Things you shouldn't use Ruby for, #63

color_scaling.rb

# Returns the framebuffer as an array of floats ranging from 0 to 1, ordered
# like [A, R, G, B, A, R, G, B, ..]
def to_a
  red_mask = mask(@header.red_length)
  green_mask = mask(@header.green_length)
  blue_mask = mask(@header.blue_length)
  alpha_mask = mask(@header.alpha_length)

  red_max = (1 << @header.red_length) - 1.0
  green_max = (1 << @header.green_length) - 1.0
  blue_max = (1 << @header.blue_length) - 1.0
  alpha_max = (1 << @header.alpha_length) - 1.0

  format = nil
  case @header.bpp
  when 16
    format = 'v*'
  when 32
    format = 'V*'
  else
    raise InvalidDataError, "Unsupported bpp: #{@header.bpp}"
  end

  data = @framebuffer.unpack(format).collect do |rgb|
    red = ((rgb >> @header.red_offset) & red_mask) / red_max
    green = ((rgb >> @header.green_offset) & green_mask) / green_max
    blue = ((rgb >> @header.blue_offset) & blue_mask) / blue_max
    if @header.alpha_length > 0
      alpha = ((rgb >> @header.alpha_offset) & alpha_mask) / alpha_max
    end
    [alpha, red, green, blue]
  end
  data.flatten
end

def mask(length)
  (1 << length) - 1
end