我正在处理相机相关的工作。
相机给用户呈现出实时视频流，当他们点击拍照按钮时，会创建一张图片并传递给用户。
问题在于这张图片被设计成位于最顶部位置，而这个位置比实时预览显示的位置更高。
你知道如何调整相机的框架，使得实时视频流的顶部与他们即将拍摄的图片的顶部匹配吗？
我以为下面的代码可以实现，但实际上不行。这是我的当前相机框架代码：
//Add the device to the session, get the video feed it produces and add it to the video feed layer
func initSessionFeed()
{
_session = AVCaptureSession()
_session.sessionPreset = AVCaptureSessionPresetPhoto
updateVideoFeed()
_videoPreviewLayer = AVCaptureVideoPreviewLayer(session: _session)
_videoPreviewLayer.frame = CGRectMake(0,0, self.frame.width, self.frame.width) //the live footage IN the video feed view
_videoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
self.layer.addSublayer(_videoPreviewLayer)//add the footage from the device to the video feed layer
}
func initOutputCapture()
{
//set up output settings
_stillImageOutput = AVCaptureStillImageOutput()
var outputSettings:Dictionary = [AVVideoCodecJPEG:AVVideoCodecKey]
_stillImageOutput.outputSettings = outputSettings
_session.addOutput(_stillImageOutput)
_session.startRunning()
}
func configureDevice()
{
if _currentDevice != nil
{
_currentDevice.lockForConfiguration(nil)
_currentDevice.focusMode = .Locked
_currentDevice.unlockForConfiguration()
}
}
func captureImage(callback:(iImage)->Void)
{
if(_captureInProcess == true)
{
return
}
_captureInProcess = true
var videoConnection:AVCaptureConnection!
for connection in _stillImageOutput.connections
{
for port in (connection as AVCaptureConnection).inputPorts
{
if (port as AVCaptureInputPort).mediaType == AVMediaTypeVideo
{
videoConnection = connection as AVCaptureConnection
break;
}
if videoConnection != nil
{
break;
}
}
}
if videoConnection != nil
{
_stillImageOutput.captureStillImageAsynchronouslyFromConnection(videoConnection)
{
(imageSampleBuffer : CMSampleBuffer!, _) in
let imageDataJpeg = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(imageSampleBuffer)
var pickedImage = UIImage(data: imageDataJpeg, scale: 1)
UIGraphicsBeginImageContextWithOptions(pickedImage.size, false, pickedImage.scale)
pickedImage.drawInRect(CGRectMake(0, 0, pickedImage.size.width, pickedImage.size.height))
pickedImage = UIGraphicsGetImageFromCurrentImageContext() //this returns a normalized image
if(self._currentDevice == self._frontCamera)
{
var context:CGContextRef = UIGraphicsGetCurrentContext()
pickedImage = UIImage(CGImage: pickedImage.CGImage, scale: 1.0, orientation: .UpMirrored)
pickedImage.drawInRect(CGRectMake(0, 0, pickedImage.size.width, pickedImage.size.height))
pickedImage = UIGraphicsGetImageFromCurrentImageContext()
}
UIGraphicsEndImageContext()
var image:iImage = iImage(uiimage: pickedImage)
self._captureInProcess = false
callback(image)
}
}
}
如果我调整AVCaptureVideoPreviewLayer的框架，比如提高y值，那么我只会看到一个黑色条，显示偏移量。我非常好奇为什么视频帧的顶部与我的输出图像不匹配。
我确实对相机进行了“裁剪”，使其成为一个完美的正方形，但为什么实时摄像头的顶部不是实际的顶部（因为图像默认显示在更高的位置，摄像头的反馈则没有显示）。
更新：
以下是我所说的前后屏幕截图：
之前的： Before image 这是现场反馈显示的内容
之后的： After image 当用户点击拍照时，这就是结果图像