How To (Properly) Use Windows Forms With XNA

Only works with XNA GSE 1.0 Refresh, not 2.0!

Update : See this post for a working sample!

Here’s something I had some difficulty doing “gracefully” with XNA : force a custom render device and user controls in the window while still using the Game framework. It’s quite easy to initialize XNA in a Managed DirectX fashion but you lose the links to the graphics device manager, the content pipeline and a lot of very useful (and well written) code behind the Game class.

I initially tried to mimic the functionality of the Game class with a home-made class, make my own ServiceProvider and everything. But by using Lutz Roeder’s .NET Reflector I found out that Microsoft actually made everything better than I usually did; the elapsed-time management, how to hook the events on the form, the overall structure… So I started reverse-engineering bits of it, then I ended up copying the whole goddamn assembly (because of course most of it is internal and sealed) just to allow me to use my own form as the viewport! Ridiculous. There had to be a better way.

And there is!! In the comments of the above article, a user named chrisf suggested to use Control.FromHandle() on the handle provided by the GameWindow class, and use the resulting Control to add whatever controls inside of it.

I just extended the technique by casting the Control to a Form (the implementation class is WindowsGameForm, an internal class that extends Form) and doing pretty much everything I want on it. The operations are done in a standard GameComponent that represents the form’s controls, and is the host of all the events.

First, make a standard GameComponent :

public class EditorControls : GameComponent
{
	public EditorControls(Game game) : base(game) { }

Then make a reference to the form (and to the graphics device) :

	Form windowsGameForm;
	IGraphicsDeviceService graphicsService;
	GraphicsDevice graphics;

	public override void Initialize()
	{
		graphicsService = Game.Services.GetService(typeof(IGraphicsDeviceService)) as IGraphicsDeviceService;
		graphics = graphicsService.GraphicsDevice;

		windowsGameForm = Control.FromHandle(Game.Window.Handle) as Form;

And add a method to add whatever components you want, in this example a MenuStrip and a rendering Panel. The cool thing is that you can do the form editing in a real form, then copy the code from the “designer” partial class underneath it :

		InitializeComponent();
	}

	Panel RenderPanel;
	MenuStrip MainMenu;

	void InitializeComponent()
	{
		MainMenu = new MenuStrip();
		RenderPanel = new Panel();
		MainMenu.SuspendLayout();
		windowsGameForm.SuspendLayout();
		MainMenu.Location = new System.Drawing.Point(0, 0);
		MainMenu.Name = "MainMenu";
		MainMenu.Size = new Size(741, 24);
		MainMenu.TabIndex = 0;
		RenderPanel.Anchor = AnchorStyles.Top | AnchorStyles.Bottom | AnchorStyles.Left | AnchorStyles.Right ;
		RenderPanel.Location = new System.Drawing.Point(0, 49);
		RenderPanel.Name = "RenderPanel";
		RenderPanel.Size = new Size(800, 600);
		RenderPanel.TabIndex = 2;
		windowsGameForm.Controls.Add(MainMenu);
		windowsGameForm.Controls.Add(RenderPanel);
		MainMenu.ResumeLayout(false);
		MainMenu.PerformLayout();
		windowsGameForm.ResumeLayout(false);
		windowsGameForm.PerformLayout();
	}

So this is all swell, but how does one render to the panel now? We need to change the device window manually, but it’s quite easy to do :

		// In Initialize() :
		graphicsService .DeviceResetting += new EventHandler(OnDeviceReset);
		graphicsService.DeviceCreated += new EventHandler(OnDeviceCreated);
		graphics.Reset();

	void OnDeviceCreated(object sender, EventArgs e)
	{
	    graphics = graphicsService.GraphicsDevice;
	    graphics.Reset();
	}

	void OnDeviceReset(object sender, EventArgs e)
	{
	    graphics.PresentationParameters.DeviceWindowHandle = RenderPanel.Handle;
	    graphics.PresentationParameters.BackBufferWidth = RenderPanel.Width;
	    graphics.PresentationParameters.BackBufferHeight = RenderPanel.Height;
	}

And that’s it! Now you can “easily” make your own form (for a level editor it’s a necessity) with controls and events just like you’d do in a normal Windows Form, but in a full XNA context.

Edits : The “Fill” docking mode doesn’t seem to work well with a render panel and a menu bar, anchors work better. Also, the OnDeviceCreated event fixes a bug on multiple screens.