Multiple cursor in form's TextFormField flutter

问题

I'm new to flutter & I try to achieve this screen with the below code, in this i'm facing a weird Multiple cursor UI.

Steps to reproduce this issue: click randomly any TextFormField, the soft keyboard pops up & by pressing the back navigation button at bottom the keyboard hides..

when i do this process several times the cursor marks are blinking in each of the TextFormField.

what was the mistake I did! Thanks for your time & help.

import 'package:flutter/material.dart';
import 'package:thought_factory/utils/colors.dart';

class RegisterScreen extends StatefulWidget {
@override
_RegisterScreenState createState() => _RegisterScreenState();
}

class _RegisterScreenState extends State<RegisterScreen> {
static var _keyValidationForm = GlobalKey<FormState>();
TextEditingController _textEditConName = TextEditingController();
TextEditingController _textEditConEmail = TextEditingController();
TextEditingController _textEditConPassword = TextEditingController();
TextEditingController _textEditConConfirmPassword = TextEditingController();
bool isPasswordVisible = false;
bool isConfirmPasswordVisible = false;

@override
void initState() {
isPasswordVisible = false;
isConfirmPasswordVisible = false;
super.initState();
}

@override
Widget build(BuildContext context) {
return Scaffold(
  backgroundColor: AppColors.colorGrey,
  body: SingleChildScrollView(
    child: Padding(
        padding: EdgeInsets.only(top: 32.0),
        child: Column(
          children: <Widget>[
            getWidgetImageLogo(),
            getWidgetRegistrationCard(),
          ],
        )),
  ),
);
}

Widget getWidgetImageLogo() {
return Container(
    alignment: Alignment.center,
    child: Padding(
      padding: const EdgeInsets.only(top: 32, bottom: 32),
      child: Icon(Icons.ac_unit),
    ));
 }

Widget getWidgetRegistrationCard() {
final FocusNode _passwordEmail = FocusNode();
final FocusNode _passwordFocus = FocusNode();
final FocusNode _passwordConfirmFocus = FocusNode();

return Padding(
  padding: const EdgeInsets.only(left: 16.0, right: 16.0),
  child: Card(
    color: Colors.white,
    shape: RoundedRectangleBorder(
      borderRadius: BorderRadius.circular(12.0),
    ),
    elevation: 10.0,
    child: Padding(
      padding: const EdgeInsets.all(16.0),
      child: Form(
        key: _keyValidationForm,
        child: Column(
          children: <Widget>[
            Container(
              alignment: Alignment.center,
              width: double.infinity,
              child: Text(
                'Register',
                style: TextStyle(
                    fontSize: 18.0, color: AppColors.colorBlack),
              ),
            ), // title: login
            Container(
              child: TextFormField(
                controller: _textEditConName,
                keyboardType: TextInputType.text,
                textInputAction: TextInputAction.next,
                validator: _validateUserName,
                onFieldSubmitted: (String value) {
                  FocusScope.of(context).requestFocus(_passwordEmail);
                },
                decoration: InputDecoration(
                    labelText: 'Full name',
                    //prefixIcon: Icon(Icons.email),
                    icon: Icon(Icons.perm_identity)),
              ),
            ), //text field : user name
            Container(
              child: TextFormField(
                controller: _textEditConEmail,
                focusNode: _passwordEmail,
                keyboardType: TextInputType.emailAddress,
                textInputAction: TextInputAction.next,
                validator: _validateEmail,
                onFieldSubmitted: (String value) {
                  FocusScope.of(context).requestFocus(_passwordFocus);
                },
                decoration: InputDecoration(
                    labelText: 'Email',
                    //prefixIcon: Icon(Icons.email),
                    icon: Icon(Icons.email)),
              ),
            ), //text field: email
            Container(
              child: TextFormField(
                controller: _textEditConPassword,
                focusNode: _passwordFocus,
                keyboardType: TextInputType.text,
                textInputAction: TextInputAction.next,
                validator: _validatePassword,
                onFieldSubmitted: (String value) {
                  FocusScope.of(context)
                      .requestFocus(_passwordConfirmFocus);
                },
                obscureText: !isPasswordVisible,
                decoration: InputDecoration(
                    labelText: 'Password',
                    suffixIcon: IconButton(
                      icon: Icon(isPasswordVisible
                          ? Icons.visibility
                          : Icons.visibility_off),
                      onPressed: () {
                        setState(() {
                          isPasswordVisible = !isPasswordVisible;
                        });
                      },
                    ),
                    icon: Icon(Icons.vpn_key)),
              ),
            ), //text field: password
            Container(
              child: TextFormField(
                  controller: _textEditConConfirmPassword,
                  focusNode: _passwordConfirmFocus,
                  keyboardType: TextInputType.text,
                  textInputAction: TextInputAction.done,
                  validator: _validateConfirmPassword,
                  obscureText: !isConfirmPasswordVisible,
                  decoration: InputDecoration(
                      labelText: 'Confirm Password',
                      suffixIcon: IconButton(
                        icon: Icon(isConfirmPasswordVisible
                            ? Icons.visibility
                            : Icons.visibility_off),
                        onPressed: () {
                          setState(() {
                            isConfirmPasswordVisible =
                                !isConfirmPasswordVisible;
                          });
                        },
                      ),
                      icon: Icon(Icons.vpn_key))),
            ),
            Container(
              margin: EdgeInsets.only(top: 32.0),
              width: double.infinity,
              child: RaisedButton(
                color: AppColors.colorAccent,
                textColor: Colors.white,
                elevation: 5.0,
                padding: EdgeInsets.only(top: 16.0, bottom: 16.0),
                child: Text(
                  'Register',
                  style: TextStyle(fontSize: 16.0),
                ),
                onPressed: () {
                  if (_keyValidationForm.currentState.validate()) {
                    _onTappedButtonRegister();
                  }
                },
                shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(25.0)),
              ),
            ), //button: login
            Container(
                margin: EdgeInsets.only(top: 16.0, bottom: 16.0),
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: <Widget>[
                    Text(
                      'Already Register? ',
                    ),
                    InkWell(
                      splashColor: AppColors.colorAccent.withOpacity(0.5),
                      onTap: () {
                        _onTappedTextlogin();
                      },
                      child: Text(
                        ' Login',
                        style: TextStyle(
                            color: AppColors.colorAccent,
                            fontWeight: FontWeight.bold),
                      ),
                    )
                  ],
                ))
          ],
        ),
      ),
    ),
  ),
);
}

String _validateUserName(String value) {
return value.trim().isEmpty ? "Name can't be empty" : null;
}

String _validateEmail(String value) {
Pattern pattern =
    r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
RegExp regex = new RegExp(pattern);
if (!regex.hasMatch(value)) {
  return 'Invalid Email';
} else {
  return null;
}
}

String _validatePassword(String value) {
return value.length < 5 ? 'Min 5 char required' : null;
}

String _validateConfirmPassword(String value) {
return value.length < 5 ? 'Min 5 char required' : null;
}

void _onTappedButtonRegister() {}

void _onTappedTextlogin() {}
}

回答1:

As the OP answered in comment section.

Declare all the focusNode from local variables to global scope that solved the problem.

I'm using focusNode in Widget build(BuildContext context) method. Which is showing multiple cursors.

class _LoginScreenState extends State<LoginScreen> {

@override
  Widget build(BuildContext context) {

    final FocusNode _emailFocus = FocusNode();
    final FocusNode _passwordFocus = FocusNode();

SOLUTION - Declare focusNode Globally.

class _LoginScreenState extends State<LoginScreen> {

  final FocusNode _emailFocus = FocusNode();
  final FocusNode _passwordFocus = FocusNode();

  @override
  Widget build(BuildContext context) {

回答2:

Removed the local scope focusNode from this method.

Widget getWidgetRegistrationCard() {
final FocusNode _passwordEmail = FocusNode(); //removed 
final FocusNode _passwordFocus = FocusNode(); //removed
final FocusNode _passwordConfirmFocus = FocusNode(); //removed
.
. 
.
} 

& declare it globally solved the problem for me.

class RegisterScreen extends StatefulWidget {
@override
_RegisterScreenState createState() => _RegisterScreenState();
}

class _RegisterScreenState extends State<RegisterScreen> {
static var _keyValidationForm = GlobalKey<FormState>();

final FocusNode _passwordEmail = FocusNode();  //added globally
final FocusNode _passwordFocus = FocusNode();  //added globally
final FocusNode _passwordConfirmFocus = FocusNode();  //added globally
.
. 
.

来源：https://stackoverflow.com/questions/56038010/multiple-cursor-in-forms-textformfield-flutter