getSize method

Size getSize (BoxConstraints constraints)

Override this method to return the size of this object given the incoming constraints.

The size cannot reflect the sizes of the children. If this layout has a fixed width or height the returned size can reflect that; the size will be constrained to the given constraints.

By default, attempts to size the box to the biggest size possible given the constraints.

Implementation 

Size getSize(BoxConstraints constraints) => constraints.biggest;