/FarseerPhysics-r78100/Samples/DemoBaseXNA/ScreenSystem/ScreenManager.cs

#region File Description



//-----------------------------------------------------------------------------

// ScreenManager.cs

//

// Microsoft XNA Community Game Platform

// Copyright (C) Microsoft Corporation. All rights reserved.

//-----------------------------------------------------------------------------



#endregion



#region Using Statements



using System;

using System.Collections.Generic;

using System.Diagnostics;

using Microsoft.Xna.Framework;

using Microsoft.Xna.Framework.Content;

using Microsoft.Xna.Framework.Graphics;



#endregion



namespace FarseerPhysics.DemoBaseXNA.ScreenSystem

{

    /// <summary>

    /// The screen manager is a component which manages one or more <see cref="GameScreen"/>

    /// instances. It maintains a stack of _screens, calls their Update and Draw

    /// methods at the appropriate times, and automatically routes _input to the

    /// topmost active screen.

    /// </summary>

    public class ScreenManager : DrawableGameComponent

    {

        public MainMenuScreen MainMenuScreen = new MainMenuScreen();

        private Texture2D _blankTexture;

        private IGraphicsDeviceService _graphicsDeviceService;

        private InputState _input = new InputState();

        private List<GameScreen> _screens = new List<GameScreen>();

        private List<GameScreen> _screensToUpdate = new List<GameScreen>();

        private SpriteFonts _spriteFonts;



        /// <summary>

        /// Constructs a new screen manager component.

        /// </summary>

        /// <exception cref="InvalidOperationException">No graphics device service.</exception>

        public ScreenManager(Game game)

            : base(game)

        {

            ContentManager = new ContentManager(game.Services);

            ContentManager.RootDirectory = "Content";

            _graphicsDeviceService = (IGraphicsDeviceService) game.Services.GetService(

                typeof (IGraphicsDeviceService));

            game.Exiting += Game_Exiting;



            if (_graphicsDeviceService == null)

                throw new InvalidOperationException("No graphics device service.");

        }



        public SpriteFonts SpriteFonts

        {

            get { return _spriteFonts; }

        }



        /// <summary>

        /// A content manager used to load data that is shared between multiple

        /// screens. This is never unloaded, so if a screen requires a large amount

        /// of temporary data, it should create a local content manager instead.

        /// </summary>

        public ContentManager ContentManager { get; private set; }



        /// <summary>

        /// A default SpriteBatch shared by all the screens. This saves

        /// each screen having to bother creating their own local instance.

        /// </summary>

        public SpriteBatch SpriteBatch { get; private set; }



        public Vector2 ScreenCenter

        {

            get

            {

                return new Vector2(_graphicsDeviceService.GraphicsDevice.Viewport.Width / 2f,

                                   _graphicsDeviceService.GraphicsDevice.Viewport.Height / 2f);

            }

        }



        public int ScreenWidth

        {

            get { return _graphicsDeviceService.GraphicsDevice.Viewport.Width; }

        }



        public int ScreenHeight

        {

            get { return _graphicsDeviceService.GraphicsDevice.Viewport.Height; }

        }



        /// <summary>

        /// If true, the manager prints out a list of all the screens

        /// each time it is updated. This can be useful for making sure

        /// everything is being added and removed at the right times.

        /// </summary>

        public bool TraceEnabled { get; set; }



        /// <summary>

        /// Goes to main menu.

        /// Removes all active screens and add a main menu

        /// </summary>

        public void GoToMainMenu()

        {

            _screens.Clear();

            _screensToUpdate.Clear();



            AddScreen(MainMenuScreen);

        }



        private void Game_Exiting(object sender, EventArgs e)

        {

            //Make sure to dispose ALL screens when the game is forcefully closed

            //We do this to ensure that open resources and threads created by screens are closed.

            foreach (GameScreen screen in _screens)

            {

                screen.Dispose();

            }



            _screens.Clear();

            _screensToUpdate.Clear();

        }



        /// <summary>

        /// Allows the game component to perform any initialization it needs to before starting

        /// to run.  This is where it can query for any required services and load content.

        /// </summary>

        public override void Initialize()

        {

            _spriteFonts = new SpriteFonts(ContentManager);

            base.Initialize();

        }



        /// <summary>

        /// Load your graphics content.

        /// </summary>

        protected override void LoadContent()

        {

            // Load content belonging to the screen manager.

            SpriteBatch = new SpriteBatch(GraphicsDevice);

            _blankTexture = ContentManager.Load<Texture2D>("Common/blank");



            // Tell each of the _screens to load their content.

            foreach (GameScreen screen in _screens)

            {

                screen.LoadContent();

            }

        }



        /// <summary>

        /// Unload your graphics content.

        /// </summary>

        protected override void UnloadContent()

        {

            ContentManager.Unload();



            // Tell each of the _screens to unload their content.

            foreach (GameScreen screen in _screens)

            {

                screen.UnloadContent();

            }

        }



        /// <summary>

        /// Allows each screen to run logic.

        /// </summary>

        public override void Update(GameTime gameTime)

        {

            // Read the keyboard and gamepad.

            _input.Update();



            // Make a copy of the master screen list, to avoid confusion if

            // the process of updating one screen adds or removes others.

            _screensToUpdate.Clear();



            for (int i = 0; i < _screens.Count; i++)

                _screensToUpdate.Add(_screens[i]);



            bool otherScreenHasFocus = !Game.IsActive;

            bool coveredByOtherScreen = false;



            // Loop as long as there are _screens waiting to be updated.

            while (_screensToUpdate.Count > 0)

            {

                // Pop the topmost screen off the waiting list.

                GameScreen screen = _screensToUpdate[_screensToUpdate.Count - 1];



                _screensToUpdate.RemoveAt(_screensToUpdate.Count - 1);



                // Update the screen.

                screen.Update(gameTime, otherScreenHasFocus, coveredByOtherScreen);



                if (screen.ScreenState == ScreenState.TransitionOn ||

                    screen.ScreenState == ScreenState.Active)

                {

                    // If this is the first active screen we came across,

                    // give it a chance to handle _input.

                    if (!otherScreenHasFocus)

                    {

                        screen.HandleInput(_input);



                        otherScreenHasFocus = true;

                    }



                    // If this is an active non-popup, inform any subsequent

                    // _screens that they are covered by it.

                    if (!screen.IsPopup)

                        coveredByOtherScreen = true;

                }

            }



            // Print debug trace?

            if (TraceEnabled)

                TraceScreens();

        }



        /// <summary>

        /// Prints a list of all the screens, for debugging.

        /// </summary>

        private void TraceScreens()

        {

            List<string> screenNames = new List<string>();



            foreach (GameScreen screen in _screens)

                screenNames.Add(screen.GetType().Name);



            Trace.WriteLine(string.Join(", ", screenNames.ToArray()));

        }



        /// <summary>

        /// Tells each screen to draw itself.

        /// </summary>

        public override void Draw(GameTime gameTime)

        {

            for (int i = 0; i < _screens.Count; i++)

            {

                if (_screens[i].ScreenState == ScreenState.Hidden)

                    continue;



                _screens[i].Draw(gameTime);

            }

        }



        /// <summary>

        /// Adds a new screen to the screen manager.

        /// </summary>

        public void AddScreen(GameScreen screen)

        {

            screen.ScreenManager = this;

            screen.Initialize();



            // If we have a graphics device, tell the screen to load content.

            if ((_graphicsDeviceService != null) &&

                (_graphicsDeviceService.GraphicsDevice != null))

            {

                screen.LoadContent();

            }



            _screens.Add(screen);



            IDemoScreen demoScreen = screen as IDemoScreen;

            if (demoScreen != null && screen.firstRun)

            {

                AddScreen(new PauseScreen(demoScreen.GetTitle(), demoScreen.GetDetails()));

                screen.firstRun = false;

            }

        }



        /// <summary>

        /// Removes a screen from the screen manager. You should normally

        /// use <see cref="GameScreen"/>.ExitScreen instead of calling this directly, so

        /// the screen can gradually transition off rather than just being

        /// instantly removed.

        /// </summary>

        public void RemoveScreen(GameScreen screen)

        {

            // If we have a graphics device, tell the screen to unload content.

            if ((_graphicsDeviceService != null) &&

                (_graphicsDeviceService.GraphicsDevice != null))

            {

                screen.UnloadContent();

            }



            _screens.Remove(screen);

            _screensToUpdate.Remove(screen);



            screen.Dispose();

        }



        /// <summary>

        /// Helper draws a translucent black full screen sprite, used for fading

        /// screens in and out, and for darkening the background behind popups.

        /// </summary>

        public void FadeBackBufferToBlack(int alpha)

        {

            Viewport viewport = GraphicsDevice.Viewport;



            SpriteBatch.Begin();



            SpriteBatch.Draw(_blankTexture,

                             new Rectangle(0, 0, viewport.Width, viewport.Height),

                             new Color(0, 0, 0, (byte) alpha));



            SpriteBatch.End();

        }

    }

}