mp_flutter_native

Wires MpVideo/MpMap/MpCamera to native <video>/<map>/<camera> components inside a WeChat Mini Program compiled by mp-flutter (flutter_miniprogram on pub.flutter-io.cn) — via its JS sync layer self.__mpNative (see packages/mp_flutter/runtime/native-views.js). On other platforms (Android/iOS/desktop) or in a plain browser, each widget renders its own fallback, and controller methods throw a clear UnsupportedError instead of failing silently.

中文版见 README.zh.md.

Install

dependencies:
  mp_flutter_native: ^0.3.2

When developing inside the mp-flutter monorepo itself (e.g. the top-level example/ app), use a relative path dependency instead:

dependencies:
  mp_flutter_native:
    path: ../mp_flutter/packages/mp_flutter_native

See example/lib/main.dart in this package for a minimal, runnable usage example (MpVideo + MpMap with an availability check).

API

MpVideo(
  src: 'https://example.com/a.mp4',
  autoplay: true,          // Prefer this over calling controller.play() right after creation
  loop: false,
  muted: false,
  controls: true,
  poster: 'https://example.com/poster.png',
  objectFit: 'contain',
  controller: myVideoController,
  onPlay: () {}, onPause: () {}, onEnded: () {},
  onTimeUpdate: (seconds) {}, onError: (msg) {},
  fallback: const Text('Video is not supported on this platform'),
)

MpMap(
  latitude: 31.2, longitude: 121.5, scale: 16,
  markers: [MpMapMarker(id: 1, latitude: 31.2, longitude: 121.5, title: 'Here')],
  showLocation: true,
  controller: myMapController,
  onTap: (lat, lng) {}, onMarkerTap: (id) {},
  // WeChat's bindregionchange event's `e.type` is already 'begin'/'end'
  // (the start/end of a viewport change); this is forwarded as-is rather
  // than collapsed into one generic 'regionchange'.
  onRegionChange: (type) {}, // type: 'begin' | 'end'
  fallback: const Text('Map is not supported on this platform'),
)

MpCamera(
  devicePosition: 'back', flash: 'auto',
  controller: myCameraController,
  onError: (msg) {},
  fallback: const Text('Camera is not supported on this platform'),
)

bool get mpNativeAvailable; // true only inside a Mini Program compiled by mp-flutter

Controllers:

• MpVideoController: play()/pause()/seek(seconds)/stop()/ requestFullScreen()/exitFullScreen()
• MpMapController: moveToLocation()/getCenterLocation() (returns ({double latitude, double longitude}))
• MpCameraController: takePhoto({quality}) (returns tempImagePath)

Behavior outside a Mini Program, or before the native view exists

Check mpNativeAvailable before deciding whether to show related UI, so you never call a controller method that throws UnsupportedError:

• All three widgets render fallback ?? const SizedBox.shrink().
• Any controller method call throws UnsupportedError('mp_flutter_native: this operation is only available inside a Mini Program compiled by mp-flutter, after the matching native component has been created').

if (mpNativeAvailable) {
  await myVideoController.play();
}

Limitations

• mpNativeAvailable is only true inside a Mini Program compiled by mp-flutter; on every other platform (Android/iOS/desktop, or a plain browser) the three widgets fall back to fallback and controllers throw.
• A controller is only usable after its matching widget has actually been built in a Mini Program environment — calling it beforehand (or after the widget is disposed) throws UnsupportedError, it does not queue the call.
• See "Native components are always layered above Flutter content" below — this is a hard WeChat Mini Program platform constraint, not something this package can work around.

★ Layering warning: native components always sit above Flutter content

The Mini Program renders these as native views, composited on top of the WXML companion layer — independent of Flutter's own paint order. If you place other Flutter content (a dialog's backdrop, decorations, a viewfinder overlay, etc.) "above" MpVideo/MpMap/MpCamera in the widget tree, in practice that content gets covered by the native component, not the other way around. If you need UI layered on top of a native component, consider the Mini Program's own cover-view/cover-image (outside the scope of this package), or keep interactive UI outside the native component's area.

Implementation notes

• On Web (lib/src/registry_web.dart): the first time an MpNativeKind is used, ui_web.platformViewRegistry.registerViewFactory registers an mp-native-<kind> view type whose factory creates a <div data-mp-native data-mp-params data-mp-id> — data-mp-id is simply the platform view viewId the Flutter engine assigns (no separate counter). Parameter changes are synced by rewriting the data-mp-params attribute directly (HtmlElementView's creationParams only takes effect at creation time and does not follow widget rebuilds); native events are listened for via a CustomEvent('mpnative') on the placeholder div, whose detail is the JSON string {type, detail}; controller commands are forwarded through self.__mpNative.command(id, method, argsJson).
• self.__mpNative may not exist yet at the moment the factory function runs (boot()'s scheduling for the first frame is asynchronous — this timing gap has been observed on real devices): per the Task 2 contract, if it exists, call register(id); if not, push the id onto self.__mpNativePending (auto-created). On disposal of the corresponding view, unregister(id) must be called, or the sync layer's scan loop keeps running indefinitely.
• On non-Web platforms (lib/src/registry_stub.dart): mpNativeAvailable is always false, and controller methods always throw UnsupportedError.
• A dart.library.js_interop conditional import switches between the stub/web implementations, mirroring mp_flutter_wechat's channel_stub.dart/ channel_web.dart pattern. flutter test runs on the VM by default, so it always selects the stub.