function from_canvas_coords({ x, y }) {
	const rect = window.canvas_bounding_client_rect;
	return {
		clientX: ~~(x / main_canvas.width * rect.width + rect.left),
		clientY: ~~(y / main_canvas.height * rect.height + rect.top),
	};
}
@param {{ x: number, y: number }} canvas_point
@returns {{ clientX: number, clientY: number }} client coordinates