        swapChain.SourceSize = newSize;
    }
}

This will work nicely in a number of cases but it’s far from perfect. Remember that I said that the specified region should be equal or smaller in size to the swap chain’s dimensions? If you make the control bigger at runtime or launch the application in snapped mode and resize it to full screen, you will receive a 0x887A0001 (DXGI_ERROR_INVALID_CALL) exception.

So, the logic outcome is to check the new size of the control and resize the swap chain if a bigger one is needed then set the SourceSize property, isn’t it?

private void SwapChainPanel_SizeChanged(object sender, SizeChangedEventArgs e)
{
    if (isDXInitialized)
    {
        Size2 newSize = RenderSizeToPixelSize(e.NewSize);        if (newSize.Width > swapChain.Description1.Width || newSize.Height > swapChain.Description1.Height)
        {
            swapChain.ResizeBuffers(swapChain.Description.BufferCount, (int)e.NewSize.Width, (int)e.NewSize.Height, swapChain.Description1.Format, swapChain.Description1.Flags);
        }

        swapChain.SourceSize = newSize;
    }
}


While technically true, it is still missing a minor detail: all resources linked to a swap chain must be destroyed before calling SwapChain2.ResizeBuffers. In our case it’s the render target and its associated resource view, so if you call the previous code as-is, you will receive the a dreaded DXGI_ERROR_INVALID_CALL exception again.

To fix this, we must destroy the associated resources, resize the swap chain and recreate them:

private void SwapChainPanel_SizeChanged(object sender, SizeChangedEventArgs e)
{
    if (isDXInitialized)
    {
        Size2 newSize = RenderSizeToPixelSize(e.NewSize);        if (newSize.Width > swapChain.Description1.Width || newSize.Height > swapChain.Description1.Height)
        {
            Utilities.Dispose(ref this.backBufferView);
            Utilities.Dispose(ref this.backBufferTexture);

            swapChain.ResizeBuffers(swapChain.Description.BufferCount, (int)e.NewSize.Width, (int)e.NewSize.Height, swapChain.Description1.Format, swapChain.Description1.Flags);

this.backBufferTexture = D3D11.Texture2D.FromSwapChain<D3D11.Texture2D>(this.swapChain, 0);
            this.backBufferView = new D3D11.RenderTargetView(this.device, this.backBufferTexture);
        }

        swapChain.SourceSize = newSize;
    }
}


 

Application suspension

At last, we are going to implement a new requisite when creating Windows Store apps that use DirectX: calling the DXGI.Device3.Trim method when the app goes into suspension. This function frees some internal buffers created by the graphics driver for faster performance and must be used to reduce the app’s memory footprint so there are less chances of it being terminated while suspended. The buffers will be transparently recreated when the app is reactivated, introducing only a minor execution delay.

So, let’s subscribe to the Suspending event of the current Application instance inside the SwapChainPanel_Loaded function, and unsubscribe inside SwapChainPanel_Unloaded to ensure proper finalization. Our new function will perform minimal processing, calling only DeviceContext.ClearState and Device3.Trim as per the guidelines. Since we aren’t storing an instance of DXGI.Device3, you can use QueryInterface on the current Direct3D 11.2 device or call GetDevice on the swap chain; remember to put it inside an using block or dispose it manually since both calls return a new object that needs to be freed:

private void Application_Suspending(object sender, Windows.ApplicationModel.SuspendingEventArgs e)
{
    if (isDXInitialized)
    {
        this.deviceContext.ClearState();        using (DXGI.Device3 dxgiDevice3 = this.swapChain.GetDevice<DXGI.Device3>())
        {
            dxgiDevice3.Trim();
        }
    }
}


Source code

As always, you can get the full soure code (Windows Store C#/XAML Universal App project, compatible with Visual Studio 2013 only) from GitHub.