1import Foundation
2import AVFoundation
3import RxSwift
4import RxCocoa
5import Vision
6
7protocol FaceDetectionViewModelInput {
8    // カメラの出力
9    var captureOutputTrigger: PublishSubject<CMSampleBuffer> { get }
10}
11
12protocol FaceDetectionViewModelOutput {
13    // 顔検出結果画像
14    var detectionResultImage: PublishSubject<UIImage?> { get }
15}
16
17protocol FaceDetectionViewModelType {
18    var input: FaceDetectionViewModelInput { get }
19    var output: FaceDetectionViewModelOutput { get }
20}
21
22final class FaceDetectionViewModel: FaceDetectionViewModelType, FaceDetectionViewModelInput, FaceDetectionViewModelOutput {
23    var input: FaceDetectionViewModelInput { return self }
24    var output: FaceDetectionViewModelOutput { return self }
25
26    // MARK: - input
27    var captureOutputTrigger = PublishSubject<CMSampleBuffer>()
28
29    // MARK: - output
30    var detectionResultImage = PublishSubject<UIImage?>()
31
32    // カメラから取得した画像のデータ
33    private var sampleBuffer: CMSampleBuffer?
34
35    private let disposeBag = DisposeBag()
36
37    init() {}
38}

1    // 顔検出処理
2    private func detectFace() -> Observable<[VNFaceObservation]> {
3        return Observable<[VNFaceObservation]>.create({ [weak self] observer in
4            if let sampleBuffer = self?.sampleBuffer,
5                let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) {
6                // 顔検出処理を要求
7                let request = VNDetectFaceRectanglesRequest { (request, error) in
8                    guard let results = request.results as? [VNFaceObservation] else {
9                        // 顔が検出されなかったら空列を流す
10                        observer.onNext([])
11                        return
12                    }
13                    // 顔が検出されたら検出結果を流す
14                    observer.onNext(results)
15                }
16                // 顔検出処理を実行
17                let handler = VNImageRequestHandler(cvPixelBuffer: pixelBuffer, options: [:])
18                try? handler.perform([request])
19            }
20            return Disposables.create()
21        })
22    }

1    // 猫の顔の画像
2    private var catFaceCgImage: CGImage?
3
4    init() {
5        // 猫の顔の画像を設定
6        guard let imagePath = Bundle.main.path(forResource: "CatFace", ofType: "png") else { return }
7        guard let image = UIImage(contentsOfFile: imagePath) else { return }
8        catFaceCgImage = image.cgImage
9    }
10
11    （省略）
12
13    // 画像の再生成
14    private func regenerationImage(_ faceObservations: [VNFaceObservation]) -> UIImage? {
15        guard let sampleBuffer = sampleBuffer else { return nil }
16        guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return nil }
17
18        CVPixelBufferLockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))
19
20        guard let pixelBufferBaseAddres = CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0) else {
21            CVPixelBufferUnlockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))
22            return nil
23        }
24
25        let width = CVPixelBufferGetWidth(imageBuffer)
26        let height = CVPixelBufferGetHeight(imageBuffer)
27        let bitmapInfo = CGBitmapInfo(rawValue: (CGBitmapInfo.byteOrder32Little.rawValue | CGImageAlphaInfo.premultipliedFirst.rawValue))
28
29        let context = CGContext(
30            data: pixelBufferBaseAddres,
31            width: width,
32            height: height,
33            bitsPerComponent: 8,
34            bytesPerRow: CVPixelBufferGetBytesPerRow(imageBuffer),
35            space: CGColorSpaceCreateDeviceRGB(),
36            bitmapInfo: bitmapInfo.rawValue
37        )
38
39        // 検出結果を元に顔の表示位置に対して処理を実行
40        faceObservations
41            // 表示位置情報（CGRect）に変換（※１）
42            .compactMap { $0.boundingBox.converted(to: CGSize(width: width, height: height)) }
43            // 検出した顔ごとに猫の顔の画像を描画
44            .forEach {
45                guard let catFaceCgImage = catFaceCgImage else { return }
46                context?.draw(catFaceCgImage, in: $0)
47            }
48
49        CVPixelBufferUnlockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))
50
51        guard let imageRef = context?.makeImage() else { return nil }
52
53        return UIImage(cgImage: imageRef, scale: 1.0, orientation: UIImage.Orientation.up)
54    }

1import AVFoundation
2
3extension CGRect {
4    func converted(to size: CGSize) -> CGRect {
5        return CGRect(
6            x: self.minX * size.width,
7            y: self.minY * size.height,
8            width: self.width * size.width,
9            height: self.height * size.height
10        )
11    }
12}

1    init() {
2        (省略）
3
4        captureOutputTrigger
5            // 画像データを設定
6            .map { [weak self] in self?.sampleBuffer = $0 }
7            // 顔検出処理
8            .flatMapLatest { return self.detectFace() }
9            // 画像の再生成
10            .map { [weak self] in self?.regenerationImage($0) }
11            // 検出結果画像にバインディング
12            .bind(to: detectionResultImage)
13            .disposed(by: disposeBag)
14    }

1import UIKit
2import AVFoundation
3import RxSwift
4import RxCocoa
5
6class FaceDetectionViewController: UIViewController {
7
8    private var viewModel: FaceDetectionViewModelType
9
10    required init(with dependency: FaceDetectionViewModel) {
11        viewModel = dependency
12        super.init(nibName: nil, bundle: nil)
13    }
14
15    required init?(coder: NSCoder) {
16        fatalError("init(coder:) has not been implemented")
17    }
18
19    override func viewDidLoad() {
20        super.viewDidLoad()
21    }
22}

1class FaceDetectionViewController: UIViewController {
2
3    （省略）
4
5    @IBOutlet weak var detectionResultImageView: UIImageView!
6
7    private var avCaptureSession = AVCaptureSession()
8    private var videoDevice: AVCaptureDevice?
9
10    // カメラの出力結果を流すためのStream
11    private let capturedOutputStream = PublishSubject<CMSampleBuffer>()
12
13    （省略）
14
15    override func viewDidLoad() {
16        super.viewDidLoad()
17
18        setupVideoProcessing()
19    }
20
21    private func onViewDidDisappear() {
22        avCaptureSession.stopRunning()
23    }
24
25    private func setupVideoProcessing() {
26        avCaptureSession.sessionPreset = .photo
27
28        // AVCaptureSession#addInput
29        videoDevice = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .front)
30        guard let videoDevice = videoDevice else { return }
31        guard let deviceInput = try? AVCaptureDeviceInput(device: videoDevice) else { return }
32        avCaptureSession.addInput(deviceInput)
33
34        // AVCaptureSession#addOutput
35        let videoDataOutput = AVCaptureVideoDataOutput()
36        videoDataOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as String : Int(kCVPixelFormatType_32BGRA)]
37        videoDataOutput.setSampleBufferDelegate(self, queue: .global())
38        avCaptureSession.addOutput(videoDataOutput)
39
40        avCaptureSession.startRunning()
41    }
42}
43
44extension FaceDetectionViewController: AVCaptureVideoDataOutputSampleBufferDelegate {
45
46    func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
47        // カメラの出力結果を流す
48        capturedOutputStream.onNext(sampleBuffer)
49        connection.videoOrientation = .portrait
50    }
51}

1    private let disposeBag = DisposeBag()
2
3    （省略）
4
5    override func viewDidLoad() {
6        super.viewDidLoad()
7
8        bind()
9        setupVideoProcessing()
10    }
11
12    private func bind() {
13        // input
14        capturedOutputStream
15            .bind(to: viewModel.input.captureOutputTrigger)
16            .disposed(by: disposeBag)
17
18        // output
19        viewModel.output.detectionResultImage
20            .bind(to: detectionResultImageView.rx.image)
21            .disposed(by: disposeBag)
22    }

1import UIKit
2
3class SceneDelegate: UIResponder, UIWindowSceneDelegate {
4
5    var window: UIWindow?
6
7    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
8
9        guard let windowScene = scene as? UIWindowScene else { return }
10        let viewModel = FaceDetectionViewModel()
11        let vc = FaceDetectionViewController(with: viewModel)
12
13        let window = UIWindow(windowScene: windowScene)
14        window.rootViewController = vc
15        window.makeKeyAndVisible()
16        self.window = window
17    }
18}