📚 Logbook

A powerful, elegant, and developer-friendly logging package for Flutter applications. Logbook provides an intuitive overlay UI for viewing logs in real-time, with support for different log levels, color coding, and optional server integration for remote debugging.

✨ Features

• 🎨 Comprehensive UI Overlay - Slide-in panel with color-coded logs
• 📊 Multiple Log Levels - Fine, Config, Info, Warning, Severe, and Custom
• 🔍 Real-Time Viewing - See logs as they happen in your app
• 📱 Server Integration - Send logs to your server for remote debugging in CSV format
• 🚀 Lightweight - Near-zero cost while the panel is closed
• 🔧 Configurable - Enable/disable and reconfigure at runtime
• 📦 No Dependencies - Only depends on Flutter SDK and the http package

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📦 Installation

Add logbook to your pubspec.yaml:

dependencies:
  logbook: ^0.6.0

Then run:

flutter pub get

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🚀 Quick Start

1. Wrap Your App

Wrap your app with the Logbook widget, preferably via MaterialApp.builder:

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

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'My App',
      home: const HomePage(),
      builder: (context, child) => Logbook(
        config: const LogbookConfig(enabled: true),
        child: child ?? const SizedBox.shrink(),
      ),
    );
  }
}

Only mount one Logbook at a time — its configuration is process-global.

2. Start Logging

Use the global l instance to log messages:

import 'package:logbook/logbook.dart';

void someFunction() {
  l.i('This is an info message');
  l.w('This is a warning');
  l.f('This is a fine (debug) message');
}

3. View Logs

Tap the small overlay handle on the side of your screen to open the log viewer — or open it programmatically:

Logbook.stateOf(context).open(); // also: .close(), .toggle(), .isOpen

The trash button in the viewer clears the view only — the underlying buffer keeps its logs, so a later "send to server" still uploads the full history. Use LogBuffer.instance.clear() to drop the buffer itself.

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📖 Basic Usage

Log Types

Logbook provides several log types, each with its own color and purpose:

// Fine - Detailed debugging information
l.f('User data loaded: ${user.name}');

// Config - Configuration information (Green)
l.c('API endpoint: https://api.example.com');

// Info - General information messages (Blue in console)
l.i('User logged in successfully');

// Warning - Potential issues (Yellow); the reason is appended to the message
l.w('Network latency is high', StackTrace.current, 'Performance Issue');

// Severe - Errors and exceptions (Red)
l.s('Failed to load data', StackTrace.current, 'API Error');

// Custom - Your own log type, with a stable per-prefix color
l.log('Custom event occurred', 'CUSTOM');

Error Handling

Perfect for catching and logging exceptions:

try {
  await someRiskyOperation();
} catch (e, stackTrace) {
  l.s('Operation failed: $e', stackTrace);
}

Global Error Handler

Catch all uncaught errors in your app:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:logbook/logbook.dart';

void main() {
  runZonedGuarded(
    () => runApp(const MyApp()),
    (error, stackTrace) {
      l.s('Uncaught error: $error', stackTrace);
    },
  );
}

Send Logs to Server

Send the buffered logs to your server as a CSV multipart upload (uses the current Logbook.config). Returns true on success:

final success = await Logbook.sendLogsToServer();

The file is posted as multipart/form-data under the document field, with multipartFileFields added as regular form fields. Requests time out after 30 seconds, and non-2xx responses are treated as failures.

Runtime Configuration

The constructor config seeds the initial value; you can read or replace it at any time and the overlay updates live:

Logbook.config = Logbook.config.copyWith(themeMode: ThemeMode.dark);

// React to changes:
Logbook.configListenable.addListener(() => print(Logbook.config));

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⚙️ Configuration

LogbookConfig

Configure Logbook behavior with LogbookConfig:

Logbook(
  config: LogbookConfig(
    enabled: kDebugMode,                        // Show overlay only in debug mode
    debugFileName: 'app_logs.csv',              // CSV export filename
    uri: Uri.parse('https://your.server/logs'), // Optional: server URI
    multipartFileFields: {'caption': '#logs'},  // Optional: extra form fields
    fontFamily: 'Monospace',                    // Optional: font family
    themeMode: ThemeMode.system,                // Optional: overlay theme
    bufferLimit: 10000,                         // Optional: max buffered logs
  ),
  child: child ?? const SizedBox.shrink(),
)

Parameters

Parameter	Type	Default	Description
enabled	bool	kDebugMode	Show/hide the logbook overlay (log collection continues either way)
debugFileName	String	'debug_info.csv'	Filename for CSV exports to the server
uri	Uri?	null	Server URI for remote logging
multipartFileFields	Map<String, String>?	null	Extra multipart form fields for remote logging
fontFamily	String	'Monospace'	Viewer font; takes effect only if your app bundles a font family with this name
themeMode	ThemeMode	ThemeMode.system	Overlay theme (light, dark, or follow the system)
bufferLimit	int	10000	Max log messages kept in memory (oldest evicted) — applies in release builds too

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📱 Example App

Check out the example directory for a complete working app showcasing all features:

cd example
flutter run

The example app demonstrates:

• All log types
• Async operations logging
• Error handling
• Background timer logs
• Runtime config changes (live theme toggle)

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🛠️ API Reference

Global Logger (l)

// Info log
l.i(Object? message);

// Fine/Debug log
l.f(Object? message);

// Config log
l.c(Object? message);

// Warning log (reason is appended to the stored message)
l.w(Object exception, [StackTrace? stackTrace, String? reason]);

// Severe/Error log
l.s(Object exception, [StackTrace? stackTrace, String? reason]);

// Custom log
l.log(Object message, String prefix, {
  StackTrace? stackTrace,
  bool withMilliseconds = false,
});

Logbook

Logbook.config;                    // Current LogbookConfig (get/set, live)
Logbook.configListenable;          // ValueListenable<LogbookConfig>
Logbook.stateOf(context).open();   // Programmatic panel control
await Logbook.sendLogsToServer();  // Future<bool>

LogBuffer

LogBuffer.instance.logs;            // Iterable<LogMessage> (oldest first)
LogBuffer.instance.logsPrefix;      // Distinct prefixes currently buffered
LogBuffer.instance.clear();         // Drop all buffered logs
LogBuffer.instance.add(logMessage); // Add your own LogMessage

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🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

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📄 License

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

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If you find this package useful, give it a ⭐ on GitHub!