Method: Origami::Stream#set_predictor

Defined in:
lib/origami/stream.rb

#set_predictor(predictor, colors: 1, bitspercomponent: 8, columns: 1) ⇒ Object

Set predictor type for the current Stream. Applies only for LZW and FlateDecode filters.



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# File 'lib/origami/stream.rb', line 227

def set_predictor(predictor, colors: 1, bitspercomponent: 8, columns: 1)
    filters = self.filters

    layer = filters.index(:FlateDecode) or filters.index(:LZWDecode)
    if layer.nil?
        raise InvalidStreamObjectError, 'Predictor functions can only be used with Flate or LZW filters'
    end

    params = Filter::LZW::DecodeParms.new
    params[:Predictor] = predictor
    params[:Colors] = colors if colors != 1
    params[:BitsPerComponent] = bitspercomponent if bitspercomponent != 8
    params[:Columns] = columns if columns != 1

    set_decode_params(layer, params)

    self
end