Flutter Calculator Widget

A simple, smart and powerful Flutter calculator widget.

Features

• Basic arithmetic: plus, minus, multiply, divide, %, brackets.
• Real-Time calculating.
• Prevent to input the invalid symbol.
• Auto-resize the formula or result font size to adapt the text box's boundary.
• Supports undo and redo.
• Supports to relocate and input symbols.
• Can be used as an embedded widget or a dialog.
• [WIP] Supports to specify the result's precision.
• [WIP] Supports to copy and past the formula and the results.

Demo

• flutter_calculator_example

Getting Started

• Add dependency to your pubspec.yaml:

dependencies:
  flutter_calculator:
    git:
      url: git://github.com/flytreeleft/flutter_calculator.git
      # Use the developing version
      ref: master
      # or use the release version
      #ref: v0.1.0

• Import package import 'package:flutter_calculator/flutter_calculator.dart'; and call await showCalculator(context: context); in your code:

import 'package:flutter/material.dart';

import 'package:flutter_calculator/flutter_calculator.dart';

void main() => runApp(FlutterCalculatorExample());

class FlutterCalculatorExample extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      // ...
      home: const HomePage(title: 'Flutter Calculator Example'),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final TextEditingController _textController = TextEditingController(text: '0.00');

  @override
  void dispose() {
    this._textController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      // ...
      body: TextField(
        showCursor: false,
        readOnly: true,
        controller: this._textController,
        onTap: () => this._showCalculatorDialog(context),
      ),
    );
  }

  void _showCalculatorDialog(BuildContext context) async {
    final result = await showCalculator(context: this.context) ?? 0.00;

    this._textController.value = this._textController.value.copyWith(
          text: result.toStringAsFixed(2),
        );
  }
}

License

Apache License 2.0

Thanks

• kenreilly/flutter-calculator-demo: Example project - how to build a simple calculator in Flutter.
• leisim/auto_size_text: Flutter widget that automatically resizes text to fit perfectly within its bounds.

Reference

• Building a Calculator App in Flutter
• Making animated GIFs of Flutter apps