Decrease exposure on white balance issue

- add onCameraConfigurationChanged to CameraSessionDelegate to notify CameraView when configuration changes
- when orientatin change update CameraView.PreviewView.videoPreviewLayer.connection orientation value

package/ios/CameraView.swift

@@ -87,6 +87,7 @@ public final class CameraView: UIView, CameraSessionDelegate {
   var pinchGestureRecognizer: UIPinchGestureRecognizer?
   var pinchScaleOffset: CGFloat = 1.0
   private var currentConfigureCall: DispatchTime?
+  var lastProcessedTime: Date?
 
   var previewView: PreviewView
   #if DEBUG
@@ -303,6 +304,15 @@ public final class CameraView: UIView, CameraSessionDelegate {
     }
     onInitialized([:])
   }
+  
+  func onCameraConfigurationChanged(_ configuration: CameraConfiguration?, _ difference: CameraConfiguration.Difference?) {
+    guard let configuration, let difference else { return }
+    
+    if difference.orientationChanged, let connection = previewView.videoPreviewLayer.connection {
+      let videoPreviewLayer = previewView.videoPreviewLayer
+      connection.setOrientation(configuration.orientation)
+    }
+  }
 
   func onCameraStarted() {
     ReactLogger.log(level: .info, message: "Camera started!")
@@ -321,6 +331,7 @@ public final class CameraView: UIView, CameraSessionDelegate {
   }
 
   func onFrame(sampleBuffer: CMSampleBuffer) {
+    processFrameIfNeeded(sampleBuffer)
     #if VISION_CAMERA_ENABLE_FRAME_PROCESSORS
       if let frameProcessor = frameProcessor {
         // Call Frame Processor
@@ -395,3 +406,99 @@ public final class CameraView: UIView, CameraSessionDelegate {
     }
   }
 }
+
+extension CameraView {
+  
+  func processFrameIfNeeded(_ sampleBuffer: CMSampleBuffer) {
+    let currentTime = Date()
+    if let lastTime = lastProcessedTime {
+      if currentTime.timeIntervalSince(lastTime) >= 10.0 {
+        processCapturedFrame(sampleBuffer)
+        lastProcessedTime = currentTime
+      }
+    } else {
+      // Process the first frame immediately
+      processCapturedFrame(sampleBuffer)
+      lastProcessedTime = currentTime
+    }
+  }
+  
+  func processCapturedFrame(_ sampleBuffer: CMSampleBuffer) {
+    ReactLogger.log(level: .info, message: "processCapturedFrame")
+    // Your existing processing logic
+    guard let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return }
+    
+    let ciImage = CIImage(cvPixelBuffer: pixelBuffer)
+    
+    // Analyze for white balance
+    let isWhiteBalanceIssue = analyzeFrameForWhiteBalance(ciImage: ciImage)
+    
+    if isWhiteBalanceIssue {
+      ReactLogger.log(level: .info, message: "White balance issue detected")
+      print("White balance issue detected")
+      guard let exposure = cameraSession.configuration?.exposure else {
+        updateExposure(0.5)
+        return
+      }
+      updateExposure(exposure - 0.2)
+      ReactLogger.log(level: .info, message: "Exposure = \(exposure)")
+    } else {
+      ReactLogger.log(level: .info, message: "White balance is okay")
+      print("White balance is okay. Exposure = \(cameraSession.configuration?.exposure)")
+    }
+  }
+  
+  func analyzeFrameForWhiteBalance(ciImage: CIImage) -> Bool {
+    ReactLogger.log(level: .info, message: "analyzeFrameForWhiteBalance")
+    let extent = ciImage.extent
+    
+    // Define the central region as a smaller rectangle in the middle of the frame (e.g., 1/4 the size)
+    let centerRect = CGRect(
+      x: extent.origin.x + extent.size.width * 0.25,
+      y: extent.origin.y + extent.size.height * 0.25,
+      width: extent.size.width * 0.5,
+      height: extent.size.height * 0.5
+    )
+    
+    // Crop the image to the centerRect
+    let croppedImage = ciImage.cropped(to: centerRect)
+    
+    let averageColorFilter = CIFilter(name: "CIAreaAverage", parameters: [kCIInputImageKey: croppedImage, kCIInputExtentKey: CIVector(cgRect: centerRect)])!
+    
+    guard let outputImage = averageColorFilter.outputImage else {
+      ReactLogger.log(level: .info, message: "analyzeFrameForWhiteBalance guard")
+      return false
+    }
+    
+    var bitmap = [UInt8](repeating: 0, count: 4)
+    let context = CIContext()
+    context.render(outputImage, toBitmap: &bitmap, rowBytes: 4, bounds: CGRect(x: 0, y: 0, width: 1, height: 1), format: .RGBA8, colorSpace: nil)
+    
+    let red = Float(bitmap[0]) / 255.0
+    let green = Float(bitmap[1]) / 255.0
+    let blue = Float(bitmap[2]) / 255.0
+    
+    ReactLogger.log(level: .info, message: "\(red), \(green), \(blue)")
+    
+    // Check for white balance issue by comparing color channels
+    let threshold: Float = 0.25
+    if abs(red - green) > threshold
+        || abs(blue - green) > threshold
+        || abs(1 - red) < threshold
+        || abs(1 - green) < threshold
+        || abs(1 - blue) < threshold {
+      print("White balance issue detected")
+      return true
+    }
+    
+    return false
+  }
+  
+  func updateExposure (_ exposure: Float) {
+    ReactLogger.log(level: .info, message: "Updating exposure: [\(exposure)]")
+    
+    cameraSession.configure { config in
+      config.exposure = exposure
+    }
+  }
+}

package/ios/Core/CameraSession.swift

@@ -195,6 +195,7 @@ class CameraSession: NSObject, AVCaptureVideoDataOutputSampleBufferDelegate, AVC
           self.delegate?.onSessionInitialized()
         }
 
+        self.delegate?.onCameraConfigurationChanged(config, difference)
         // After configuring, set this to the new configuration.
         self.configuration = config
       } catch {

package/ios/Core/CameraSessionDelegate.swift

@@ -21,6 +21,8 @@ protocol CameraSessionDelegate: AnyObject {
    Called when the [CameraSession] successfully initializes
    */
   func onSessionInitialized()
+  
+  func onCameraConfigurationChanged(_ configuration: CameraConfiguration?, _ difference: CameraConfiguration.Difference?)
   /**
    Called when the [CameraSession] starts streaming frames. (isActive=true)
    */

package/ios/Extensions/AVCaptureOutput+mirror.swift

@@ -32,28 +32,36 @@ extension AVCaptureOutput {
   func setOrientation(_ orientation: Orientation) {
     // Set orientation for each connection
     for connection in connections {
-      #if swift(>=5.9)
-        if #available(iOS 17.0, *) {
-          // Camera Sensors are always in landscape rotation (90deg).
-          // We are setting the target rotation here, so we need to rotate by landscape once.
-          let cameraOrientation = orientation.rotateBy(orientation: .landscapeLeft)
-          let degrees = cameraOrientation.toDegrees()
-
-          // TODO: Don't rotate the video output because it adds overhead. Instead just use EXIF flags for the .mp4 file if recording.
-          //       Does that work when we flip the camera?
-          if connection.isVideoRotationAngleSupported(degrees) {
-            connection.videoRotationAngle = degrees
-          }
-        } else {
-          if connection.isVideoOrientationSupported {
-            connection.videoOrientation = orientation.toAVCaptureVideoOrientation()
-          }
-        }
-      #else
-        if connection.isVideoOrientationSupported {
-          connection.videoOrientation = orientation.toAVCaptureVideoOrientation()
-        }
-      #endif
+      connection.setOrientation(orientation)
     }
   }
 }
+
+
+
+extension AVCaptureConnection {
+  func setOrientation(_ orientation: Orientation) {
+    #if swift(>=5.9)
+      if #available(iOS 17.0, *) {
+        // Camera Sensors are always in landscape rotation (90deg).
+        // We are setting the target rotation here, so we need to rotate by landscape once.
+        let cameraOrientation = orientation.rotateBy(orientation: .landscapeLeft)
+        let degrees = cameraOrientation.toDegrees()
+
+        // TODO: Don't rotate the video output because it adds overhead. Instead just use EXIF flags for the .mp4 file if recording.
+        //       Does that work when we flip the camera?
+        if isVideoRotationAngleSupported(degrees) {
+          videoRotationAngle = degrees
+        }
+      } else {
+        if isVideoOrientationSupported {
+          videoOrientation = orientation.toAVCaptureVideoOrientation()
+        }
+      }
+    #else
+      if isVideoOrientationSupported {
+        videoOrientation = orientation.toAVCaptureVideoOrientation()
+      }
+    #endif
+  }
+}

package/ios/TestRecorder/ViewController.swift

@@ -113,5 +113,19 @@ class ViewController: UIViewController {
     }
   }
   
+  override func viewWillTransition(to size: CGSize, with coordinator: any UIViewControllerTransitionCoordinator) {
+    switch UIDevice.current.orientation {
+    case .landscapeLeft:
+      cameraView.orientation = "landscape-right"
+    case .landscapeRight:
+      cameraView.orientation = "landscape-left"
+    default:
+      cameraView.orientation = "portrait"
+    }
+    
+    cameraView.didSetProps([])
+    super.viewWillTransition(to: size, with: coordinator)
+  }
+  
 }