swift - 如何自定义大小 AVcapture

Question

我需要捕获我的条形码但是我的代码捕获是全屏的。如何自定义尺寸或固定为小尺寸。请告诉我自定义尺寸的想法或代码，谢谢。

我的代码捕获是全屏的。

import UIKit
import AVFoundation

protocol BarcodeDelegate {
    func barcodeReaded(barcode: String)
}


class barcodeCapViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {

    var delegate: BarcodeDelegate?
    var captureSession: AVCaptureSession!
    var code: String?


    override func viewDidLoad() {
        super.viewDidLoad()

        self.captureSession = AVCaptureSession();

        let videoCaptureDevice: AVCaptureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)

        do {

            let videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)

            if self.captureSession.canAddInput(videoInput) {
                self.captureSession.addInput(videoInput)
            } else {
                print("Could not add video input")
            }

            let metadataOutput = AVCaptureMetadataOutput()
            if self.captureSession.canAddOutput(metadataOutput) {
                self.captureSession.addOutput(metadataOutput)

                metadataOutput.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
                metadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode, AVMetadataObjectTypeEAN13Code]
            } else {
                print("Could not add metadata output")
            }

            let previewLayer = AVCaptureVideoPreviewLayer(session: self.captureSession)
            previewLayer.frame = self.view.layer.bounds
            self.view.layer .addSublayer(previewLayer)
            self.captureSession.startRunning()
        } catch let error as NSError {
            print("Error while creating vide input device: \(error.localizedDescription)")
        }

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
        for metadata in metadataObjects {
            let readableObject = metadata as! AVMetadataMachineReadableCodeObject
            let code = readableObject.stringValue
            if !code.isEmpty {
                self.captureSession.stopRunning()
                self.dismissViewControllerAnimated(true, completion: nil)
                self.delegate?.barcodeReaded(code)
            }
        }
    }

}

当我添加 CGRectMake(20, 40, 200, 50) show this

添加 CGRectMake(20, 40, 500, 100) show this

我不知道为什么宽度和高度不按照代码加起来。

Answer 1

更改 AVCaptureVideoPreviewLayer 的帧大小:

let previewLayer = AVCaptureVideoPreviewLayer(session: self.captureSession)
previewLayer.frame = CGRectMake(10, 20, 100, 50)    // something else!

如果你正在使用自动布局，你可能不想处理 CALayer 帧，所以你应该创建一个 UIView 子类，添加你的 AVCaptureVideoPreviewLayer 并在 layoutSubviews 中设置图层的 frame:

override func layoutSubviews() {
    super.layoutSubviews()
    self.previewLayer.frame = self.frame
}