Keyboard Avoiding Flutter Hook

keyboard_top_hook.dart

import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

/// Returns the top of the keyboard.
/// Thus, if the keyboard is hidden, it returns the height of the screen.
/// Can be used to avoid the keyboard on a screen with text fields.
double useKeyboardTop() {
  return use(const _KeyboardTopHook());
}

class _KeyboardTopHook extends Hook<double> {
  const _KeyboardTopHook();

  @override
  __KeyboardTopHookState createState() => __KeyboardTopHookState();
}

class __KeyboardTopHookState extends HookState<double, _KeyboardTopHook>
    with
        // ignore: prefer_mixin
        WidgetsBindingObserver {
  late double _state;

  @override
  void initHook() {
    super.initHook();
    _state = _getKeyboardTop();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  double build(BuildContext context) => _state;

  @override
  void dispose() {
    super.dispose();
    WidgetsBinding.instance.removeObserver(this);
  }

  @override
  void didChangeMetrics() {
    final newState = _getKeyboardTop();

    if (newState != _state) {
      _state = newState;
      setState(() {});
    }
    super.didChangeMetrics();
  }

  double _getKeyboardTop() {
    final view = WidgetsBinding.instance.platformDispatcher.views.first;
    final Size size = view.physicalSize / view.devicePixelRatio;
    return size.height -
        EdgeInsets.fromViewPadding(view.viewInsets, view.devicePixelRatio)
            .bottom;
  }
}