HorizontalScrollViewSelector

ExampleActivity.java

int totalItems=10;

horizontalScrollView = (HorizontalScrollViewSelector) findViewById(R.id.horizontalScrollView);
horizontalScrollView.setListener(new HorizontalScrollViewSelector.OnScrollChangedListener() {
    @Override
    public void onScrollChanged(int totalX, int x) {
      items = x * totalItems / maxX);
    }
});

HorizontalScrollViewSelector.java

public class HorizontalScrollViewSelector extends HorizontalScrollView {
    private static final boolean DEFAULT_FLING_STATE = true;
    private OnScrollChangedListener listener;
    private boolean flingState;

    public HorizontalScrollViewSelector(Context context) {
        this(context, null);
    }

    public HorizontalScrollViewSelector(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public HorizontalScrollViewSelector(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    private void init() {
        flingState = DEFAULT_FLING_STATE;
    }

    @Override
    public void fling(int velocityY) {
        if (flingState) {
            super.fling(velocityY);
        }
    }

    public boolean isFlingState() {
        return flingState;
    }

    public void setFlingState(boolean flingState) {
        this.flingState = flingState;
    }

    @Override
    protected void onScrollChanged(int x, int y, int oldX, int oldY) {
        View view = getChildAt(getChildCount() - 1);
        int totalX = (view.getRight() - (getWidth()));
        if (listener != null) {
            listener.onScrollChanged(totalX, x);
        }
        super.onScrollChanged(x, y, oldX, oldY);
    }

    public OnScrollChangedListener getListener() {
        return listener;
    }

    public void setListener(OnScrollChangedListener listener) {
        this.listener = listener;
    }

    public interface OnScrollChangedListener {
        void onScrollChanged(int totalX, int x);
    }
}