hitTestSelf method
Override this method if this render object can be hit even if its children were not hit.
Returns true if the specified position should be considered a hit
on this render object.
The caller is responsible for transforming position from global
coordinates to its location relative to the origin of this RenderBox.
This RenderBox is responsible for checking whether the given position is
within its bounds.
Used by hitTest. If you override hitTest and do not call this function, then you don't need to implement this function.
Implementation
@override
bool hitTestSelf(Offset screenOffset) => true;