Moving ball with accelerometer inside a view on camera preview in android - android-layout

Question

I have been searching and coding for 3 days now on this problem, no result :(
I made a camera overlay which the code is here + the Accelerometer
public class CameraActivity extends Activity implements SurfaceHolder.Callback, SensorEventListener {
Camera camera;
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
boolean previewing = false;
LayoutInflater controlInflater = null;
static String TAG = CameraActivity.class.getSimpleName();
// Accelerometer
private SensorManager mSensorManager;
private Sensor mAccelerometer;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.surface_view);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
surfaceView = (SurfaceView) findViewById(R.id.camerapreview);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
controlInflater = LayoutInflater.from(getBaseContext());
View viewControl = controlInflater.inflate(R.layout.camera_control,
null);
LayoutParams layoutParamsControl = new LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
this.addContentView(viewControl, layoutParamsControl);
// Accelerometer
mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
mAccelerometer = mSensorManager
.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
mSensorManager.registerListener(this, mAccelerometer,
SensorManager.SENSOR_DELAY_NORMAL);
}
#Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
#Override
public void onSensorChanged(SensorEvent event) {
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
if (previewing) {
camera.stopPreview();
previewing = false;
}
if (camera != null) {
try {
camera.setPreviewDisplay(surfaceHolder);
camera.startPreview();
previewing = true;
} catch (IOException e) {
e.printStackTrace();
}
}
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
camera = Camera.open();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
camera.stopPreview();
camera.release();
camera = null;
previewing = false;
}
}
Then in the camera_control.xml I have this:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/layout_holder"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#android:color/transparent"
android:gravity="bottom" >
<ImageView
android:id="#+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="#+id/camera_red_button"
android:layout_alignLeft="#+id/camera_back_button"
android:layout_marginBottom="27dp"
android:src="#drawable/camera_accelerometer_red" />
</RelativeLayout>
and in the surface_view.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/camerapreview_holder"
>
<SurfaceView
android:id="#+id/camerapreview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>
</LinearLayout>
The Image View is a image for spirit level.
The idea is user needs to level the camera before she takes a photo. I have cleared all the un-nessessery code. The above code are working code.
Question:
I need to make a ball for the spirit level. it doesnt need to be the smoothest spirit level. If I can find the way to confine the ball within the spirit level and move it based on the Accelerometer results I will be as happy as Larry :)/
If someone please put me in the right direction regarding these 3 things:
confining the animation within an area
confinement area to be Circle, how to make it
Thanks in advance.
H.

Answer 1

Ok I have got the answer. Hope it can help someone. You need to use calculate the distance from the middle to the corner (radius) the offset the corners.
Also I have change the Accelerometor to Orientation Sensor which then I can get the 3d rotation of the phone in the X and Y Axis.
The following code is working code and I tested them. I am using the Android 2.3.3+
The ball movement is not very smooth as this is not the purpose of the application.
I think in order to smooth the movement you might need to add the timer and collision detection to it too. Please check the android sample.
I haven't refactor the code too yet. So this is not a production level code :)
Codes:
public class CameraActivity extends Activity implements SurfaceHolder.Callback,
SensorEventListener {
// Accelerometer
private SensorManager mSensorManager;
private Sensor mAccelerometer;
/** Called when the activity is first created. */
public static float x;
public static float y;
FrameLayout layout_holder;
FrameLayout ball_holder;
// private float hOriginSize;
float halfOfWidth;
int centerYOnImage;
private Sensor mOrientation;
// float viewInset = 14.0f; // I remove this simply to make the code cleaner. I used this to calculate the radius and the offset later on
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.surface_view);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
surfaceView = (SurfaceView) findViewById(R.id.camerapreview);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
controlInflater = LayoutInflater.from(getBaseContext());
View viewControl = controlInflater.inflate(R.layout.camera_control,
null);
LayoutParams layoutParamsControl = new LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
this.addContentView(viewControl, layoutParamsControl);
// Accelerometer
mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
mOrientation = mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION);
mSensorManager.registerListener(this, mAccelerometer,
SensorManager.SENSOR_DELAY_NORMAL);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.ball);
CustomDrawableView mCustomDrawableView = new CustomDrawableView(this,
bitmap);
ball_holder = (FrameLayout) findViewById(R.id.ball_holder);
ball_holder.addView(mCustomDrawableView);
halfOfWidth = 40; // You can calculate this, I just put this so I can test it. This is the half of the width of target image - attached in the question
centerYOnImage = 40; // Not important :)
}
#Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
// This method will update the UI on new sensor events
public void onSensorChanged(SensorEvent event) {
// float azimuth_angle = event.values[0];
x = event.values[1];
y = event.values[2];
// FIXME: Fine tune this for the image taking part
float ratio = 70.0f / 25.0f;
x = x * ratio;
y = y * ratio;
Log.d(TAG, "x and y: " + x + " " + y);
float maxDistance = 35; // To calculate this halfOfWidth - viewInset;
// to calculate between 2 distances
float distance = (float) Math.sqrt(((x) * (x)) + ((y) * (y)));
if (distance > maxDistance) {
float angle = (float) Math.atan2(x, y);
/ Get new point on the edge of the circle
y = (float) (Math.cos(angle) * maxDistance);
x = (float) (Math.sin(angle) * maxDistance);
}
x = x + 40; // 40 is the half od the distance of the full width
y = (y * -1.0f) + 40; // -1.0f is so orientation works like the actual spirit level
canUserTakePhoto(distance);
}
// Change the background
public void canUserTakePhoto(float treshold) {
if (treshold > 10) {
// Not Yet
} else {
// take it
}
}
#Override
protected void onResume() {
super.onResume();
mSensorManager.registerListener(this, mOrientation,
SensorManager.SENSOR_DELAY_NORMAL);
}
#Override
protected void onPause() {
super.onPause();
mSensorManager.unregisterListener(this);
}
public class CustomDrawableView extends ImageView {
Bitmap b;
public CustomDrawableView(Context context, Bitmap bitmap) {
super(context);
this.b = bitmap;
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(this.b, x, y, null);
invalidate();
}
}
#Override
public void onDestroy() // main thread stopped
{
super.onDestroy();
// wait for threads to exit before clearing app
System.runFinalizersOnExit(true);
// remove app from memory
android.os.Process.killProcess(android.os.Process.myPid());
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
if (previewing) {
camera.stopPreview();
previewing = false;
}
if (camera != null) {
try {
camera.setPreviewDisplay(surfaceHolder);
camera.startPreview();
previewing = true;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera = Camera.open();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera.stopPreview();
camera.release();
camera = null;
previewing = false;
}
}
Cheers.