WebF Native UI Development

Want to create your own native UI library for WebF by wrapping Flutter widgets? This skill guides you through the complete process of building custom native UI libraries that make Flutter widgets accessible from JavaScript/TypeScript with React and Vue support.

What is Native UI Development?

Native UI development in WebF means:

• Wrapping Flutter widgets as WebF custom elements
• Bridging native Flutter UI to web technologies (HTML/JavaScript)
• Creating reusable component libraries that work with React, Vue, and vanilla JavaScript
• Publishing npm packages with type-safe TypeScript definitions

When to Create a Native UI Library

Use Cases:

• ✅ You want to expose Flutter widgets to web developers
• ✅ You need to wrap a Flutter package for WebF use
• ✅ You're building a design system with native performance
• ✅ You want to create platform-specific components (iOS, Android, etc.)
• ✅ You need custom widgets beyond HTML/CSS capabilities

Don't Create a Native UI Library When:

• ❌ HTML/CSS can achieve the same result (use standard web)
• ❌ You just need to use existing UI libraries (see webf-native-ui skill)
• ❌ You're building a one-off component (use WebF widget element directly)

Architecture Overview

A native UI library consists of three layers:

┌─────────────────────────────────────────┐
│  JavaScript/TypeScript (React/Vue)      │  ← Generated by CLI
│  @openwebf/my-component-lib             │
├─────────────────────────────────────────┤
│  TypeScript Definitions (.d.ts)         │  ← You write this
│  Component interfaces and events        │
├─────────────────────────────────────────┤
│  Dart (Flutter)                         │  ← You write this
│  Flutter widget wrappers                │
│  my_component_lib package                │
└─────────────────────────────────────────┘

Development Workflow

Overview

# 1. Create Flutter package with Dart wrappers
# 2. Write TypeScript definition files
# 3. Generate React/Vue components with WebF CLI
# 4. Test and publish

webf codegen my-ui-lib --flutter-package-src=./flutter_package

Step-by-Step Guide

Step 1: Create Flutter Package Structure

Create a standard Flutter package:

# Create Flutter package
flutter create --template=package my_component_lib

cd my_component_lib

Directory structure:

my_component_lib/
├── lib/
│   ├── my_component_lib.dart     # Main export file
│   └── src/
│       ├── button.dart           # Dart widget wrapper
│       ├── button.d.ts           # TypeScript definitions
│       ├── input.dart
│       └── input.d.ts
├── pubspec.yaml
└── README.md

pubspec.yaml dependencies:

dependencies:
  flutter:
    sdk: flutter
  webf: ^0.24.0  # Latest WebF version

Step 2: Write Dart Widget Wrappers

Create a Dart class that wraps your Flutter widget:

Example: lib/src/button.dart

import 'package:flutter/widgets.dart';
import 'package:webf/webf.dart';
import 'button_bindings_generated.dart';  // Will be generated by CLI

/// Custom button component wrapping Flutter widgets
class MyCustomButton extends MyCustomButtonBindings {
  MyCustomButton(super.context);

  // Internal state
  String _variant = 'filled';
  bool _disabled = false;

  // Property getters/setters (implement interface from bindings)
  @override
  String get variant => _variant;

  @override
  set variant(String value) {
    _variant = value;
    // Trigger rebuild when property changes
    setState(() {});
  }

  @override
  bool get disabled => _disabled;

  @override
  set disabled(bool value) {
    _disabled = value;
    setState(() {});
  }

  @override
  WebFWidgetElementState createState() {
    return MyCustomButtonState(this);
  }
}

class MyCustomButtonState extends WebFWidgetElementState {
  MyCustomButtonState(super.widgetElement);

  @override
  MyCustomButton get widgetElement => super.widgetElement as MyCustomButton;

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: widgetElement.disabled ? null : () {
        // Dispatch click event to JavaScript
        widgetElement.dispatchEvent(Event('click'));
      },
      child: Container(
        padding: EdgeInsets.all(12),
        decoration: BoxDecoration(
          color: _getBackgroundColor(),
          borderRadius: BorderRadius.circular(8),
        ),
        child: Text(
          // Get text from child nodes
          widgetElement.getTextContent() ?? 'Button',
          style: TextStyle(
            color: widgetElement.disabled ? Colors.grey : Colors.white,
          ),
        ),
      ),
    );
  }

  Color _getBackgroundColor() {
    if (widgetElement.disabled) return Colors.grey[400]!;
    switch (widgetElement.variant) {
      case 'filled':
        return Colors.blue;
      case 'outlined':
        return Colors.transparent;
      default:
        return Colors.blue;
    }
  }
}

Step 3: Write TypeScript Definitions

Create a .d.ts file alongside your Dart file:

Example: lib/src/button.d.ts

/**
 * Custom button component with multiple variants.
 */

/**
 * Properties for <my-custom-button>.
 */
interface MyCustomButtonProperties {
  /**
   * Button variant style.
   * Supported values: 'filled' | 'outlined' | 'text'
   * @default 'filled'
   */
  variant?: string;

  /**
   * Whether the button is disabled.
   * @default false
   */
  disabled?: boolean;
}

/**
 * Events for <my-custom-button>.
 */
interface MyCustomButtonEvents {
  /**
   * Fired when the button is clicked.
   */
  click: Event;
}

TypeScript Guidelines:

• Interface names must end with Properties or Events
• Use ? for optional properties (except booleans, which are always non-nullable in Dart)
• Use CustomEvent<T> for events with data
• Add JSDoc comments for documentation
• See the TypeScript Definition Guide for more details

Step 4: Create Main Export File

lib/my_component_lib.dart:

library my_component_lib;

import 'package:webf/webf.dart';
import 'src/button.dart';

export 'src/button.dart';

/// Install all components in this library
void installMyComponentLib() {
  // Register custom elements
  WebFController.defineCustomElement(
    'my-custom-button',
    (context) => MyCustomButton(context),
  );

  // Add more components here
  // WebFController.defineCustomElement('my-custom-input', ...);
}

Step 5: Generate React/Vue Components

Use the WebF CLI to generate JavaScript/TypeScript components:

# Install WebF CLI globally (if not already installed)
npm install -g @openwebf/webf-cli

# Generate TypeScript bindings and React/Vue components
webf codegen my-ui-lib-react \
  --flutter-package-src=./my_component_lib \
  --framework=react

webf codegen my-ui-lib-vue \
  --flutter-package-src=./my_component_lib \
  --framework=vue

What the CLI does:

1. ✅ Parses your .d.ts files
2. ✅ Generates Dart binding classes (*_bindings_generated.dart)
3. ✅ Creates React components with proper TypeScript types
4. ✅ Creates Vue components with TypeScript support
5. ✅ Copies .d.ts files to output directory
6. ✅ Creates package.json with correct metadata
7. ✅ Runs npm run build if a build script exists

Generated output structure:

my-ui-lib-react/
├── src/
│   ├── MyCustomButton.tsx        # React component
│   └── index.ts                  # Main export
├── dist/                         # Built files (after npm run build)
├── package.json
├── tsconfig.json
└── README.md

Step 6: Test Your Components

Test in Flutter App

In your Flutter app's main.dart:

import 'package:my_component_lib/my_component_lib.dart';

void main() {
  WebFControllerManager.instance.initialize(WebFControllerManagerConfig(
    maxAliveInstances: 2,
    maxAttachedInstances: 1,
  ));

  // Install your component library
  installMyComponentLib();

  runApp(MyApp());
}

Test in JavaScript/TypeScript

React example:

import { MyCustomButton } from '@openwebf/my-ui-lib-react';

function App() {
  return (
    <div>
      <MyCustomButton
        variant="filled"
        onClick={() => console.log('Clicked!')}
      >
        Click Me
      </MyCustomButton>
    </div>
  );
}

Vue example:

<template>
  <div>
    <MyCustomButton
      variant="filled"
      @click="handleClick"
    >
      Click Me
    </MyCustomButton>
  </div>
</template>

<script setup>
import { MyCustomButton } from '@openwebf/my-ui-lib-vue';

const handleClick = () => {
  console.log('Clicked!');
};
</script>

Step 7: Publish Your Library

Publish Flutter Package

# In Flutter package directory
flutter pub publish

# Or for private packages
flutter pub publish --server=https://your-private-registry.com

Publish npm Packages

# Automatic publishing with CLI
webf codegen my-ui-lib-react \
  --flutter-package-src=./my_component_lib \
  --framework=react \
  --publish-to-npm

# Or manual publishing
cd my-ui-lib-react
npm publish

For custom npm registry:

webf codegen my-ui-lib-react \
  --flutter-package-src=./my_component_lib \
  --framework=react \
  --publish-to-npm \
  --npm-registry=https://registry.your-company.com/

Advanced Patterns

1. Handling Complex Properties

TypeScript:

interface MyComplexWidgetProperties {
  // JSON string properties for complex data
  items?: string;  // Will be JSON.parse() in Dart

  // Enum-like values
  alignment?: 'left' | 'center' | 'right';

  // Numeric properties
  maxLength?: number;
  opacity?: number;
}

Dart:

@override
set items(String? value) {
  if (value != null) {
    try {
      final List<dynamic> parsed = jsonDecode(value);
      _items = parsed.cast<Map<String, dynamic>>();
      setState(() {});
    } catch (e) {
      print('Error parsing items: $e');
    }
  }
}

2. Dispatching Custom Events with Data

Dart:

void _handleValueChange(String newValue) {
  // Dispatch CustomEvent with data
  widgetElement.dispatchEvent(CustomEvent(
    'change',
    detail: {'value': newValue},
  ));
}

TypeScript:

interface MyInputEvents {
  change: CustomEvent<{value: string}>;
}

3. Calling Methods from JavaScript

TypeScript:

interface MyInputProperties {
  // Regular properties
  value?: string;

  // Methods
  focus(): void;
  clear(): void;
}

Dart:

class MyInput extends MyInputBindings {
  final FocusNode _focusNode = FocusNode();

  @override
  void focus() {
    _focusNode.requestFocus();
  }

  @override
  void clear() {
    // Clear the input
    value = '';
    // Dispatch event
    dispatchEvent(Event('input'));
  }
}

4. Reading CSS Styles

Dart:

@override
Widget build(BuildContext context) {
  // Read CSS properties
  final renderStyle = widgetElement.renderStyle;
  final backgroundColor = renderStyle.backgroundColor?.value;
  final borderRadius = renderStyle.borderRadius;

  return Container(
    decoration: BoxDecoration(
      color: backgroundColor ?? Colors.blue,
      borderRadius: BorderRadius.circular(
        borderRadius?.topLeft?.x ?? 8.0
      ),
    ),
    child: buildChild(),
  );
}

5. Handling Child Elements

Dart:

@override
Widget build(BuildContext context) {
  // Get text content from child nodes
  final text = widgetElement.getTextContent() ?? '';

  // Build child widgets
  final children = widgetElement.children.map((child) {
    return child.renderObject?.widget ?? SizedBox();
  }).toList();

  return Column(
    children: children,
  );
}

Common Patterns and Best Practices

1. Property Validation

@override
set variant(String value) {
  const validVariants = ['filled', 'outlined', 'text'];
  if (validVariants.contains(value)) {
    _variant = value;
  } else {
    print('Warning: Invalid variant "$value"');
    _variant = 'filled';
  }
  setState(() {});
}

2. Debouncing Frequent Updates

Timer? _debounceTimer;

@override
set searchQuery(String value) {
  _searchQuery = value;

  // Debounce search
  _debounceTimer?.cancel();
  _debounceTimer = Timer(Duration(milliseconds: 300), () {
    _performSearch();
  });
}

3. Lifecycle Management

@override
void didMount() {
  super.didMount();
  // Called when element is inserted into DOM
  _initializeWidget();
}

@override
void dispose() {
  // Clean up resources
  _debounceTimer?.cancel();
  _focusNode.dispose();
  super.dispose();
}

4. Error Handling

@override
set jsonData(String? value) {
  if (value == null || value.isEmpty) {
    _data = null;
    return;
  }

  try {
    _data = jsonDecode(value);
    setState(() {});
  } catch (e) {
    print('Error parsing JSON: $e');
    // Dispatch error event
    dispatchEvent(CustomEvent('error', detail: {'message': e.toString()}));
  }
}

CLI Command Reference

Basic Generation

# Generate React components
webf codegen output-dir --flutter-package-src=./my_package --framework=react

# Generate Vue components
webf codegen output-dir --flutter-package-src=./my_package --framework=vue

# Specify package name
webf codegen output-dir \
  --flutter-package-src=./my_package \
  --framework=react \
  --package-name=@mycompany/my-ui-lib

Auto-Publishing

# Publish to npm after generation
webf codegen output-dir \
  --flutter-package-src=./my_package \
  --framework=react \
  --publish-to-npm

# Publish to custom registry
webf codegen output-dir \
  --flutter-package-src=./my_package \
  --framework=react \
  --publish-to-npm \
  --npm-registry=https://registry.company.com/

Project Auto-Creation

The CLI auto-creates projects if files are missing:

• If package.json, tsconfig.json, or global.d.ts are missing, it creates a new project
• If framework is not specified, it prompts interactively
• Uses existing configuration if project already exists

Troubleshooting

Issue: Bindings file not found

Error: Error: Could not find 'button_bindings_generated.dart'

Solution:

1. Make sure you've run the CLI code generation
2. Check that .d.ts files are in the same directory as .dart files
3. Verify interface naming (must end with Properties or Events)

Issue: Properties not updating in UI

Cause: Not calling setState() after property changes

Solution:

@override
set myProperty(String value) {
  _myProperty = value;
  setState(() {});  // ← Don't forget this!
}

Issue: Events not firing in JavaScript

Cause: Event name mismatch or not dispatching events

Solution:

// Make sure event names match your TypeScript definitions
widgetElement.dispatchEvent(Event('click'));  // matches 'click' in TypeScript

Issue: TypeScript types not working

Cause: Generated types not exported properly

Solution: Check that generated package.json exports types:

{
  "types": "./dist/index.d.ts",
  "exports": {
    ".": {
      "types": "./dist/index.d.ts",
      "import": "./dist/index.js"
    }
  }
}

Complete Example: Text Input Component

See Complete Example for a full implementation of a text input component with:

• Flutter TextFormField wrapper
• TypeScript definitions
• Event handling
• Validation
• Methods (focus, blur, clear)
• CSS integration

Resources

• CLI Development Guide: cli/CLAUDE.md
• TypeScript Guide: CLI TYPING_GUIDE.md
• Example Package: native_uis/webf_cupertino_ui
• WebF Architecture: docs/ARCHITECTURE.md
• Official Documentation: https://openwebf.com/en/docs/developer-guide/native-ui

Next Steps

After creating your native UI library:

1. Test thoroughly on all target platforms (iOS, Android, desktop)
2. Write documentation for each component (see existing .md files in webf_cupertino_ui)
3. Create example apps demonstrating usage
4. Publish to pub.dev (Flutter) and npm (JavaScript)
5. Maintain compatibility with WebF version updates

Summary

• ✅ Native UI libraries wrap Flutter widgets as web-accessible custom elements
• ✅ Write Dart wrappers extending WebFWidgetElement
• ✅ Write TypeScript definitions (.d.ts) for each component
• ✅ Use WebF CLI to generate React/Vue components
• ✅ Test in both Flutter and JavaScript environments
• ✅ Publish to pub.dev (Flutter) and npm (JavaScript)
• ✅ Follow existing patterns from webf_cupertino_ui for reference