class ChunkyPNG::Image

def self.from_datastream(ds)
  image = super(ds)
  image.metadata = ds.metadata
  return image
end

def initialize(width, height, initial = ChunkyPNG::Color::TRANSPARENT, metadata = {})
  super(width, height, initial)
  @metadata = metadata
  @metadata_compression_treshhold = 300
end

def initialize_copy(other)
  super(other)
  @metdata = other.metadata
end

def metadata_chunks
  metadata.map do |key, value|
    if value.length >= METADATA_COMPRESSION_TRESHOLD
      ChunkyPNG::Chunk::CompressedText.new(key, value)
    else
      ChunkyPNG::Chunk::Text.new(key, value)
    end
  end
end

def to_datastream(constraints = {})
  ds = super(constraints)
  ds.other_chunks += metadata_chunks
  return ds
end