My Formula Calculator 🧪

Note

A robust, cross-platform mathematical calculator designed for users who need more than just arithmetic. Create, save, and evaluate custom formulas with variables and constants, all stored securely on your device.

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🎨 Overview

My Formula Calculator is built with Clean Architecture and a Feature-First approach. It allows users to define their own mathematical models, perform complex calculations with ease, and maintain a history of their work. This app is 100% offline-first, ensuring your data is always available without needing an internet connection.

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✨ Key Features

• 🧠 Custom Formula Engine

  • Define variables, constants, and complex expressions.
  • Support for trigonometric, logarithmic, and standard functions via math_expressions.
  • Built-in validation to prevent syntax errors during formula creation.

• 📴 Offline-First Storage

  • Powered by ObjectBox: High-performance NoSQL database for Flutter.
  • Lightning-fast local persistence for formulas and history.
  • zero-latency data access.

• 📤 Data Portability (Import/Export)

  • Backup your entire library to JSON files.
  • Restore formulas across devices or share them with others.
  • Automatic duplicate handling with "(Copy)" suffixing.

• 📅 Calculation History

  • Track every calculation with detailed logs of inputs used and outputs generated.
  • Easily re-run or reference past computations.

• 💻 Multi-Platform Excellence

  • Native performance on Android.
  • Optimized Windows desktop experience.

• 🌓 Premium UI/UX

  • Modern Material 3 design system.
  • Dynamic theme switching (Light, Dark, and System).
  • Clean, intuitive interface powered by GoRouter.

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🛠️ Technology Stack

Layer	Technology	Purpose
Framework	Flutter 3.x	Multi-platform UI development
Logic	BLoC / Cubit	Predictable state management
Database	ObjectBox	Primary offline-first storage
DI	Injectable / Get_It	Scalable dependency management
Routing	GoRouter	Declarative navigation
Math	eval_ex	High-performance evaluation engine
Persistence	Shared Preferences	User settings and theme state

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🏗️ Architecture

This project follows Feature-First Clean Architecture, ensuring high maintainability and testability.

graph TD
    subgraph Presentation
        UI[Widgets/Pages] --> B[BLoC / Cubit]
    end
    
    subgraph Domain
        B --> UC[Use Cases]
        UC --> E[Entities]
        UC --> RI[Repository Interfaces]
    end
    
    subgraph Data
        RI -.-> RP[Repository Implementations]
        RP --> DS[Data Sources - ObjectBox/Local]
    end
    
    style Presentation fill:#e1f5fe,stroke:#01579b
    style Domain fill:#e8f5e9,stroke:#1b5e20
    style Data fill:#fff3e0,stroke:#e65100

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Folder Structure

lib/
├── core/               # App-wide utilities, themes, and global constants
│   ├── database/       # ObjectBox Store setup
│   ├── math/           # Formula evaluation logic
│   ├── router/         # GoRouter definitions
│   └── di/             # Dependency injection setup
├── features/           # Independent feature modules
│   ├── formula/        # Core formula domain & data layers
│   ├── formula_editor/ # Formula creation UI
│   ├── formula_calculator/ # Evaluation UI
│   ├── history/        # History tracking
│   └── settings/       # User preferences
└── main.dart           # Entry point & app configuration

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🚀 Getting Started

Prerequisites

• Flutter SDK: ^3.11.1

Development Setup

1. Clone & Fetch

   git clone https://github.com/Kheemwel/my_formula_calculator.git
   cd my_formula_calculator
   flutter pub get

2. Code Generation This project heavily relies on objectbox_generator, freezed, and injectable. Generate the boilerplate using:

   flutter pub run build_runner build --delete-conflicting-outputs

3. Run

   flutter run

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🧪 Testing

We follow a strict TDD (Test-Driven Development) workflow.

• Unit Tests: Logic and BLoCs are tested using mocktail and bloc_test.
• Integration Tests: E2E flows are located in integration_test/.

Run all tests:

flutter test

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