/flutter2js

Builds web apps out of Flutter apps.

Primary LanguageDartBSD 3-Clause "New" or "Revised" LicenseBSD-3-Clause

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Introduction

Flutter2js is an experimental project that investigates feasibility of making Flutter apps run in browser using drawing primitives (canvas, CSS and SVG).

Licensed under the BSD 3-Clause License.

Implications of the approach

If the project gets drawing working, the approach taken by this project ("drawing, no HTML elements") has the following implications:

  • All Flutter widgets will work.
  • Apps look (more or less) identical to iOS/Android.
  • Scrolling/animation performance is bad compared to web apps (but possibly acceptable).
  • Code size and accessibility are inevitably poor compared to normal web apps.

Status

Ready

  • Flutter SDK and sample apps compile

Next

  • "Hello world"-like examples draw correctly
  • Mouse/tap handling

You can help!

Notes for developers

  • The project uses dart2js. Unfortunately dartdevc seems to have issues with Flutter SDK packages.

Getting started

Hello world

Clone Git repository

git clone https://github.com/flutter2js/flutter2js

Try "Hello world"

cd examples/hello_world-browser
pub get
pub run webdev serve

Open browser at: http://localhost:8080/main.html

Technical details

Libraries from original Flutter SDK

Flutter SDK libraries are derived from the original Flutter SDK.

These include:

  • dart:ui (original, docs)
    • Because Pub doesn't allow overriding "dart:something" packages, it's exposed as "package:flutter/ui.dart".
  • package:flutter (original, docs)
  • package:flutter_localization (original, docs)
  • package:flutter_test (original, docs)

The modifications include:

  • Many classes in dart:ui such as Canvas delegate implementation to package:flutter2js or expose previously private/external fields.
  • Eliminated usage of language features not supported by dart2js:
    • Assertions in initializers. After dart2js started to support them, this became unnecessary.
    • Some mixins (issue #23770)