MapBoard.py 文件源码

def get_dist_to_center(self):
        """
        :return: The distance in meters between the last known position and the position represented by the middle
        of the screen. If no distance can be calculated, it returns -1.
        """
        if self.map is None:
            return -1
        try:
            merc_x, merc_y = self.map.map_coord_to_map_projection(*self.to_local(Window.size[0]/2, Window.size[1]/2))
        except ZeroDivisionError:
            return -1
        lat, lon = Map.to_geographic(merc_x, merc_y)
        lat_last, lon_last = self.last_pos_wgs84
        dist = Map.distance(lat_last, lon_last, lat, lon)
        return dist