MacOSでカメラの映像を加工して表示する

![ 2019-01-25 15.58.56.png](https://qiita-image-store.s3.amazonaws.com/0/174081/347e238a-7314-ade1-028b-037742781c0b.png)

## カメラ使用の許可
`info.plistにNSCameraUsageDescriptionの追加`
## 基本コード
ほとんどiOSアプリの場合と同じです。

```swift:CameraManager.swift
import Cocoa
import AVFoundation

/// カメラ周りの処理担当するやつ
class CameraManager {
    //ターゲットのカメラがあれば設定（見つからなければデフォルト）
    private let targetDeviceName = ""
//    private let targetDeviceName = "FaceTime HDカメラ（ディスプレイ）"
//    private let targetDeviceName = "FaceTime HD Camera"
    
    // AVFoundation
    private let session = AVCaptureSession()
    private var captureDevice : AVCaptureDevice!
    private var videoOutput = AVCaptureVideoDataOutput()
    
    /// セッション開始
    func startSession(delegate:AVCaptureVideoDataOutputSampleBufferDelegate){
        
        let devices = AVCaptureDevice.devices()
        if devices.count > 0 {
            captureDevice = AVCaptureDevice.default(for: AVMediaType.video)
            // ターゲットが設定されていればそれを選択
            print("\n[接続カメラ一覧]")
            for d in devices {
                if d.localizedName == targetDeviceName {
                    captureDevice = d
                }
                print(d.localizedName)
            }
            print("\n[使用カメラ]\n\(captureDevice!.localizedName)\n\n")
            // セッションの設定と開始
            session.beginConfiguration()
            let videoInput = try? AVCaptureDeviceInput.init(device: captureDevice)
            session.sessionPreset = .low
            session.addInput(videoInput!)
            session.addOutput(videoOutput)
            session.commitConfiguration()
            session.startRunning()
            // 画像バッファ取得のための設定
            let queue:DispatchQueue = DispatchQueue(label: "videoOutput", attributes: .concurrent)
            videoOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable as! String : Int(kCVPixelFormatType_32BGRA)]
            videoOutput.setSampleBufferDelegate(delegate, queue: queue)
            videoOutput.alwaysDiscardsLateVideoFrames = true
        } else {
            print("カメラが接続されていません")
        }
    }
    
}

// Singleton
extension CameraManager {
    class var shared : CameraManager {
        struct Static { static let instance : CameraManager = CameraManager() }
        return Static.instance
    }
}
```

## NSViewController からカメラの映像を取得

AVCaptureVideoDataOutputSampleBufferDelegateを設定してcaptureOutputでカメラ映像を受け取れます。

```swift:MainVC.swift
import Cocoa
import AVFoundation

/// メイン画面のViewController
class MainVC: NSViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        //セッション開始
        CameraManager.shared.startSession(delegate: self)
    }

    override var representedObject: Any? {
        didSet {}
    }

}

/// カメラ映像を取得して処理
extension MainVC: AVCaptureVideoDataOutputSampleBufferDelegate {

    /// カメラ映像取得時
    func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
        DispatchQueue.main.sync(execute: {
            connection.videoOrientation = .portrait
            let pixelBuffer:CVImageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)!
            //CIImage
            let ciImage = CIImage(cvPixelBuffer: pixelBuffer)
            let w = CGFloat(CVPixelBufferGetWidth(pixelBuffer))
            let h = CGFloat(CVPixelBufferGetHeight(pixelBuffer))
            let rect:CGRect = CGRect.init(x: 0, y: 0, width: w, height: h)
            let context = CIContext.init()
            //CGImage
            let cgimage = context.createCGImage(ciImage, from: rect)
            //UIImage
            let image = NSImage(cgImage: cgimage!, size: NSSize(width: w, height: h))
            //加工してNSImageViewなどに..
        })
    }

}
```

## 加工例
本記事では、CIFilterを利用しますが、Vision.FrameworkやOpenCVとの組み合わせで画像解析にも利用できます。

```swift:MainVC.swift
let filter = ThresouldFilter()
filter.inputImage = ciImage
filter.inputAmount = filterThresholdSlider.floatValue
ciImage = filter.outputImage()!
```

```swift:ThresouldFilter.swift
import Cocoa

class ThresouldFilter: CIFilter {
    private let kernelStr = "kernel vec4 threshold(__sample image, float threshold) { vec3 col = image.rgb; float bright = 0.33333 * (col.r + col.g + col.b); float b = mix(0.0, 1.0, step(threshold, bright)); return vec4(vec3(b), 1.0);}"
    
    private let kernel: CIColorKernel
    var inputImage: CIImage?
    var inputAmount: Float = 0.5
    override init() {
        kernel = CIColorKernel(source: kernelStr)!
        super.init()
    }
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    func outputImage() -> CIImage? {
        guard let inputImage = inputImage else {return nil}
        return kernel.apply(extent: inputImage.extent, arguments: [inputImage, inputAmount])
    }
}
```