ListView that knows how much has been scrolled downwards

ScrollAwareListView

public class ScrollAwareListView extends ListView {

    /**
     * Vertical offset listener
     */
    OnVerticalScrollOffsetListener offsetListener;
    /**
     * Maximum vertical size
     */
    int verticalRange = 0;

    /**
     * {@inheritDoc}
     */
    public ScrollAwareListView(Context context) {
        super(context);
    }

    /**
     * {@inheritDoc}
     */
    public ScrollAwareListView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    /**
     * {@inheritDoc}
     */
    public ScrollAwareListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected int computeVerticalScrollOffset() {
        final int result = super.computeVerticalScrollOffset();
        if (offsetListener != null) {
            offsetListener.onScrollOffsetComputed(result, verticalRange, verticalRange == 0 ? 0 : ((float) result / verticalRange) * getHeight());
        }
        return result;
    }

    @Override
    protected int computeVerticalScrollRange() {
        final int result = super.computeVerticalScrollRange();
        if (verticalRange != result) {
            verticalRange = result;
        }
        return result;
    }

    /**
     * Sets a new Vertical Scroll offset listener
     *
     * @param offsetListener OffsetListener instance for listening
     */
    public void setOffsetListener(OnVerticalScrollOffsetListener offsetListener) {
        this.offsetListener = offsetListener;
    }

    /**
     * This interface will allow a class to listen for changes on the current offset of the
     * Y-scroll of the list. Take into account that the changes in the size of the scroll
     * are not constantly updated, however the offset will be
     */
    public interface OnVerticalScrollOffsetListener {

        /**
         * Receives the Current offset of the ListView
         *
         * @param currentOffset Current offset of the Y-scroll
         * @param totalOffset   Total offset of the Y-scroll
         * @param percentage    Percentage of the available offset of the Y-scroll moved.
         */
        void onScrollOffsetComputed(int currentOffset, int totalOffset, float percentage);
    }