Contents

module BMP
  module Utils

    extend self

    # @return [Integer]
    def calc_image_data_size(arg_width, arg_height)
      ((BMP::BITS_PER_PIXEL * arg_width ) / 32.0).ceil * 4 * arg_height
    end

    def int_to_octets_string_endian_little(int)
      [int].pack("V").each_byte.map {|b| b.to_s(16).rjust(2, '0')}.join(':')
    end

    def octets_string_endian_little_to_int(octets_str)
      octets_str.split(':').map {|o| o.to_i(16).chr}.join.unpack('V').first
    end

    # @return [Integer]
    def calc_file_size(img_size, header_size=BMP::HEADER_SIZE)
      img_size + header_size
    end

    def pixel_array_template(arg_width, arg_height)
      Array.new(arg_height) {Array.new(arg_width) {nil}}
    end

    def write_pixel_array(img_px)
      str = ''

      img_px.reverse_each do |row|
        row.each do |color|
          str << pixel_binstring(color)
        end
      end

      return str
    end

    def pixel_binstring(rgba_string)
      raise ArgumentError unless rgba_string =~ /\A\h{8}\z/
      [rgba_string].pack("H*")
    end

    def parse_image(img_in)
      img_width             = img_in.width
      img_height            = img_in.height
      img_data_size         = calc_image_data_size(img_width, img_height)
      img_file_size         = calc_file_size(img_data_size)
      img_pixels            = pixel_array_template(img_width, img_height)

      img_height.times do |row|
        img_width.times do |col|
          rgba = ChunkyPNG::Color.to_hex(img_in.get_pixel(row,col), true)[1..-1]
          rr, gg, bb, aa = rgba.scan(/../)
          img_pixels[col][row] = [bb,gg,rr,aa].join

          #puts row.to_s + ',' + col.to_s + ' => ' + rgba.inspect if @debug
        end
      end

      hash = {}
      hash[:file_size]     = img_file_size
      hash[:image_size]    = img_data_size
      hash[:image_width]   = img_width
      hash[:image_height]  = img_height
      hash[:pixel_array]   = write_pixel_array(img_pixels)

      hash
    end

  end
end

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
bmp-ruby-0.1.1	lib/bmp/utils.rb