rebuildIfNecessary method Null safety
Invoke the callback supplied via updateCallback.
Typically this results in ConstrainedLayoutBuilder.builder being called during layout.
Implementation
void rebuildIfNecessary() {
assert(_callback != null);
if (_needsBuild || constraints != _previousConstraints) {
_previousConstraints = constraints;
_needsBuild = false;
invokeLayoutCallback(_callback!);
}
}