From c7d4d9cb3386d12cc28016b40b64e45786ddc397 Mon Sep 17 00:00:00 2001
From: Nick Fisher <nick.fisher@avinium.com>
Date: Tue, 24 Jun 2025 10:35:33 +0800
Subject: [PATCH] add NativeHandle interface and refactor SwapChain to use
 getNativeHandle

---
 .../src/implementation/ffi_filament_app.dart    | 17 ++++++++++++-----
 .../src/implementation/ffi_swapchain.dart       | 10 +++++++---
 .../filament/src/interface/native_handle.dart   | 11 +++++++++++
 .../src/filament/src/interface/swap_chain.dart  |  4 +++-
 4 files changed, 33 insertions(+), 9 deletions(-)
 create mode 100644 thermion_dart/lib/src/filament/src/interface/native_handle.dart

diff --git a/thermion_dart/lib/src/filament/src/implementation/ffi_filament_app.dart b/thermion_dart/lib/src/filament/src/implementation/ffi_filament_app.dart
index 7d74d7d9..c15ff593 100644
--- a/thermion_dart/lib/src/filament/src/implementation/ffi_filament_app.dart
+++ b/thermion_dart/lib/src/filament/src/implementation/ffi_filament_app.dart
@@ -145,7 +145,7 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
         }
       }
       RenderTicker_setRenderable(
-          renderTicker, swapChain.swapChain, viewsPtr, numRenderable);
+          renderTicker, swapChain.getNativeHandle(), viewsPtr, numRenderable);
       _logger.info("Updated render order, $numRenderable renderable views");
     }
   }
@@ -223,7 +223,7 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
     _logger.info("Destroying swapchain");
     await withVoidCallback((requestId, callback) {
       Engine_destroySwapChainRenderThread(
-          engine, (swapChain as FFISwapChain).swapChain, requestId, callback);
+          engine, swapChain.getNativeHandle(), requestId, callback);
     });
     _swapChains.remove(swapChain);
     _logger.info("Destroyed swapchain");
@@ -575,7 +575,7 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
     final view = _swapChains[swapchain]!.first;
     await withBoolCallback((cb) {
       Renderer_beginFrameRenderThread(
-          renderer, swapchain.swapChain, 0.toBigInt, cb);
+          renderer, swapchain.getNativeHandle(), 0.toBigInt, cb);
     });
     await withVoidCallback((requestId, cb) {
       Renderer_renderRenderThread(
@@ -622,6 +622,13 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
     await updateRenderOrder();
   }
 
+  ///
+  ///
+  ///
+  Future<Iterable<SwapChain>> getSwapChains() async {
+    return _swapChains.keys;
+  }
+
   final _hooks = <Future Function()>[];
 
   ///
@@ -756,7 +763,7 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
 
     final beginFrame = await withBoolCallback((cb) {
       Renderer_beginFrameRenderThread(
-          renderer, swapChain!.swapChain, 0.toBigInt, cb);
+          renderer, swapChain!.getNativeHandle(), 0.toBigInt, cb);
     });
 
     final pixelBuffers = <(View, Uint8List)>[];
@@ -838,7 +845,7 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
     // synchronous, so we'll add a ~2 frame delay to wait for this to be available.
     if (FILAMENT_SINGLE_THREADED) {
       await withBoolCallback((cb) => Renderer_beginFrameRenderThread(
-          renderer, swapChain!.swapChain, 0.toBigInt, cb));
+          renderer, swapChain!.getNativeHandle(), 0.toBigInt, cb));
       for (final view in views) {
         await withVoidCallback((requestId, cb) {
           Renderer_renderRenderThread(
diff --git a/thermion_dart/lib/src/filament/src/implementation/ffi_swapchain.dart b/thermion_dart/lib/src/filament/src/implementation/ffi_swapchain.dart
index 9b57c7f5..0096978f 100644
--- a/thermion_dart/lib/src/filament/src/implementation/ffi_swapchain.dart
+++ b/thermion_dart/lib/src/filament/src/implementation/ffi_swapchain.dart
@@ -1,7 +1,11 @@
 import 'package:thermion_dart/thermion_dart.dart';
 
-class FFISwapChain extends SwapChain {
-  final Pointer<TSwapChain> swapChain;
+class FFISwapChain extends SwapChain<Pointer> {
+  
+  final Pointer<TSwapChain> pointer;
 
-  FFISwapChain(this.swapChain);
+  T getNativeHandle<T>() => pointer as T;
+
+  FFISwapChain(this.pointer);
+  
 }
diff --git a/thermion_dart/lib/src/filament/src/interface/native_handle.dart b/thermion_dart/lib/src/filament/src/interface/native_handle.dart
new file mode 100644
index 00000000..0bb975fe
--- /dev/null
+++ b/thermion_dart/lib/src/filament/src/interface/native_handle.dart
@@ -0,0 +1,11 @@
+/// A top-level interface for any object that need to be passed
+/// across "native" boundaries (either via FFI or Javascript interop).
+///
+/// Currently, [T] must always be a [Pointer] (which is defined and implemented
+/// differently depending on the target platform). However, T is unbounded so
+/// this is never checked at compile-time (so getNativeHandle<Matrix4>() is 
+/// not a compile-time error). 
+///
+abstract class NativeHandle<T> {
+  T getNativeHandle<T>();
+}
diff --git a/thermion_dart/lib/src/filament/src/interface/swap_chain.dart b/thermion_dart/lib/src/filament/src/interface/swap_chain.dart
index e15393c3..faac0616 100644
--- a/thermion_dart/lib/src/filament/src/interface/swap_chain.dart
+++ b/thermion_dart/lib/src/filament/src/interface/swap_chain.dart
@@ -1,3 +1,5 @@
-abstract class SwapChain {
+import 'native_handle.dart';
+
+abstract class SwapChain<T> extends NativeHandle<T> {
   
 }