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// Copyright 2019 The TensorFlow Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import AVFoundation
import UIKit
import os
// MARK: - CameraFeedManagerDelegate Declaration
@objc protocol CameraFeedManagerDelegate: class {
/// This method delivers the pixel buffer of the current frame seen by the device's camera.
@objc optional func cameraFeedManager(
_ manager: CameraFeedManager, didOutput pixelBuffer: CVPixelBuffer
)
/// This method initimates that a session runtime error occured.
func cameraFeedManagerDidEncounterSessionRunTimeError(_ manager: CameraFeedManager)
/// This method initimates that the session was interrupted.
func cameraFeedManager(
_ manager: CameraFeedManager, sessionWasInterrupted canResumeManually: Bool
)
/// This method initimates that the session interruption has ended.
func cameraFeedManagerDidEndSessionInterruption(_ manager: CameraFeedManager)
/// This method initimates that there was an error in video configurtion.
func presentVideoConfigurationErrorAlert(_ manager: CameraFeedManager)
/// This method initimates that the camera permissions have been denied.
func presentCameraPermissionsDeniedAlert(_ manager: CameraFeedManager)
}
/// This enum holds the state of the camera initialization.
// MARK: - Camera Initialization State Enum
enum CameraConfiguration {
case success
case failed
case permissionDenied
}
/// This class manages all camera related functionalities.
// MARK: - Camera Related Functionalies Manager
class CameraFeedManager: NSObject {
// MARK: Camera Related Instance Variables
private let session: AVCaptureSession = AVCaptureSession()
private let previewView: PreviewView
private let sessionQueue = DispatchQueue(label: "sessionQueue")
private var cameraConfiguration: CameraConfiguration = .failed
private lazy var videoDataOutput = AVCaptureVideoDataOutput()
private var isSessionRunning = false
// MARK: CameraFeedManagerDelegate
weak var delegate: CameraFeedManagerDelegate?
// MARK: Initializer
init(previewView: PreviewView) {
self.previewView = previewView
super.init()
// Initializes the session
session.sessionPreset = .high
self.previewView.session = session
self.previewView.previewLayer.connection?.videoOrientation = .portrait
self.previewView.previewLayer.videoGravity = .resizeAspectFill
self.attemptToConfigureSession()
}
// MARK: Session Start and End methods
/// This method starts an AVCaptureSession based on whether the camera configuration was successful.
func checkCameraConfigurationAndStartSession() {
sessionQueue.async {
switch self.cameraConfiguration {
case .success:
self.addObservers()
self.startSession()
case .failed:
DispatchQueue.main.async {
self.delegate?.presentVideoConfigurationErrorAlert(self)
}
case .permissionDenied:
DispatchQueue.main.async {
self.delegate?.presentCameraPermissionsDeniedAlert(self)
}
}
}
}
/// This method stops a running an AVCaptureSession.
func stopSession() {
self.removeObservers()
sessionQueue.async {
if self.session.isRunning {
self.session.stopRunning()
self.isSessionRunning = self.session.isRunning
}
}
}
/// This method resumes an interrupted AVCaptureSession.
func resumeInterruptedSession(withCompletion completion: @escaping (Bool) -> Void) {
sessionQueue.async {
self.startSession()
DispatchQueue.main.async {
completion(self.isSessionRunning)
}
}
}
/// This method starts the AVCaptureSession
private func startSession() {
self.session.startRunning()
self.isSessionRunning = self.session.isRunning
}
// MARK: Session Configuration Methods.
/// This method requests for camera permissions and handles the configuration of the session and stores the result of configuration.
private func attemptToConfigureSession() {
switch AVCaptureDevice.authorizationStatus(for: .video) {
case .authorized:
self.cameraConfiguration = .success
case .notDetermined:
self.sessionQueue.suspend()
self.requestCameraAccess(completion: { granted in
self.sessionQueue.resume()
})
case .denied:
self.cameraConfiguration = .permissionDenied
default:
break
}
self.sessionQueue.async {
self.configureSession()
}
}
/// This method requests for camera permissions.
private func requestCameraAccess(completion: @escaping (Bool) -> Void) {
AVCaptureDevice.requestAccess(for: .video) { (granted) in
if !granted {
self.cameraConfiguration = .permissionDenied
} else {
self.cameraConfiguration = .success
}
completion(granted)
}
}
/// This method handles all the steps to configure an AVCaptureSession.
private func configureSession() {
guard cameraConfiguration == .success else {
return
}
session.beginConfiguration()
// Tries to add an AVCaptureDeviceInput.
guard addVideoDeviceInput() == true else {
self.session.commitConfiguration()
self.cameraConfiguration = .failed
return
}
// Tries to add an AVCaptureVideoDataOutput.
guard addVideoDataOutput() else {
self.session.commitConfiguration()
self.cameraConfiguration = .failed
return
}
session.commitConfiguration()
self.cameraConfiguration = .success
}
/// This method tries to an AVCaptureDeviceInput to the current AVCaptureSession.
private func addVideoDeviceInput() -> Bool {
/// Tries to get the default back camera.
guard
let camera = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .back)
else {
fatalError("Cannot find camera")
}
do {
let videoDeviceInput = try AVCaptureDeviceInput(device: camera)
if session.canAddInput(videoDeviceInput) {
session.addInput(videoDeviceInput)
return true
} else {
return false
}
} catch {
fatalError("Cannot create video device input")
}
}
/// This method tries to an AVCaptureVideoDataOutput to the current AVCaptureSession.
private func addVideoDataOutput() -> Bool {
let sampleBufferQueue = DispatchQueue(label: "sampleBufferQueue")
videoDataOutput.setSampleBufferDelegate(self, queue: sampleBufferQueue)
videoDataOutput.alwaysDiscardsLateVideoFrames = true
videoDataOutput.videoSettings = [
String(kCVPixelBufferPixelFormatTypeKey): kCMPixelFormat_32BGRA
]
if session.canAddOutput(videoDataOutput) {
session.addOutput(videoDataOutput)
videoDataOutput.connection(with: .video)?.videoOrientation = .portrait
return true
}
return false
}
// MARK: Notification Observer Handling
private func addObservers() {
NotificationCenter.default.addObserver(
self, selector: #selector(CameraFeedManager.sessionRuntimeErrorOccured(notification:)),
name: NSNotification.Name.AVCaptureSessionRuntimeError, object: session)
NotificationCenter.default.addObserver(
self, selector: #selector(CameraFeedManager.sessionWasInterrupted(notification:)),
name: NSNotification.Name.AVCaptureSessionWasInterrupted, object: session)
NotificationCenter.default.addObserver(
self, selector: #selector(CameraFeedManager.sessionInterruptionEnded),
name: NSNotification.Name.AVCaptureSessionInterruptionEnded, object: session)
}
private func removeObservers() {
NotificationCenter.default.removeObserver(
self, name: NSNotification.Name.AVCaptureSessionRuntimeError, object: session)
NotificationCenter.default.removeObserver(
self, name: NSNotification.Name.AVCaptureSessionWasInterrupted, object: session)
NotificationCenter.default.removeObserver(
self, name: NSNotification.Name.AVCaptureSessionInterruptionEnded, object: session)
}
// MARK: Notification Observers
@objc func sessionWasInterrupted(notification: Notification) {
if let userInfoValue = notification.userInfo?[AVCaptureSessionInterruptionReasonKey]
as AnyObject?,
let reasonIntegerValue = userInfoValue.integerValue,
let reason = AVCaptureSession.InterruptionReason(rawValue: reasonIntegerValue)
{
os_log("Capture session was interrupted with reason: %s", type: .error, reason.rawValue)
var canResumeManually = false
if reason == .videoDeviceInUseByAnotherClient {
canResumeManually = true
} else if reason == .videoDeviceNotAvailableWithMultipleForegroundApps {
canResumeManually = false
}
delegate?.cameraFeedManager(self, sessionWasInterrupted: canResumeManually)
}
}
@objc func sessionInterruptionEnded(notification: Notification) {
delegate?.cameraFeedManagerDidEndSessionInterruption(self)
}
@objc func sessionRuntimeErrorOccured(notification: Notification) {
guard let error = notification.userInfo?[AVCaptureSessionErrorKey] as? AVError else {
return
}
os_log("Capture session runtime error: %s", type: .error, error.localizedDescription)
if error.code == .mediaServicesWereReset {
sessionQueue.async {
if self.isSessionRunning {
self.startSession()
} else {
DispatchQueue.main.async {
self.delegate?.cameraFeedManagerDidEncounterSessionRunTimeError(self)
}
}
}
} else {
delegate?.cameraFeedManagerDidEncounterSessionRunTimeError(self)
}
}
}
/// AVCaptureVideoDataOutputSampleBufferDelegate
extension CameraFeedManager: AVCaptureVideoDataOutputSampleBufferDelegate {
/// This method delegates the CVPixelBuffer of the frame seen by the camera currently.
func captureOutput(
_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer,
from connection: AVCaptureConnection
) {
// Converts the CMSampleBuffer to a CVPixelBuffer.
let pixelBuffer: CVPixelBuffer? = CMSampleBufferGetImageBuffer(sampleBuffer)
guard let imagePixelBuffer = pixelBuffer else {
return
}
// Delegates the pixel buffer to the ViewController.
delegate?.cameraFeedManager?(self, didOutput: imagePixelBuffer)
}
}
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