Setting the frame for the preview layer results in incorrect frame settings

Question

I'm having some trouble with PBJVision.

I integrated it into a Swift project and when I'm trying to set the frame of the preview layer, it results in an inconsistent frame:

I have this code:

var _previewLayer: AVCaptureVideoPreviewLayer = PBJVision.sharedInstance().previewLayer
@IBOutlet weak var previewView: UIView! // this is the white view in the back

let bounds = self.previewView.layer.bounds
_previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
_previewLayer.bounds = bounds
_previewLayer.position = CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds))
previewView.layer.addSublayer(_previewLayer)

Where you put this code? Are you build your interface using autolayout? If so, and you use this code before layout is ready you get wrong size in `bounds` variable. you could try to put it inside `viewDidLayoutSubviews` method — rkyr, Feb 01 '16 at 08:36

score 4 · Accepted Answer · answered Feb 03 '16 at 04:24

Have you tried resizing the frame of the _previewLayer when the previewView lays out its subviews?

Subclass UIView for your previewView, set a property for your AVCaptureVideoPreviewLayer, and set its frame to to match your view's bounds:

class PreviewView: UIView {

    let previewLayer: AVCaptureVideoPreviewLayer?

    override func layoutSubviews() {
        self.previewLayer?.frame = self.bounds;
    }
}

score 0 · Answer 2 · answered May 31 '18 at 16:15

I had the same issue.

I tried @rkyr recommendation (setting the frame in the viewDidLayoutSubviews method), with no success. I also wanted to fix it without adding subclasses.

I was able to fix it with 2 changes: - Ensure that the previewLayer is defined as AVCaptureVideoPreviewLayer (subclass of CALayer) instead of CALayer, that was my case

var previewLayer: AVCaptureVideoPreviewLayer? // :CALayer

Ensuring that the frame of the layer is set, and it is added to the view after all the settings of the layer session have been set: This code works:

captureSession = AVCaptureSession()
let captureDevice = AVCaptureDevice.default(for: AVMediaType.video)
do {
    let input = try AVCaptureDeviceInput(device: captureDevice!)
    captureSession?.addInput(input)
} catch {
    onErrorCloseAndReturn(error: error)
}
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: "captureQueue")
dataOutput.setSampleBufferDelegate(self, queue: queue)
captureSession?.startRunning()

previewLayer = AVCaptureVideoPreviewLayer(session: captureSession!)
previewLayer?.frame = self.view.layer.bounds
self.view.layer.addSublayer(previewLayer!)

I hoe it helps... e

Setting the frame for the preview layer results in incorrect frame settings

2 Answers2