@Override
    protected void onDraw(Canvas canvas) {
        if (viewPager == null || pageCount == 0) return;
        drawUnselected(canvas);
        drawSelected(canvas);
    }
An ink inspired widget for indicating pages in a {@link ViewPager}.
library/src/main/java/com/heinrichreimersoftware/materialintro/view/InkPageIndicator.java