fix: Fix UI Thread race condition in setFrameProcessor(...) (#265)

* fix: Fix UI Thread race condition in `setFrameProcessor(...)`

* Revert "fix: Fix UI Thread race condition in `setFrameProcessor(...)`"

This reverts commit 9c524e123cff6843d7d11db602a5027d1bb06b4b.

* Use `setImmediate` to call `setFrameProcessor(...)`

* Fix frame processor order of applying

* Add `enableFrameProcessor` prop that defines if a FP is added

* rename constant

* Implement `enableFrameProcessor` prop for Android and make `frameProcessorFps` faster

* link to troubleshooting guide

* Update TROUBLESHOOTING.mdx

* Add logs for use-cases

* fix log

* set initial frame processor in `onLayout` instead of `componentDidMount`

android/src/main/cpp/CameraView.cpp

@@ -30,8 +30,7 @@ void CameraView::registerNatives() {
 
 void CameraView::frameProcessorCallback(const alias_ref<JImageProxy::javaobject>& frame) {
   if (frameProcessor_ == nullptr) {
-    __android_log_write(ANDROID_LOG_WARN, TAG, "Frame Processor is null!");
-    setEnableFrameProcessor(false);
+    __android_log_write(ANDROID_LOG_WARN, TAG, "Called Frame Processor callback, but `frameProcessor` is null!");
     return;
   }
 
@@ -45,24 +44,12 @@ void CameraView::frameProcessorCallback(const alias_ref<JImageProxy::javaobject>
   }
 }
 
-void CameraView::setEnableFrameProcessor(bool enable) {
-  if (enable) {
-    __android_log_write(ANDROID_LOG_INFO, TAG, "Enabling Frame Processor Callback...");
-  } else {
-    __android_log_write(ANDROID_LOG_INFO, TAG, "Disabling Frame Processor Callback...");
-  }
-  static const auto javaMethod = javaPart_->getClass()->getMethod<void(bool)>("setEnableFrameProcessor");
-  javaMethod(javaPart_.get(), enable);
-}
-
 void CameraView::setFrameProcessor(const FrameProcessor&& frameProcessor) {
   frameProcessor_ = frameProcessor;
-  setEnableFrameProcessor(true);
 }
 
 void vision::CameraView::unsetFrameProcessor() {
   frameProcessor_ = nullptr;
-  setEnableFrameProcessor(false);
 }
 
 } // namespace vision

android/src/main/cpp/CameraView.h

@@ -26,7 +26,6 @@ class CameraView : public jni::HybridClass<CameraView> {
   // TODO: Use template<> to avoid heap allocation for std::function<>
   void setFrameProcessor(const FrameProcessor&& frameProcessor);
   void unsetFrameProcessor();
-  void setEnableFrameProcessor(bool enable);
 
  private:
   friend HybridBase;

android/src/main/java/com/mrousavy/camera/CameraView.kt

@@ -71,6 +71,7 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
   var photo: Boolean? = null
   var video: Boolean? = null
   var audio: Boolean? = null
+  var enableFrameProcessor = false
   // props that require format reconfiguring
   var format: ReadableMap? = null
   var fps: Int? = null
@@ -88,8 +89,6 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
   private val reactContext: ReactContext
     get() = context as ReactContext
 
-  private var enableFrameProcessor = false
-
   @Suppress("JoinDeclarationAndAssignment")
   internal val previewView: PreviewView
   private val cameraExecutor = Executors.newSingleThreadExecutor()
@@ -99,7 +98,10 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
   internal var camera: Camera? = null
   internal var imageCapture: ImageCapture? = null
   internal var videoCapture: VideoCapture? = null
-  internal var imageAnalysis: ImageAnalysis? = null
+  private var imageAnalysis: ImageAnalysis? = null
+
+  private var lastFrameProcessorCall = System.currentTimeMillis()
+
   private var extensionsManager: ExtensionsManager? = null
 
   private val scaleGestureListener: ScaleGestureDetector.SimpleOnScaleGestureListener
@@ -191,26 +193,6 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
   private external fun initHybrid(): HybridData
   private external fun frameProcessorCallback(frame: ImageProxy)
 
-  @Suppress("unused")
-  @DoNotStrip
-  fun setEnableFrameProcessor(enable: Boolean) {
-    Log.d(TAG, "Set enable frame processor: $enable")
-    val before = enableFrameProcessor
-    enableFrameProcessor = enable
-
-    if (before != enable) {
-      // reconfigure session if frame processor was added/removed to adjust use-cases.
-      GlobalScope.launch(Dispatchers.Main) {
-        try {
-          configureSession()
-        } catch (e: Throwable) {
-          Log.e(TAG, "Failed to configure session after setting frame processor! ${e.message}")
-          invokeOnError(e)
-        }
-      }
-    }
-  }
-
   override fun getLifecycle(): Lifecycle {
     return lifecycleRegistry
   }
@@ -383,6 +365,7 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
       // Bind use cases to camera
       val useCases = ArrayList<UseCase>()
       if (video == true) {
+        Log.i(TAG, "Adding VideoCapture use-case...")
         videoCapture = videoCaptureBuilder.build()
         useCases.add(videoCapture!!)
       }
@@ -391,18 +374,19 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
           Log.i(TAG, "Tried to add photo use-case (`photo={true}`) but the Camera device only supports " +
             "a single use-case at a time. Falling back to Snapshot capture.")
         } else {
+          Log.i(TAG, "Adding ImageCapture use-case...")
           imageCapture = imageCaptureBuilder.build()
           useCases.add(imageCapture!!)
         }
       }
       if (enableFrameProcessor) {
-        var lastCall = System.currentTimeMillis() - 1000
-        val intervalMs = (1.0 / frameProcessorFps) * 1000.0
+        Log.i(TAG, "Adding ImageAnalysis use-case...")
         imageAnalysis = imageAnalysisBuilder.build().apply {
           setAnalyzer(cameraExecutor, { image ->
             val now = System.currentTimeMillis()
-            if (now - lastCall > intervalMs) {
-              lastCall = now
+            val intervalMs = (1.0 / frameProcessorFps) * 1000.0
+            if (now - lastFrameProcessorCall > intervalMs) {
+              lastFrameProcessorCall = now
               frameProcessorCallback(image)
             }
             image.close()
@@ -477,7 +461,7 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
     const val TAG = "CameraView"
     const val TAG_PERF = "CameraView.performance"
 
-    private val propsThatRequireSessionReconfiguration = arrayListOf("cameraId", "format", "fps", "hdr", "lowLightBoost", "photo", "video", "frameProcessorFps")
+    private val propsThatRequireSessionReconfiguration = arrayListOf("cameraId", "format", "fps", "hdr", "lowLightBoost", "photo", "video", "enableFrameProcessor")
     private val arrayListOfZoom = arrayListOf("zoom")
   }
 }

android/src/main/java/com/mrousavy/camera/CameraViewManager.kt

@@ -43,6 +43,13 @@ class CameraViewManager : SimpleViewManager<CameraView>() {
     view.audio = audio
   }
 
+  @ReactProp(name = "enableFrameProcessor")
+  fun setEnableFrameProcessor(view: CameraView, enableFrameProcessor: Boolean) {
+    if (view.enableFrameProcessor != enableFrameProcessor)
+      addChangedPropToTransaction(view, "enableFrameProcessor")
+    view.enableFrameProcessor = enableFrameProcessor
+  }
+
   @ReactProp(name = "enableDepthData")
   fun setEnableDepthData(view: CameraView, enableDepthData: Boolean) {
     if (view.enableDepthData != enableDepthData)