Toggle password visibility using Gesture Detector - flutter

Question

I'm new to flutter and following a tutorial where using an icon, the visibility of a password changes from hidden to visible.
I saw some cases where IconButton is used but even though I tried that method I'm still getting red lines everywhere. I wish to know where exactly the problem is unless it's a version related issue.
the variables are defined as such:
late String _password, _email;
bool _isObscure = true;
The Form Field
Widget _showPasswordInput() {
return TextFormField(
onSaved: (val) => _password = val!,
obscureText: _isObscure,
decoration: const InputDecoration(
// border: OutlineInputBorder(),
suffixIcon: GestureDetector(
onTap: () {
setState(() {
_isObscure = !_isObscure;
});
},
child: Icon(
_isObscure ? Icons.visibility : Icons.visibility_off,
),
),
labelText: 'Password',
hintText: 'Enter valid password, min: 6 chars',
icon: Icon(Icons.lock),
),
validator: (value) {
if (value!.isEmpty) {
return 'Please enter some text';
}
return null;
},
);
}
How it's used in the build
Widget build(BuildContext context) {
return Scaffold(
body: Container(
padding: const EdgeInsets.symmetric(horizontal: 20),
child: Center(
child: SingleChildScrollView(
child: Form(
key: _formKey,
child: Column(children: <Widget>[
_showRegisterButton(),
]))),
)),
);
}

Answer 1

Inside InputDecoration, data is changing on runtime, therefore it cannot be const
decoration: InputDecoration(
// border: OutlineInputBorder(),
suffixIcon: GestureDetector(
onTap: () {
setState(() {
_isObscure = !_isObscure;
});
},
child: Icon(
_isObscure ? Icons.visibility : Icons.visibility_off,
),
),
and create a method like myTextFiled(BuildContext context) => TextFormField(....)