Class: Branding::PNG::Imagedata

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/branding/png.rb

Overview

Private class for holding and deflating image data

Instance Method Summary collapse

Constructor Details

#initialize(data: nil, scanline_width: 0, color_channels: 3) ⇒ Imagedata

Returns a new instance of Imagedata.



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# File 'lib/branding/png.rb', line 17

def initialize(data: nil, scanline_width: 0, color_channels: 3)
  @scanline_width = scanline_width
  @color_channels = color_channels

  zstream = Zlib::Inflate.new
  zstream << data
  @inflated = zstream.finish
  zstream.close
end

Instance Method Details

#each ⇒ Object

yields byte



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# File 'lib/branding/png.rb', line 29

def each
  @inflated.each_byte do |byte|
    yield byte
  end
end

#each_pixel ⇒ Object 



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# File 'lib/branding/png.rb', line 51

def each_pixel
  each_scanline do |scanline|
    scanline.each_slice(@color_channels) do |*rgba|
      yield Pixel.new(*rgba)
    end
  end
end

#each_scanline ⇒ Object 



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# File 'lib/branding/png.rb', line 35

def each_scanline
  # the number of bytes is + 1 because of the filter byte
  bytes_in_scanline = @scanline_width * @color_channels + 1

  previous_scanline = nil

  each_slice(bytes_in_scanline) do |scanline|
    filter_bit, *rest = *scanline
    filter = Filter.new(filter_bit, rest, previous_scanline, @color_channels)

    recon = filter.reconstructed_scanline
    yield recon
    previous_scanline = recon
  end
end