Function SwapDirection

src/viewport.cpp:2925–2942

* Check if the direction of start and end tile should be swapped based on * the dragging-style. Default directions are: * in the case of a line (HT_RAIL, HT_LINE): DIR_NE, DIR_NW, DIR_N, DIR_E * in the case of a rect (HT_RECT, HT_POINT): DIR_S, DIR_E * For example dragging a rectangle area from south to north should be swapped to * north-south (DIR_S) to obtain the same results with less cod

 * @return boolean value which when true means start/end should be swapped
 */
static bool SwapDirection(HighLightStyle style, TileIndex start_tile, TileIndex end_tile)
{
	uint start_x = TileX(start_tile);
	uint start_y = TileY(start_tile);
	uint end_x = TileX(end_tile);
	uint end_y = TileY(end_tile);

	switch (style & HT_DRAG_MASK) {
		case HT_RAIL:
		case HT_LINE: return (end_x > start_x || (end_x == start_x && end_y > start_y));

		case HT_RECT:
		case HT_POINT: return (end_x != start_x && end_y < start_y);
		default: NOT_REACHED();
	}

	return false;
}

/**
 * Calculates height difference between one tile and another.