offsetBy method
provides an offset relative to this one.
zoom
the zoom of the offset. For example, for a tile size of 256 and
offset of 0, providing a zoom
of -1 will produce an offset with
tile size 512 and zoomOffset of -1
Implementation
TileOffset offsetBy({required int zoom}) {
if (zoom == 0) {
return this;
}
assert(zoom < 0);
return TileOffset(zoomOffset: zoomOffset + zoom);
}