CircleScrollListView

public class CircleScrollListView extends SurfaceView implements
    SurfaceHolder.Callback, OnGestureListener {
private GestureDetector mGestureDetector;
private Thread mThread;
private ArrayList<CircleDrawItem> datas = new ArrayList<CircleDrawItem>();
int[] playerDrawableResourceIds = new int[] { R.drawable.ronaldo,
        R.drawable.zindance, R.drawable.congvinh, R.drawable.huynhduc,
        R.drawable.gerrard, R.drawable.nagatomo, R.drawable.messi,
        R.drawable.minhphuong, R.drawable.neymar, R.drawable.ronaldo_beo,
        R.drawable.ronaldinho, R.drawable.xavi };
public int mCenterX;
public int mCenterY;
public int mRadius;
public double mStartAngleInRadian = Math.PI / 4;
private boolean isStop = false;

public CircleScrollListView(Context context, AttributeSet attrs) {
    super(context, attrs);
    mGestureDetector = new GestureDetector(context, this);
    getHolder().addCallback(this);
    this.setFocusable(true);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    mGestureDetector.onTouchEvent(event);
    return true;
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
        int height) {
}

public static int calculateInSampleSize(BitmapFactory.Options options,
        int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        // Calculate ratios of height and width to requested height and
        // width
        final int heightRatio = Math.round((float) height
                / (float) reqHeight);
        final int widthRatio = Math.round((float) width / (float) reqWidth);

        // Choose the smallest ratio as inSampleSize value, this will
        // guarantee
        // a final image with both dimensions larger than or equal to the
        // requested height and width.
        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
    }

    return inSampleSize;
}

public static Bitmap decodeSampledBitmapFromResource(Resources res,
        int resId, int reqWidth, int reqHeight) {

    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeResource(res, resId, options);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, reqWidth,
            reqHeight);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeResource(res, resId, options);
}

private double calculateScrollAngle(float px1, float py1, float px2,
        float py2) {
    double radian1 = Math.atan2(py1, px1);
    double radian2 = Math.atan2(py2, px2);
    double diff = radian2 - radian1;
    return diff;
}

@Override
public void surfaceCreated(SurfaceHolder holder) {

    setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,
            LayoutParams.MATCH_PARENT));

    Global.density = getResources().getDisplayMetrics().density;
    Global.dw = getResources().getDisplayMetrics().widthPixels;
    Global.dh = getResources().getDisplayMetrics().heightPixels;
    Global.dp = Global.density / 1.5f;

    // For circle data
    mCenterX = (int) (Global.dw / 2.0f);
    mCenterY = (int) (Global.dh);
//      mCenterX = (int) (Global.dp * 200);
//      mCenterY = (int) (Global.dh / 2.0f);
    mRadius = (int) (300 * Global.dp);
    mStartAngleInRadian = Math.PI / 4;

    for (int i = 0; i < playerDrawableResourceIds.length; i++) {
        CircleDrawItem circleDrawItem = new CircleDrawItem();
        circleDrawItem.mIconBitmap = decodeSampledBitmapFromResource(
                getResources(), playerDrawableResourceIds[i], 50, 50);
        circleDrawItem.mAngle = mStartAngleInRadian +i * Math.PI / 10;
        datas.add(circleDrawItem);
    }

    mThread = new Thread(new Runnable() {
        @Override
        public void run() {
            while (!isStop) {
                draw();
            }
        }
    });

    mThread.start();
}

protected void draw() {
    Canvas canvas = getHolder().lockCanvas();
    if (canvas == null) {
        return;
    }
    canvas.save();
    canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);
    Paint paint = new Paint();
    paint.setAntiAlias(true);
    paint.setFilterBitmap(true);
    paint.setAntiAlias(true);

    for (int i = 0; i < datas.size(); i++) {
        canvas.save();
        CircleDrawItem item = datas.get(i);
        double x = mCenterX + Math.cos(item.mAngle) * mRadius;
        double y = mCenterY - Math.sin(item.mAngle) * mRadius;
        canvas.drawBitmap(item.mIconBitmap,
                (int) x - item.mIconBitmap.getWidth() / 2, (int) y
                        - item.mIconBitmap.getHeight() / 2, paint);
        canvas.restore();
    }
    canvas.restore();
    getHolder().unlockCanvasAndPost(canvas);
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    isStop = true;
}

@Override
public boolean onDown(MotionEvent e) {
    return false;
}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
        float velocityY) {
    return false;
}

@Override
public void onLongPress(MotionEvent e) {

}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
        float distanceY) {
    float tpx = e1.getY();
    float tpy = e2.getX();
    float disx = (int) distanceY;
    float disy = (int) distanceX;
    double scrollAngle = calculateScrollAngle(tpx, tpy, tpx + disx, tpy
            + disy);
    for (int i = 0; i < datas.size(); i++) {
        datas.get(i).mAngle += scrollAngle;
    }
    return true;
}

@Override
public void onShowPress(MotionEvent e) {
}

@Override
public boolean onSingleTapUp(MotionEvent e) {
    return false;
}
}

source: http://stackoverflow.com/questions/18822465/how-to-put-an-onclick-event-for-the-item-coming-at-the-center-of-the-canvas-in-a 

Note: not checked

Android Camera Intent

private static int TAKE_PICTURE = 1;    
private Uri imageUri;

public void takePhoto(View view) {
    Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
    File photo = new File(Environment.getExternalStorageDirectory(),  "Pic.jpg");
    intent.putExtra(MediaStore.EXTRA_OUTPUT,
            Uri.fromFile(photo));
    imageUri = Uri.fromFile(photo);
    startActivityForResult(intent, TAKE_PICTURE);
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {
    case TAKE_PICTURE:
        if (resultCode == Activity.RESULT_OK) {
            Uri selectedImage = imageUri;
            getContentResolver().notifyChange(selectedImage, null);
            ImageView imageView = (ImageView) findViewById(R.id.ImageView);
            ContentResolver cr = getContentResolver();
            Bitmap bitmap;
            try {
                 bitmap = android.provider.MediaStore.Images.Media
                 .getBitmap(cr, selectedImage);

                imageView.setImageBitmap(bitmap);
                Toast.makeText(this, selectedImage.toString(),
                        Toast.LENGTH_LONG).show();
            } catch (Exception e) {
                Toast.makeText(this, "Failed to load", Toast.LENGTH_SHORT)
                        .show();
                Log.e("Camera", e.toString());
            }
        }
    }
}

Android Camera Intent

private static int TAKE_PICTURE = 1;    
private Uri imageUri;

public void takePhoto(View view) {
    Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
    File photo = new File(Environment.getExternalStorageDirectory(),  "Pic.jpg");
    intent.putExtra(MediaStore.EXTRA_OUTPUT,
            Uri.fromFile(photo));
    imageUri = Uri.fromFile(photo);
    startActivityForResult(intent, TAKE_PICTURE);
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {
    case TAKE_PICTURE:
        if (resultCode == Activity.RESULT_OK) {
            Uri selectedImage = imageUri;
            getContentResolver().notifyChange(selectedImage, null);
            ImageView imageView = (ImageView) findViewById(R.id.ImageView);
            ContentResolver cr = getContentResolver();
            Bitmap bitmap;
            try {
                 bitmap = android.provider.MediaStore.Images.Media
                 .getBitmap(cr, selectedImage);

                imageView.setImageBitmap(bitmap);
                Toast.makeText(this, selectedImage.toString(),
                        Toast.LENGTH_LONG).show();
            } catch (Exception e) {
                Toast.makeText(this, "Failed to load", Toast.LENGTH_SHORT)
                        .show();
                Log.e("Camera", e.toString());
            }
        }
    }
}

source : http://stackoverflow.com/questions/2729267/android-camera-intent 

Monitoring Foreground Activity in Android

ActivityManager am = (ActivityManager) this.getSystemService(ACTIVITY_SERVICE);
List< ActivityManager.RunningTaskInfo > taskInfo = am.getRunningTasks(1); 
Log.d("topActivity", "CURRENT Activity ::"
            + taskInfo.get(0).topActivity.getClassName());
ComponentName componentInfo = taskInfo.get(0).topActivity;
componentInfo.getPackageName();

You will need the following permission:

<uses-permission android:name="android.permission.GET_TASKS"/>

source : http://stackoverflow.com/questions/17629053/how-do-android-monitor-usage-applications-work 

    How to Solve OutOfMemory Error (OOM) in Android ?

When you try to decode large files on your Android device (where you have only 16MB memory available) you wil surely get an OutOfMemory exception.

We have found that if you create a temp storage and pass it to BitmapFactory before decoding might help.

So, before using BitmapFactory.decodeFile() create a byte array of 16kb and pass it to temp storage in decoding process.

BitmapFactory.Options options = new BitmapFactory.Options();
options.inTempStorage = new byte[16*1024];

Bitmap bitmapImage = BitmapFactory.decodeFile(path,opt);

Also you might consider passing your own outputstream that streams out to server or other storage to minimize memory consumtion during the process.

PS, do not forget to bitmapImage.recycle() after usage.

Also consider using options.inSampleSize with values other than 1. From SDK: If set to a value > 1, requests the decoder to subsample the original image, returning a smaller image to save memory. (1 -> decodes full size; 2 -> decodes 1/4th size; 4 -> decode 1/16th size). Because you rarely need to show and have full size bitmap images on your phone. For manipulations smaller sizes are usually enough.

Source: http://eclipseandroid.blogspot.in/2012/02/how-to-solve-outofmemory-error-oom-in.html