[英]iOS: Capture image during camera preview without action
我正在尝试从相机预览中捕获图像,但无法从预览层获取图像。 我想做的有点类似于照片应用程序中的 iOS 15 OCR 模式,它在相机预览期间处理图像,不需要用户拍摄或开始录制视频,只需在预览中处理图像。 我查看了文档并在网上搜索,但找不到任何有用的信息。
我尝试的是,保存 previewLayer 并定期调用 previewLayer.draw(in: context) 。 但是在上下文中绘制的图像是空白的。 现在我想知道这是否可能首先。 那里可能存在一些安全问题,以限制在相机预览中处理图像,我猜只允许正版应用程序访问,所以我可能需要找到其他方法。
如果有任何解决方法,请赐教。
谢谢!
好的。 在 MadProgrammer 的帮助下,我得到了正常工作。 Anurag Ajwani 的网站很有帮助。
这是我捕获视频帧的简单片段。 您需要在 CameraView 实例化之前确保权限。
class VideoCapture: NSObject, AVCaptureVideoDataOutputSampleBufferDelegate {
//private var previewLayer: AVCaptureVideoPreviewLayer? = nil
private var session: AVCaptureSession? = nil
private var videoOutput: AVCaptureVideoDataOutput? = nil
private var videoHandler: ((UIImage) -> Void)?
override init() {
super.init()
let deviceSession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInDualWideCamera, .builtInWideAngleCamera], mediaType: .video, position: .back)
guard deviceSession.devices.count > 0 else { return }
if let input = try? AVCaptureDeviceInput(device: deviceSession.devices.first!) {
let session = AVCaptureSession()
session.addInput(input)
let videoOutput = AVCaptureVideoDataOutput()
videoOutput.videoSettings = [(kCVPixelBufferPixelFormatTypeKey as NSString): NSNumber(value: kCVPixelFormatType_32BGRA)] as [String:Any]
videoOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "my.image.handling.queue"))
videoOutput.alwaysDiscardsLateVideoFrames = true
if session.canAddOutput(videoOutput) {
session.sessionPreset = .high
session.addOutput(videoOutput)
self.videoOutput = videoOutput
}
for connection in videoOutput.connections {
if connection.isVideoOrientationSupported {
connection.videoOrientation = .portrait
}
}
session.commitConfiguration()
self.session = session
/*
self.previewLayer = AVCaptureVideoPreviewLayer(session: session)
if let previewLayer = self.previewLayer {
previewLayer.videoGravity = .resizeAspectFill
layer.insertSublayer(previewLayer, at: 0)
CameraPreviewView.initialized = true
}
*/
}
}
func startCapturing(_ videoHandler: @escaping (UIImage) -> Void) -> Void {
if let session = session {
session.startRunning()
}
self.videoHandler = videoHandler
}
// AVCaptureVideoDataOutputSampleBufferDelegate
func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
debugPrint("unable to get video frame")
return
}
//print("got video frame")
if let videoHandler = self.videoHandler {
let rect = CGRect(x: 0, y: 0, width: CVPixelBufferGetWidth(imageBuffer), height: CVPixelBufferGetHeight(imageBuffer))
let ciImage = CIImage.init(cvImageBuffer: imageBuffer)
let ciContext = CIContext()
let cgImage = ciContext.createCGImage(ciImage, from: rect)
guard cgImage != nil else {return }
let uiImage = UIImage(cgImage: cgImage!)
videoHandler(uiImage)
}
}
}
struct CameraView: View {
@State var capturedVideo: UIImage? = nil
let videoCapture = VideoCapture()
var body: some View {
VStack {
ZStack(alignment: .center) {
if let capturedVideo = self.capturedVideo {
Image(uiImage: capturedVideo)
.resizable()
.scaledToFill()
}
}
}
.background(Color.black)
.onAppear {
self.videoCapture.startCapturing { uiImage in
self.capturedVideo = uiImage
}
}
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.