自定义相机和裁剪图像斯威夫特(Custom Camera and Crop image in Swi

在预览层我创建了一个自定义的摄像头和下面的代码已经实现裁剪所拍摄的图像，我已经展示了导游，所以我要裁剪出现在该区域的图像。

func imageByCropToRect(rect:CGRect, scale:Bool) -> UIImage {    
    var rect = rect
    var scaleFactor: CGFloat = 1.0
    if scale  {
        scaleFactor = self.scale
        rect.origin.x *= scaleFactor
        rect.origin.y *= scaleFactor
        rect.size.width *= scaleFactor
        rect.size.height *= scaleFactor
    }

    var image: UIImage? = nil;
    if rect.size.width > 0 && rect.size.height > 0 {
        let imageRef = self.cgImage!.cropping(to: rect)
        image = UIImage(cgImage: imageRef!, scale: scaleFactor, orientation: self.imageOrientation)
    }

    return image!
}

此代码只是正常工作时，与给出精确的裁切图像时的代码下面的行注释掉，但我想要的图像流是全屏，所以我不得不使用下面的一行代码。拍摄的图像缩放几分出来。

(self.previewLayer as! AVCaptureVideoPreviewLayer).videoGravity = AVLayerVideoGravity.resizeAspectFill

我该如何解决这个问题？是种植的代码错了吗？

以下是完整的类代码

import UIKit
import AVFoundation

class CameraViewController: UIViewController {

    @IBOutlet weak var guideImageView: UIImageView!
    @IBOutlet weak var guidesView: UIView!
    @IBOutlet weak var cameraPreviewView: UIView!
    @IBOutlet weak var cameraButtonView: UIView!

    @IBOutlet weak var captureButton: UIButton!

    var captureSession = AVCaptureSession()
    var previewLayer: CALayer!
    var captureDevice: AVCaptureDevice!

    /// This will be true when the user clicks on the click photo button.
    var takePhoto = false

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        captureSession = AVCaptureSession()
        previewLayer = CALayer()
        takePhoto = false

        requestAuthorization()
    }

    private func userinteractionToButton(_ interaction: Bool) {
        captureButton.isEnabled = interaction
    }

    /// This function will request authorization, If authorized then start the camera.
    private func requestAuthorization() {
        switch AVCaptureDevice.authorizationStatus(for: AVMediaType.video) {
        case .authorized:
            prepareCamera()

        case .denied, .restricted, .notDetermined:
            AVCaptureDevice.requestAccess(for: AVMediaType.video, completionHandler: { (granted) in
                if !Thread.isMainThread {
                    DispatchQueue.main.async {
                        if granted {
                            self.prepareCamera()
                        } else {
                            let alert = UIAlertController(title: "unable_to_access_the_Camera", message: "to_enable_access_go_to_setting_privacy_camera_and_turn_on_camera_access_for_this_app", preferredStyle: UIAlertControllerStyle.alert)
                            alert.addAction(UIAlertAction(title: "ok", style: .default, handler: {_ in
                                self.navigationController?.popToRootViewController(animated: true)
                            }))
                            self.present(alert, animated: true, completion: nil)
                        }
                    }
                } else {
                    if granted {
                        self.prepareCamera()
                    } else {
                        let alert = UIAlertController(title: "unable_to_access_the_Camera", message: "to_enable_access_go_to_setting_privacy_camera_and_turn_on_camera_access_for_this_app", preferredStyle: UIAlertControllerStyle.alert)
                        alert.addAction(UIAlertAction(title: "ok", style: .default, handler: {_ in
                            self.navigationController?.popToRootViewController(animated: true)
                        }))
                        self.present(alert, animated: true, completion: nil)
                    }
                }
            })
        }
    }

    /// Will see if the primary camera is avilable, If found will call method which will asign the available device to the AVCaptureDevice.
    private func prepareCamera() {
        // Resets the session.
        self.captureSession.sessionPreset = AVCaptureSession.Preset.photo

        if #available(iOS 10.0, *) {
            let availableDevices = AVCaptureDevice.DiscoverySession(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera], mediaType: AVMediaType.video, position: .back).devices
            self.assignCamera(availableDevices)
        } else {
            // Fallback on earlier versions
            // development, need to test this on iOS 8
            if let availableDevices = AVCaptureDevice.default(for: AVMediaType.video) {
                self.assignCamera([availableDevices])
            } else {
                self.showAlert()
            }
        }
    }

    /// Assigns AVCaptureDevice to the respected the variable, will begin the session.
    ///
    /// - Parameter availableDevices: [AVCaptureDevice]
    private func assignCamera(_ availableDevices: [AVCaptureDevice]) {
        if availableDevices.first != nil {
            captureDevice = availableDevices.first
            beginSession()
        } else {
            self.showAlert()
        }
    }

    /// Configures the camera settings and begins the session, this function will be responsible for showing the image on the UI.
    private func beginSession() {
        do {
            let captureDeviceInput = try AVCaptureDeviceInput(device: captureDevice)
            captureSession.addInput(captureDeviceInput)
        } catch {
            print(error.localizedDescription)
        }

        let previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        self.previewLayer = previewLayer
        self.cameraPreviewView.layer.addSublayer(self.previewLayer)
        self.previewLayer.frame = self.view.layer.frame
        self.previewLayer.frame.origin.y = +self.cameraPreviewView.frame.origin.y
        (self.previewLayer as! AVCaptureVideoPreviewLayer).videoGravity = AVLayerVideoGravity.resizeAspectFill
        self.previewLayer.masksToBounds = true
        self.cameraPreviewView.clipsToBounds = true
        captureSession.startRunning()

        self.view.bringSubview(toFront: self.cameraPreviewView)
        self.view.bringSubview(toFront: self.cameraButtonView)
        self.view.bringSubview(toFront: self.guidesView)

        let dataOutput = AVCaptureVideoDataOutput()
        dataOutput.videoSettings = [((kCVPixelBufferPixelFormatTypeKey as NSString) as String):NSNumber(value:kCVPixelFormatType_32BGRA)]

        dataOutput.alwaysDiscardsLateVideoFrames = true

        if captureSession.canAddOutput(dataOutput) {
            captureSession.addOutput(dataOutput)
        }

        captureSession.commitConfiguration()

        let queue = DispatchQueue(label: "com.letsappit.camera")
        dataOutput.setSampleBufferDelegate(self, queue: queue)

        self.userinteractionToButton(true)
    }


    /// Get the UIImage from the given CMSampleBuffer.
    ///
    /// - Parameter buffer: CMSampleBuffer
    /// - Returns: UIImage?
    func getImageFromSampleBuffer(buffer:CMSampleBuffer, orientation: UIImageOrientation) -> UIImage? {
        if let pixelBuffer = CMSampleBufferGetImageBuffer(buffer) {
            let ciImage = CIImage(cvPixelBuffer: pixelBuffer)
            let context = CIContext()
            let imageRect = CGRect(x: 0, y: 0, width: CVPixelBufferGetWidth(pixelBuffer), height: CVPixelBufferGetHeight(pixelBuffer))

            if let image = context.createCGImage(ciImage, from: imageRect) {
                return UIImage(cgImage: image, scale: UIScreen.main.scale, orientation: orientation)

            }

        }
        return nil
    }

    /// This function will destroy the capture session.
    func stopCaptureSession() {
        self.captureSession.stopRunning()

        if let inputs = captureSession.inputs as? [AVCaptureDeviceInput] {
            for input in inputs {
                self.captureSession.removeInput(input)
            }
        }
    }

    func showAlert() {
        let alert = UIAlertController(title: "Unable to access the camera", message: "It appears that either your device doesn't have camera or its broken", preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "cancel", style: .cancel, handler: {_ in
            self.navigationController?.dismiss(animated: true, completion: nil)
        }))
        self.present(alert, animated: true, completion: nil)
    }

    @IBAction func didTapClick(_ sender: Any) {
        userinteractionToButton(false)
        takePhoto = true
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "showImage" {
            let vc = segue.destination as! ShowImageViewController
            vc.image = sender as! UIImage
        }
    }
}

extension CameraViewController: AVCaptureVideoDataOutputSampleBufferDelegate {
    func captureOutput(_ captureOutput: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {

        if connection.isVideoOrientationSupported {
            connection.videoOrientation = .portrait
        }

        if takePhoto {
            takePhoto = false

            // Rotation should be unlocked to work.
            var orientation = UIImageOrientation.up
            switch UIDevice.current.orientation {
            case .landscapeLeft:
                orientation = .left

            case .landscapeRight:
                orientation = .right

            case .portraitUpsideDown:
                orientation = .down

            default:
                orientation = .up
            }

            if let image = self.getImageFromSampleBuffer(buffer: sampleBuffer, orientation: orientation) {
                DispatchQueue.main.async {
                    let newImage = image.imageByCropToRect(rect: self.guideImageView.frame, scale: true)
                    self.stopCaptureSession()
                    self.previewLayer.removeFromSuperlayer()
                    self.performSegue(withIdentifier: "showImage", sender: newImage)
                }
            }
        }
    }
}

这里是视图层次图像

Answer 1:

问题出在哪里目前尚不清楚。我要么使用调试器或一些打印语句找出问题是否与图像或显示图像的视图。打印出裁剪图像大小，以确保它是正确的。

然后，打印出ShowImageViewController在viewDidAppear图像视图大小，以确保它是正确的。

Answer 2:

对于缩小裁剪图像的修正，你必须使用图像的方向来改变你的裁剪功能这一点。

func croppedInRect(rect: CGRect) -> UIImage? {
    func rad(_ degree: Double) -> CGFloat {
        return CGFloat(degree / 180.0 * .pi)
    }

    var rectTransform: CGAffineTransform
    switch imageOrientation {
    case .left:
        rectTransform = CGAffineTransform(rotationAngle: rad(90)).translatedBy(x: 0, y: -self.size.height)
    case .right:
        rectTransform = CGAffineTransform(rotationAngle: rad(-90)).translatedBy(x: -self.size.width, y: 0)
    case .down:
        rectTransform = CGAffineTransform(rotationAngle: rad(-180)).translatedBy(x: -self.size.width, y: -self.size.height)
    default:
        rectTransform = .identity
    }
    rectTransform = rectTransform.scaledBy(x: self.scale, y: self.scale)

    var cgImage = self.cgImage

    if cgImage == nil{

        let ciContext = CIContext()
        if let ciImage = self.ciImage{
            cgImage = ciContext.createCGImage(ciImage, from: ciImage.extent)
        }
    }

    if let imageRef = cgImage?.cropping(to: rect.applying(rectTransform)){
        let result = UIImage(cgImage: imageRef, scale: self.scale, orientation: self.imageOrientation)
        return result
    }


    return nil

}