Fix iOS Camera Texture memory leak on dispose (#1135)

* Fix issue where camera texture delegate was stopping reset from being called on camera texture dispose.

* Remove implData reference from CameraTextureDelegate, and just pass down textureCache.

* PR Feedback

Author: Alex-MSFT

Plugins/NativeCamera/Source/Apple/NativeCameraImpl.h

@@ -29,7 +29,7 @@ namespace Babylon::Plugins
         Graphics::DeviceContext* m_deviceContext;
         Napi::Env m_env;
 
-        std::shared_ptr<ImplData> m_implData;
+        std::unique_ptr<ImplData> m_implData;
 
         bool m_overrideCameraTexture{};
 

Plugins/NativeCamera/Source/Apple/NativeCameraImpl.mm

@@ -25,13 +25,14 @@ @interface CameraTextureDelegate : NSObject <AVCaptureVideoDataOutputSampleBuffe
 {
     @public AVCaptureVideoOrientation videoOrientation;
 
-    std::shared_ptr<Babylon::Plugins::Camera::Impl::ImplData> implData;
+    CVMetalTextureCacheRef textureCache;
     bool orientationUpdated;
 }
 
-- (id)init:(std::shared_ptr<Babylon::Plugins::Camera::Impl::ImplData>)implData;
+- (id)init:(CVMetalTextureCacheRef)textureCache;
 - (id<MTLTexture>)getCameraTextureY;
 - (id<MTLTexture>)getCameraTextureCbCr;
+- (void)reset;
 
 @end
 
@@ -140,7 +141,9 @@ fragment float4 fragmentShader(RasterizerData in [[stage_in]],
                 [currentCommandBuffer waitUntilCompleted];
             }
 
-            [avCaptureSession stopRunning];
+            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+                [avCaptureSession stopRunning];
+            });
 
             if (textureCache)
             {
@@ -152,7 +155,7 @@ fragment float4 fragmentShader(RasterizerData in [[stage_in]],
         CameraTextureDelegate* cameraTextureDelegate{};
         AVCaptureSession* avCaptureSession{};
         CVMetalTextureCacheRef textureCache{};
-        id <MTLTexture> textureRGBA{};
+        id<MTLTexture> textureRGBA{};
         id<MTLRenderPipelineState> cameraPipelineState{};
         id<MTLDevice> metalDevice{};
         id<MTLCommandQueue> commandQueue{};
@@ -191,7 +194,7 @@ fragment float4 fragmentShader(RasterizerData in [[stage_in]],
 
         dispatch_async(dispatch_get_main_queue(), ^{
             CVMetalTextureCacheCreate(nullptr, nullptr, m_implData->metalDevice, nullptr, &m_implData->textureCache);
-            m_implData->cameraTextureDelegate = [[CameraTextureDelegate alloc]init:m_implData];
+            m_implData->cameraTextureDelegate = [[CameraTextureDelegate alloc]init:m_implData->textureCache];
             m_implData->avCaptureSession = [[AVCaptureSession alloc] init];
             m_implData->textureRGBA = nil;
 
@@ -347,7 +350,9 @@ fragment float4 fragmentShader(RasterizerData in [[stage_in]],
             // Actually start the camera session.
             [m_implData->avCaptureSession addOutput:dataOutput];
             [m_implData->avCaptureSession commitConfiguration];
-            [m_implData->avCaptureSession startRunning];
+            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+                [m_implData->avCaptureSession startRunning];
+            });
 
             // Create a pipeline state for converting the camera output to RGBA.
             id<MTLLibrary> lib = CompileShader(m_implData->metalDevice, shaderSource);
@@ -463,7 +468,9 @@ fragment float4 fragmentShader(RasterizerData in [[stage_in]],
 
     void Camera::Impl::Close()
     {
-        m_implData.reset(new ImplData);
+        [m_implData->cameraTextureDelegate reset];
+        m_implData.reset();
+        m_implData = std::make_unique<ImplData>();
     }
 }
 
@@ -472,10 +479,10 @@ @implementation CameraTextureDelegate {
     CVMetalTextureRef cameraTextureCbCr;
 }
 
-- (id)init:(std::shared_ptr<Babylon::Plugins::Camera::Impl::ImplData>)implData
+- (id)init:(CVMetalTextureCacheRef)textureCache
 {
     self = [super init];
-    self->implData = implData;
+    self->textureCache = textureCache;
 #if (TARGET_OS_IPHONE)
     [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(OrientationDidChange:) name:UIDeviceOrientationDidChangeNotification object:nil];
     [self updateOrientation];
@@ -513,6 +520,12 @@ - (id)init:(std::shared_ptr<Babylon::Plugins::Camera::Impl::ImplData>)implData
     return nil;
 }
 
+- (void) reset {
+    @synchronized (self) {
+        self->textureCache = nil;
+    }
+}
+
 #if (TARGET_OS_IPHONE)
 /**
  Updates target video orientation.
@@ -603,11 +616,16 @@ - (CVMetalTextureRef)getCameraTexture:(CVPixelBufferRef)pixelBuffer plane:(int)p
     auto pixelFormat = planeIndex ? MTLPixelFormatRG8Unorm : MTLPixelFormatR8Unorm;
     CVMetalTextureRef textureRef;
 
-    // Create a texture from the corresponding plane.
-    auto status = CVMetalTextureCacheCreateTextureFromImage(kCFAllocatorDefault, implData->textureCache, pixelBuffer, nil, pixelFormat, planeWidth, planeHeight, planeIndex, &textureRef);
-    if (status != kCVReturnSuccess) {
-        CVBufferRelease(textureRef);
-        textureRef = nil;
+    @synchronized (self) {
+        if (self->textureCache == nil) {
+            return{};
+        }
+
+        auto status = CVMetalTextureCacheCreateTextureFromImage(kCFAllocatorDefault, textureCache, pixelBuffer, nil, pixelFormat, planeWidth, planeHeight, planeIndex, &textureRef);
+        if (status != kCVReturnSuccess) {
+            CVBufferRelease(textureRef);
+            textureRef = nil;
+        }
     }
 
     return textureRef;