我想用加速度计控制我的简单安卓游戏（arcanoid）。游戏中的桨现在正在通过触摸屏事件进行控制。我想用加速度计控制它。
我试图将Accelerometer实现到GameActivity类中，它正在“控制”BreakOutView类，如下所示：
public class GameActivity extends Activity implements SensorEventListener {
// gameView will be the view of the Menu_Layout
// It will also hold the logic of the Menu_Layout
// and respond to screen touches as well
BreakOutView breakoutView;
private SensorManager sManager;
Sensor accelerometer;
Paddle paddle;
float x;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
breakoutView = new BreakOutView(this);
sManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE); // zisk managera
if (sManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER) != null) {
accelerometer = sManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
sManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL);
}
// Initialize gameView and set it as the view
setContentView(breakoutView);
}
// This method executes when the player starts the Game
@Override
protected void onResume() {
super.onResume();
sManager.registerListener(this,accelerometer,SensorManager.SENSOR_DELAY_NORMAL);
// Tell the gameView resume method to execute
breakoutView.resume();
}
// This method executes when the player quits the Menu_Layout
@Override
protected void onPause() {
super.onPause();
sManager.unregisterListener(this);
// Tell the gameView pause method to execute
breakoutView.pause();
}
@Override
public void onSensorChanged(SensorEvent sensorEvent) {
if (sensorEvent.sensor.getType() == Sensor.TYPE_ACCELEROMETER)
{
x = sensorEvent.values[0];
if (x > 0) {
breakoutView.paddle.setMovementState(paddle.LEFT);
}
else { breakoutView.paddle.setMovementState(paddle.RIGHT);
}
}
}
@Override
public void onAccuracyChanged(Sensor sensor, int i) {
}
}
这是BreakOutView类的代码。 onTouchEvent方法现在已禁用，因为我想在应用程序中使用加速计来控制Paddle。
public class BreakOutView extends SurfaceView implements Runnable{
// This is our thread
Thread gameThread = null;
// This is new. We need a SurfaceHolder
// When we use Paint and Canvas in a thread
// We will see it in action in the draw method soon.
SurfaceHolder ourHolder;
// A boolean which we will set and unset
// when the Menu_Layout is running- or not.
volatile boolean playing;
// Game is paused at the start
boolean paused = true;
// A Canvas and a Paint object
Canvas canvas;
Paint paint;
// This variable tracks the Menu_Layout frame rate
long fps;
Bitmap bitmapBob;
Bitmap bitmapBall;
Bitmap bitmapPaddal;
Bitmap bitmapBrick1;
Bitmap bitmapBrick2;
Bitmap bitmapBrick3;
// The size of the screen in pixels
int screenX;
int screenY;
// The players paddle
Paddle paddle;
// A ball
Ball ball;
// Up to 200 bricks
Brick[] bricks = new Brick[24];
int numBricks = 0;
// For sound FX
SoundPool soundPool;
int beep1ID = -1;
int beep2ID = -1;
int beep3ID = -1;
int loseLifeID = -1;
int explodeID = -1;
// The score
int score = 0;
int level = 1;
// Lives
int lives = 3;
Rect dest;
DisplayMetrics dm;
int densityDpi;
// When we initialize (call new()) on BreakOutView
// This special constructor method runs
public BreakOutView(Context context) {
super(context);
// The next line of code asks the
// SurfaceView class to set up our object.
// How kind.
// Initialize ourHolder and paint objects
ourHolder = getHolder();
paint = new Paint();
// Get a Display object to access screen details
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
// Load the resolution into a Point object
Point size = new Point();
// TODO target API < 13
display.getSize(size);
screenX = size.x;
screenY = size.y;
// using dpi to set sizes for objects
dm = context.getResources().getDisplayMetrics();
densityDpi = dm.densityDpi;
paddle = new Paddle(screenX, screenY, densityDpi);
// Create a ball
ball = new Ball(screenX, screenY);
// Load the sounds
// This SoundPool is deprecated but don't worry
soundPool = new SoundPool(10, AudioManager.STREAM_MUSIC, 0);
try {
// Create objects of the 2 required classes
AssetManager assetManager = context.getAssets();
AssetFileDescriptor descriptor;
// Load our fx in memory ready for use
descriptor = assetManager.openFd("beep1.wav");
beep1ID = soundPool.load(descriptor, 0);
descriptor = assetManager.openFd("beep2.wav");
beep2ID = soundPool.load(descriptor, 0);
descriptor = assetManager.openFd("beep3.wav");
beep3ID = soundPool.load(descriptor, 0);
descriptor = assetManager.openFd("loseLife.wav");
loseLifeID = soundPool.load(descriptor, 0);
descriptor = assetManager.openFd("explode.wav");
explodeID = soundPool.load(descriptor, 0);
} catch (IOException e) {
// Print an error message to the console
Log.e("error", "failed to load sound files");
}
// Load Images from resource files
bitmapBob = BitmapFactory.decodeResource(this.getResources(), R.drawable.wall);
bitmapBall = BitmapFactory.decodeResource(this.getResources(), R.drawable.ball);
bitmapPaddal = BitmapFactory.decodeResource(this.getResources(), R.drawable.ball);
bitmapBrick1 = BitmapFactory.decodeResource(this.getResources(), R.drawable.brick_red);
bitmapBrick2 = BitmapFactory.decodeResource(this.getResources(), R.drawable.brick_green);
bitmapBrick3 = BitmapFactory.decodeResource(this.getResources(), R.drawable.brick_monster);
//Make Sizes Depending on DPI
int heightX = densityDpi / 8;
float length_Paddal = densityDpi / 1.50f;
int height_Paddal = densityDpi / 7;
int brickWidth = screenX / 8;
int brickHeight = screenY / 10;
bitmapBall = getResizedBitmap(bitmapBall, heightX, heightX);
bitmapPaddal = getResizedBitmap(bitmapPaddal, length_Paddal, height_Paddal);
bitmapBrick1 = getResizedBitmap(bitmapBrick1, brickWidth, brickHeight);
bitmapBrick2 = getResizedBitmap(bitmapBrick2, brickWidth, brickHeight);
bitmapBrick3 = getResizedBitmap(bitmapBrick3, brickWidth, brickHeight);
// Create bricks for level 1
createBricksAndRestart(1);
}
public void createBricksAndRestart(int Xlevel) {
// Put the ball back to the start
ball.reset(screenX, screenY);
level = Xlevel;
switch (Xlevel) {
case 2:
// level 2
ball.xVelocity = 600;
ball.yVelocity = -1000;
break;
// level 3
case 3:
ball.xVelocity = 1000;
ball.yVelocity = -1400;
break;
// level 1
default:
ball.xVelocity = 400;
ball.yVelocity = -800;
break;
}
// Brick Size
int brickWidth = screenX / 8;
int brickHeight = screenY / 10;
// Build a wall of bricks
numBricks = 0;
for (int column = 0; column < 8; column++) {
for (int row = 0; row < 3; row++) {
bricks[numBricks] = new Brick(row, column, brickWidth, brickHeight);
numBricks++;
}
}
// if Game is over reset scores ,lives &Level
if (lives == 0) {
score = 0;
lives = 3;
level = 1;
}
}
@Override
public void run() {
while (playing) {
// Capture the current time in milliseconds in startFrameTime
long startFrameTime = System.currentTimeMillis();
// Update the frame
if (!paused) {
update();
}
// Draw the frame
draw();
// Calculate the fps this frame
// We can then use the result to
// time animations and more.
long timeThisFrame = System.currentTimeMillis() - startFrameTime;
if (timeThisFrame >= 1) {
fps = 1000 / timeThisFrame;
}
}
}
// Everything that needs to be updated goes in here
// Movement, collision detection etc.
public void update() {
// Move the paddle if required
paddle.update(fps);
ball.update(fps);
// Check for ball colliding with a brick
for (int i = 0; i < numBricks; i++) {
if (bricks[i].getVisibility()) {
if (RectF.intersects(bricks[i].getRect(), ball.getRect())) {
bricks[i].setInvisible();
ball.reverseYVelocity();
score = score + 10;
soundPool.play(explodeID, 1, 1, 0, 0, 1);
}
}
}
// Check for ball colliding with paddle
if (
ball.getRect().intersect(paddle.getRect()) ||
RectF.intersects(paddle.getRect(), ball.getRect()) ||
paddle.getRect().intersect(ball.getRect())
) {
ball.reverseYVelocity();
// ReverseX Direction + IncreaseX speed
if (paddle.getMovementState() == paddle.RIGHT && ball.xVelocity < 0 || paddle.getMovementState() == paddle.LEFT && ball.xVelocity > 0) {
ball.reverseXVelocity();
}
// SameX Direction + IncreaseX speed
else if (paddle.getMovementState() == paddle.RIGHT && ball.xVelocity > 0 || paddle.getMovementState() == paddle.LEFT && ball.xVelocity < 0) {
ball.sameXVelocity();
}
/*// Paddle is still, DecreaseX speed
else if (paddle.getMovementState() == paddle.STOPPED) {
ball.zeroXVelocity();
}*/
// Some intersection Bugs
ball.clearObstacleY(paddle.getRect().top - 20);
soundPool.play(beep1ID, 1, 1, 0, 0, 1);
}
// Bounce the ball back when it hits the bottom of screen
// And Lose a life
if (ball.getRect().bottom > screenY) {
ball.reverseYVelocity();
ball.clearObstacleY(screenY - 5);
// Lose a life
lives--;
soundPool.play(loseLifeID, 1, 1, 0, 0, 1);
if (lives == 0) {
paused = true;
//draw Loss;
canvas = ourHolder.lockCanvas();
paint.setColor(getResources().getColor(R.color.orange));
paint.setTextSize(getResources().getDimension(R.dimen.text_size_big));
canvas.drawText("أنت خسرت!",
screenX / 2 - (densityDpi / 1.90f), screenY / 2 + (densityDpi), paint);
ourHolder.unlockCanvasAndPost(canvas);
try {
// Wait 3 seconds then reset a new game
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
// Create bricks at level 1
createBricksAndRestart(1);
}
}
// Pause if cleared screen
if (score == numBricks * 10) {
// Create bricks at level 2
createBricksAndRestart(2);
// fix for a pause bug
// so that it won't Pause After finishing the Game
score = score + 10;
// Gift the player with 1 new live
lives = lives + 1;
} else if (score == (numBricks * 20) + 10) {
// Create bricks at level 3
createBricksAndRestart(3);
// fix for a pause bug
// so that it won't Pause After finishing the Game
score = score + 10;
// Gift the player with 2 new lives
lives = lives + 2;
}
// Pause if cleared screen
// if score equals to the whole Bricks scores after 3 levels
else if (score == (numBricks * 10 * 3) + 20) {
paused = true;
}
// Bounce the ball back when it hits the top of screen
if (ball.getRect().top < 0) {
ball.reverseYVelocity();
ball.clearObstacleY(40);
soundPool.play(beep2ID, 1, 1, 0, 0, 1);
}
// If the ball hits left wall bounce
if (ball.getRect().left < 0) {
ball.reverseXVelocity();
ball.clearObstacleX(2);
soundPool.play(beep3ID, 1, 1, 0, 0, 1);
}
// If the ball hits right wall Velocity
if (ball.getRect().right > screenX) {
ball.reverseXVelocity();
ball.clearObstacleX(screenX - 57);
soundPool.play(beep3ID, 1, 1, 0, 0, 1);
}
}
// Draw the newly updated scene
public void draw() {
// Make sure our drawing surface is valid or we crash
if (ourHolder.getSurface().isValid()) {
// Lock the canvas ready to draw
canvas = ourHolder.lockCanvas();
// Draw the background color
// canvas.drawColor(getResources().getColor(R.color.deeppurple));
dest = new Rect(0, 0, getWidth(), getHeight());
// Draw bob as background with dest size
canvas.drawBitmap(bitmapBob, null, dest, paint);
// Choose the brush color for drawing
paint.setColor(Color.argb(255, 255, 255, 255));
// Draw the ball
// canvas.drawCircle(ball.getRect().centerX(), ball.getRect().centerY(), 25, paint);
canvas.drawBitmap(bitmapBall, ball.getRect().left, ball.getRect().top, null);
// Draw the paddle
//canvas.drawRect(paddle.getRect(), paint);
canvas.drawBitmap(bitmapPaddal, paddle.getRect().left, paddle.getRect().top, null);
// Change the brush color for drawing
// paint.setColor(getResources().getColor(R.color.redorange));
// Draw the bricks if visible
for (int i = 0; i < numBricks; i++) {
if (bricks[i].getVisibility()) {
// canvas.drawRect(bricks[i].getRect(), paint);
switch (level) {
case 1:
canvas.drawBitmap(bitmapBrick1, bricks[i].getRect().left, bricks[i].getRect().top, null);
break;
case 2:
canvas.drawBitmap(bitmapBrick2, bricks[i].getRect().left, bricks[i].getRect().top, null);
break;
case 3:
canvas.drawBitmap(bitmapBrick3, bricks[i].getRect().left, bricks[i].getRect().top, null);
break;
}
}
}
// Choose the brush color for drawing
paint.setColor(Color.argb(255, 255, 255, 255));
// Draw the score
paint.setTextSize(getResources().getDimension(R.dimen.text_size));
// Score Text
canvas.drawText(
"النقاط: " + score
, screenX - (densityDpi / 1.50f), screenY / 2, paint);
// Lives Text
canvas.drawText("الصحة: " + lives
, densityDpi / 5, screenY / 2, paint);
// Levels Text
canvas.drawText("المرحلة: " + level
, screenX / 2 - (densityDpi / 5), screenY / 2 + (densityDpi / 5), paint);
// Has the player cleared the screen?
if (score >= (numBricks * 10 * 3) + 20) {
paint.setColor(getResources().getColor(R.color.colorAccent));
paint.setTextSize(getResources().getDimension(R.dimen.text_size_big));
canvas.drawText("أنت كسبت!", screenX / 2 - (densityDpi / 1.90f), screenY / 2 + (densityDpi / 1), paint);
}
// Draw everything to the screen
ourHolder.unlockCanvasAndPost(canvas);
}
}
// If GameActivity is paused/stopped
// shutdown our thread.
public void pause() {
playing = false;
try {
gameThread.join();
} catch (InterruptedException e) {
Log.e("Error:", "joining thread");
}
}
// If GameActivity is started
// start our thread.
public void resume() {
playing = true;
gameThread = new Thread(this);
gameThread.start();
}
// The SurfaceView class implements onTouchListener
// So we can override this method and detect screen touches.
/* @Override
public boolean onTouchEvent(MotionEvent motionEvent) {
switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {
// Player has touched the screen
case MotionEvent.ACTION_DOWN:
if (!(lives == 0)) {
paused = false;
}
// If touch motion > Half of the Screen
if (motionEvent.getX() > screenX / 2) {
// move paddle right
paddle.setMovementState(paddle.RIGHT);
} else {
// move paddle left
paddle.setMovementState(paddle.LEFT);
}
break;
// Player has removed finger from screen
case MotionEvent.ACTION_UP:
// paddle stopped
paddle.setMovementState(paddle.STOPPED);
break;
}
return true;
}*/
// Resize Bitmap function to Handle all the Images from resources the right size
public Bitmap getResizedBitmap(Bitmap bm, float newWidth, int newHeight) {
int width = bm.getWidth();
int height = bm.getHeight();
float scaleWidth = newWidth / width;
float scaleHeight = ((float) newHeight) / height;
// CREATE A MATRIX FOR THE MANIPULATION
Matrix matrix = new Matrix();
// RESIZE THE BIT MAP
matrix.postScale(scaleWidth, scaleHeight);
// "RECREATE" THE NEW BITMAP
Bitmap resizedBitmap = Bitmap.createBitmap(
bm, 0, 0, width, height, matrix, false);
bm.recycle();
return resizedBitmap;
}
}
这是Paddle类的代码：
import android.graphics.RectF;
public class Paddle {
// Which ways can the paddle move
public final int STOPPED = 0;
public final int LEFT = 1;
public final int RIGHT = 2;
int scrX;
// RectF is an object that holds four coordinates - just what we need
private RectF rect;
// How long and high our paddle will be
private float length;
private float height;
// X is the far left of the rectangle which forms our paddle
private float x;
// Y is the top coordinate
private float y;
// This will hold the pixels per second speedthat the paddle will move
private float paddleSpeed;
// Is the paddle moving and in which direction
private int paddleMoving = STOPPED;
private int MYscreenDPI;
// This the the constructor method
// When we create an object from this class we will pass
// in the screen width and height
public Paddle(int screenX, int screenY, int screenDPI) {
// Dynamic size based on each device DPI
length = screenDPI / 2;
height = screenDPI / 5;
MYscreenDPI = screenDPI;
scrX = screenX;
// Start paddle in roughly the sceen centre
x = screenX / 2;
y = screenY - screenDPI / 4.50f;
rect = new RectF(x, y, x + length, y + height);
// How fast is the paddle in pixels per second
paddleSpeed = 800;
}
public float getX() {
return x;
}
public void setX(float x) {
this.x = x;
}
public float getY() {
return y;
}
public void setY(float y) {
this.y = y;
}
// This is a getter method to make the rectangle that
// defines our paddle available in BreakoutView class
public RectF getRect() {
return rect;
}
public int getMovementState() {
return paddleMoving;
}
// This method will be used to change/set if the paddle is going left, right or nowhere
public void setMovementState(int state) {
paddleMoving = state;
}
// This update method will be called from update in BreakoutView
// It determines if the paddle needs to move and changes the coordinates
// contained in rect if necessary
public void update(long fps) {
if (paddleMoving == LEFT) {
// to fix Paddle going off the Screen
if (x >= -MYscreenDPI / 10)
// Decrement position
x = x - paddleSpeed / fps;
}
if (paddleMoving == RIGHT) {
// to fix Paddle going off the Screen
if (x <= scrX - length - MYscreenDPI / 14)
// Increment position
x = x + paddleSpeed / fps;
}
// Apply the New position
rect.left = x;
rect.right = x + length;
}
}
当我试图运行它时，应用程序总是崩溃而不能正常工作。当我尝试使用onTouchEvent方法来控制桨时它没有崩溃，但加速度计不起作用。
我知道我做的很糟糕。我试图解决它一周，但我不知道如何让它工作。
如果你能告诉我任何建议，我会非常感激。感谢您的回复。
- 编辑 -
这是我在模拟器中点击新游戏时来自logcat的错误消息：
2019-04-13 17:30:55.116 7082-7082/com.kazaky.breakout E/SensorManager: Exception dispatching input event. 2019-04-13 17:30:55.122 7082-7082/com.kazaky.breakout E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.kazaky.breakout, PID: 7082
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Class java.lang.Object.getClass()' on a null object reference
at com.kazaky.breakout.GameActivity.onSensorChanged(GameActivity.java:73)
at android.hardware.SystemSensorManager$SensorEventQueue.dispatchSensorEvent(SystemSensorManager.java:833)
at android.os.MessageQueue.nativePollOnce(Native Method)
at android.os.MessageQueue.next(MessageQueue.java:326)
at android.os.Looper.loop(Looper.java:160)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 2019-04-13 17:31:06.794 7082-7117/com.kazaky.breakout E/Surface: queueBuffer: error queuing buffer to SurfaceTexture, -19 2019-04-13 17:31:06.794 7082-7117/com.kazaky.breakout E/Surface: queueBuffer (handle=0xe9f16140) failed (No such device)
正如堆栈跟踪所示，您正在尝试访问一个空对象，在这种情况下，我猜测sensroEvent中的onSensorChanged。
如果sensorEvent是null，添加一个可空性检查并返回，如下所示：
if (sensorEvent == null) return
并在Guard Condition之后写下函数的其余部分。