static_licenses

A minimalistic Dart/Flutter tool to statically extract and compile Open Source licenses from your project's dependencies into a generated Dart file at build-time.

The Problem with Traditional License Parsing

Flutter provides built-in mechanisms like showLicensePage() and the LicenseRegistry. However, these approaches evaluate and parse licenses at runtime, which causes two primary issues:

  1. Performance Overhead: Parsing licenses on the device consumes CPU and blocks the UI thread if not handled carefully, negatively impacting the user experience when opening the licenses page.
  2. Dynamic Generation Limits: On constrained or highly optimized builds, relying on dynamic runtime registry extraction can be unpredictable and hard to customize if you want full control over your application's UI.

The Advantage of static_licenses

static_licenses shifts the workload from runtime (on the user's device) to build-time (on your CI/CD or local machine).

  • Zero Runtime Parsing: Licenses are pre-compiled as simple Dart strings within a generated licenses.g.dart file. Displaying them is as fast as rendering a static List.
  • Full UI Control: You get a clean List<PackageLicenseInfo> containing the package name, version, and license text. You can build exactly the UI you want without fighting against the default Material/Cupertino dialogs.
  • No Dev Dependencies: The generator automatically reads your pubspec.lock, filtering out dev_dependencies. Only the licenses of packages shipped in your app are included.
  • Testable & Reliable: The tool interacts safely with .dart_tool to locate the exact license files cached on your system.

Disadvantages of this Package

To be honest and open about disadvantages:

  • Build-time overhead: The generator needs to read all license files, which can take some time on large projects.
  • Generated file size: The generated file can be large on large projects.
  • Not a drop-in replacement: This is not a drop-in replacement for the default license page. You need to build your own UI.
  • No Flutter integration: This package does not provide any Flutter integration. You need to generate the licenses manually or integrate it into your build process.

Getting Started

1. Add the Dependency

Add static_licenses to your pubspec.yaml under dev_dependencies:

dev_dependencies:
  static_licenses: #latest

2. Run the Generator

Run the provided script to generate the licenses file.

dart run static_licenses:generate

By default, this creates a lib/licenses.g.dart file in your project.

Options:

  • --out=<path>: Change the output directory (e.g., --out=lib/src). Defaults to lib.
  • --help or -h: Shows the help menu.

3. Use in Your App

The generated file exposes a constant list called allLicenses. Simply import it and build your own UI!

import 'package:flutter/material.dart';
import 'licenses.g.dart';

class MyLicensePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: allLicenses.length,
      itemBuilder: (context, index) {
        final license = allLicenses[index];
        return ListTile(
          title: Text(license.packageName),
          subtitle: Text('Version: ${license.version}'),
          onTap: () {
            // Show license.licenseText in a new page!
          },
        );
      },
    );
  }
}

Check out the example/ folder in this repository for a complete, runnable demonstration.

Libraries