198 lines
8.1 KiB
Markdown
198 lines
8.1 KiB
Markdown
---
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name: "flutter-embedding-native-views"
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description: "Embeds native Android, iOS, or macOS views into a Flutter app. Use when integrating complex native components like maps or web views."
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metadata:
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model: "models/gemini-3.1-pro-preview"
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last_modified: "Thu, 12 Mar 2026 22:20:28 GMT"
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---
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# Integrating Platform Views and Web Content
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## Contents
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- [Platform Views Architecture](#platform-views-architecture)
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- [Web Embedding Architecture](#web-embedding-architecture)
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- [Workflow: Implementing Android Platform Views](#workflow-implementing-android-platform-views)
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- [Workflow: Implementing iOS Platform Views](#workflow-implementing-ios-platform-views)
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- [Workflow: Embedding Flutter in Web Applications](#workflow-embedding-flutter-in-web-applications)
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- [Examples](#examples)
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## Platform Views Architecture
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Platform Views allow embedding native views (Android, iOS, macOS) directly into a Flutter application, enabling the application of transforms, clips, and opacity from Dart.
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### Android Implementations (API 23+)
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Choose the appropriate implementation based on your performance and fidelity requirements:
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* **Hybrid Composition:** Renders Flutter content into a texture and uses `SurfaceFlinger` to compose both.
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* *Pros:* Best performance and fidelity for Android views.
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* *Cons:* Lowers overall application FPS. Certain Flutter widget transformations will not work.
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* **Texture Layer (Texture Layer Hybrid Composition):** Renders Platform Views into a texture. Flutter draws them via the texture and renders its own content directly into a Surface.
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* *Pros:* Best performance for Flutter rendering. All transformations work correctly.
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* *Cons:* Quick scrolling (e.g., WebViews) can be janky. `SurfaceView` is problematic (breaks accessibility). Text magnifiers break unless Flutter is rendered into a `TextureView`.
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### iOS & macOS Implementations
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* **iOS:** Uses Hybrid Composition exclusively. The native `UIView` is appended to the view hierarchy.
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* *Limitations:* `ShaderMask` and `ColorFiltered` widgets are not supported. `BackdropFilter` has composition limitations.
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* **macOS:** Uses Hybrid Composition (`NSView`).
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* *Limitations:* Not fully functional in current releases (e.g., gesture support is unavailable).
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### Performance Mitigation
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Mitigate performance drops during complex Dart animations by rendering a screenshot of the native view as a placeholder texture while the animation runs.
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## Web Embedding Architecture
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Embed Flutter into existing web applications (Vanilla JS, React, Angular, etc.) using either Full Page mode or Embedded (Multi-view) mode.
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* **Full Page Mode:** Flutter takes over the entire browser window. Use an `iframe` if you need to constrain the Flutter app without modifying the Flutter bootstrap process.
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* **Embedded Mode (Multi-view):** Render Flutter into specific HTML elements (`div`s). Requires `multiViewEnabled: true` during engine initialization.
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* Manage views from JavaScript using `app.addView()` and `app.removeView()`.
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* In Dart, replace `runApp` with `runWidget`.
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* Manage the dynamic list of views using `WidgetsBinding.instance.platformDispatcher.views` and render them using `ViewCollection` and `View` widgets.
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## Workflow: Implementing Android Platform Views
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Follow this sequential workflow to implement a Platform View on Android.
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**Task Progress:**
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- [ ] 1. Determine the composition mode (Hybrid vs. Texture Layer).
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- [ ] 2. Implement the Dart widget.
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- [ ] 3. Implement the native Android View and Factory.
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- [ ] 4. Register the Platform View in the Android host.
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- [ ] 5. Run validator -> review rendering -> fix manual invalidation issues.
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### 1. Dart Implementation
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If using **Hybrid Composition**, use `PlatformViewLink`, `AndroidViewSurface`, and `PlatformViewsService.initSurfaceAndroidView`.
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If using **Texture Layer**, use the `AndroidView` widget.
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### 2. Native Implementation
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Create a class implementing `io.flutter.plugin.platform.PlatformView` that returns your native `android.view.View`.
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Create a factory extending `PlatformViewFactory` to instantiate your view.
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### 3. Registration
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Register the factory in your `MainActivity.kt` (or plugin) using `flutterEngine.platformViewsController.registry.registerViewFactory`.
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*Note: If your native view uses `SurfaceView` or `SurfaceTexture`, manually call `invalidate` on the View or its parent when content changes, as they do not invalidate themselves automatically.*
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## Workflow: Implementing iOS Platform Views
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Follow this sequential workflow to implement a Platform View on iOS.
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**Task Progress:**
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- [ ] 1. Implement the Dart widget using `UiKitView`.
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- [ ] 2. Implement the native iOS View (`FlutterPlatformView`) and Factory (`FlutterPlatformViewFactory`).
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- [ ] 3. Register the Platform View in `AppDelegate.swift` or the plugin registrar.
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- [ ] 4. Run validator -> review composition limitations -> fix unsupported filters.
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## Workflow: Embedding Flutter in Web Applications
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Follow this sequential workflow to embed Flutter into an existing web DOM.
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**Task Progress:**
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- [ ] 1. Update `flutter_bootstrap.js` to enable multi-view.
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- [ ] 2. Update `main.dart` to use `runWidget` and `ViewCollection`.
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- [ ] 3. Implement JavaScript logic to add/remove host elements.
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- [ ] 4. Run validator -> review view constraints -> fix CSS conflicts.
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### 1. JavaScript Configuration
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In `flutter_bootstrap.js`, initialize the engine with `multiViewEnabled: true`.
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Use the returned `app` object to add views: `app.addView({ hostElement: document.getElementById('my-div') })`.
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### 2. Dart Configuration
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Replace `runApp()` with `runWidget()`.
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Create a root widget that listens to `WidgetsBindingObserver.didChangeMetrics`.
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Map over `WidgetsBinding.instance.platformDispatcher.views` to create a `View` widget for each attached `FlutterView`, and wrap them all in a `ViewCollection`.
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## Examples
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### Example: Android Texture Layer (Dart)
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```dart
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import 'package:flutter/material.dart';
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import 'package:flutter/services.dart';
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class NativeAndroidView extends StatelessWidget {
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@override
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Widget build(BuildContext context) {
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const String viewType = 'my_native_view';
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final Map<String, dynamic> creationParams = <String, dynamic>{};
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return AndroidView(
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viewType: viewType,
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layoutDirection: TextDirection.ltr,
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creationParams: creationParams,
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creationParamsCodec: const StandardMessageCodec(),
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);
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}
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}
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```
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### Example: Web Multi-View Initialization (JavaScript)
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```javascript
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_flutter.loader.load({
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onEntrypointLoaded: async function(engineInitializer) {
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let engine = await engineInitializer.initializeEngine({
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multiViewEnabled: true,
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});
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let app = await engine.runApp();
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// Add a view to a specific DOM element
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let viewId = app.addView({
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hostElement: document.querySelector('#flutter-host-container'),
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initialData: { customData: 'Hello from JS' }
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});
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}
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});
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```
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### Example: Web Multi-View Root Widget (Dart)
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```dart
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import 'dart:ui' show FlutterView;
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import 'package:flutter/widgets.dart';
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void main() {
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runWidget(MultiViewApp(viewBuilder: (context) => const MyEmbeddedWidget()));
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}
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class MultiViewApp extends StatefulWidget {
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final WidgetBuilder viewBuilder;
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const MultiViewApp({super.key, required this.viewBuilder});
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@override
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State<MultiViewApp> createState() => _MultiViewAppState();
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}
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class _MultiViewAppState extends State<MultiViewApp> with WidgetsBindingObserver {
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Map<Object, Widget> _views = {};
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@override
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void initState() {
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super.initState();
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WidgetsBinding.instance.addObserver(this);
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_updateViews();
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}
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@override
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void didChangeMetrics() => _updateViews();
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void _updateViews() {
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final newViews = <Object, Widget>{};
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for (final FlutterView view in WidgetsBinding.instance.platformDispatcher.views) {
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newViews[view.viewId] = _views[view.viewId] ?? View(
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view: view,
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child: Builder(builder: widget.viewBuilder),
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);
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}
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setState(() => _views = newViews);
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}
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@override
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void dispose() {
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WidgetsBinding.instance.removeObserver(this);
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super.dispose();
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}
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@override
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Widget build(BuildContext context) {
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return ViewCollection(views: _views.values.toList(growable: false));
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}
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}
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```
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