问将ARFrame#capturedImage转换为视图大小

EN

guard let frame = session.currentFrame else { return }
let imageBuffer = frame.capturedImage

let imageSize = CGSize(width: CVPixelBufferGetWidth(imageBuffer), height: CVPixelBufferGetHeight(imageBuffer))
let viewPort = sceneView.bounds
let viewPortSize = sceneView.bounds.size

let interfaceOrientation : UIInterfaceOrientation
if #available(iOS 13.0, *) {
    interfaceOrientation = self.sceneView.window!.windowScene!.interfaceOrientation
} else {
    interfaceOrientation = UIApplication.shared.statusBarOrientation
}

let image = CIImage(cvImageBuffer: imageBuffer)

// The camera image doesn't match the view rotation and aspect ratio
// Transform the image:

// 1) Convert to "normalized image coordinates"
let normalizeTransform = CGAffineTransform(scaleX: 1.0/imageSize.width, y: 1.0/imageSize.height)

// 2) Flip the Y axis (for some mysterious reason this is only necessary in portrait mode)
let flipTransform = (interfaceOrientation.isPortrait) ? CGAffineTransform(scaleX: -1, y: -1).translatedBy(x: -1, y: -1) : .identity

// 3) Apply the transformation provided by ARFrame
// This transformation converts:
// - From Normalized image coordinates (Normalized image coordinates range from (0,0) in the upper left corner of the image to (1,1) in the lower right corner)
// - To view coordinates ("a coordinate space appropriate for rendering the camera image onscreen")
// See also: https://developer.apple.com/documentation/arkit/arframe/2923543-displaytransform

let displayTransform = frame.displayTransform(for: interfaceOrientation, viewportSize: viewPortSize)

// 4) Convert to view size
let toViewPortTransform = CGAffineTransform(scaleX: viewPortSize.width, y: viewPortSize.height)

// Transform the image and crop it to the viewport
let transformedImage = image.transformed(by: normalizeTransform.concatenating(flipTransform).concatenating(displayTransform).concatenating(toViewPortTransform)).cropped(to: viewPort)