lcd.rb

#! /usr/bin/env ruby

# ==================================
# = SOLUTION TO RUBY QUIZ NUMBER 2 =
# ==================================
# by Will & Stef

require 'optparse'

# map of positions to characters for each number
Patterns = {
  "0" => {  :t  => "-",  :tl => "|", :tr => "|",  :m  => " ",   :bl => "|", :br => "|",  :b  => "-"},
  "1" => {  :t  => " ",  :tl => " ", :tr => "|",  :m  => " ",   :bl => " ", :br => "|",  :b  => " "},
  "2" => {  :t  => "-",  :tl => " ", :tr => "|",  :m  => "-",   :bl => "|", :br => " ",  :b  => "-"},
  "3" => {  :t  => "-",  :tl => " ", :tr => "|",  :m  => "-",   :bl => " ", :br => "|",  :b  => "-"},
  "4" => {  :t  => " ",  :tl => "|", :tr => "|",  :m  => "-",   :bl => " ", :br => "|",  :b  => " "},
  "5" => {  :t  => "-",  :tl => "|", :tr => " ",  :m  => "-",   :bl => " ", :br => "|",  :b  => "-"},
  "6" => {  :t  => "-",  :tl => "|", :tr => " ",  :m  => "-",   :bl => "|", :br => "|",  :b  => "-"},
  "7" => {  :t  => "-",  :tl => " ", :tr => "|",  :m  => " ",   :bl => " ", :br => "|",  :b  => " "},
  "8" => {  :t  => "-",  :tl => "|", :tr => "|",  :m  => "-",   :bl => "|", :br => "|",  :b  => "-"},
  "9" => {  :t  => "-",  :tl => "|", :tr => "|",  :m  => "-",   :bl => " ", :br => "|",  :b  => "-"}
}

class LcdNumberPrinter
  
  # constructor
  def initialize(numbers, size)
    @numbers = numbers.split(//)
    @size    = size.to_i
  end
  
  # total height of the lcd display
  def height
    (2 * @size) + 3
  end
  
  # width of each digit in the display
  def digit_width
    @size + 2
  end
  
  # total width of the display
  def total_width 
    (digit_width * @numbers.size)
  end
  
  # print each line in the display
  def print_lines
    0.upto(height - 1).each do |row|
      print_columns(row)
    end
  end
  
  # print the column list and add a line break
  def print_columns row
    0.upto(total_width - 1).each do |column|
      print_character_for_coordinates(row, column)
    end
    print "\n"
  end
  
  # print a character based on the position in the number slot 
  # the current number and spacing
  def print_character_for_coordinates(row, column)
    print " " if is_right_side_of_digit?(column - 1)
    slot = get_digit_slot(row, column) 
    character = slot ? Patterns[get_number(column)][slot] : " "
    character = " " if [:t,:b,:m].include?(slot) && !is_in_the_middle?(column)
    print character
  end

  # determine the location within the number slot map to print
  def get_digit_slot(row, column)
    return :t if row == 0         
    return :b if row == height - 1
    return :m if row == 1 + @size
    return :tl if is_top_half_of_digit?(row)    && is_left_side_of_digit?(column)
    return :tr if is_top_half_of_digit?(row)    && is_right_side_of_digit?(column)
    return :bl if is_bottom_half_of_digit?(row) && is_left_side_of_digit?(column)
    return :br if is_bottom_half_of_digit?(row) && is_right_side_of_digit?(column)
    return nil  
  end
  
  # true if we are in the middle section of a number slot
  def is_in_the_middle?(column)
    !is_left_side_of_digit?(column) && !is_right_side_of_digit?(column) 
  end
  
  # true if we are on the top half of a number slot
  def is_top_half_of_digit?(row)
    row <= @size
  end
  
  # true if we are on the bottom half of a number slot
  def is_bottom_half_of_digit?(row)
    row > @size
  end

  # true if we are on the the left boundary of a number slot
  def is_left_side_of_digit?(column)
    (column==0 || column % digit_width == 0)
  end
  
  # true if we are on the the right boundary of a number slot
  def is_right_side_of_digit?(column)
    (((number_position(column) + 1) * digit_width) -1 == column)
  end
  
  # get the ordinal position of the current number in the array of numbers
  def number_position(column)
    (column)/digit_width
  end
  
  # get the number for the current column
  def get_number column
    @numbers[number_position(column)]
  end
  
end

if __FILE__ == $0
  params  = ARGV.getopts("s:")
  size    = params["s"] || 2
  numbers = ARGV[0]
  unless numbers && numbers.match(/^\d+$/)
    puts "usage you must provide a list of numbers"
    exit
  end
  LcdNumberPrinter.new(numbers, size).print_lines
end