MonoGame.Samples/RolePlayingGame/GameScreens/GameplayScreen.cs

#region File Description
//-----------------------------------------------------------------------------
// GameplayScreen.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.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using RolePlayingGameData;
using System.Collections.Generic;
using System.IO;
#endregion

namespace RolePlaying
{
    /// <summary>
    /// This screen implements the actual game logic. It is just a
    /// placeholder to get the idea across: you'll probably want to
    /// put some more interesting gameplay in here!
    /// </summary>
    class GameplayScreen : GameScreen
    {
        #region Initialization

        GameStartDescription gameStartDescription = null;
        SaveGameDescription saveGameDescription = null;


        /// <summary>
        /// Create a new GameplayScreen object.
        /// </summary>
        private GameplayScreen()
            : base()
        {
            CombatEngine.ClearCombat();
            this.Exiting += new EventHandler(GameplayScreen_Exiting);
        }


        /// <summary>
        /// Create a new GameplayScreen object from a new-game description.
        /// </summary>
        public GameplayScreen(GameStartDescription gameStartDescription) 
            : this()
        {
            this.gameStartDescription = gameStartDescription;
            this.saveGameDescription = null;
        }


        /// <summary>
        /// Create a new GameplayScreen object from a saved-game description.
        /// </summary>
        public GameplayScreen(SaveGameDescription saveGameDescription)
            : this()
        {
            this.gameStartDescription = null;
            this.saveGameDescription = saveGameDescription;
        }
        

        /// <summary>
        /// Handle the closing of this screen.
        /// </summary>
        void GameplayScreen_Exiting(object sender, EventArgs e)
        {
            // make sure the session is ending
            // -- EndSession must be re-entrant safe, as the EndSession may be 
            //    making this screen close itself
            Session.EndSession();
        }
        
        
        /// <summary>
        /// Load graphics content for the game.
        /// </summary>
        public override void LoadContent()
        {
            if (gameStartDescription != null)
            {
                Session.StartNewSession(gameStartDescription, ScreenManager, this);
            }
            else if (saveGameDescription != null)
            {
                Session.LoadSession(saveGameDescription, ScreenManager, this);
            }

            // once the load has finished, we use ResetElapsedTime to tell the game's
            // timing mechanism that we have just finished a very long frame, and that
            // it should not try to catch up.
            ScreenManager.Game.ResetElapsedTime();
        }


        #endregion


        #region Update and Draw


        /// <summary>
        /// Updates the state of the game. This method checks the GameScreen.IsActive
        /// property, so the game will stop updating when the pause menu is active,
        /// or if you tab away to a different application.
        /// </summary>
        public override void Update(GameTime gameTime, bool otherScreenHasFocus,
                                                       bool coveredByOtherScreen)
        {
            base.Update(gameTime, otherScreenHasFocus, coveredByOtherScreen);

            if (IsActive && !coveredByOtherScreen)
            {
                Session.Update(gameTime);
            }
        }


        /// <summary>
        /// Lets the game respond to player input. Unlike the Update method,
        /// this will only be called when the gameplay screen is active.
        /// </summary>
        public override void HandleInput()
        {
            if (InputManager.IsActionTriggered(InputManager.Action.MainMenu))
            {
                ScreenManager.AddScreen(new MainMenuScreen());
                return;
            }

            if (InputManager.IsActionTriggered(InputManager.Action.ExitGame))
            {
                // add a confirmation message box
                const string message = 
                    "Are you sure you want to exit?  All unsaved progress will be lost.";
                MessageBoxScreen confirmExitMessageBox = new MessageBoxScreen(message);
                confirmExitMessageBox.Accepted += ConfirmExitMessageBoxAccepted;
                ScreenManager.AddScreen(confirmExitMessageBox);
                return;
            }

            if (!CombatEngine.IsActive &&
                InputManager.IsActionTriggered(InputManager.Action.CharacterManagement))
            {
                ScreenManager.AddScreen(new StatisticsScreen(Session.Party.Players[0]));
                return;
            }
        }


        /// <summary>
        /// Event handler for when the user selects Yes 
        /// on the "Are you sure?" message box.
        /// </summary>
        void ConfirmExitMessageBoxAccepted(object sender, EventArgs e)
        {
            ScreenManager.Game.Exit();
        }                


        /// <summary>
        /// Draws the gameplay screen.
        /// </summary>
        public override void Draw(GameTime gameTime)
        {
            Session.Draw(gameTime);
        }


        #endregion
    }
}