版本记录

前言

ios 11+和macOS 10.13+ 新出了Vision框架，提供了人脸识别、物体检测、物体跟踪等技术，它是基于Core ML的。可以说是人工智能的一部分，接下来几篇我们就详细的解析一下Vision框架。感兴趣的看下面几篇文章。
1. Vision框架详细解析（一） —— 基本概览（一）
2. Vision框架详细解析（二） —— 基于Vision的人脸识别（一）

源码

1. Swift

首先看下代码组织结构

接着看下xib

最后就是源码了

1. FaceDetectionViewController.swift

import AVFoundation
import UIKit
import Vision

class FaceDetectionViewController: UIViewController {
  var sequenceHandler = VNSequenceRequestHandler()

  @IBOutlet var faceView: FaceView!
  @IBOutlet var laserView: LaserView!
  @IBOutlet var faceLaserLabel: UILabel!
  
  let session = AVCaptureSession()
  var previewLayer: AVCaptureVideoPreviewLayer!
  
  let dataOutputQueue = DispatchQueue(
    label: "video data queue",
    qos: .userInitiated,
    attributes: [],
    autoreleaseFrequency: .workItem)

  var faceViewHidden = false
  
  var maxX: CGFloat = 0.0
  var midY: CGFloat = 0.0
  var maxY: CGFloat = 0.0

  override func viewDidLoad() {
    super.viewDidLoad()
    configureCaptureSession()
    
    laserView.isHidden = true
    
    maxX = view.bounds.maxX
    midY = view.bounds.midY
    maxY = view.bounds.maxY
    
    session.startRunning()
  }
}

// MARK: - Gesture methods

extension FaceDetectionViewController {
  @IBAction func handleTap(_ sender: UITapGestureRecognizer) {
    faceView.isHidden.toggle()
    laserView.isHidden.toggle()
    faceViewHidden = faceView.isHidden
    
    if faceViewHidden {
      faceLaserLabel.text = "Lasers"
    } else {
      faceLaserLabel.text = "Face"
    }
  }
}

// MARK: - Video Processing methods

extension FaceDetectionViewController {
  func configureCaptureSession() {
    // Define the capture device we want to use
    guard let camera = AVCaptureDevice.default(.builtInWideAngleCamera,
                                               for: .video,
                                               position: .front) else {
      fatalError("No front video camera available")
    }
    
    // Connect the camera to the capture session input
    do {
      let cameraInput = try AVCaptureDeviceInput(device: camera)
      session.addInput(cameraInput)
    } catch {
      fatalError(error.localizedDescription)
    }
    
    // Create the video data output
    let videoOutput = AVCaptureVideoDataOutput()
    videoOutput.setSampleBufferDelegate(self, queue: dataOutputQueue)
    videoOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA]
    
    // Add the video output to the capture session
    session.addOutput(videoOutput)
    
    let videoConnection = videoOutput.connection(with: .video)
    videoConnection?.videoOrientation = .portrait
    
    // Configure the preview layer
    previewLayer = AVCaptureVideoPreviewLayer(session: session)
    previewLayer.videoGravity = .resizeAspectFill
    previewLayer.frame = view.bounds
    view.layer.insertSublayer(previewLayer, at: 0)
  }
}

// MARK: - AVCaptureVideoDataOutputSampleBufferDelegate methods

extension FaceDetectionViewController: AVCaptureVideoDataOutputSampleBufferDelegate {
  func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
    // 1
    guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
      return
    }

    // 2
    let detectFaceRequest = VNDetectFaceLandmarksRequest(completionHandler: detectedFace)

    // 3
    do {
      try sequenceHandler.perform(
        [detectFaceRequest],
        on: imageBuffer,
        orientation: .leftMirrored)
    } catch {
      print(error.localizedDescription)
    }
  }
}

extension FaceDetectionViewController {
  func convert(rect: CGRect) -> CGRect {
    // 1
    let origin = previewLayer.layerPointConverted(fromCaptureDevicePoint: rect.origin)

    // 2
    let size = previewLayer.layerPointConverted(fromCaptureDevicePoint: rect.size.cgPoint)

    // 3
    return CGRect(origin: origin, size: size.cgSize)
  }

  // 1
  func landmark(point: CGPoint, to rect: CGRect) -> CGPoint {
    // 2
    let absolute = point.absolutePoint(in: rect)

    // 3
    let converted = previewLayer.layerPointConverted(fromCaptureDevicePoint: absolute)

    // 4
    return converted
  }

  func landmark(points: [CGPoint]?, to rect: CGRect) -> [CGPoint]? {
    guard let points = points else {
      return nil
    }

    return points.compactMap { landmark(point: $0, to: rect) }
  }
  
  func updateFaceView(for result: VNFaceObservation) {
    defer {
      DispatchQueue.main.async {
        self.faceView.setNeedsDisplay()
      }
    }

    let box = result.boundingBox
    faceView.boundingBox = convert(rect: box)

    guard let landmarks = result.landmarks else {
      return
    }

    if let leftEye = landmark(
      points: landmarks.leftEye?.normalizedPoints,
      to: result.boundingBox) {
      faceView.leftEye = leftEye
    }

    if let rightEye = landmark(
      points: landmarks.rightEye?.normalizedPoints,
      to: result.boundingBox) {
      faceView.rightEye = rightEye
    }

    if let leftEyebrow = landmark(
      points: landmarks.leftEyebrow?.normalizedPoints,
      to: result.boundingBox) {
      faceView.leftEyebrow = leftEyebrow
    }

    if let rightEyebrow = landmark(
      points: landmarks.rightEyebrow?.normalizedPoints,
      to: result.boundingBox) {
      faceView.rightEyebrow = rightEyebrow
    }

    if let nose = landmark(
      points: landmarks.nose?.normalizedPoints,
      to: result.boundingBox) {
      faceView.nose = nose
    }

    if let outerLips = landmark(
      points: landmarks.outerLips?.normalizedPoints,
      to: result.boundingBox) {
      faceView.outerLips = outerLips
    }

    if let innerLips = landmark(
      points: landmarks.innerLips?.normalizedPoints,
      to: result.boundingBox) {
      faceView.innerLips = innerLips
    }

    if let faceContour = landmark(
      points: landmarks.faceContour?.normalizedPoints,
      to: result.boundingBox) {
      faceView.faceContour = faceContour
    }
  }

  // 1
  func updateLaserView(for result: VNFaceObservation) {
    // 2
    laserView.clear()

    // 3
    let yaw = result.yaw ?? 0.0

    // 4
    if yaw == 0.0 {
      return
    }

    // 5
    var origins: [CGPoint] = []

    // 6
    if let point = result.landmarks?.leftPupil?.normalizedPoints.first {
      let origin = landmark(point: point, to: result.boundingBox)
      origins.append(origin)
    }

    // 7
    if let point = result.landmarks?.rightPupil?.normalizedPoints.first {
      let origin = landmark(point: point, to: result.boundingBox)
      origins.append(origin)
    }

    // 1
    let avgY = origins.map { $0.y }.reduce(0.0, +) / CGFloat(origins.count)

    // 2
    let focusY = (avgY < midY) ? 0.75 * maxY : 0.25 * maxY

    // 3
    let focusX = (yaw.doubleValue < 0.0) ? -100.0 : maxX + 100.0

    // 4
    let focus = CGPoint(x: focusX, y: focusY)

    // 5
    for origin in origins {
      let laser = Laser(origin: origin, focus: focus)
      laserView.add(laser: laser)
    }

    // 6
    DispatchQueue.main.async {
      self.laserView.setNeedsDisplay()
    }
  }

  func detectedFace(request: VNRequest, error: Error?) {
    // 1
    guard
      let results = request.results as? [VNFaceObservation],
      let result = results.first
      else {
        // 2
        faceView.clear()
        return
    }

    if faceViewHidden {
      updateLaserView(for: result)
    } else {
      updateFaceView(for: result)
    }
  }
}

2. FaceView.swift

import UIKit
import Vision

class FaceView: UIView {
  var leftEye: [CGPoint] = []
  var rightEye: [CGPoint] = []
  var leftEyebrow: [CGPoint] = []
  var rightEyebrow: [CGPoint] = []
  var nose: [CGPoint] = []
  var outerLips: [CGPoint] = []
  var innerLips: [CGPoint] = []
  var faceContour: [CGPoint] = []

  var boundingBox = CGRect.zero
  
  func clear() {
    leftEye = []
    rightEye = []
    leftEyebrow = []
    rightEyebrow = []
    nose = []
    outerLips = []
    innerLips = []
    faceContour = []
    
    boundingBox = .zero
    
    DispatchQueue.main.async {
      self.setNeedsDisplay()
    }
  }
  
  override func draw(_ rect: CGRect) {
    // 1
    guard let context = UIGraphicsGetCurrentContext() else {
      return
    }

    // 2
    context.saveGState()

    // 3
    defer {
      context.restoreGState()
    }

    // 4
    context.addRect(boundingBox)

    // 5
    UIColor.red.setStroke()

    // 6
    context.strokePath()

    // 1
    UIColor.white.setStroke()

    if !leftEye.isEmpty {
      // 2
      context.addLines(between: leftEye)

      // 3
      context.closePath()

      // 4
      context.strokePath()
    }

    if !rightEye.isEmpty {
      context.addLines(between: rightEye)
      context.closePath()
      context.strokePath()
    }

    if !leftEyebrow.isEmpty {
      context.addLines(between: leftEyebrow)
      context.strokePath()
    }

    if !rightEyebrow.isEmpty {
      context.addLines(between: rightEyebrow)
      context.strokePath()
    }

    if !nose.isEmpty {
      context.addLines(between: nose)
      context.strokePath()
    }

    if !outerLips.isEmpty {
      context.addLines(between: outerLips)
      context.closePath()
      context.strokePath()
    }

    if !innerLips.isEmpty {
      context.addLines(between: innerLips)
      context.closePath()
      context.strokePath()
    }

    if !faceContour.isEmpty {
      context.addLines(between: faceContour)
      context.strokePath()
    }
  }
}

3. LaserView.swift

import UIKit

struct Laser {
  var origin: CGPoint
  var focus: CGPoint
}

class LaserView: UIView {
  private var lasers: [Laser] = []
  
  func add(laser: Laser) {
    lasers.append(laser)
  }
  
  func clear() {
    lasers.removeAll()
    DispatchQueue.main.async {
      self.setNeedsDisplay()
    }
  }
  
  override func draw(_ rect: CGRect) {
    // 1
    guard let context = UIGraphicsGetCurrentContext() else {
      return
    }

    // 2
    context.saveGState()

    // 3
    for laser in lasers {
      // 4
      context.addLines(between: [laser.origin, laser.focus])

      context.setStrokeColor(red: 1.0, green: 1.0, blue: 1.0, alpha: 0.5)
      context.setLineWidth(4.5)
      context.strokePath()

      // 5
      context.addLines(between: [laser.origin, laser.focus])

      context.setStrokeColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 0.8)
      context.setLineWidth(3.0)
      context.strokePath()
    }

    // 6
    context.restoreGState()
  }
}

4. CoreGraphicsExtensions.swift

import CoreGraphics

func + (left: CGPoint, right: CGPoint) -> CGPoint {
  return CGPoint(x: left.x + right.x, y: left.y + right.y)
}

func - (left: CGPoint, right: CGPoint) -> CGPoint {
  return CGPoint(x: left.x - right.x, y: left.y - right.y)
}

func * (left: CGPoint, right: CGFloat) -> CGPoint {
  return CGPoint(x: left.x * right, y: left.y * right)
}

extension CGSize {
  var cgPoint: CGPoint {
    return CGPoint(x: width, y: height)
  }
}

extension CGPoint {
  var cgSize: CGSize {
    return CGSize(width: x, height: y)
  }
  
  func absolutePoint(in rect: CGRect) -> CGPoint {
    return CGPoint(x: x * rect.size.width, y: y * rect.size.height) + rect.origin
  }
}

5. UIViewExtension.swift

import UIKit

extension UIView {
  @IBInspectable
  var cornerRadius: CGFloat {
    get {
      return layer.cornerRadius
    }
    
    set {
      layer.cornerRadius = newValue
    }
  }
}

下面就是实际效果了

后记

本篇主要讲述了基于Vision的人脸识别，感兴趣的给个赞或者关注~~~