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

"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)

jban332/flutter2js