Viewer events and notifications

Nutrient Flutter SDK emits events when users interact with documents in the viewer.

Viewer events

NutrientDocumentView exposes a typed controller.events stream from the onControllerReady callback, which replaces the legacy onViewCreated callback. NutrientEvent is a sealed class, so you can switch over the full stream exhaustively or use the per-event filter getters.

The SDK supports the following viewer events:

• controller.events.documentLoaded — DocumentLoadedEvent (event.document, the loaded NutrientDocumentInterface, which is the same instance as controller.document).
• controller.events.documentError — DocumentErrorEvent (event.error). On Web, load errors throw instead of emitting this event.
• controller.events.documentSaved — DocumentSavedEvent (event.path, or null when saving in place).
• controller.events.pageChanged — PageChangedEvent (event.pageIndex).
• controller.events.pageClicked — PageClickedEvent (event.pageIndex, event.point, event.annotation). On Web, point is null.

Use the following listeners to respond to document and page events:

NutrientDocumentView(
  documentPath: documentPath,
  onControllerReady: (controller) {
    controller.events.documentLoaded.listen((event) async {
      final pageCount = await event.document.getPageCount();
      print('Loaded — $pageCount pages');
    });
    controller.events.documentError.listen((e) => print('Document load failed: ${e.error}'));
    controller.events.pageChanged.listen((e) => print('Page changed to ${e.pageIndex}'));
    controller.events.pageClicked.listen((e) => print('Page clicked: ${e.pageIndex}'));
  },
)

Platform-specific lifecycle events

The cross-platform stream doesn’t include native view lifecycle events. Use your platform adapter’s event stream to access them:

• Android — androidEvents emits AndroidActivityPausedEvent when the hosting activity pauses.
• iOS — iosEvents emits IOSViewControllerWillDismissEvent and IOSViewControllerDidDismissEvent around the view controller’s dismissal.

Refer to the platform adapters guide for more information. The following example subscribes inside a custom adapter:

class MyIOSAdapter extends IOSAdapter implements MyController {
  @override
  Future<void> onViewControllerReady(PSPDFViewController viewController) async {
    iosEvents.listen((event) {
      switch (event) {
        case IOSViewControllerWillDismissEvent():
          print('View controller will dismiss');
        case IOSViewControllerDidDismissEvent():
          print('View controller did dismiss');
        default:
          break;
      }
    });
  }
}