目前,我有一个vie控制器,它模态地呈现一个包含摄像头的视图控制器。但是,每当我转换时,预览图层都会有一个动画,因此它会从左上角循环增长以填充屏幕的其余部分。我已经尝试禁用CALayer隐式动画但没有成功。这是视图出现时的代码。
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
previewLayer?.frame = self.view.frame
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
capturedImageView.center = self.view.center
captureSession = AVCaptureSession()
if usingFrontCamera == true {
captureSession?.sessionPreset = AVCaptureSession.Preset.hd1920x1080
}
else {
captureSession?.sessionPreset = AVCaptureSession.Preset.hd1280x720
}
captureDevice = AVCaptureDevice.default(for: AVMediaType.video)
do {
let input = try AVCaptureDeviceInput(device: captureDevice!)
if (captureSession?.canAddInput(input) != nil) {
captureSession?.addInput(input)
stillImageOutput = AVCapturePhotoOutput()
captureSession?.addOutput(stillImageOutput!)
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession!)
previewLayer?.videoGravity = AVLayerVideoGravity.resizeAspect
self.view.layer.addSublayer(previewLayer!)
captureSession?.startRunning()
}
} catch {
}
}
反正有没有删除这个不断增长的动画?这是问题的GIF:
更改图层框架时,会有隐式动画。您可以使用CATransaction
禁用动画。
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
CATransaction.begin()
CATransaction.setDisableActions(true)
previewLayer?.frame = self.view.frame
CATransaction.commit()
}
你分两个阶段做事。在viewWillAppear
中,您添加预览图层时根本不给它任何大小,因此它在零原点处是零大小的图层:
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession!)
previewLayer?.videoGravity = AVLayerVideoGravity.resizeAspect
self.view.layer.addSublayer(previewLayer!)
然后,在viewDidAppear
中,通过给它一个实际的框架来增长预览图层:
previewLayer?.frame = self.view.frame
这两个阶段按此顺序发生,我们可以看到由预览图层框架的变化引起的跳跃。
如果您不想看到跳跃,请不要这样做。不要添加预览图层,直到您可以先将其显示为实际框架。