仅捕获AVCapture Swift中的camerapreview

Question

这是我的代码

import UIKit
import AVFoundation

class ViewController: UIViewController {

    @IBOutlet weak var cameraView: UIView!

    var image: UIImage!

    var captureSession = AVCaptureSession()
    var backCamera: AVCaptureDevice?
    var frontCamera: AVCaptureDevice?
    var currentCamera: AVCaptureDevice?

    var photoOutput: AVCapturePhotoOutput?

    var cameraPreviewLayer: AVCaptureVideoPreviewLayer?

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.


    }

    override func viewDidAppear(_ animated: Bool) {

        setupCaptureSession()
        setupDevice()
        setupInputOutput()
        setupPreviewLayer()
        startRunningCaptureSession()

    }

    @IBAction func cameraButton_Tab(_ sender: Any) {

        let settings = AVCapturePhotoSettings()

//        performSegue(withIdentifier: "showPhoto_Segue", sender: nil)
        photoOutput?.capturePhoto(with: settings, delegate: self)

    }

    func setupCaptureSession() {

        captureSession.sessionPreset = AVCaptureSession.Preset.photo

    }

    func setupDevice() {

        let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera], mediaType: AVMediaType.video, position: AVCaptureDevice.Position.unspecified)

        let devices = deviceDiscoverySession.devices

        for device in devices {

            if device.position == AVCaptureDevice.Position.back {

                backCamera = device

            }else if device.position == AVCaptureDevice.Position.front{

                frontCamera = device

            }

        }

        currentCamera = backCamera

    }

    func setupInputOutput() {

        do{

            let captureDeviceInput = try AVCaptureDeviceInput(device: currentCamera!)
            captureSession.addInput(captureDeviceInput)
            photoOutput = AVCapturePhotoOutput()
            photoOutput?.setPreparedPhotoSettingsArray([AVCapturePhotoSettings(format: [AVVideoCodecKey : AVVideoCodecType.jpeg])], completionHandler: nil)
            captureSession.addOutput(photoOutput!)

        }catch {
            print(error)
        }

    }

    func setupPreviewLayer() {

        cameraPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        cameraPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
        cameraPreviewLayer?.connection?.videoOrientation = AVCaptureVideoOrientation.portrait
        cameraPreviewLayer!.frame = self.cameraView.bounds
        self.cameraView.layer.insertSublayer(cameraPreviewLayer!, at: 0)

    }

    func startRunningCaptureSession() {

        captureSession.startRunning()

    }

}

extension ViewController: AVCapturePhotoCaptureDelegate {

    func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
        if let imageData = photo.fileDataRepresentation(){
            image = UIImage(data: imageData)

        }
    }

}

查看图片， 我要保存背景颜色为黄色的图像 我可以透过镜头看到它

但是我保存了图像，似乎保存了整个视图，而不是正方形。

我将UIImageView设置为与黄色UIView相同的大小，并保存输出， 它需要捕获整个视图并调整其大小。

就像用挤压将矩形更改为正方形一样

我怎么不能只捕捉黄色背景大小并保存？

Answer 1

此didFinishProcessingPhoto将返回完整的图像，就像摄像机看到的一样。您不会直接显示PreviewLayer中显示的图像。因此，为了获得显示的UIImage的{​​{1}}，您可以调整捕获图像的大小。

调整大小也可以通过两种方法完成：一种保持宽高比，另一种通过传递准确的大小。我建议您使用长宽比，因为它可以确保您的图像不会被任何大小的挤压或拉长，而传递错误的大小将无法满足您的要求。

  

调整大小PreviewLayer并传递新的UIImage：

CGSize

用法： extension UIImage { func scaleImage(toSize newSize: CGSize) -> UIImage? { var newImage: UIImage? let newRect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height).integral UIGraphicsBeginImageContextWithOptions(newSize, false, 0) if let context = UIGraphicsGetCurrentContext(), let cgImage = self.cgImage { context.interpolationQuality = .high let flipVertical = CGAffineTransform(a: 1, b: 0, c: 0, d: -1, tx: 0, ty: newSize.height) context.concatenate(flipVertical) context.draw(cgImage, in: newRect) if let img = context.makeImage() { newImage = UIImage(cgImage: img) } UIGraphicsEndImageContext() } return newImage } }

  

调整capturedImage.scaleImage(toSize: CGSize(width: 300, height: 300))的大小并保持宽高比：

UIImage

用法： extension UIImage { func scaleImage(toWidth newWidth: CGFloat) -> UIImage { let scale = newWidth / self.size.width let newHeight = self.size.height * scale let newSize = CGSize(width: newWidth, height: newHeight) let renderer = UIGraphicsImageRenderer(size: newSize) let image = renderer.image { (context) in self.draw(in: CGRect(origin: CGPoint(x: 0, y: 0), size: newSize)) } return image } }

参考：Resize UIImage to 200x200pt/px

  

更新：

保持下面的方法与您的代码相同：

capturedImage.scaleImage(toWidth: 300)