Class: IPTC::JPEG::Image

Inherits:
Object
  • Object
show all
Defined in:
lib/iptc/jpeg/image.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data_name, content, quick = true) ⇒ Image

Real constructor. Should never be called directly take a “data name” that is used for error reporting.



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# File 'lib/iptc/jpeg/image.rb', line 31

def initialize data_name, content, quick=true
  @logger = Logger.new(STDOUT)
  @logger.datetime_format = "%H:%M:%S"
  @logger.level = $DEBUG?(Logger::DEBUG):(Logger::INFO)

  @data_name = data_name
  @content = content

  @position = 0

  if MARKERS[read(2)]!="SOI"
    raise  NotJPEGFileException.new("Not JPEG data: #{@data_name}")
  end

  @markers = Array.new()

  begin

    catch(:end_of_metadata) do
      while true
        @markers << read_marker
      end
    end
  
  rescue Exception=>e
    @logger.info "Exception in data #{@data_name}:\n"+e.to_s
    raise e
  end
  # Markers all read
  # move back
  seek(-2)

  # in full mode, read the rest
  if !quick
    @data = read_rest
  end

  @values = MultipleHash.new

  @markers.each do |marker|
    # puts "processing marker: #{marker.inspect}"
    marker.parse
    # puts marker.valid?
    @values.add(marker, marker.values)
  end
end

Instance Attribute Details

#values ⇒ Object (readonly)

Array of MultipleHashItem objects



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# File 'lib/iptc/jpeg/image.rb', line 10

def values
  @values
end

Class Method Details

.from_blob(blob, quick = true) ⇒ Object

creates a JPEG image from a data blob and does a “quick” load (Only the metadata are loaded, not the whole file).



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# File 'lib/iptc/jpeg/image.rb', line 14

def Image.from_blob blob, quick=true
  return Image.new("Data blob", blob, true)
end

.from_file(filename, quick = true) ⇒ Object

creates a JPEG image from a file and does a “quick” load (Only the metadata are loaded, not the whole file).



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# File 'lib/iptc/jpeg/image.rb', line 19

def Image.from_file filename, quick=true
  content = nil
  raise "File #{filename} not found" if !File.exists?(filename)
  File.open(filename) do |f|
    f.binmode
    content = f.read
  end
  return Image.new(filename, content, quick)        

end

Instance Method Details

#l(message) ⇒ Object 



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# File 'lib/iptc/jpeg/image.rb', line 86

def l message
  @logger.debug message
end

#read(count) ⇒ Object 



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# File 'lib/iptc/jpeg/image.rb', line 78

def read(count)
  @position += count
  return @content[@position-count...@position]
end

#read_marker ⇒ Object 



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# File 'lib/iptc/jpeg/image.rb', line 103

def read_marker
  type = read(2)
  # finished reading all the metadata
  throw :end_of_metadata if MARKERS[type]=='SOS'
  size = read(2)
  data = read(size.unpack('n')[0]-2)

  return Marker.NewMarker(MARKERS[type], type+size+data, @logger)
end

#read_rest ⇒ Object 



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# File 'lib/iptc/jpeg/image.rb', line 112

def read_rest
  rest = @content[@position..-1]
  return Marker.new("BIN",rest)
end

#seek(count) ⇒ Object 



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# File 'lib/iptc/jpeg/image.rb', line 82

def seek(count)
  @position += count
end

#to_s ⇒ Object 



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# File 'lib/iptc/jpeg/image.rb', line 116

def to_s
	"Image #{@data_name}:\n" +
	@markers.map{ |m| m.to_s  }.join("\n")
end

#write(data_name) ⇒ Object

write the image to the disk



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# File 'lib/iptc/jpeg/image.rb', line 91

def write data_name
  f = File.open(data_name,"wb+")
  f.print "\xFF\xD8"

  @markers.each do |marker|
    f.print marker.to_binary
  end
  f.print @data.to_binary
  f.close

end