Flutter Number Flow

A beautiful Flutter widget that animates number changes with smooth, customizable transitions. Perfect for displaying animated counters, currency values, statistics, and more with a professional, polished look.

✨ Features

• 🎯 Smooth Number Animations: Animate only the digits that change, keeping unchanged digits stable
• 🎨 Multiple Animation Styles: Choose between slide and crossFade animations for different visual effects
• 🌍 Locale-Aware Formatting: Support for different locales, currencies, and number formats using intl
• 📊 Compact Notation: Display large numbers in compact format (1.2K, 1.5M, 2.1B)
• ⚡ High Performance: Optimized with text metrics caching and tabular figures for consistent layout
• 🎛️ Group Synchronization: Synchronize animations across multiple NumberFlow widgets
• 🎮 Manual Control: Drive animations manually with scrub progress for timeline controls
• ♿ Accessibility: Proper semantics support for screen readers
• 🎭 Customizable: Full control over text styles, animation duration, and curves
• 📱 Material 3: Built with Material Design 3 principles

📱 Demo

Mobile App

Web App

📱 Live Demo

Try the interactive web demo to see all features in action.

🚀 Quick Start

Installation

Add flutter_number_flow to your pubspec.yaml:

dependencies:
  flutter_number_flow: ^0.1.0

Then run:

flutter pub get

Basic Usage

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

class CounterExample extends StatefulWidget {
  @override
  _CounterExampleState createState() => _CounterExampleState();
}

class _CounterExampleState extends State<CounterExample> {
  double _value = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            NumberFlow(
              value: _value,
              textStyle: const TextStyle(
                fontSize: 48,
                fontWeight: FontWeight.bold,
              ),
            ),
            const SizedBox(height: 32),
            ElevatedButton(
              onPressed: () => setState(() => _value += 1),
              child: const Text('Increment'),
            ),
          ],
        ),
      ),
    );
  }
}

🎨 Animation Styles

Slide Animation

Numbers slide vertically when changing, creating a smooth rolling effect:

NumberFlow(
  value: 1234.56,
  animationStyle: NumberFlowAnimation.slide,
  duration: const Duration(milliseconds: 600),
)

CrossFade Animation

Numbers fade between old and new values for a subtle transition:

NumberFlow(
  value: 1234.56,
  animationStyle: NumberFlowAnimation.crossFade,
  duration: const Duration(milliseconds: 400),
)

🌍 Formatting & Localization

Currency Formatting

NumberFlow(
  value: 1234.56,
  format: const NumberFlowFormat(
    prefix: '\$',
    minimumFractionDigits: 2,
    maximumFractionDigits: 2,
  ),
  textStyle: const TextStyle(
    fontSize: 32,
    color: Colors.green,
    fontWeight: FontWeight.bold,
  ),
)

Compact Notation

Display large numbers in a readable format:

NumberFlow(
  value: 1500000,
  format: const NumberFlowFormat(
    notation: NumberNotation.compact,
    maximumFractionDigits: 1,
  ),
) // Displays "1.5M"

Locale Support

NumberFlow(
  value: 1234.56,
  format: const NumberFlowFormat(
    locale: 'de_DE', // German locale
    minimumFractionDigits: 2,
  ),
) // Displays "1.234,56"

🎛️ Advanced Features

Group Synchronization

Synchronize animations across multiple widgets:

NumberFlowGroupProvider(
  groupKey: 'financials',
  duration: const Duration(milliseconds: 800),
  child: Column(
    children: [
      NumberFlow(
        value: revenue,
        groupKey: 'financials',
        format: const NumberFlowFormat(prefix: '\$'),
      ),
      NumberFlow(
        value: expenses,
        groupKey: 'financials',
        format: const NumberFlowFormat(prefix: '\$'),
      ),
    ],
  ),
)

Manual Animation Control

Drive animations manually for timeline scrubbing:

class ScrubExample extends StatefulWidget {
  @override
  _ScrubExampleState createState() => _ScrubExampleState();
}

class _ScrubExampleState extends State<ScrubExample> {
  double _progress = 0.0;
  final double _startValue = 0;
  final double _endValue = 1000000;

  @override
  Widget build(BuildContext context) {
    final currentValue = _startValue + (_endValue - _startValue) * _progress;
    
    return Column(
      children: [
        NumberFlow(
          value: currentValue,
          scrubProgress: _progress,
          format: const NumberFlowFormat(
            prefix: '\$',
            notation: NumberNotation.compact,
          ),
        ),
        Slider(
          value: _progress,
          onChanged: (value) => setState(() => _progress = value),
        ),
      ],
    );
  }
}

📋 API Reference

NumberFlow Widget

Property	Type	Default	Description
value	num	required	Current number value to display
previousValue	num?	null	Previous value for animation (auto-detected if null)
textStyle	TextStyle?	null	Text style for the number display
animationStyle	NumberFlowAnimation	slide	Animation style (slide or crossFade)
duration	Duration	600ms	Animation duration
curve	Curve	easeInOut	Animation curve
format	NumberFlowFormat?	null	Number formatting options
textAlign	TextAlign	center	Text alignment
groupKey	String?	null	Group key for synchronization
scrubProgress	double?	null	Manual animation progress (0.0-1.0)
enableMask	bool	true	Enable edge masking for smooth clipping

NumberFlowFormat

Property	Type	Default	Description
locale	String?	null	Locale for number formatting
notation	NumberNotation	standard	Number notation (standard or compact)
prefix	String?	null	Text to display before the number
suffix	String?	null	Text to display after the number
minimumFractionDigits	int?	null	Minimum decimal places
maximumFractionDigits	int?	null	Maximum decimal places

NumberFlowAnimation

enum NumberFlowAnimation {
  slide,     // Vertical sliding animation
  crossFade, // Opacity transition animation
}

NumberNotation

enum NumberNotation {
  standard, // 1,234,567
  compact,  // 1.2M
}

🎯 Performance

Flutter Number Flow is optimized for performance:

• Text Metrics Caching: Glyph dimensions are cached to avoid repeated calculations
• Tabular Figures: Uses FontFeature.tabularFigures() for consistent digit widths
• Efficient Diffing: Only animates digits that actually change
• Minimal Rebuilds: Smart widget composition minimizes unnecessary rebuilds

♿ Accessibility

The widget follows Flutter accessibility best practices:

• Semantic Labels: Screen readers announce the complete number value
• Proper Focus: Supports keyboard navigation and focus management
• High Contrast: Works well with system accessibility settings

🧪 Testing

The package includes comprehensive tests:

flutter test

Run golden tests to verify visual output:

flutter test --update-goldens

🤝 Contributing

Contributions are welcome! Please read our contributing guide and code of conduct.

Development Setup

1. Clone the repository:

   git clone https://github.com/example/flutter_number_flow.git
   cd flutter_number_flow
   

2. Get dependencies:

   flutter pub get
   

3. Run the example:

   cd example
   flutter run
   

4. Run tests:

   flutter test
   

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Inspired by the number-flow React library
• Built with Flutter and Dart
• Uses the intl package for internationalization

📊 Changelog

See CHANGELOG.md for a detailed list of changes and migration guides.

💬 Support

• 📖 Documentation
• 🐛 Issue Tracker
• 💬 Discussions
• 📧 Email Support

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Made with ❤️ by the Flutter Number Flow team