C#开发跨平台游戏——游戏的全屏窗口及退出

在上一篇，我们介绍了在游戏中使用中文，接下去我们介绍如何在游戏中使用键盘修改游戏的显示模式（窗口和全屏）以及游戏的退出。

退出游戏

打开Game1.cs文件，找到Update(GameTime gameTime)方法。在方法体中有一段【 if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)】，这一段代码的含义是当按下游戏手柄上的返回键，则退出游戏，由于我们现在创建的游戏是Windows游戏，所以并没有游戏手柄GamePad。所以将它修改为【if(Keyboard.GetState(PlayerIndex.One).IsKeyDown(Keys.Escape))】。也可以拆分这段代码，让思路更加清晰：

KeyboardState keyboardState = Keyboard.GetState(PlayerIndex.One);//获取键盘状态
if(keyboardState.IsKeyDown(Keys.Escape))//判断是否按下了Escape键盘
{
      this.Exit();//退出游戏
}

可以注意到Keyboard的GetState方法带一个PlayerIndex枚举参数（存在四个值One、Two、Three、Four），当游戏是多人游戏的时候（支持四个）就可以判断哪个人按下来什么键盘。当前游戏可以省略这个参数！

点击【启动】

按下键盘上的ESC键盘，游戏便退出了！

游戏全屏显示

还是打开Game1.cs文件，找到Update(GameTime gameTime)方法。在退出游戏的代码下面输入:

if(keyboardState.IsKeyDown(Keys.F10))
{
     graphics.IsFullScreen = true;//设为全屏
     graphics.ApplyChanges();//全屏立即生效
}
if(keyboardState.IsKeyDown(Keys.F11))
{
     graphics.IsFullScreen = false;//退出全屏
     graphics.ApplyChanges();//立即生效
}

将graphics的IsFullScreen属性设置为true或false，就可以改变游戏的显示状态（全屏和窗口），设置以后调用graphics的ApplyChanges方法执行！前面提到graphics可以看作是显卡，很多显示相关的操作都可以在里面找到相应的属性和方法。以后将会做更多的介绍

完整代码如下：

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 HelloWorld.XNA
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;
        SpriteFont defaultFont;

        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            // TODO: Add your initialization logic here

            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            // Create a new SpriteBatch, which can be used to draw textures.
            spriteBatch = new SpriteBatch(GraphicsDevice);

            // TODO: use this.Content to load your game content here

            defaultFont = Content.Load<SpriteFont>("DefaultFont");


        }

        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// all content.
        /// </summary>
        protected override void UnloadContent()
        {
            // TODO: Unload any non ContentManager content here
        }

        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
            // Allows the game to exit
            KeyboardState keyboardState = Keyboard.GetState(PlayerIndex.One);
            if(keyboardState.IsKeyDown(Keys.Escape))
            {
                this.Exit();
            }
            if(keyboardState.IsKeyDown(Keys.F10))
            {
                graphics.IsFullScreen = true;
                graphics.ApplyChanges();
            }
            if(keyboardState.IsKeyDown(Keys.F11))
            {
                graphics.IsFullScreen = false;
                graphics.ApplyChanges();
            }

            // TODO: Add your update logic here

            base.Update(gameTime);
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // TODO: Add your drawing code here
            spriteBatch.Begin();
            spriteBatch.DrawString(defaultFont, "这是我的第一个游戏", Vector2.Zero, Color.White);
            spriteBatch.End();

            base.Draw(gameTime);
        }
    }
}

点击【启动】

按下键盘F10，游戏全屏。按下F11退出全屏变为窗口模式。按下Esc退出游戏

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