class ChunkyPNG::Vector

def self.multiple_from_array(source)
  return [] if source.empty?
  if source.first.is_a?(Numeric) || source.first =~ /^\d+$/
    raise ArgumentError, "The points array is expected to have an even number of items!" if source.length % 2 != 0
    points = []
    source.each_slice(2) { |x, y| points << ChunkyPNG::Point.new(x, y) }
    return points
  else
    source.map { |p| ChunkyPNG::Point(p) }
  end
end