@Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int left = getPaddingLeft();
        int top = getPaddingTop();
        int right = getWidth() - getPaddingRight();
        int bottom = getHeight() - getPaddingBottom();
        //the TetView is always layout at the top
        mNumber.layout(left, top, left + mWidth, top + mWidth);
        //the MarkerDrawable uses the whole view, it will adapt itself...
        // or it seems so...
        mMarkerDrawable.setBounds(left, top, right, bottom);
    }
{@link ViewGroup} to be used as the real indicator.
<p>
I've used this to be able to accommodate the TextView
with the required positions and offsets
</p>

@hide
app/src/main/java/com/duan/musicoco/view/discreteseekbar/internal/Marker.java