fix: Fix view-not-found race condition in C++ code (#511)

* Add custom `onViewReady` event to get layout

`componentDidMount` is async, so the native view _might_ not exist yet causing a race condition in the `setFrameProcessor` code.

This PR fixes this by calling `setFrameProcessor` only after the native view has actually mounted, and to ensure that I created a custom event that fires at that point.

* Update CameraView.swift

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

@@ -42,6 +42,12 @@ fun CameraView.invokeOnFrameProcessorPerformanceSuggestionAvailable(currentFps:
   reactContext.getJSModule(RCTEventEmitter::class.java).receiveEvent(id, "cameraPerformanceSuggestionAvailable", event)
 }
 
+fun CameraView.invokeOnViewReady() {
+  val event = Arguments.createMap()
+  val reactContext = context as ReactContext
+  reactContext.getJSModule(RCTEventEmitter::class.java).receiveEvent(id, "cameraViewReady", event)
+}
+
 private fun errorToMap(error: Throwable): WritableMap {
   val map = Arguments.createMap()
   map.putString("message", error.message)

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

@@ -108,6 +108,7 @@ class CameraView(context: Context, private val frameProcessorThread: ExecutorSer
     }
 
   // private properties
+  private var isMounted = false
   private val reactContext: ReactContext
     get() = context as ReactContext
 
@@ -266,6 +267,10 @@ class CameraView(context: Context, private val frameProcessorThread: ExecutorSer
   override fun onAttachedToWindow() {
     super.onAttachedToWindow()
     updateLifecycleState()
+    if (!isMounted) {
+      isMounted = true
+      invokeOnViewReady()
+    }
   }
 
   override fun onDetachedFromWindow() {

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

@@ -55,6 +55,7 @@ class CameraViewManager(reactContext: ReactApplicationContext) : SimpleViewManag
 
   override fun getExportedCustomDirectEventTypeConstants(): MutableMap<String, Any>? {
     return MapBuilder.builder<String, Any>()
+      .put("cameraViewReady", MapBuilder.of("registrationName", "onViewReady"))
       .put("cameraInitialized", MapBuilder.of("registrationName", "onInitialized"))
       .put("cameraError", MapBuilder.of("registrationName", "onError"))
       .put("cameraPerformanceSuggestionAvailable", MapBuilder.of("registrationName", "onFrameProcessorPerformanceSuggestionAvailable"))

ios/CameraView.swift

@@ -65,6 +65,7 @@ public final class CameraView: UIView {
   @objc var onInitialized: RCTDirectEventBlock?
   @objc var onError: RCTDirectEventBlock?
   @objc var onFrameProcessorPerformanceSuggestionAvailable: RCTDirectEventBlock?
+  @objc var onViewReady: RCTDirectEventBlock?
   // zoom
   @objc var enableZoomGesture = false {
     didSet {
@@ -77,7 +78,7 @@ public final class CameraView: UIView {
   }
 
   // pragma MARK: Internal Properties
-
+  internal var isMounted = false
   internal var isReady = false
   // Capture Session
   internal let captureSession = AVCaptureSession()
@@ -179,6 +180,17 @@ public final class CameraView: UIView {
                                               object: nil)
   }
 
+  override public func willMove(toSuperview newSuperview: UIView?) {
+    super.willMove(toSuperview: newSuperview)
+    if !isMounted {
+      isMounted = true
+      guard let onViewReady = onViewReady else {
+        return
+      }
+      onViewReady(nil)
+    }
+  }
+
   // pragma MARK: Props updating
   override public final func didSetProps(_ changedProps: [String]!) {
     ReactLogger.log(level: .info, message: "Updating \(changedProps.count) prop(s)...")

ios/CameraViewManager.m

@@ -45,10 +45,11 @@ RCT_EXPORT_VIEW_PROPERTY(preset, NSString);
 RCT_EXPORT_VIEW_PROPERTY(torch, NSString);
 RCT_EXPORT_VIEW_PROPERTY(zoom, NSNumber);
 RCT_EXPORT_VIEW_PROPERTY(enableZoomGesture, BOOL);
-// Camera View Properties
+// Camera View Events
 RCT_EXPORT_VIEW_PROPERTY(onError, RCTDirectEventBlock);
 RCT_EXPORT_VIEW_PROPERTY(onInitialized, RCTDirectEventBlock);
 RCT_EXPORT_VIEW_PROPERTY(onFrameProcessorPerformanceSuggestionAvailable, RCTDirectEventBlock);
+RCT_EXPORT_VIEW_PROPERTY(onViewReady, RCTDirectEventBlock);
 
 // Camera View Functions
 RCT_EXTERN_METHOD(startRecording:(nonnull NSNumber *)node options:(NSDictionary *)options onRecordCallback:(RCTResponseSenderBlock)onRecordCallback);

src/Camera.tsx

@@ -30,6 +30,7 @@ type NativeCameraViewProps = Omit<
   onInitialized?: (event: NativeSyntheticEvent<void>) => void;
   onError?: (event: NativeSyntheticEvent<OnErrorEvent>) => void;
   onFrameProcessorPerformanceSuggestionAvailable?: (event: NativeSyntheticEvent<FrameProcessorPerformanceSuggestion>) => void;
+  onViewReady: () => void;
 };
 type RefType = React.Component<NativeCameraViewProps> & Readonly<NativeMethods>;
 //#endregion
@@ -82,6 +83,7 @@ export class Camera extends React.PureComponent<CameraProps> {
   /** @internal */
   constructor(props: CameraProps) {
     super(props);
+    this.onViewReady = this.onViewReady.bind(this);
     this.onInitialized = this.onInitialized.bind(this);
     this.onError = this.onError.bind(this);
     this.onFrameProcessorPerformanceSuggestionAvailable = this.onFrameProcessorPerformanceSuggestionAvailable.bind(this);
@@ -367,15 +369,13 @@ export class Camera extends React.PureComponent<CameraProps> {
     global.unsetFrameProcessor(this.handle);
   }
 
-  componentDidMount(): void {
+  private onViewReady(): void {
-    requestAnimationFrame(() => {
+    this.isNativeViewMounted = true;
-      this.isNativeViewMounted = true;
+    if (this.props.frameProcessor != null) {
-      if (this.props.frameProcessor != null) {
+      // user passed a `frameProcessor` but we didn't set it yet because the native view was not mounted yet. set it now.
-        // user passed a `frameProcessor` but we didn't set it yet because the native view was not mounted yet. set it now.
+      this.setFrameProcessor(this.props.frameProcessor);
-        this.setFrameProcessor(this.props.frameProcessor);
+      this.lastFrameProcessor = this.props.frameProcessor;
-        this.lastFrameProcessor = this.props.frameProcessor;
+    }
-      }
-    });
   }
 
   /** @internal */
@@ -411,6 +411,7 @@ export class Camera extends React.PureComponent<CameraProps> {
         frameProcessorFps={frameProcessorFps === 'auto' ? -1 : frameProcessorFps}
         cameraId={device.id}
         ref={this.ref}
+        onViewReady={this.onViewReady}
         onInitialized={this.onInitialized}
         onError={this.onError}
         onFrameProcessorPerformanceSuggestionAvailable={this.onFrameProcessorPerformanceSuggestionAvailable}