/// <summary>
        /// Creates a new sequence bitmap by apply I-Step with a given item-bitmap.
        /// </summary>
        internal SeqBitmap CreateNewByIStep(SeqBitmap itemBitmap)
        {
            var newBitmap = new SeqBitmap();

            if (_bitmap8 != null)
            {
                newBitmap._bitmap8 = _bitmap8.CreateNewByIStep(itemBitmap._bitmap8);
            }

            if (_bitmap16 != null)
            {
                newBitmap._bitmap16 = _bitmap16.CreateNewByIStep(itemBitmap._bitmap16);
            }

            if (_bitmap32 != null)
            {
                newBitmap._bitmap32 = _bitmap32.CreateNewByIStep(itemBitmap._bitmap32);
            }

            if (_bitmap64 != null)
            {
                newBitmap._bitmap64 = _bitmap64.CreateNewByIStep(itemBitmap._bitmap64);
            }

            if (_bitmap128 != null)
            {
                newBitmap._bitmap128 = _bitmap128.CreateNewByIStep(itemBitmap._bitmap128);
            }

            return(newBitmap);
        }