Figure 11: The shorten pattern algorithm

1.  Copy the pattern to a temp_pattern
2.  new_width = cuurent_width - size
3.  index = (index + size) modulus current_width
4.  Loop for new_index = 0, new_width
   5.  pattern[new_index] = temp_pattern[index]
   6.  index = (index + 1) modulus current_width
7.  current_width = new_width
8.  index = 0