pub fn pan(
centre_longitude: f64,
centre_latitude: f64,
zoom: f64,
dx_px: f64,
dy_px: f64,
tile_size: u32,
) -> (f64, f64)Expand description
Apply a pan: the user dragged the visible map by (dx_px, dy_px)
pixels. Returns the new camera centre.
Sign convention: a positive dx_px means “drag right” — the
content under the finger moves right, so the camera moves left
in geo space and longitude decreases. Same for dy_px /
latitude: drag down → camera moves up → latitude increases.