Module: Colorpress

Defined in:
lib/colorpress.rb,
lib/colorpress/version.rb

Constant Summary collapse

VERSION = 
'2.0.0'

Class Method Summary collapse

Class Method Details

.decode(image_name, output_name = nil, cleanup = true) ⇒ Object

Decode a file from PNG format.

Parameters:

  • image_name (String) —

    the name of the image to decode, ex: ‘filename.txt.png’

  • output_name (String, nil) (defaults to: nil) —

    the name of the output file (no extension needed), ex: ‘my_file’

  • cleanup (Boolean) (defaults to: true) —

    whether to delete PNG file after decoding



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# File 'lib/colorpress.rb', line 38

def self.decode(image_name, output_name=nil, cleanup=true)
  output_name = image_name[0...-4] unless output_name # Remove .png extension
  image = ChunkyPNG::Image.from_file(image_name)

  write_data(output_name, '', true) # Make sure the output file is empty

  bytes = []
  (0..image.dimension.height-1).each do |y|
    (0..image.dimension.width-1).each do |x|
      # It's either red, green, or blue, so add them all
      bytes << ChunkyPNG::Color.r(image[x, y]) +
        ChunkyPNG::Color.g(image[x, y]) +
        ChunkyPNG::Color.b(image[x, y])
    end
    write_data(output_name, bytes)
    bytes = []
  end

  write_data(output_name, bytes) if bytes.any? # Write if any bytes still in array

  File.delete(image_name) if cleanup
end

.encode(file_name, output_name = nil, min_width = 50) ⇒ Object

Encode a file to PNG format.

Parameters:

  • file_name (String) —

    the name of the file to encode

  • output_name (String, nil) (defaults to: nil) —

    the optional name of the output file

  • min_width (Integer) (defaults to: 50) —

    the minimum width of the image, in pixels



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# File 'lib/colorpress.rb', line 10

def self.encode(file_name, output_name=nil, min_width=50)
  file_size = File.stat(file_name).size
  # Increase width until it divides number of bytes evenly
  while file_size % min_width != 0
    min_width += 1
  end
  image = ChunkyPNG::Image.new(min_width, file_size/min_width)

  y = 0
  read_bytes(file_name, min_width) do |buffer|
    unpacked_data = buffer.unpack('C*')
    unpacked_data.each_with_index do |value, index|
      # Randomly pick between red/green/blue
      rgb = [0, 0, 0]
      rgb[(rand * 3).to_i] = value
      image[index, y] = ChunkyPNG::Color.rgb(*rgb)
    end
    y += 1
  end

  image.save(output_name.nil? ? file_name + '.png' : output_name)
end