Shaking Error Text Widget

shaking_error_text.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:simple_animations/simple_animations.dart';

enum ErrorAnimationProp { offset }

class ShakingErrorText extends StatelessWidget {
  final ShakingErrorController controller;
  final int timesToShake;
  final MultiTween<ErrorAnimationProp> _tween;

  ShakingErrorText({
    this.controller,
    this.timesToShake = 4,
  }) : _tween = MultiTween<ErrorAnimationProp>() {
    List.generate(
        timesToShake,
        (_) => _tween
          ..add(ErrorAnimationProp.offset, Tween<double>(begin: 0, end: 10), Duration(milliseconds: 100))
          ..add(ErrorAnimationProp.offset, Tween<double>(begin: 10, end: -10), Duration(milliseconds: 100))
          ..add(ErrorAnimationProp.offset, Tween<double>(begin: -10, end: 0), Duration(milliseconds: 100)));
  }

  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider<ShakingErrorController>.value(
      value: controller,
      child: Consumer<ShakingErrorController>(
        builder: (context, errorController, child) {
          return CustomAnimation<MultiTweenValues<ErrorAnimationProp>>(
            control: errorController.controlSignal,
            curve: Curves.easeOut,
            duration: _tween.duration,
            tween: _tween,
            animationStatusListener: (status) {
              if (status == AnimationStatus.forward) {
                controller._onAnimationStarted();
              }
            },
            builder: (BuildContext context, Widget child, tweenValues) {
              return Transform.translate(
                offset: Offset(tweenValues.get(ErrorAnimationProp.offset), 0),
                child: child,
              );
            },
            child: Visibility(
              visible: controller.isVisible && controller.isMounted,
              maintainSize: controller.isMounted,
              maintainAnimation: controller.isMounted,
              maintainState: controller.isMounted,
              child: Text(
                errorController.errorText,
                textAlign: TextAlign.start,
                style: TextStyle(color: Colors.red)
              ),
            ),
          );
        },
      ),
    );
  }
}

shaking_error_text_controller.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:simple_animations/simple_animations.dart';

class ShakingErrorController extends ChangeNotifier {
  String _errorText;
  bool _isVisible = true;
  bool _isMounted = true;

  CustomAnimationControl _controlSignal = CustomAnimationControl.PLAY;

  ShakingErrorController(
      {String initialErrorText = 'Error', bool revealWithAnimation = true, bool hiddenInitially = true})
      : _errorText = initialErrorText ?? '',
        _isVisible = !hiddenInitially,
        _controlSignal = (revealWithAnimation ?? true) ? CustomAnimationControl.PLAY : CustomAnimationControl.STOP;

  set errorText(String errorText) {
    _errorText = errorText;
    notifyListeners();
  }

  void _onAnimationStarted() {
    _controlSignal = CustomAnimationControl.PLAY;
  }

  void shakeErrorText() {
    _controlSignal = CustomAnimationControl.PLAY_FROM_START;
    notifyListeners();
  }

  ///fully [unmount] and remove the error text
  void unMountError() {
    _isMounted = false;
    notifyListeners();
  }

  ///[remount] error text. will not be effective if its already mounted
  void mountError() {
    _isMounted = true;
    notifyListeners();
  }

  ///hide the error. but it will still be taking its space.
  void hideError() {
    _isVisible = false;
    notifyListeners();
  }

  ///just shows error without any animation
  void showError() {
    _isVisible = true;
    notifyListeners();
  }

  bool get isMounted => _isMounted;

  ///shows error with the reveal [animation]
  void revealError() {
    showError();
    shakeErrorText();
  }

  bool get isVisible => _isVisible;

  String get errorText => _errorText;

  CustomAnimationControl get controlSignal => _controlSignal;
}