Module: FlickrCli::ImageCutter

Defined in:
lib/image_cutter.rb

Constant Summary collapse

CHARS = 
[ 'W', 'M', '$', '@', '#', '%', '^', 'x', '*', 'o', '=', '+',':', '~', '.', ' ' ]
FONT_ROWS = 
8
FONT_COLS = 
4

Class Method Summary collapse

Class Method Details

.convert_to_ascii(file) ⇒ Object 



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# File 'lib/image_cutter.rb', line 8

def self.convert_to_ascii(file)

  img = Magick::Image.read(file).first

  # Resize too-large images. The resulting image is going to be
  # about twice the size of the input, so if the original image is too
  # large we need to make it smaller so the ASCII version won't be too
  # big. The `change_geometry' method computes new dimensions for an
  # image based on the geometry argument. The '320x320>' argument says
  # "If the image is too big to fit in a 320x320 square, compute the
  # dimensions of an image that will fit, but retain the original aspect
  # ratio. If the image is already smaller than 320x320, keep the same
  # dimensions."
  img.change_geometry('728x728>') do |cols, rows|
    img.resize!(cols, rows) if cols != img.columns || rows != img.rows
  end

  # Compute the image size in ASCII "pixels" and resize the image to have
  # those dimensions. The resulting image does not have the same aspect
  # ratio as the original, but since our "pixels" are twice as tall as
  # they are wide we'll get our proportions back (roughly) when we render.
  pr = img.rows / FONT_ROWS
  pc = img.columns / FONT_COLS
  img.resize!(pc, pr)

  img = img.quantize(16, Magick::GRAYColorspace)
  img = img.normalize

  # Draw the image surrounded by a border. The `view' method is slow but
  # it makes it easy to address individual pixels. In grayscale images,
  # all three RGB channels have the same value so the red channel is as
  # good as any for choosing which character to represent the intensity of
  # this particular pixel.
  border = '+' + ('-' * pc) + '+'
  puts border

  img.view(0, 0, pc, pr) do |view|
    pr.times do |i|
    putc '|'
    pc.times { |j| putc CHARS[view[i][j].red/16] }
    puts '|'
  end

  end
  border
end