ios - 如何使用 AVFoundation 将预览(缩放)图像保存为照片？

Question

所以，我已经弄清楚了如何使用 CATransform3DMakeScale(2.4, 2.4, 2.4) 制作缩放效果，但现在我在尝试保存 Zoome 预览消息时遇到了问题(在我进行缩放时编写代码):

 // init camera device
    let captureDevice : AVCaptureDevice? = initCaptureDevice()
    print("camera was initialized")
    // Prepare output
    initOutput()
    if (captureDevice != nil) {
        let deviceInput : AVCaptureInput? = initInputDevice(captureDevice: captureDevice!)
        if (deviceInput != nil) {
            initSession(deviceInput: deviceInput!)
            // Preview Size
            let previewLayer: AVCaptureVideoPreviewLayer = AVCaptureVideoPreviewLayer(session: self.session)
            previewLayer.frame = self.view.bounds
            previewLayer.transform = CATransform3DMakeScale(2.4, 2.4, 2.4)
             imagePreviewScale = previewLayer.contentsScale
            self.view.layer.addSublayer(previewLayer)
            self.session?.startRunning()

现在我尝试像这样保存预览的缩放图像:

 let videoConnection : AVCaptureConnection? = self.imageOutput?.connection(withMediaType: AVMediaTypeVideo)
    if (videoConnection != nil) {

        videoConnection?.videoScaleAndCropFactor = imagePreviewScale

        self.imageOutput?.captureStillImageAsynchronously(from: videoConnection, completionHandler: { (imageDataSampleBuffer, error) -> Void in
            if (imageDataSampleBuffer != nil) {
                                    // Capture JPEG

                let imageData : NSData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(imageDataSampleBuffer) as NSData
                // JPEG
                let image = UIImage(data: imageData as Data)

并添加了行

 imagePreviewScale = previewLayer.contentsScale

但是还是没有任何反应，请问谁能告诉我如何保存精确缩放的图片？

Answer 1

问题是 previewLayer.contentsScale 为 1，因此您要将 videoScaleAndCropFactor 设置为 1。

你需要将它设置为

videoConnection?.videoScaleAndCropFactor = 2.4