Question

I’m learning F#, and decided to try making simple XNA games for windows using F# (pure enthusiasm) , and got a window with some images showing up.

Here’s the code:

(*Methods*)     
member self.DrawSprites() = 
    _spriteBatch.Begin()
    for i = 0 to _list.Length-1 do
        let spentity = _list.List.ElementAt(i)
        _spriteBatch.Draw(spentity.ImageTexture,new Rectangle(100,100,(int)spentity.Width,(int)spentity.Height),Color.White)      
    _spriteBatch.End()

(*Overriding*)   
override self.Initialize() =
    ChangeGraphicsProfile()                              
    _graphicsDevice <- _graphics.GraphicsDevice
    _list.AddSprite(0,"NagatoYuki",992.0,990.0)
    base.Initialize() 

override self.LoadContent() =         
    _spriteBatch <- new SpriteBatch(_graphicsDevice)
    base.LoadContent()

override self.Draw(gameTime : GameTime) =
    base.Draw(gameTime)
    _graphics.GraphicsDevice.Clear(Color.CornflowerBlue)
    self.DrawSprites()

And the AddSprite Method:

   member self.AddSprite(ID : int,imageTexture : string , width : float, height : float) = 
      let texture = content.Load<Texture2D>(imageTexture)
      list <- list @ [new SpriteEntity(ID,list.Length, texture,Vector2.Zero,width,height)]

The _list object has a ContentManager, here’s the constructor:

   type SpriteList(_content : ContentManager byref) =
      let mutable content = _content
      let mutable list = []

But I can’t minimize the window, since when it regains its focus, i get this error:

ObjectDisposedException

Cannot access a disposed object.
Object name: ‘GraphicsDevice’.

What is happening?

Answer 1

What you are observing is normal behaviour, it’s by the way not specific to F#. See http://msdn.microsoft.com/en-us/library/microsoft.xna.framework.game.loadcontent.aspx

This method is called by Initialize. Also, it is called any time the game content needs to be reloaded, such as when the DeviceReset event occurs.

Are you loading all of your content in Game.LoadContent? If you do, you should not be getting these errors.