private float[] createRadii() {
        if (mPosition == FastScroller.FastScrollerPopupPosition.CENTER) {
            return new float[]{mCornerRadius, mCornerRadius, mCornerRadius, mCornerRadius, mCornerRadius, mCornerRadius, mCornerRadius, mCornerRadius};
        }

        if (Utils.isRtl(mRes)) {
            return new float[]{mCornerRadius, mCornerRadius, mCornerRadius, mCornerRadius, mCornerRadius, mCornerRadius, 0, 0};
        } else {
            return new float[]{mCornerRadius, mCornerRadius, mCornerRadius, mCornerRadius, 0, 0, mCornerRadius, mCornerRadius};
        }
    }
Animates the visibility of the fast scroller popup.
android/third_party/recyclerview-fastscroll/src/main/java/com/simplecityapps/recyclerview_fastscroll/views/FastScrollPopup.java