WheelViewLib/src/main/java/com/lukedeighton/wheelview/WheelView.java
public void invalidateWheelItemDrawable(int position) {
        int adapterPos = rawPositionToAdapterPosition(position);
        if (isEmptyItemPosition(adapterPos)) return;

        CacheItem cacheItem = mItemCacheArray[adapterPos];
        if (cacheItem != null) cacheItem.mDirty = true;
        invalidate();
    }
public void invalidateWheelItemDrawable(int position) {
        int adapterPos = rawPositionToAdapterPosition(position);
        if (isEmptyItemPosition(adapterPos)) return;

        CacheItem cacheItem = mItemCacheArray[adapterPos];
        if (cacheItem != null) cacheItem.mDirty = true;
        invalidate();
    }
Invalidate the drawable at the specific position so that the next Draw call
will refresh the Drawable at this given position in the adapter.