读 Beginning Android Games 2nd Edition (二十) 游戏GameScreen类

GameScreen类的主要工作是负责显示几种游戏不同状态下的界面

这个分屏分别是:准备游戏，游戏中，游戏暂停，游戏结束

package com.badlogic.androidgames.mrnom;import java.util.List;import android.graphics.Color;import com.badlogic.androidgames.framework.Game;import com.badlogic.androidgames.framework.Graphics;import com.badlogic.androidgames.framework.Input.TouchEvent;import com.badlogic.androidgames.framework.Pixmap;import com.badlogic.androidgames.framework.Screen;//枚举游戏的四种状态，准备游戏，游戏中，游戏暂停，游戏结束public class GameScreen extends Screen {    enum GameState {        Ready,        Running,        Paused,        GameOver    }        GameState state = GameState.Ready;    World world;    int oldScore = 0;    String score = "0";        public GameScreen(Game game) {        super(game);        world = new World();    }    @Override    public void update(float deltaTime) {        List<TouchEvent> touchEvents = game.getInput().getTouchEvents();        game.getInput().getKeyEvents();                if(state == GameState.Ready)            updateReady(touchEvents);        if(state == GameState.Running)            updateRunning(touchEvents, deltaTime);        if(state == GameState.Paused)            updatePaused(touchEvents);        if(state == GameState.GameOver)            updateGameOver(touchEvents);            }    //在准备游戏状态，触碰屏幕就进入游戏    private void updateReady(List<TouchEvent> touchEvents) {        if(touchEvents.size() > 0)            state = GameState.Running;    }    //游戏中状态    private void updateRunning(List<TouchEvent> touchEvents, float deltaTime) {                int len = touchEvents.size();        for(int i = 0; i < len; i++) {            TouchEvent event = touchEvents.get(i);            if(event.type == TouchEvent.TOUCH_UP) {            //如果碰到暂停按钮                if(event.x < 64 && event.y < 64) {                    if(Settings.soundEnabled)                        Assets.click.play(1);                    state = GameState.Paused;                    return;                }            }            if(event.type == TouchEvent.TOUCH_DOWN) {            //如果碰到逆时钟转向按钮                if(event.x < 64 && event.y > 416) {                    world.snake.turnLeft();                }                //如果碰到顺时钟转向按钮                if(event.x > 256 && event.y > 416) {                    world.snake.turnRight();                }            }        }                world.update(deltaTime);        //游戏结束        if(world.gameOver) {            if(Settings.soundEnabled)                Assets.bitten.play(1);            state = GameState.GameOver;        }        //累加游戏得分,并播放吃中目标的音效        if(oldScore != world.score) {            oldScore = world.score;            score = "" + oldScore;            if(Settings.soundEnabled)                Assets.eat.play(1);        }    }    private void updatePaused(List<TouchEvent> touchEvents) {        int len = touchEvents.size();        for(int i = 0; i < len; i++) {            TouchEvent event = touchEvents.get(i);            if(event.type == TouchEvent.TOUCH_UP) {                if(event.x > 80 && event.x <= 240) {                //如果选择恢复游戏                    if(event.y > 100 && event.y <= 148) {                        if(Settings.soundEnabled)                            Assets.click.play(1);                        state = GameState.Running;                        return;                    }                                       //如果选择退出                    if(event.y > 148 && event.y < 196) {                        if(Settings.soundEnabled)                            Assets.click.play(1);                        game.setScreen(new MainMenuScreen(game));                         return;                    }                }            }        }    }    private void updateGameOver(List<TouchEvent> touchEvents) {        int len = touchEvents.size();        for(int i = 0; i < len; i++) {            TouchEvent event = touchEvents.get(i);            if(event.type == TouchEvent.TOUCH_UP) {            //如果选择退出                if(event.x >= 128 && event.x <= 192 &&                   event.y >= 200 && event.y <= 264) {                    if(Settings.soundEnabled)                        Assets.click.play(1);                    game.setScreen(new MainMenuScreen(game));                    return;                }            }        }    }    //初始化游戏背景等     @Override    public void present(float deltaTime) {        Graphics g = game.getGraphics();                g.drawPixmap(Assets.background, 0, 0);        drawWorld(world);        if(state == GameState.Ready)             drawReadyUI();        if(state == GameState.Running)            drawRunningUI();        if(state == GameState.Paused)            drawPausedUI();        if(state == GameState.GameOver)            drawGameOverUI();                drawText(g, score, g.getWidth() / 2 - score.length()*20 / 2, g.getHeight() - 42);    }    //根据world对象来画出游戏背景和人物    private void drawWorld(World world) {        Graphics g = game.getGraphics();        Snake snake = world.snake;        SnakePart head = snake.parts.get(0);        Stain stain = world.stain;                //画出"污渍"        Pixmap stainPixmap = null;        if(stain.type == Stain.TYPE_1)            stainPixmap = Assets.stain1;        if(stain.type == Stain.TYPE_2)            stainPixmap = Assets.stain2;        if(stain.type == Stain.TYPE_3)            stainPixmap = Assets.stain3;        int x = stain.x * 32;        int y = stain.y * 32;              g.drawPixmap(stainPixmap, x, y);                     //画出蛇的身体        int len = snake.parts.size();        for(int i = 1; i < len; i++) {            SnakePart part = snake.parts.get(i);            x = part.x * 32;            y = part.y * 32;            g.drawPixmap(Assets.tail, x, y);        }        //画出蛇头        Pixmap headPixmap = null;        if(snake.direction == Snake.UP)             headPixmap = Assets.headUp;        if(snake.direction == Snake.LEFT)             headPixmap = Assets.headLeft;        if(snake.direction == Snake.DOWN)             headPixmap = Assets.headDown;        if(snake.direction == Snake.RIGHT)             headPixmap = Assets.headRight;                x = head.x * 32 + 16;        y = head.y * 32 + 16;        g.drawPixmap(headPixmap, x - headPixmap.getWidth() / 2, y - headPixmap.getHeight() / 2);    }    //画出准备游戏界面    private void drawReadyUI() {        Graphics g = game.getGraphics();                g.drawPixmap(Assets.ready, 47, 100);        g.drawLine(0, 416, 480, 416, Color.BLACK);    }    //画出游戏中画面    private void drawRunningUI() {        Graphics g = game.getGraphics();        g.drawPixmap(Assets.buttons, 0, 0, 64, 128, 64, 64);        g.drawLine(0, 416, 480, 416, Color.BLACK);        g.drawPixmap(Assets.buttons, 0, 416, 64, 64, 64, 64);        g.drawPixmap(Assets.buttons, 256, 416, 0, 64, 64, 64);    }    //画出游戏暂停画面    private void drawPausedUI() {        Graphics g = game.getGraphics();                g.drawPixmap(Assets.pause, 80, 100);        g.drawLine(0, 416, 480, 416, Color.BLACK);    }    //画出游戏结束画面    private void drawGameOverUI() {        Graphics g = game.getGraphics();                g.drawPixmap(Assets.gameOver, 62, 100);        g.drawPixmap(Assets.buttons, 128, 200, 0, 128, 64, 64);        g.drawLine(0, 416, 480, 416, Color.BLACK);    }    //画出游戏的当前得分    public void drawText(Graphics g, String line, int x, int y) {        int len = line.length();        for (int i = 0; i < len; i++) {            char character = line.charAt(i);            if (character == ' ') {                x += 20;                continue;            }            int srcX = 0;            int srcWidth = 0;            if (character == '.') {                srcX = 200;                srcWidth = 10;            } else {                srcX = (character - '0') * 20;                srcWidth = 20;            }            g.drawPixmap(Assets.numbers, x, y, srcX, 0, srcWidth, 32);            x += srcWidth;        }    }    //判断游戏状态，把状态置为暂停,并把得分保存到文件中    @Override    public void pause() {        if(state == GameState.Running)            state = GameState.Paused;                if(world.gameOver) {            Settings.addScore(world.score);            Settings.save(game.getFileIO());        }    }    @Override    public void resume() {            }    @Override    public void dispose() {            }}