testing ensure visible

ensure_visible_test.dart

void main() async {
  FutureBuilder.debugRethrowError = true;
  runApp(const _ScrollTestWidget());
}

class _ScrollTestWidget extends StatefulWidget {
  const _ScrollTestWidget();

  @override
  State<_ScrollTestWidget> createState() => _ScrollTestWidgetState();
}

class _ScrollTestWidgetState extends State<_ScrollTestWidget> {
  final FocusNode focusNode = FocusNode();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: SingleChildScrollView(
          child: Column(
            children: [
              Offstage(child: TextField(focusNode: focusNode)),
              const Text('Here\'s some dead space above and below my widget.'),
              const SizedBox(height: 400),
              JumpToOnTap(focusNode: focusNode),
              const SizedBox(height: 200),
            ],
          ),
        ),
      ),
    );
  }
}

class JumpToOnTap extends StatelessWidget {
  const JumpToOnTap({required this.focusNode});

  final FocusNode focusNode;

  @override
  Widget build(BuildContext context) {
    return ElevatedButton(
      onPressed: () async {
        final ScrollableState scrollable = Scrollable.of(context);
        focusNode.requestFocus();
        await Future.delayed(const Duration(milliseconds: 800));
        // Ignore that this is unsafe for now.
        // ignore: use_build_context_synchronously
        final RenderBox renderBox = context.findRenderObject() as RenderBox;
        await scrollable.position.ensureVisible(renderBox);
      },
      child: const Text('Tap me to open keyboard'),
    );
  }
}