MonoGame.Samples/HoneycombRush/Screens/LoadingAndInstructionScreen.cs

#region File Description
//-----------------------------------------------------------------------------
// LoadingAndInstructionScreen.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion

#region Using Statements


using System;
using System.Threading;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input.Touch;
using Microsoft.Xna.Framework.Input;


#endregion

namespace HoneycombRush
{
    class LoadingAndInstructionScreen : GameScreen
    {
        #region Fields


        SpriteFont font;
        bool isLoading;
        GameplayScreen gameplayScreen;
        System.Threading.Thread thread;

	bool assetsLoaded = false;	

        #endregion

        #region Initialization


        public LoadingAndInstructionScreen()
        {
            TransitionOnTime = TimeSpan.FromSeconds(0);
            TransitionOffTime = TimeSpan.FromSeconds(0.5);

            EnabledGestures = GestureType.Tap;
        }
        
        /// <summary>
        /// Load the screen resources
        /// </summary>
        public override void LoadContent()
        {
            font = Load<SpriteFont>(@"Fonts\MenuFont");

            // Create a new instance of the gameplay screen
            gameplayScreen = new GameplayScreen(DifficultyMode.Easy);
            gameplayScreen.ScreenManager = ScreenManager;
        }


        #endregion

        #region Update


        /// <summary>
        /// Exit the screen after a tap gesture
        /// </summary>
        /// <param name="input"></param>
        public override void HandleInput(GameTime gameTime, InputState input)
        {
            if (!isLoading)
            {
                PlayerIndex player;

                // Handle touch input
                if (input.Gestures.Count > 0)
                {
                    if (input.Gestures[0].GestureType == GestureType.Tap)
                    {
                        LoadResources();
                    }
                }
                else if (input.IsNewKeyPress(Keys.Escape, ControllingPlayer, out player))
                {
                    foreach (GameScreen screen in ScreenManager.GetScreens())
                    {
                        screen.ExitScreen();
                    }

                    ScreenManager.AddScreen(new BackgroundScreen("titleScreen"), null);
                    ScreenManager.AddScreen(new MainMenuScreen(), PlayerIndex.One);
                }
                else if (input.IsNewKeyPress(Keys.Enter, ControllingPlayer, out player) ||
                    input.IsNewKeyPress(Keys.Space, ControllingPlayer, out player))
                {
                    LoadResources();
                }
            }

            base.HandleInput(gameTime, input);
        }

        /// <summary>
        /// Screen update logic
        /// </summary>
        /// <param name="gameTime"></param>
        /// <param name="otherScreenHasFocus"></param>
        /// <param name="coveredByOtherScreen"></param>
        public override void Update(GameTime gameTime, bool otherScreenHasFocus, bool coveredByOtherScreen)
        {
            // If necessary, load the highscore. Remember that calling LoadHighscores multiple times does not have
            // and adverse effect. Highscore will only be loaded once.
            if (!HighScoreScreen.HighscoreLoaded)
            {
                HighScoreScreen.LoadHighscores();
            }
            // If additional thread is running, do nothing
            else if (null != thread)
            {
                // If additional thread finished loading and the screen is not exiting
                if (thread.ThreadState == ThreadState.Stopped && !IsExiting)
                {
                    // Move on to the game play screen once highscore data is loaded                    
                    foreach (GameScreen screen in ScreenManager.GetScreens())
                    {
                        screen.ExitScreen();
                    }

                    ScreenManager.AddScreen(gameplayScreen, null);
                }
            }
            else if (assetsLoaded)
            {
                // Screen is not exiting
                if ( !IsExiting)
                {
                    // Move on to the game play screen once highscore data is loaded                    
                    foreach (GameScreen screen in ScreenManager.GetScreens())
                    {
                        screen.ExitScreen();
                    }

                    ScreenManager.AddScreen(gameplayScreen, null);
                }
            }

            base.Update(gameTime, otherScreenHasFocus, coveredByOtherScreen);
        }


        #endregion

        #region Render


        /// <summary>
        /// Render screen 
        /// </summary>
        /// <param name="gameTime"></param>
        public override void Draw(GameTime gameTime)
        {
            SpriteBatch spriteBatch = ScreenManager.SpriteBatch;

            spriteBatch.Begin();

            // If loading game play screen resource in the 
            // background, show "Loading..." text

            if (isLoading)
            {
                string text = "Loading...";
                Vector2 size = font.MeasureString(text);
                Vector2 position = new Vector2((ScreenManager.GraphicsDevice.Viewport.Width - size.X) / 2,
                    (ScreenManager.GraphicsDevice.Viewport.Height - size.Y) / 2);
                spriteBatch.DrawString(font, text, position, Color.White);
            }

            spriteBatch.End();
        }


        #endregion

        #region Private functionality

        private void LoadResources()
        {

#if MONOMAC		
		// Start loading the resources on main thread
		// If not then all sorts of errors happen for 
		// AutoReleasPools and OpenGL does not handle 
		// multiple thread to well when using Thread
		MonoMac.AppKit.NSApplication.SharedApplication.BeginInvokeOnMainThread(delegate {  
			gameplayScreen.LoadAssets ();
			isLoading = false;
			assetsLoaded = true;
		});
#else
            // Start loading the resources in an additional thread
            thread = new Thread(new ThreadStart(gameplayScreen.LoadAssets));

            thread.Start();
            isLoading = true;
#endif
        }


        #endregion
    }
}