rfw_gen 0.1.0

Annotations and runtime helpers for converting Flutter Widget code to RFW (Remote Flutter Widgets) format.

rfw_gen

A code generation package that converts Flutter Widget code into Remote Flutter Widgets (RFW) format. Annotate top-level functions with @RfwWidget, run build_runner, and get .rfwtxt and .rfw files ready for server-driven UI.

Installation

Add rfw_gen to your dependencies and rfw_gen_builder + build_runner to your dev dependencies:

dependencies:
  rfw_gen: ^0.1.0

dev_dependencies:
  rfw_gen_builder: ^0.1.0
  build_runner: ^2.4.0

Quick Start

1. Write a widget function and annotate it with @RfwWidget:

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

@RfwWidget('greeting')
Widget buildGreeting() {
  return Container(
    color: Color(0xFF2196F3),
    child: Text('Hello, RFW!'),
  );
}

2. Run the code generator:

dart run build_runner build

3. The generator produces two files:
   • greeting.rfwtxt -- human-readable RFW text format
   • greeting.rfw -- binary format for production use

Supported Widgets

65 widgets are supported across two categories.

Core Widgets (~48)

• Layout: Align, AspectRatio, Center, Column, Expanded, Flexible, FittedBox, FractionallySizedBox, IntrinsicHeight, IntrinsicWidth, Row, SizedBox, SizedBoxExpand, SizedBoxShrink, Spacer, Stack, Wrap
• Scrolling: GridView, ListBody, ListView, SingleChildScrollView
• Styling: ClipRRect, ColoredBox, Container, DefaultTextStyle, Directionality, Icon, IconTheme, Image, Opacity, Padding, Placeholder, Text
• Transform: Positioned, Rotation, Scale
• Interaction: GestureDetector
• Other: AnimationDefaults, SafeArea

Material Widgets (~17)

AppBar, Card, CircularProgressIndicator, Divider, Drawer, ElevatedButton, FloatingActionButton, InkWell, LinearProgressIndicator, ListTile, Material, OutlinedButton, OverflowBar, Scaffold, Slider, TextButton, VerticalDivider

See rules/rfw-widgets.md for the full parameter reference.

Dynamic Features

Data Binding

Reference server-supplied data with DataRef:

Text(DataRef('user.name'))

Generates: Text(text: data.user.name)

Args

Reference widget constructor arguments with ArgsRef:

Text(ArgsRef('product.id'))

Generates: Text(text: args.product.id)

State

Declare local widget state and reference it with StateRef:

@RfwWidget('toggle', state: {'isActive': false})
Widget buildToggle() {
  return Container(
    color: RfwSwitchValue(
      value: StateRef('isActive'),
      cases: {true: Color(0xFF4CAF50), false: Color(0xFFE0E0E0)},
    ),
  );
}

Loops

Iterate over lists with RfwFor:

RfwFor(
  items: DataRef('items'),
  itemName: 'item',
  builder: (item) => ListTile(
    title: Text(item['name']),
  ),
)

Generates: ...for item in data.items: ListTile(title: Text(text: item.name))

Conditionals

Use RfwSwitch for child widgets and RfwSwitchValue for values:

RfwSwitch(
  value: StateRef('status'),
  cases: {
    'loading': CircularProgressIndicator(),
    'done': Text('Complete'),
  },
)

String Concatenation

Combine static text and dynamic references with RfwConcat:

Text(RfwConcat(['Hello, ', DataRef('name'), '!']))

Generates: Text(text: ["Hello, ", data.name, "!"])

Event Handlers

Mutate local state:

GestureDetector(
  onTap: RfwHandler.setState('pressed', true),
)

Generates: onTap: set state.pressed = true

Dispatch events to the Flutter host:

GestureDetector(
  onTap: RfwHandler.event('cart.add', {'itemId': 42}),
)

Generates: onTap: event "cart.add" { itemId: 42 }

Custom Widgets

Register custom (non-standard) widgets via rfw_gen.yaml at the project root:

widgets:
  MyCustomWidget:
    import: custom.widgets

The generator will recognize MyCustomWidget and use the specified import library in the output.

Limitations

• @RfwWidget must be applied to top-level functions only.
• Only the 65 built-in widgets (core + material) are supported out of the box. Other widgets require custom configuration.

Pre-1.0 Note

This package is pre-1.0. Minor version bumps may include breaking changes. Pin to a specific version if stability is critical for your project.