Question

I can’t figure out why this is the case. I’m creating a View class from Game class and then I’m trying to call a method from View in Game and send it the entire game object as a parameter. If I send single variables as a parameter then it work’s no problem but I wanted to send the whole Game object so that only one thing would be passed.

Game class

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;

namespace Airfield
{
    public class Game : Microsoft.Xna.Framework.Game
    {
        // Device Objects
        GraphicsDevice device = null;
        GraphicsDeviceManager graphics = null;
        MouseState mouse;

        // Game Objects
        SpriteBatch spriteBatch;
        Texture2D b = null;
        View view = null;

        // Arrays
        Buoy [] buoy = new Buoy[3];
        Plane [] plane = new Plane[3];

        // Variables
        bool selected = false;
        int index = 0;

        public Game()
        {
            graphics = new GraphicsDeviceManager(this);
        }

        protected override void Initialize()
        {
            Content.RootDirectory = "Content"; 
            this.IsMouseVisible = true;
            graphics.PreferredBackBufferWidth = 800;
            graphics.PreferredBackBufferHeight = 600;
            graphics.ApplyChanges();
            base.Initialize();

            view = new View();

            for (index = 0; index < buoy.Length; index++)
            {
                buoy[index] = new Buoy();
                plane[index] = buoy[index].CreatePlane();
            }
        }

        protected override void LoadContent()
        {
            device = graphics.GraphicsDevice;
            spriteBatch = new SpriteBatch(device);
            b = Content.Load<Texture2D>("buoy");
        }

        protected override void UnloadContent()
        {

        }

        protected override void Update(GameTime gameTime)
        {
            base.Update(gameTime);

            mouse = Mouse.GetState();

            if (selected == true || mouse.X >= buoy[0].position.X - 3 && mouse.X <= buoy[0].position.X + 19 && mouse.Y >= buoy[0].position.Y - 3 && mouse.Y <= buoy[0].position.Y + 19)
            {
                if (mouse.LeftButton == ButtonState.Pressed)
                {
                    selected = true;
                    buoy[0].position= new Vector2(mouse.X - 8, mouse.Y - 8);
                }

                else
                {
                    selected = false;
                }
            }
        }

        protected override void Draw(GameTime gameTime)
        {
            base.Draw(gameTime);
            view.DrawScreen(this);
        }
    }
}

View Class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;

namespace Airfield
{
    class View
    {
        public View()
        {

        }

        public void DrawScreen(Game game)
        {
            game.device.Clear(Color.CornflowerBlue);

            game.spriteBatch.Begin();
            DrawBuoys(game);
            game.spriteBatch.End();
        }

        public void DrawBuoys(Game game)
        {
            for (int x = 0; x < game.buoy.Length; x++)
            {
                game.buoy[x].DrawBuoy(game.spriteBatch, game.b);
            }
        }
    }
}

Basically I get the error for every time that I try and use something that has come from Game.

Answer 1

The problem here is that all of the members inside of Game are marked as protected or not marked at all which defaults to private. This means that only Game and any classes which derive from it will have access to those protected members and no-one else to private. The type View is a completely separate type and hence can’t access any members that are protected or private.

To expose the private fields they need to be marked as internal or public.

public class Game : Microsoft.Xna.Framework.Game
{
  ...
  public SpriteBatch spriteBatch;
}

Most of these members are also labeled as override hence you are locked into protected. But you can use another non-protected member to call into the protected. It’s not clear from the sample if you want to invoke these methods or not.