How to detect when a TextField is selected in Flutter? - keyboard

Question

I have a Flutter TextField which gets covered by the soft keyboard when the field is selected. I need to scroll the field up and out of the way when the keyboard is displayed. This is a pretty common problem and a solution is presented in this StackOverflow post.
I think I have the ScrollController part figured out but how do I detect when the TextField has been selected? There doesn't appear to be any event method (e.g. onFocus(), onSelected(), onTap(), etc).
I tried wrapping the TextField in a GestureDetector but that didn't work either -- apparently the event was never captured.
new GestureDetector(
child: new TextField(
decoration: const InputDecoration(labelText: 'City'),
),
onTap: () => print('Text Selected'),
),
This is such a basic requirement that I know there must be an easy solution.

Answer 1

I suppose you are looking for FocusNode.
To listen to focus change, you can add a listner to the FocusNode and specify the focusNode to TextField.
Example:
class TextFieldFocus extends StatefulWidget {
#override
_TextFieldFocusState createState() => _TextFieldFocusState();
}
class _TextFieldFocusState extends State<TextFieldFocus> {
FocusNode _focus = FocusNode();
TextEditingController _controller = TextEditingController();
#override
void initState() {
super.initState();
_focus.addListener(_onFocusChange);
}
#override
void dispose() {
super.dispose();
_focus.removeListener(_onFocusChange);
_focus.dispose();
}
void _onFocusChange() {
debugPrint("Focus: ${_focus.hasFocus.toString()}");
}
#override
Widget build(BuildContext context) {
return new Container(
color: Colors.white,
child: new TextField(
focusNode: _focus,
),
);
}
}
This gist represents how to ensure a focused node to be visible on the ui.

Answer 2

To be notified about a focus event, you can avoid manually managing widget's state, by using the utility classes FocusScope, Focus.
From the docs (https://api.flutter.dev/flutter/widgets/FocusNode-class.html):
Please see the Focus and FocusScope widgets, which are utility widgets that manage their own FocusNodes and FocusScopeNodes, respectively. If they aren't appropriate, FocusNodes can be managed directly.
Here is a simple example:
FocusScope(
child: Focus(
onFocusChange: (focus) => print("focus: $focus"),
child: TextField(
decoration: const InputDecoration(labelText: 'City'),
)
)
)

Answer 3

The easiest and simplest solution is to add the onTap method on TextField.
TextField(
onTap: () {
print('Editing stated $widget');
},
)

Answer 4

There is another way if your textfield needs to be disabled for some purpose like mine. for that case, you can wrap your textField with InkWell like this,
InkWell(
onTap: () {
print('clicked');
},
child: TextField(
enabled: false,
),
);