Class: Pruim::PBM

Inherits:
Object
  • Object
show all
Includes:
Codec
Defined in:
lib/pruim/pbm.rb

Overview

Tiny PBM parser integrated with Prium codecs.

Instance Method Summary collapse

Methods included from Codec

for_filename, for_filename_name, for_name, new_for_filename, new_for_filename_name, new_for_name, register, #text

Instance Method Details

#can_decode?(stream) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pruim/pbm.rb', line 54

def can_decode?(stream)
  header = stream.gets
  stream.rewind
  return header == "P1\n"
end

#can_encode?(image) ⇒ Boolean

Can only encode monocrome images.

Returns:

  • (Boolean) 


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# File 'lib/pruim/pbm.rb', line 61

def can_encode?(image)      
  return image.mode == :monochrome
end

#decode(stream) ⇒ Object

Read in a pbm file from an io object.



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# File 'lib/pruim/pbm.rb', line 10

def decode(stream)
  header    = stream.gets
  lines     = []
  until stream.eof?
    lines << stream.gets
  end
  data      = []
  image   = nil
  page    = nil
  w, h    = nil, nil
  y       = 0
  comment = ''
  lines.each do |line|
    if line[0] == '#'
      comment << line.chomp.sub(/\A#/, '')
      next
    end
    if !w
      w , h = line.chomp.split(' ').map { |v| v.to_i }
      next
    end
    # Converts 1 to true, rest to false.
    bits = line.chomp.split('').map { |v| (v == '1') }
    data += bits
  end
  image = Image.new(w, h, :mode => :monochrome, :data => data)
  image.comment = comment
  return image
end

#encode(image, stream) ⇒ Object 



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# File 'lib/pruim/pbm.rb', line 40

def encode(image, stream)
  stream.puts("P1")
  stream.puts("##{image.comment}") if image.comment
  stream.puts("#{image.w} #{image.h}")
  page = image.pages.first
  for y in (0...page.h) do
    for x in (0...page.w) do
      white   = page.getpixel!(x, y)
      stream.write(white ? '1' : '0')
    end
    stream.puts()
  end
end

#encode_will_degrade?(image) ⇒ Boolean

Will only save first page of image.

Returns:

  • (Boolean) 


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# File 'lib/pruim/pbm.rb', line 66

def encode_will_degrade?(image)
  return (image.pages.size > 1)
end