feat: Keep one last Video Frame in memory for Snapshot (#2980)

* feat: Keep one last Video Frame in memory for Snapshot

* Other way around

* Update CameraView+TakeSnapshot.swift

package/ios/React/CameraView+TakeSnapshot.swift

@@ -11,49 +11,27 @@ import UIKit
 
 extension CameraView {
   func takeSnapshot(options _: NSDictionary, promise: Promise) {
-    // If video is not enabled, we won't get any buffers in onFrameListeners. abort it.
-    guard video else {
-      promise.reject(error: .capture(.videoNotEnabled))
-      return
-    }
-
-    // If after 3 seconds we still didn't receive a snapshot, we abort it.
-    CameraQueues.cameraQueue.asyncAfter(deadline: .now() + 3) {
-      if !promise.didResolve {
-        promise.reject(error: .capture(.timedOut))
+    withPromise(promise) {
+      guard let snapshot = latestVideoFrame else {
+        throw CameraError.capture(.snapshotFailed)
       }
-    }
-
-    // Add a listener to the onFrame callbacks which will get called later if video is enabled.
-    snapshotOnFrameListeners.append { buffer in
-      if promise.didResolve {
-        // capture was already aborted (timed out)
-        return
+      guard let imageBuffer = CMSampleBufferGetImageBuffer(snapshot) else {
+        throw CameraError.capture(.imageDataAccessError)
       }
 
       self.onCaptureShutter(shutterType: .snapshot)
 
-      guard let imageBuffer = CMSampleBufferGetImageBuffer(buffer) else {
-        promise.reject(error: .capture(.imageDataAccessError))
-        return
-      }
       let ciImage = CIImage(cvPixelBuffer: imageBuffer)
       let orientation = self.cameraSession.outputOrientation
       let image = UIImage(ciImage: ciImage, scale: 1.0, orientation: orientation.imageOrientation)
-      do {
-        let path = try FileUtils.writeUIImageToTempFile(image: image)
-        promise.resolve([
-          "path": path.absoluteString,
-          "width": image.size.width,
-          "height": image.size.height,
-          "orientation": orientation.jsValue,
-          "isMirrored": false,
-        ])
-      } catch let error as CameraError {
-        promise.reject(error: error)
-      } catch {
-        promise.reject(error: .capture(.unknown(message: "An unknown error occured while capturing the snapshot!")), cause: error as NSError)
-      }
+      let path = try FileUtils.writeUIImageToTempFile(image: image)
+      return [
+        "path": path.absoluteString,
+        "width": image.size.width,
+        "height": image.size.height,
+        "orientation": orientation.jsValue,
+        "isMirrored": false,
+      ]
     }
   }
 }

package/ios/React/CameraView.swift

@@ -89,20 +89,23 @@ public final class CameraView: UIView, CameraSessionDelegate, PreviewViewDelegat
     }
   }
 
+  #if VISION_CAMERA_ENABLE_FRAME_PROCESSORS
+    @objc public var frameProcessor: FrameProcessor?
+  #endif
+
   // pragma MARK: Internal Properties
   var cameraSession = CameraSession()
   var previewView: PreviewView?
   var isMounted = false
-  #if VISION_CAMERA_ENABLE_FRAME_PROCESSORS
-    @objc public var frameProcessor: FrameProcessor?
-  #endif
+  private var currentConfigureCall: DispatchTime?
+  private let fpsSampleCollector = FpsSampleCollector()
 
   // CameraView+Zoom
   var pinchGestureRecognizer: UIPinchGestureRecognizer?
   var pinchScaleOffset: CGFloat = 1.0
-  var snapshotOnFrameListeners: [(_: CMSampleBuffer) -> Void] = []
-  private var currentConfigureCall: DispatchTime?
-  private let fpsSampleCollector = FpsSampleCollector()
+
+  // CameraView+TakeSnapshot
+  var latestVideoFrame: CMSampleBuffer?
 
   // pragma MARK: Setup
 
@@ -354,6 +357,10 @@ public final class CameraView: UIView, CameraSessionDelegate, PreviewViewDelegat
   }
 
   func onFrame(sampleBuffer: CMSampleBuffer, orientation: Orientation) {
+    // Update latest frame that can be used for snapshot capture
+    latestVideoFrame = sampleBuffer
+
+    // Notify FPS Collector that we just had a Frame
     fpsSampleCollector.onTick()
 
     #if VISION_CAMERA_ENABLE_FRAME_PROCESSORS
@@ -363,11 +370,6 @@ public final class CameraView: UIView, CameraSessionDelegate, PreviewViewDelegat
         frameProcessor.call(frame)
       }
     #endif
-
-    for callback in snapshotOnFrameListeners {
-      callback(sampleBuffer)
-    }
-    snapshotOnFrameListeners.removeAll()
   }
 
   func onCodeScanned(codes: [CameraSession.Code], scannerFrame: CameraSession.CodeScannerFrame) {