SingleChildScrollView is not working or I'm doing something wrong

Question

I have a login page with two textField when I have to type keyboard hides login Button and other fields.

Widget build(BuildContext context) {
return Scaffold(
  resizeToAvoidBottomPadding: false,
  body: Container(
    child: SingleChildScrollView(
     //color: Colors.white,
    padding: EdgeInsets.only(top: 120.0, right: 48.0, left: 48.0, bottom: 20.0),
    child: Column(
      children: <Widget>[
        new Image.asset('assets/images/login.png',height: 170, width: 170,),
        SizedBox(height: 40.0,),
        _input("Roll Number",_rollnumberController, false),
        SizedBox(height: 20.0,),
        _input("Phone Number",_phonenumberController, false),
        SizedBox(height: 40.0,),
        buildLogInButton(),
      ],
    ),
  ),
  ),
);
}

Answer 1

I have changed the solution to using the keyboard visibility to decide when to scroll up or down. I am using a package called flutter_keyboard_visibility.

I have written an example using most of your code, but replacing your specific inputs and login button with generic ones:

Import

import 'package:flutter_keyboard_visibility/flutter_keyboard_visibility.dart';

Class

ScrollController _scrollController = ScrollController();
FocusNode _focusNodePassword = FocusNode();

@override
void initState() {
  KeyboardVisibilityNotification().addNewListener(
    onChange: (bool visible) {
      visible ? scrollToBottom() : scrollToTop();
    },
  );
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: LayoutBuilder(
      builder: (BuildContext context, BoxConstraints viewportConstraints) {
        return SingleChildScrollView(
          controller: _scrollController,
          padding: EdgeInsets.only(
            top: 120.0, right: 48.0, left: 48.0, bottom: 20.0),
          child: Column(
            children: <Widget>[
              Container(height: 170, width: 170, color: Colors.blue,),
              SizedBox(height: 40.0,),
              TextFormField(
                decoration: InputDecoration(
                  labelText: 'Email'
                ),
                onEditingComplete: () {
                  _focusNodePassword.requestFocus();
                }
              ),
              SizedBox(height: 20.0,),
              TextFormField(
                decoration: InputDecoration(
                  labelText: 'Password'
                ),
                focusNode: _focusNodePassword,
                onEditingComplete: () {
                  FocusScope.of(context).requestFocus(new FocusNode());
                }
              ),
              SizedBox(height: 40.0,),
              RaisedButton(
                child: Text('Login'),
                onPressed: () {
                  _scrollController.animateTo(0,
                    duration: Duration(milliseconds: 200),
                    curve: ElasticOutCurve()
                  );
                },
              ),
            ],
          ),
        );
      }
    ),
  );
}

void scrollToTop() {
  Timer(Duration(milliseconds: 50), (){
    _scrollController.animateTo(0,
      duration: Duration(milliseconds: 400),
      curve: ElasticOutCurve()
    );
  });
}

void scrollToBottom() {
  Timer(Duration(milliseconds: 50), (){
    _scrollController.animateTo(2000,
      duration: Duration(milliseconds: 400),
      curve: ElasticOutCurve()
    );
  });
}