add onDestroy hooks for FilamentApp

thermion_dart/lib/src/filament/src/filament_app.dart

@@ -11,7 +11,6 @@ class FilamentConfig<T, U> {
   final U? renderCallbackOwner;
   final Future<Uint8List> Function(String) resourceLoader;
   final U? platform;
-  final U? driver;
   final U? sharedContext;
   final String? uberArchivePath;
   final int stereoscopicEyeCount;
@@ -24,7 +23,6 @@ class FilamentConfig<T, U> {
       this.renderCallback,
       this.renderCallbackOwner,
       this.platform,
-      this.driver,
       this.sharedContext,
       this.stereoscopicEyeCount = 1,
       this.disableHandleUseAfterFreeCheck = false});
@@ -306,4 +304,9 @@ abstract class FilamentApp<T> {
   ///
   ///
   Future flush();
+
+  ///
+  ///
+  ///
+  void onDestroy(Future Function() callback);
 }

thermion_dart/lib/src/viewer/src/ffi/src/ffi_filament_app.dart

@@ -15,6 +15,7 @@ import 'package:thermion_dart/src/viewer/src/ffi/src/ffi_texture.dart';
 import 'package:thermion_dart/src/viewer/src/ffi/src/ffi_view.dart';
 import 'package:thermion_dart/src/viewer/src/ffi/src/thermion_viewer_ffi.dart';
 import 'package:thermion_dart/thermion_dart.dart';
+import 'package:logging/logging.dart';
 
 typedef RenderCallback = Pointer<NativeFunction<Void Function(Pointer<Void>)>>;
 
@@ -22,7 +23,6 @@ class FFIFilamentConfig extends FilamentConfig<RenderCallback, Pointer<Void>> {
   FFIFilamentConfig(
       {required super.resourceLoader,
       super.backend = Backend.DEFAULT,
-      super.driver = null,
       super.platform = null,
       super.sharedContext = null,
       super.uberArchivePath = null});
@@ -41,6 +41,8 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
 
   final Future<Uint8List> Function(String uri) resourceLoader;
 
+  late final _logger = Logger(this.runtimeType.toString());
+
   FFIFilamentApp(
       this.engine,
       this.gltfAssetLoader,
@@ -195,11 +197,13 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
   ///
   ///
   Future destroySwapChain(SwapChain swapChain) async {
+    _logger.info("Destroying swapchain");
     await withVoidCallback((callback) {
       Engine_destroySwapChainRenderThread(
           engine, (swapChain as FFISwapChain).swapChain, callback);
     });
     _swapChains.remove(swapChain);
+    _logger.info("Destroyed swapchain");
   }
 
   ///
@@ -227,6 +231,11 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
 
     calloc.free(viewsPtr);
     FilamentApp.instance = null;
+    for (final callback in _onDestroy) {
+      await callback.call();
+    }
+
+    _onDestroy.clear();
   }
 
   ///
@@ -914,6 +923,15 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
   Future flush() async {
     await withVoidCallback((cb) => Engine_flushAndWaitRenderThead(engine, cb));
   }
+
+  final _onDestroy = <Future Function()>[];
+  
+  ///
+  ///
+  ///
+  void onDestroy(Future Function() callback) {
+    _onDestroy.add(callback);
+  }
 }
 
 class FinalizableUint8List implements Finalizable {

thermion_dart/lib/src/viewer/src/ffi/src/thermion_viewer_ffi.dart

@@ -146,12 +146,14 @@ class ThermionViewerFFI extends ThermionViewer {
   }
 
   final _onDispose = <Future Function()>[];
+  bool _disposed = false;
 
   ///
   ///
   ///
   @override
   Future dispose() async {
+    _disposed = true;
     await setRendering(false);
     await destroyAssets();
     await destroyLights();
@@ -268,6 +270,10 @@ class ThermionViewerFFI extends ThermionViewer {
   ///
   @override
   Future removeSkybox() async {
+    if(_disposed) {
+      throw ViewerDisposedException();
+    }
+
     if (skybox != null) {
       await withVoidCallback(
           (cb) => Engine_destroySkyboxRenderThread(app.engine, skybox!, cb));
@@ -713,3 +719,5 @@ class ThermionViewerFFI extends ThermionViewer {
     await scene.remove(asset);
   }
 }
+
+class ViewerDisposedException implements Exception {}