ios - 相机 View 与结果图像不同

Question

我正在制作一个 iPad 应用程序，它可以拍摄照片并将其与用户选择的相框混合。我的问题是相机 View 显示了更多将在框架上使用的图像，因为它会被剪切和调整大小以适合框架。

我尝试将相机 View 设置为框架内照片的大小，但框架分辨率太高且大于 iPad 屏幕。

我也在处理图片以适合框架，如果我不这样做，图像就会缩小填充。所以我想做的是让相机只显示不会被裁剪的内容。

这是我的裁剪方法:

func crop(image: UIImage, width: Double, height: Double) -> UIImage {

        let cgimage = image.cgImage!
        let contextImage: UIImage = UIImage(cgImage: cgimage)
        let contextSize: CGSize = contextImage.size
        var posX: CGFloat = 0.0
        var posY: CGFloat = 0.0
        var cgwidth: CGFloat = CGFloat(width)
        var cgheight: CGFloat = CGFloat(height)

        // See what size is longer and create the center off of that
        if contextSize.width > contextSize.height {
            posX = ((contextSize.width - contextSize.height) / 2)
            posY = 0
            cgwidth = contextSize.height
            cgheight = contextSize.height
        } else {
            posX = 0
            posY = ((contextSize.height - contextSize.width) / 2)
            cgwidth = contextSize.width
            cgheight = contextSize.width
        }

        let rect: CGRect = CGRect(x: posX, y: posY, width: cgwidth, height: cgheight)

        // Create bitmap image from context using the rect
        let imageRef: CGImage = cgimage.cropping(to: rect)!

        // Create a new image based on the imageRef and rotate back to the original orientation
        let image: UIImage = UIImage(cgImage: imageRef, scale: image.scale, orientation: image.imageOrientation)

        return image
    }

这就是我设置相机的方式，prviewView 是相机 View :

  guard let frontCamera = AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .front)
            else {
                fatalError("Front camera not found")
        }
        var error: NSError?
        var input: AVCaptureDeviceInput!
        do{
            input = try AVCaptureDeviceInput(device: frontCamera)
        }catch let error1 as NSError{
            error = error1
            input = nil
            print(error!.localizedDescription)
        }
        stillImageOutput = AVCapturePhotoOutput()
        if error == nil && session!.canAddInput(input) {
            session!.addInput(input)
            if session!.canAddOutput(stillImageOutput!){
                session!.addOutput(stillImageOutput!)                
                videoPreviewLayer = AVCaptureVideoPreviewLayer(session: session!)
                videoPreviewLayer!.videoGravity = .resizeAspect
                var videoOrientation = AVCaptureVideoOrientation(rawValue: 1)
                switch deviceOrientation {
                case .portrait:
                    videoOrientation = .portrait
                    break
                case .portraitUpsideDown:
                    videoOrientation = .portraitUpsideDown
                    break
                case .landscapeRight:
                    videoOrientation = .landscapeLeft
                    break
                case .landscapeLeft:
                    videoOrientation = .landscapeRight
                    break
                default:
                    break
                }
                videoPreviewLayer!.connection?.videoOrientation = videoOrientation ?? .portrait
                previewView.layer.addSublayer(videoPreviewLayer!)
                DispatchQueue.global(qos: .userInitiated).async { 
                    self.session!.startRunning()
                    DispatchQueue.main.async {
                        self.videoPreviewLayer!.frame = self.previewView.bounds
                    }
                }                
            }

        }

Answer 1

这实际上是一个愚蠢的错误，我传递了错误的原始图像尺寸。函数中的一切都正常工作。