Class: EXIFR::TIFF::IFD

Inherits:

Object

• Object
• EXIFR::TIFF::IFD

show all

Defined in:

lib/exifr/tiff.rb

Overview

Instance Attribute Summary (collapse)

• - (Object) fields readonly

  Returns the value of attribute fields.

• - (Object) offset readonly

  Returns the value of attribute offset.

• - (Object) type readonly

  Returns the value of attribute type.

Instance Method Summary (collapse)

• - (Object) height
• - (IFD) initialize(data, offset = nil, type = :image) constructor

  A new instance of IFD.

• - (Object) inspect
• - (Object) method_missing(method, *args)
• - (Object) next
• - (Boolean) next?
• - (Object) to_hash
• - (Object) to_yaml_properties
• - (Object) width

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# File 'lib/exifr/tiff.rb', line 430

def initialize(data, offset = nil, type = :image)
  @data, @offset, @type, @fields = data, offset, type, {}

  pos = offset || @data.readlong(4)
  num = @data.readshort(pos)
  pos += 2

  num.times do
    add_field(Field.new(@data, pos))
    pos += 12
  end

  @offset_next = @data.readlong(pos)
rescue
  @offset_next = 0
end

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# File 'lib/exifr/tiff.rb', line 447

def method_missing(method, *args)
  super unless args.empty? && TAGS.include?(method.to_s)
  to_hash[method]
end

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# File 'lib/exifr/tiff.rb', line 428

def fields
  @fields
end

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# File 'lib/exifr/tiff.rb', line 428

def offset
  @offset
end

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# File 'lib/exifr/tiff.rb', line 428

def type
  @type
end

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# File 'lib/exifr/tiff.rb', line 453

def height; image_length; end

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# File 'lib/exifr/tiff.rb', line 467

def inspect
  to_hash.inspect
end

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# File 'lib/exifr/tiff.rb', line 475

def next
  IFD.new(@data, @offset_next) if next?
end

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# File 'lib/exifr/tiff.rb', line 471

def next?
  @offset_next != 0 && @offset_next < @data.size
end

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# File 'lib/exifr/tiff.rb', line 455

def to_hash
  @hash ||= @fields.map do |key,value|
    if value.nil?
      {}
    elsif IFD_TAGS.include?(key)
      value.to_hash
    else
      {key => value}
    end
  end.inject { |m,v| m.merge(v) } || {}
end

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# File 'lib/exifr/tiff.rb', line 479

def to_yaml_properties
  ['@fields']
end

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# File 'lib/exifr/tiff.rb', line 452

def width; image_width; end