transcriber.rb

# encoding: UTF-8

require 'mini_magick'
require 'tmpdir'
require 'securerandom'

include MiniMagick

module Transcriber
  GLYPH_DIR = 'glyphs'

  # Maps a phoneme to its appropriate glyph
  CONSONANT_MAP = {
    'm'=>'m',
    'p'=>'m',
    'b'=>'b',
    'g'=>'g',
    'd'=>'d',
    'ɖ'=>'ɖ',
    'l'=>'l',
    't'=>'l',
    'ɣ'=>'k',
    'k'=>'k',
    'ʈ'=>'ʈ',
    'ɭ'=>'ʈ'
  }

  # String containing all vowels
  VOWELS = 'aioue'

  # String containing all consonants
  CONSONANTS = (CONSONANT_MAP.keys + CONSONANT_MAP.values).uniq.join

  def morphemes str
    ## 
    # Pulls morphemes (based on the CVC rule) from the given string
    re = Regexp.new "([#{CONSONANTS}])?([#{VOWELS}]+)([#{CONSONANTS}])?"
    str.scan re
  end

  def make_char_glyph morpheme, canvas = nil
    ##
    # Creates a glyph for the given morpheme.
    # If a canvas is specified, increases the width of the canvas as needed
    # and paints the image onto it
    # Returns an instance of Image
    consonant = CONSONANT_MAP[morpheme[0]]
    vowels = morpheme[1].split('')
    consonant2 = CONSONANT_MAP[morpheme[2]]

    dir = GLYPH_DIR + File::SEPARATOR

    v1img = Image.open(dir + vowels[0] + '.png', 'png')
    v2img = nil
    c2img = nil

    if(consonant == nil)
      # assume this is a phoneme of the form VC
      image = v1img
    else
      image = Image.open(dir + consonant + '.png', 'png')
      image = image.composite(v1img) # append vowel
    end

    if(vowels[1] != nil)
      v2img = Image.open(dir + vowels[1] + '.png')

      # cut me in two
      w = v2img['width']
      h = v2img['height']
      v2img.crop("#{w}x#{h}+#{w/2}+0")

      # append second vowel
      image = image.composite(v2img) do |c|
        c.gravity 'NorthEast'
      end
    end
   
    if consonant2 != nil
      c2img = Image.open(dir + consonant2 + '.png')
      c2img.flip
      image = image.composite(c2img)
    end

    if canvas != nil
      path = Dir.tmpdir + File::SEPARATOR + SecureRandom.hex + 'glyph.png'
      # TODO: Could not easily use +append function; will need to research more
      `convert #{canvas.path} #{image.path} +append #{path}`
      image = Image.open(path)
    end
    return image
  end

  def valid_word word
    word.each_char do |c|
      if CONSONANT_MAP[c] == nil && VOWELS.index(c) == nil
        puts "Found invalid phoneme: #{c}"
        return false
      end
    end
    true
  end

  def transcribe word, output
    ##
    # Given a word, written in the IPA, writes to the specified output file
    # return: boolean - whether or not it was successful

    if not valid_word(word)
      return false
    end

    glyph = nil
    morphemes(word).each{|morpheme|
      glyph = make_char_glyph(morpheme, glyph)
    }

    if glyph == nil
      return false
    end

    glyph.write output
    true
  end
  
  module_function :transcribe
  module_function :morphemes
  module_function :make_char_glyph
  module_function :valid_word
end