Generated code from pixels2flutter.dev

main.dart

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

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

class CalculatorApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: Colors.black,
      ),
      home: CalculatorScreen(),
    );
  }
}

class CalculatorScreen extends StatefulWidget {
  @override
  _CalculatorScreenState createState() => _CalculatorScreenState();
}

class _CalculatorScreenState extends State<CalculatorScreen> {
  String _display = '0';
  double _firstOperand = 0.0;
  double _secondOperand = 0.0;
  String _operator = '';
  bool _shouldCalculate = false;

  void _onButtonPressed(String value) {
    setState(() {
      if (value == 'C') {
        _display = '0';
        _firstOperand = 0.0;
        _secondOperand = 0.0;
        _operator = '';
        _shouldCalculate = false;
      } else if ('+-×÷%'.contains(value)) {
        _firstOperand = double.tryParse(_display) ?? 0.0;
        _operator = value;
        _shouldCalculate = true;
      } else if (value == '=') {
        _secondOperand = double.tryParse(_display) ?? 0.0;
        double result = _calculateResult();
        _display = result.toString();
        _shouldCalculate = false;
      } else {
        if (_shouldCalculate) {
          _display = '';
          _shouldCalculate = false;
        }
        _display = _display == '0' ? value : _display + value;
      }
    });
  }

  double _calculateResult() {
    switch (_operator) {
      case '+':
        return _firstOperand + _secondOperand;
      case '-':
        return _firstOperand - _secondOperand;
      case '×':
        return _firstOperand * _secondOperand;
      case '÷':
        return _firstOperand / _secondOperand;
      case '%':
        return _firstOperand % _secondOperand;
      default:
        return 0.0;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        children: [
          Expanded(
            child: Container(
              padding: EdgeInsets.all(32),
              alignment: Alignment.bottomRight,
              child: Text(
                _display,
                style: TextStyle(
                  color: Colors.white,
                  fontSize: 100,
                  fontWeight: FontWeight.w200,
                ),
                maxLines: 1,
                overflow: TextOverflow.ellipsis,
              ),
            ),
          ),
          GridView.count(
            shrinkWrap: true,
            crossAxisCount: 4,
            childAspectRatio: 1.0,
            children: [
              'C', '+/-', '%', '÷',
              '7', '8', '9', '×',
              '4', '5', '6', '-',
              '1', '2', '3', '+',
              '0', '.', '=',
            ].map((value) {
              bool isOperator = '+-×÷=%'.contains(value);
              bool isZeroButton = value == '0';
              return GridTile(
                child: GestureDetector(
                  onTap: () => _onButtonPressed(value),
                  child: Container(
                    margin: EdgeInsets.all(8),
                    decoration: BoxDecoration(
                      color: isOperator ? Colors.orange : Colors.grey[850],
                      shape: isZeroButton ? BoxShape.rectangle : BoxShape.circle,
                      borderRadius: isZeroButton ? BorderRadius.circular(50) : null,
                    ),
                    child: Center(
                      child: Text(
                        value,
                        style: TextStyle(
                          color: isOperator ? Colors.white : Colors.grey[300],
                          fontSize: 36,
                          fontWeight: FontWeight.normal,
                        ),
                      ),
                    ),
                  ),
                ),
              );
            }).toList(),
          ),
        ],
      ),
    );
  }
}