1. override
double getMaxIntrinsicWidth(double height, int childCount)

Returns the smallest width beyond which increasing the width never decreases the preferred height.

Override this to provide a more efficient or more correct solution. The default implementation actually instantiates a grid specification and measures the grid at the given height and child count.

For more details on implementing this method, see RenderBox.computeMaxIntrinsicWidth.

Source 

@override
double getMaxIntrinsicWidth(double height, int childCount) {
  return maxTileWidth * childCount;
}