我正在尝试使用bloc切换屏幕(无状态小部件), 当使用BlocBuilder根据状态输出不同的窗口小部件时,上下文将更改为显示的新窗口小部件。 状态侦听器在新的小部件中被调用。
当状态改变时,我设法显示了一个小部件, 问题是当状态再次更改时,然后更改上下文,并在显示的小部件中调用builder函数。
所以我创建了一个继承的小部件,其中将包含该块,因此我可以从子小部件分派一个事件,使其在父级发生,然后根据状态显示其他小部件。
class SignupViewManager extends InheritedWidget {
final SignupBloc bloc;
final Widget child;
SignupViewManager({Key key,this.child,this.bloc}) : super(key: key,child: child);
static SignupViewManager of(BuildContext context) {
return (context.inheritFromWidgetOfExactType(SignupViewManager) as SignupViewManager);
}
@override
bool updateShouldNotify(SignupViewManager oldWidget) {
return true;
}
}
class SignupHomePage extends StatelessWidget {
final SignupBloc signupBloc = SignupBloc();
SignupHomePage({Key key}) : super(key: key);
@override
Widget build(BuildContext context) {
return SignupViewManager(
bloc: SignupBloc(),child: BlocProvider<SignupBloc>(
builder: (context) => signupBloc,child: BlocBuilder<SignupBloc,SignupState>(
builder: (context,state) => _signupBuilder(context,state),condition: (previousState,state) => _signupCondition(previousState,),)
);
}
Widget _signupBuilder(BuildContext context,SignupState state) {
print("IN SIGNUP MAIN BUILDER $state");
// Changing the UI based on the current state
if (state is SignupInitial) { // Show credentials for initial state
return SignupCredentials();
} else if (state is SavedCredentials) { // Show Agreements after credentials has been saved.
return SignupAgreements(user: state.user);
}
return Text("default");
}
}
class SignupCredentials extends StatelessWidget {
SignupBloc signupBloc;
void _signup(email,password,confirmPassword) {
if(password == confirmPassword) {
signupBloc.add(SaveCredentials(email,password));
} else {
print("passwords do not match");
}
}
Widget _bloc() {
return BlocBuilder<SignupBloc,SignupState>(
builder: (context,state) {
print("IN SIGNUP credentials builder $state");
if(state is SavedCredentials) {
return SignupDetails();
}
return Text("${state.runtimeType}");
},);
}
}
因此,当状态设置为SignupInitial时,应显示SignupCredentials无状态窗口小部件。 然后,当用户输入凭据并提交凭据时,将调度SavedCredentials事件,并应显示SignupAgreements。 但是发生的是SignupCredentials构建器正在接收新状态,而不是SignupHomePage。