# File lib/rubygame/gfx.rb, line 525
  def self.zoom_size( size, zoom )
    w, h = size

    case zoom
    when Array
      zx, zy = zoom.collect { |n| n.to_f }
      SDL::Gfx.zoomSurfaceSize(w, h, zx, zy)
    when Numeric
      zoom = zoom.to_f
      SDL::Gfx.zoomSurfaceSize(w, h, zoom, zoom)
    else
      raise ArgumentError, "Invalid zoom factor: #{zoom.inspect}"
    end
  end