dart - How to listen focus change in flutter?

Question

In Android, we can call setOnFocusChangeListener(), do something in onFocusChanged() method, but flutter does not provider onFocus() interface like onTap() in GestureDetector or onKey() in RawKeyboardListener.

I have read flutter api about focus, https://docs.flutter.io/flutter/widgets/FocusManager-class.html but I can't find a way to realize my request, anyone who can give me a hand?

Answer 1

In addtion you can use Focus widget.

Focus(
  child: TextFormField(...),
  onFocusChange: (hasFocus) {
    if(hasFocus) {
      // do stuff
    }
  },
)