hang animation until focus completes

Signal/src/ViewControllers/Attachment Keyboard/AttachmentFormatPickerView.swift

@@ -166,6 +166,10 @@ extension AttachmentFormatPickerView: PhotoCaptureDelegate {
     func endCaptureButtonAnimation(_ duration: TimeInterval) {
         owsFailDebug("\(#function) should never be called")
     }
+
+    func photoCapture(_ photoCapture: PhotoCapture, didCompleteFocusingAtPoint focusPoint: CGPoint) {
+        owsFailDebug("\(#function) should never be called")
+    }
 }
 
 // MARK: - UICollectionViewDataSource

Signal/src/ViewControllers/Photos/PhotoCapture.swift

@@ -13,7 +13,7 @@ protocol PhotoCaptureDelegate: AnyObject {
     func photoCapture(_ photoCapture: PhotoCapture, didFinishProcessingAttachment attachment: SignalAttachment)
     func photoCapture(_ photoCapture: PhotoCapture, processingDidError error: Error)
 
-    // MARK: Video
+    // MARK: Movie
 
     func photoCaptureDidBeginMovie(_ photoCapture: PhotoCapture)
     func photoCaptureDidCompleteMovie(_ photoCapture: PhotoCapture)
@@ -28,6 +28,9 @@ protocol PhotoCaptureDelegate: AnyObject {
 
     func beginCaptureButtonAnimation(_ duration: TimeInterval)
     func endCaptureButtonAnimation(_ duration: TimeInterval)
+
+    func photoCapture(_ photoCapture: PhotoCapture, didCompleteFocusingAtPoint focusPoint: CGPoint)
+
 }
 
 @objc
@@ -61,11 +64,25 @@ class PhotoCapture: NSObject {
 
     private let recordingAudioActivity = AudioActivity(audioDescription: "PhotoCapture", behavior: .playAndRecord)
 
+    var focusObservation: NSKeyValueObservation?
     override init() {
         self.session = AVCaptureSession()
         self.captureOutput = CaptureOutput()
     }
 
+    func didCompleteFocusing() {
+        Logger.debug("")
+        guard let currentCaptureInput = currentCaptureInput else {
+            return
+        }
+
+        let focusPoint = currentCaptureInput.device.focusPointOfInterest
+
+        DispatchQueue.main.async {
+            self.delegate?.photoCapture(self, didCompleteFocusingAtPoint: focusPoint)
+        }
+    }
+
     // MARK: - Dependencies
 
     private var audioSession: OWSAudioSession {
@@ -265,6 +282,26 @@ class PhotoCapture: NSObject {
         session.addInput(newInput)
         NotificationCenter.default.addObserver(self, selector: #selector(subjectAreaDidChange), name: .AVCaptureDeviceSubjectAreaDidChange, object: newInput.device)
 
+        if let focusObservation = focusObservation {
+            focusObservation.invalidate()
+        }
+        self.focusObservation = newInput.observe(\.device.isAdjustingFocus,
+                                                 options: [.old, .new]) { [weak self] _, change in
+                                                    guard let self = self else { return }
+
+                                                    guard let oldValue = change.oldValue else {
+                                                        return
+                                                    }
+
+                                                    guard let newValue = change.newValue else {
+                                                        return
+                                                    }
+
+                                                    if oldValue == true && newValue == false {
+                                                        self.didCompleteFocusing()
+                                                    }
+        }
+
         currentCaptureInput = newInput
 
         resetFocusAndExposure()

Signal/src/ViewControllers/Photos/PhotoCaptureViewController.swift

@@ -362,13 +362,29 @@ class PhotoCaptureViewController: OWSViewController {
     func didTapFocusExpose(tapGesture: UITapGestureRecognizer) {
         let viewLocation = tapGesture.location(in: view)
         let devicePoint = previewView.previewLayer.captureDevicePointConverted(fromLayerPoint: viewLocation)
-
+        currentlyFocusingAtPoint = devicePoint
         tapToFocusView.center = viewLocation
-        tapToFocusView.play()
-
+        startFocusAnimation()
         photoCapture.focus(with: .autoFocus, exposureMode: .autoExpose, at: devicePoint, monitorSubjectAreaChange: true)
     }
 
+    // MARK: - Focus Animations
+
+    func startFocusAnimation() {
+        tapToFocusView.stop()
+        tapToFocusView.play(fromProgress: 0.0, toProgress: 0.9)
+    }
+
+    var currentlyFocusingAtPoint = CGPoint(x: 0.5, y: 0.5)
+    func completeFocusAnimation(forFocusPoint focusPoint: CGPoint) {
+        guard currentlyFocusingAtPoint.within(0.005, of: focusPoint) else {
+            Logger.verbose("focus completed for obsolete focus point. User has refocused on.")
+            return
+        }
+
+        tapToFocusView.play(toProgress: 1.0)
+    }
+
     // MARK: - Orientation
 
     // MARK: -
@@ -543,6 +559,10 @@ extension PhotoCaptureViewController: PhotoCaptureDelegate {
             photoCapture.updateVideoPreviewConnection(toOrientation: orientation)
         }
     }
+
+    func photoCapture(_ photoCapture: PhotoCapture, didCompleteFocusingAtPoint focusPoint: CGPoint) {
+        completeFocusAnimation(forFocusPoint: focusPoint)
+    }
 }
 
 // MARK: - Views

SignalMessaging/categories/UIView+OWS.swift

@@ -342,6 +342,16 @@ public extension CGPoint {
         return sqrt(x * x + y * y)
     }
 
+    @inlinable
+    func distance(_ other: CGPoint) -> CGFloat {
+        return sqrt(pow(x - other.x, 2) + pow(y - other.y, 2))
+    }
+
+    @inlinable
+    func within(_ delta: CGFloat, of other: CGPoint) -> Bool {
+        return distance(other) <= delta
+    }
+
     static let unit: CGPoint = CGPoint(x: 1.0, y: 1.0)
 
     static let unitMidpoint: CGPoint = CGPoint(x: 0.5, y: 0.5)