捕获静止图像异步问题

Question

我目前在使用AVCaptureStillImageOutput时遇到问题，当我尝试拍照时，图像当前为零。我目前在错误修复方面的尝试发现 captureStillImageAsyncly 方法根本没有被调用，并且我无法测试样本缓冲区是否为零。我正在使用此方法将相机图像馈送到另一种方法中，该方法将相机图像和另一个图像组合成单个图像。线程在最后一个方法期间失败。当我尝试从捕获方法检查图像时，它不可用。我需要做什么才能使相机捕获正常工作？

public func capturePhotoOutput()->UIImage
{
var image:UIImage = UIImage()
if let videoConnection = stillImageOutput!.connection(withMediaType: AVMediaTypeVideo)
{
print("Video Connection established ---------------------")
stillImageOutput?.captureStillImageAsynchronously(from: videoConnection, completionHandler: {(sampleBuffer, error) in
if (sampleBuffer != nil)
{
print("Sample Buffer not nil ---------------------")
let imageData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(sampleBuffer)
let dataProvider = CGDataProvider(data: imageData! as CFData)
let cgImageRef = CGImage(jpegDataProviderSource: dataProvider!, decode: nil, shouldInterpolate: true, intent: .defaultIntent)
let camImage = UIImage(cgImage: cgImageRef!, scale: CGFloat(1.0), orientation: UIImageOrientation.right)
image = camImage
}
else
{
print("nil sample buffer ---------------------")
}
})
}
if (stillImageOutput?.isCapturingStillImage)!
{
print("image capture in progress ---------------------")
}
else
{
print("capture not in progress -------------------")
}
return image
}

编辑：添加了以下使用相机图像的方法。

func takePicture()-> UIImage
{
/*
videoComponent!.getVideoController().capturePhotoOutput
{ (image) in
//Your code
guard let topImage = image else
{
print("No image")
return
}
}
*/
let topImage = videoComponent!.getVideoController().capturePhotoOutput() //overlay + Camera
let bottomImage = captureTextView() //text
let size = CGSize(width:(topImage.size.width),height:(topImage.size.height)+(bottomImage.size.height))
UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
topImage.draw(in: CGRect(x:0, y:0, width:size.width, height: (topImage.size.height)))
bottomImage.draw(in: CGRect(x:(size.width-bottomImage.size.width)/2, y:(topImage.size.height), width: bottomImage.size.width,  height: (bottomImage.size.height)))
let newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}

Answer 1

如果使用异步方法，该函数将返回错误的值，因为异步调用仍在进行中。您可以使用完成块，如下所示：

public func capturePhotoOutput(completion: (UIImage?) -> ())
{
if let videoConnection = stillImageOutput!.connection(withMediaType: AVMediaTypeVideo)
{
print("Video Connection established ---------------------")
stillImageOutput?.captureStillImageAsynchronously(from: videoConnection, completionHandler: {(sampleBuffer, error) in
if (sampleBuffer != nil)
{
print("Sample Buffer not nil ---------------------")
let imageData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(sampleBuffer)
let dataProvider = CGDataProvider(data: imageData! as CFData)
let cgImageRef = CGImage(jpegDataProviderSource: dataProvider!, decode: nil, shouldInterpolate: true, intent: .defaultIntent)
let camImage = UIImage(cgImage: cgImageRef!, scale: CGFloat(1.0), orientation: UIImageOrientation.right)
completion(camImage)
}
else
{
completion(nil)
}
})
}
else
{
completion(nil)
}
}

如何使用它：

capturePhotoOutput
{ (image) in
guard let topImage = image else{
print("No image")
return
}
//Your code
}

编辑：

func takePicture()
{
videoComponent!.getVideoController().capturePhotoOutput
{ (image) in
guard let topImage = image else
{
print("No image")
return
}
let bottomImage = self.captureTextView() //text
let size = CGSize(width:(topImage.size.width),height:(topImage.size.height)+(bottomImage.size.height))
UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
topImage.draw(in: CGRect(x:0, y:0, width:size.width, height: (topImage.size.height)))
bottomImage.draw(in: CGRect(x:(size.width-bottomImage.size.width)/2, y:(topImage.size.height), width: bottomImage.size.width,  height: (bottomImage.size.height)))
let newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
self.setPicture(image: newImage)
}
}
func setPicture(image:UIImage)
{
//Your code after takePicture
}