class Magick::RVG::Utility::GraphicContext

def rotate(degrees)
    degrees = Magick::RVG.convert_one_to_float(degrees)
    @gc.rotate(degrees)
    @sx =  Math.cos(GraphicContext.degrees_to_radians(degrees))
    @rx =  Math.sin(GraphicContext.degrees_to_radians(degrees))
    @ry = -Math.sin(GraphicContext.degrees_to_radians(degrees))
    @sy =  Math.cos(GraphicContext.degrees_to_radians(degrees))
    concat_matrix
    nil
end