Module: RubyIdenticon

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

Constant Summary collapse

DEFAULT_PARAMETERS =

the default paramters used when creating identicons

background_color: (Integer, default 0) the background color of the identicon in rgba notation (e.g. xffffffff for white) border_size: (Integer, default 35) the size in pixels to leave as an empty border around the identicon image grid_size: (Integer, default 7) the number of rows and columns in the identicon, minimum 4, maximum 9 square_size: (Integer, default 50) the size in pixels of each square that makes up the identicon key: (String) a 16 byte key used by siphash when calculating the hash value (see note below)

varying the key ensures uniqueness of an identicon for a given title, it is assumed desirable for different applications to use a different key.

{
  border_size: 35,
  square_size: 50,
  grid_size: 7,
  background_color: ChunkyPNG::Color::TRANSPARENT,
  key: "\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xAA\xBB\xCC\xDD\xEE\xFF"
}
VERSION = 
"0.0.3"

Class Method Summary collapse

Class Method Details

.create(title, options = {}) ⇒ Object

create an identicon png and return it as a binary string

Example:

>> RubyIdenticon.create("identicons are great!")
=> binary blob (String)

Arguments:

title: (String)
options: (Hash)



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# File 'lib/ruby_identicon.rb', line 99

def self.create(title, options = {})
  options = DEFAULT_PARAMETERS.merge(options)
  
  raise "title cannot be nil" if title == nil
  raise "key is nil or less than 16 bytes" if options[:key] == nil || options[:key].length < 16
  raise "grid_size must be between 4 and 9" if options[:grid_size] < 4 || options[:grid_size] > 9
  raise "invalid border size" if options[:border_size] < 0
  raise "invalid square size" if options[:square_size] < 0

  hash = SipHash.digest(options[:key], title)

  png = ChunkyPNG::Image.new((options[:border_size] * 2) + (options[:square_size] * options[:grid_size]),
   (options[:border_size] * 2) + (options[:square_size] * options[:grid_size]), options[:background_color])

  # set the foreground color by using the first three bytes of the hash value
  color = ChunkyPNG::Color.rgba((hash & 0xff), ((hash >> 8) & 0xff), ((hash >> 16) & 0xff), 0xff)

  # remove the first three bytes that were used for the foreground color
  hash >>= 24

  sqx = sqy = 0
  for i in 0..(options[:grid_size] * ((options[:grid_size]+1) / 2))
    if hash & 1 == 1
      x = options[:border_size] + (sqx * options[:square_size])
      y = options[:border_size] + (sqy * options[:square_size])

      # left hand side
      png.rect(x, y, x + options[:square_size], y + options[:square_size], color, color)

      # mirror right hand side
      x = options[:border_size] + ((options[:grid_size] - 1 - sqx) * options[:square_size])
      png.rect(x, y, x + options[:square_size], y + options[:square_size], color, color)
    end

    hash >>= 1
    sqy += 1
    if sqy == options[:grid_size]
      sqy = 0
      sqx += 1
    end
  end

  png.to_blob :color_mode => ChunkyPNG::COLOR_INDEXED
end

.create_and_save(title, filename, options = {}) ⇒ Object

create an identicon png and save it to the given filename

Example:

>> RubyIdenticon.create_and_save("identicons are great!", "test_identicon.png")
=> result (Boolean)

Arguments:

title: (String)
filename: (String)
options: (Hash)



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# File 'lib/ruby_identicon.rb', line 80

def self.create_and_save(title, filename, options = {})
  raise "filename cannot be nil" if filename == nil

  blob = create(title, options)
  return false if blob == nil

  File.open(filename, "wb") do |f| f.write(blob) end
end