pixelYToTileY method
Converts a pixel Y coordinate to the corresponding tile Y number.
pixelY The pixel Y coordinate to convert
Returns the tile Y coordinate containing this pixel
Implementation
int pixelYToTileY(double pixelY) {
assert(pixelY >= 0, "pixelY ($pixelY) should be >= 0");
assert(pixelY <= _mapSize, "pixelY ($pixelY) should be <= mapSize ($_mapSize)");
return max(min(pixelY / tileSize, scalefactor.scalefactor - 1), 0).floor();
}