Trabajar con varios sprites. Programación de Juegos en Android 6.

package com.edu4java.android.killthemall;

import java.util.ArrayList;

import java.util.List;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Color;

import android.view.SurfaceHolder;

import android.view.SurfaceView;

public class GameView extends SurfaceView {

       private SurfaceHolder holder;

       private GameLoopThread gameLoopThread;

       private List<Sprite> sprites = new ArrayList<Sprite>();

       public GameView(Context context) {

             super(context);

             gameLoopThread = new GameLoopThread(this);

             holder = getHolder();

             holder.addCallback(new SurfaceHolder.Callback() {

                    @Override

                    public void surfaceDestroyed(SurfaceHolder holder) {

                           boolean retry = true;

                           gameLoopThread.setRunning(false);

                           while (retry) {

                                  try {

                                        gameLoopThread.join();

                                        retry = false;

                                  } catch (InterruptedException e) {

                                  }

                           }

                    }

                    @Override

                    public void surfaceCreated(SurfaceHolder holder) {

                           createSprites();

                           gameLoopThread.setRunning(true);

                           gameLoopThread.start();

                    }

                    @Override

                    public void surfaceChanged(SurfaceHolder holder, int format,

                                  int width, int height) {

                    }

             });

       }

       private void createSprites() {

             sprites.add(createSprite(R.drawable.bad1));

             sprites.add(createSprite(R.drawable.bad2));

             sprites.add(createSprite(R.drawable.bad3));

             sprites.add(createSprite(R.drawable.bad4));

             sprites.add(createSprite(R.drawable.bad5));

             sprites.add(createSprite(R.drawable.bad6));

             sprites.add(createSprite(R.drawable.good1));

             sprites.add(createSprite(R.drawable.good2));

             sprites.add(createSprite(R.drawable.good3));

             sprites.add(createSprite(R.drawable.good4));

             sprites.add(createSprite(R.drawable.good5));

             sprites.add(createSprite(R.drawable.good6));

       }

       private Sprite createSprite(int resouce) {

             Bitmap bmp = BitmapFactory.decodeResource(getResources(), resouce);

             return new Sprite(this,bmp);

       }

       @Override

       protected void onDraw(Canvas canvas) {

             canvas.drawColor(Color.BLACK);

             for (Sprite sprite : sprites) {

                    sprite.onDraw(canvas);

             }

       }

}

package com.edu4java.android.killthemall;

import java.util.Random;

import android.graphics.Bitmap;

import android.graphics.Canvas;

import android.graphics.Rect;

public class Sprite {

       // direction = 0 up, 1 left, 2 down, 3 right,

       // animation = 3 back, 1 left, 0 front, 2 right

       int[] DIRECTION_TO_ANIMATION_MAP = { 3, 1, 0, 2 };

       private static final int BMP_ROWS = 4;

       private static final int BMP_COLUMNS = 3;

       private static final int MAX_SPEED = 5;

       private GameView gameView;

       private Bitmap bmp;

       private int x = 0;

       private int y = 0;

       private int xSpeed;

       private int ySpeed;

       private int currentFrame = 0;

       private int width;

       private int height;

       public Sprite(GameView gameView, Bitmap bmp) {

             this.width = bmp.getWidth() / BMP_COLUMNS;

             this.height = bmp.getHeight() / BMP_ROWS;

             this.gameView = gameView;

             this.bmp = bmp;

             Random rnd = new Random();

             x = rnd.nextInt(gameView.getWidth() - width);

             y = rnd.nextInt(gameView.getHeight() - height);

             xSpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED;

             ySpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED;

       }

       private void update() {

             if (x >= gameView.getWidth() - width - xSpeed || x + xSpeed <= 0) {

                    xSpeed = -xSpeed;

             }

             x = x + xSpeed;

             if (y >= gameView.getHeight() - height - ySpeed || y + ySpeed <= 0) {

                    ySpeed = -ySpeed;

             }

             y = y + ySpeed;

             currentFrame = ++currentFrame % BMP_COLUMNS;

       }

       public void onDraw(Canvas canvas) {

             update();

             int srcX = currentFrame * width;

             int srcY = getAnimationRow() * height;

             Rect src = new Rect(srcX, srcY, srcX + width, srcY + height);

             Rect dst = new Rect(x, y, x + width, y + height);

             canvas.drawBitmap(bmp, src, dst, null);

       }

       private int getAnimationRow() {

             double dirDouble = (Math.atan2(xSpeed, ySpeed) / (Math.PI / 2) + 2);

             int direction = (int) Math.round(dirDouble) % BMP_ROWS;

             return DIRECTION_TO_ANIMATION_MAP[direction];

       }

}