问题
I have created a custom camera and have implemented below code to crop the taken image, I have shown guides in the preview layer so I want to crop the image which appears in that area.
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!
}
This code just works fine when & give the exact cropped image when the below line of code is commented, though I want the image streaming to be full screen so I have to use the below line of code. The image comes zoomed out sort of.
(self.previewLayer as! AVCaptureVideoPreviewLayer).videoGravity = AVLayerVideoGravity.resizeAspectFill
How do I solve this issue? Is the cropping code wrong?
Here is the full Class code
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)
}
}
}
}
}
Here is the view hierarchy image
回答1:
It's not clear where the problem is. I would either use the debugger or some print statements to figure out whether the issue is with the image or the view displaying the image. Print out size of the cropped image to make sure it is correct.
Then, print out the image view size in the ShowImageViewController in viewDidAppear to make sure it is correct.
回答2:
For the correction of zooming out of cropped image, you have to change your crop function to this by using image orientation.
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
}
来源：https://stackoverflow.com/questions/49302828/custom-camera-and-crop-image-in-swift