dual_screen_hinge

iPhone Duo-first foldable support for Flutter: continuous hinge angles, posture, reserved regions, screen role, and Android display modes.

Use it alongside MediaQuery

On Android, prefer MediaQuery.displayFeatures for adaptive layout and the basic opened/half-opened state Flutter already exposes. Use this plugin when you need continuous angles for animation, richer fold/hinge metadata, supported postures, rear/dual-screen display sessions, or iOS support.

Install

dependencies:
  dual_screen_hinge: ^0.2.1

Requires Flutter 3.38+, Dart 3.10+, Android API 21+, or iOS 13+. iPhone Duo hinge telemetry requires a UIKit SDK that declares UIHingeInteraction. Reserved-region geometry requires an SDK that declares reservedRegions. CocoaPods and Swift Package Manager detect these APIs automatically; Xcode 27.0 SDKs without them keep the safe, unsupported fallback. No Podfile workaround is needed. Runtime support still depends on the iOS version and hardware.

Read state and animate

final subscription = DualScreenHinge.instance.events.listen((state) {
  print('${state.posture} ${state.hingeAngle}°');
});

StreamBuilder<double>(
  stream: DualScreenHinge.instance.hingeAngleEvents,
  builder: (context, snapshot) {
    final angle = snapshot.data ?? 180;
    return Transform.rotate(
      angle: (180 - angle) * math.pi / 180,
      child: const MyFoldEffect(),
    );
  },
);

The native event stream is shared by all Dart listeners, sends a snapshot on listen, deduplicates state, and coalesces sensor updates to approximately one per display frame.

Read regions for custom layout

final state = await DualScreenHinge.instance.currentState();
final activeRegionBounds = state.reservedRegions
    .where((region) => region.isActive)
    .map((region) => region.bounds)
    .toList(growable: false);

On iOS 27.1, reservedRegions contains the folding region (division) and camera regions (occlusion) in Flutter logical coordinates. Inactive regions are included so a grid can, for example, prefer an even number of columns before the fold becomes active. Active division regions are also exposed in displayFeatures for cross-platform layout code.

Use MediaQuery.sizeOf(context), MediaQuery.paddingOf(context), and flexible constraints for the overall layout. Use reserved regions only to displace important custom-positioned elements using activeRegionBounds; don't drive layout from the hinge angle or fixed iPhone Duo dimensions. See Apple's iPhone Duo HIG.

Display modes (Android)

final capabilities = await DualScreenHinge.instance.capabilities();

if (capabilities.rearDisplay) {
  await DualScreenHinge.instance.startRearDisplay();
}

if (capabilities.dualScreenPresentation) {
  await DualScreenHinge.instance.startDualScreen(
    entrypoint: 'dualScreenSecondaryMain',
    arguments: ['initial payload'],
  );
}

@pragma('vm:entry-point')
void dualScreenSecondaryMain(List<String> arguments) {
  runApp(SecondaryDisplayApp(arguments: arguments));
}

Only one display session can be pending or active. V1 deliberately supports startup arguments, not a cross-engine message bus. On iOS, display-mode methods return DualScreenException(code: 'unsupported') because there is no equivalent app-controlled public session API.

Platform behavior

Capability	Android	iOS
Continuous angle	API 30+ TYPE_HINGE_ANGLE when present	iOS 27 UIHingeInteraction on supported hardware
Fold geometry/posture	AndroidX WindowManager 1.5.1	iOS 27 hinge status; iOS 27.1 reserved regions
Camera/fold avoidance	Flutter MediaQuery.displayFeatures	Division and occlusion reserved regions on iOS 27.1
Inner/outer identity	Only while a Window Area session establishes it	Region and scene evidence; unknown when multitasking is ambiguous
Rear-display transfer	Experimental Window Area API	Unsupported
Dual-screen presentation	Experimental Window Area API + secondary Flutter engine	Unsupported

No device allowlist, OEM reflection, or private API is used. Unsupported data is nullable or reported through runtime capabilities.

Flutter-rendered toolbars don't automatically become UIKit's iPhone Duo vertical bars. Keep controls inside each independent safe-area edge, preserve their relative order across sizes, and let decorative backgrounds extend edge-to-edge separately from interactive content.

Documentation

See the documentation site, the complete wire contract, device matrix, the deployment guide, and testing guide. The example/ app includes a live fold animation and compares plugin output with MediaQuery.displayFeatures.

License

MIT. See LICENSE.