feat: add capture() function and expose viewportDimensions on ThermionViewer (allows easier saving of captured images to PNG)

thermion_dart/lib/thermion_dart/compatibility/native/thermion_dart.g.dart

@@ -1059,6 +1059,15 @@ external void render_ffi(
   ffi.Pointer<ffi.Void> viewer,
 );
 
+@ffi.Native<
+    ffi.Void Function(ffi.Pointer<ffi.Void>, ffi.Pointer<ffi.Uint8>,
+        ffi.Pointer<ffi.NativeFunction<ffi.Void Function()>>)>()
+external void capture_ffi(
+  ffi.Pointer<ffi.Void> viewer,
+  ffi.Pointer<ffi.Uint8> out,
+  ffi.Pointer<ffi.NativeFunction<ffi.Void Function()>> onComplete,
+);
+
 @ffi.Native<FilamentRenderCallback Function(FilamentRenderCallback)>()
 external FilamentRenderCallback make_render_callback_fn_pointer(
   FilamentRenderCallback arg0,

thermion_dart/lib/thermion_dart/thermion_viewer.dart

@@ -1,4 +1,5 @@
 import 'dart:math';
+import 'dart:typed_data';
 
 import 'package:thermion_dart/thermion_dart/scene.dart';
 import 'package:vector_math/vector_math_64.dart';
@@ -19,11 +20,11 @@ enum LightType {
   SPOT,
 }
 
-enum ShadowType { 
-    PCF,        //!< percentage-closer filtered shadows (default)
-    VSM,        //!< variance shadows
-    DPCF,       //!< PCF with contact hardening simulation
-    PCSS,       //!< PCF with soft shadows and contact hardening
+enum ShadowType {
+  PCF, //!< percentage-closer filtered shadows (default)
+  VSM, //!< variance shadows
+  DPCF, //!< PCF with contact hardening simulation
+  PCSS, //!< PCF with soft shadows and contact hardening
 }
 
 // copied from filament/backened/DriverEnums.h
@@ -57,6 +58,11 @@ abstract class ThermionViewer {
   
   Future<bool> get initialized;
 
+  ///
+  /// The current dimensions of the viewport (in physical pixels).
+  ///
+  late (double, double) viewportDimensions;
+
   ///
   /// The result(s) of calling [pick] (see below).
   /// This may be a broadcast stream, so you should ensure you have subscribed to this stream before calling [pick].
@@ -79,6 +85,12 @@ abstract class ThermionViewer {
   ///
   Future render();
 
+  
+  ///
+  /// Render a single frame to the viewport and copy the pixel buffer to [out].
+  ///
+  Future<Uint8List> capture();
+
   ///
   /// Sets the framerate for continuous rendering when [setRendering] is enabled.
   ///
@@ -270,10 +282,9 @@ abstract class ThermionViewer {
       {List<String>? targetMeshNames});
 
   ///
-  /// Clear all current morph animations for [entity]. 
+  /// Clear all current morph animations for [entity].
   ///
-  Future clearMorphAnimationData(
-      ThermionEntity entity);
+  Future clearMorphAnimationData(ThermionEntity entity);
 
   ///
   /// Resets all bones in the given entity to their rest pose.
@@ -736,7 +747,6 @@ abstract class ThermionViewer {
   /// Register a callback to be invoked when this viewer is disposed.
   ///
   void onDispose(Future Function() callback);
-  
 }
 
 abstract class AbstractGizmo {

thermion_dart/lib/thermion_dart/thermion_viewer_ffi.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:math';
+import 'dart:typed_data';
 import 'package:animation_tools_dart/animation_tools_dart.dart';
 import 'package:thermion_dart/thermion_dart/compatibility/compatibility.dart';
 import 'package:thermion_dart/thermion_dart/entities/gizmo.dart';
@@ -24,8 +25,6 @@ class ThermionViewerFFI extends ThermionViewer {
 
   double _pixelRatio = 1.0;
 
-  late (double, double) viewportDimensions;
-
   Pointer<Void>? _sceneManager;
 
   Pointer<Void>? _viewer;
@@ -163,6 +162,23 @@ class ThermionViewerFFI extends ThermionViewer {
     render_ffi(_viewer!);
   }
 
+  ///
+  ///
+  ///
+  @override
+  Future<Uint8List> capture() async {
+    final length = this.viewportDimensions.$1.toInt() *
+        this.viewportDimensions.$2.toInt() *
+        4;
+    final out = allocator<Uint8>(length);
+    await withVoidCallback((cb) {
+      capture_ffi(_viewer!, out, cb);
+    });
+    final data = Uint8List.fromList(out.asTypedList(length));
+    allocator.free(out);
+    return data;
+  }
+
   ///
   ///
   ///
@@ -198,7 +214,6 @@ class ThermionViewerFFI extends ThermionViewer {
       await callback.call();
     }
     _onDispose.clear();
-
   }
 
   ///
@@ -602,13 +617,9 @@ class ThermionViewerFFI extends ThermionViewer {
   Future clearMorphAnimationData(ThermionEntity entity) async {
     var meshEntities = await getChildEntities(entity, true);
 
-    for(final childEntity in meshEntities) {
-        clear_morph_animation(
-          _sceneManager!,
-          childEntity);
+    for (final childEntity in meshEntities) {
+      clear_morph_animation(_sceneManager!, childEntity);
     }
-
-
   }
 
   ///
@@ -982,8 +993,8 @@ class ThermionViewerFFI extends ThermionViewer {
       bool replaceActive = true,
       double crossfade = 0.0,
       double startOffset = 0.0}) async {
-    play_animation(
-        _sceneManager!, entity, index, loop, reverse, replaceActive, crossfade, startOffset);
+    play_animation(_sceneManager!, entity, index, loop, reverse, replaceActive,
+        crossfade, startOffset);
   }
 
   ///

thermion_dart/lib/thermion_dart/thermion_viewer_stub.dart

@@ -1,4 +1,5 @@
 import 'dart:math';
+import 'dart:typed_data';
 
 import 'package:thermion_dart/thermion_dart/scene.dart';
 import 'package:thermion_dart/thermion_dart/thermion_viewer.dart';
@@ -750,4 +751,10 @@ class ThermionViewerStub extends ThermionViewer {
     // TODO: implement setSoftShadowOptions
     throw UnimplementedError();
   }
+
+  @override
+  Future<Uint8List> capture() {
+    // TODO: implement capture
+    throw UnimplementedError();
+  }
 }