def pixel_to_size_ratio(self):
        """Calculates the ratio between pixel and OpenGL distances

        OpenGL keeps its own coordinate system. This method can be used to transform between pixel and OpenGL
        coordinates.

        :return: pixel/size ratio
        """
        left, right, _, _ = self.get_view_coordinates()
        width = right - left
        display_width = self.get_allocation().width
        return display_width / float(width)
Calculates the ratio between pixel and OpenGL distances

        OpenGL keeps its own coordinate system. This method can be used to transform between pixel and OpenGL
        coordinates.

        :return: pixel/size ratio