number_decimals.dart

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

void main() {
  runApp(MyApp());
}

/// this is comment
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Learning',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(),
    );
  }
}

// ignore: public_member_api_docs
class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

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

class _MyHomePageState extends State<MyHomePage> implements TextInputClient {
  TextEditingValue _editingValue;
  FocusNode _focusNode;
  TextInputConnection _connection;

  bool get _hasInputConnection => _connection != null && _connection.attached;

  void requestKeyboard() {
    if (_focusNode.hasFocus) {
      _openInputConnection();
    } else {
      FocusScope.of(context).requestFocus(_focusNode);
    }
  }

  void _openInputConnection() {
    if (!_hasInputConnection) {
      _connection = TextInput.attach(
        this,
        TextInputConfiguration(
          inputType: TextInputType.number,
          autocorrect: false,
          inputAction: TextInputAction.done,
        ),
      );
      _connection.setEditingState(_editingValue);
    }
    _connection.show();
  }

  void _closeInputConnectionIfNeeded() {
    if (_hasInputConnection) {
      _connection.close();
      _connection = null;
    }
  }

  void _onFocusChanged() {
    if (_focusNode.hasFocus) {
      _openInputConnection();
    } else {
      _closeInputConnectionIfNeeded();
    }
    setState(() {});
  }

  @override
  void initState() {
    _editingValue = TextEditingValue.empty;
    _focusNode = FocusNode();
    _focusNode.addListener(_onFocusChanged);

    WidgetsBinding.instance.addPostFrameCallback(
      (_) => requestKeyboard(),
    );

    super.initState();
  }

  @override
  void dispose() {
    _focusNode?.dispose();
    _closeInputConnectionIfNeeded();
    super.dispose();
  }

  String _formatNumber(String value) => value.padLeft(2, '0');

  @override
  Widget build(BuildContext context) {
    final value = int.tryParse(_editingValue.text);
    String first = '00';
    String decimal = '00';
    if (value != null && value > 100) {
      first = _formatNumber((value ~/ 100).toString());
      decimal = _formatNumber((value % 100).toString());
    } else if (value != null) {
      decimal = _formatNumber(value.toString());
    }

    return Scaffold(
      body: GestureDetector(
        behavior: HitTestBehavior.opaque,
        onTap: requestKeyboard,
        child: Center(
          child: Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Text(
                first,
                style: TextStyle(fontSize: 40, color: Colors.black),
              ),
              Padding(
                padding: const EdgeInsets.only(bottom: 15.0),
                child: Text(
                  decimal,
                  style: TextStyle(fontSize: 20, color: Colors.black),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  @override
  void connectionClosed() {}

  @override
  AutofillScope get currentAutofillScope => throw UnimplementedError();

  @override
  TextEditingValue get currentTextEditingValue => _editingValue;

  @override
  void performAction(TextInputAction action) {
    _focusNode.unfocus();
  }

  @override
  void updateEditingValue(TextEditingValue value) {
    setState(() {
      _editingValue = value;
      if (value.text.length == 12) {
        print('maximum length');
      }
    });
  }

  @override
  void performPrivateCommand(String action, Map<String, dynamic> data) {}

  @override
  void showAutocorrectionPromptRect(int start, int end) {}

  @override
  void updateFloatingCursor(RawFloatingCursorPoint point) {}
}