Class: IPTC::JPEG::Marker

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

Overview

Marker

A Jpeg marker, generic class used by all others markers

Constant Summary collapse

@@missing = 
[]

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(type, data) ⇒ Marker

Returns a new instance of Marker.



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# File 'lib/iptc/jpeg/marker.rb', line 42

def initialize(type, data)
    @logger = Logger.new(STDOUT)
    @logger.datetime_format = "%H:%M:%S"
    @logger.level = $DEBUG?(Logger::DEBUG):(Logger::INFO)
    
    @original_content = data
  
    @content = StringIO.new(data)
    @type = @content.read(2)
    @size = @content.read(2).unpack('n')[0]-2
  
    if !valid?
        raise InvalidBlockException.new("In block #{self.class}: invalid marker\n#{@content.read(20)}")
    end

    @prefix = self.class.to_s
  
    @prefix = @prefix[@prefix.rindex("::")+2..-7]
    if @prefix==""
        @prefix= 'Marker'
    end

    @values = Hash.new
end

Instance Attribute Details

#prefix ⇒ Object (readonly)

Returns the value of attribute prefix.



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# File 'lib/iptc/jpeg/marker.rb', line 8

def prefix
  @prefix
end

#values ⇒ Object (readonly)

Returns the value of attribute values.



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# File 'lib/iptc/jpeg/marker.rb', line 9

def values
  @values
end

Class Method Details

.NewMarker(type, data, logger) ⇒ Object

The NewMarker constructor method. Inspect the object space in order to find something usable later



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# File 'lib/iptc/jpeg/marker.rb', line 15

def Marker.NewMarker(type, data, logger)
  marker_class = "#{type}Marker"
    if JPEG::Markers.constants.include?(marker_class.to_sym)
        return JPEG::Markers.const_get(marker_class).new(type, data)
    else
      if !@@missing.include?(type)
        logger.debug "Marker #{type+"Marker"} not found." if logger!=nil
        @@missing << type
      end
    end
    return Marker.new(type,data)
end

Instance Method Details

#l(message) ⇒ Object 



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# File 'lib/iptc/jpeg/marker.rb', line 28

def l message
  @logger.debug message
end

#parse ⇒ Object

parse the data



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# File 'lib/iptc/jpeg/marker.rb', line 75

def parse
    return []
end

#properties ⇒ Object

returns the available properties for the given tag



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# File 'lib/iptc/jpeg/marker.rb', line 80

def properties
    return []
end

#read(count) ⇒ Object 



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# File 'lib/iptc/jpeg/marker.rb', line 66

def read count
    return @content.read(count)
end

#to_binary(data = nil) ⇒ Object

binary serialization transform the marker to its final form



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# File 'lib/iptc/jpeg/marker.rb', line 34

def to_binary data=nil
    if data!=nil
        return @type+[data.length+2].pack('n')+data
    else
        return @original_content
    end
end

#valid? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/iptc/jpeg/marker.rb', line 69

def valid?
    return true
end