Swift 学习笔记(九)

2019-03-01
Developing
终于把视频流的图片取出来了
先构建session设置输入输出
override func viewDidLoad() {
		super.viewDidLoad()
		
		let session = AVCaptureSession() //创建会话
		let device = AVCaptureDevice.default(_:.builtInWideAngleCamera, for: .video, position: .back) //选择设备
		
		//设置输入
		do {
			let videoInput = try AVCaptureDeviceInput(device: device!)
			session.addInput(videoInput)
		} catch {
			print("error")
			return
		}
		//设置输出
		let videoOutput = AVCaptureVideoDataOutput() //相当于截获输出🔴可以访问帧
		
		//这里设置了回调队列才可以让下面的captureOutput函数能够同时运行
		let myQueue = DispatchQueue(label: "myQueue")//设置队列
		videoOutput.setSampleBufferDelegate(self, queue: myQueue)//回调
		
		session.addOutput(videoOutput)
		
		//对于UIView控件要设置预览层//相当于图层. 可以多个图层叠加
		let ViewLayer = AVCaptureVideoPreviewLayer(session: session) //设置预览层
		ViewLayer.frame = myView!.bounds
		myView?.layer.addSublayer(ViewLayer)

		self.mySession = session //会话传到外部变量中
	}
	
	@IBOutlet weak var myView2: UIImageView!
	@IBOutlet weak var myView: UIView? //视窗
	//按钮
	@IBAction func myButton(_ sender: Any) {
		self.mySession!.startRunning()
	}
	@IBAction func myBt2(_ sender: Any) {
		self.mySession!.stopRunning()
	}
	
	//这个函数会在俘获到每一帧运行. sampleBuffer参数就是多媒体缓存
	func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
		
		//取出图片缓存
		guard let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { print("提取图片失败")
			return }
	
		
		let image: UIImage = self.convert(pixelBuffer: pixelBuffer) //CVImageBuffer转换成UIImage
			//设置图片角度
			let jiaodu = image.imageOrientation.rawValue + 3
			let okimage = UIImage(cgImage: image.cgImage!, scale: image.scale, orientation:UIImage.Orientation(rawValue: jiaodu)!)
		DispatchQueue.main.sync {
		//这里是UIImageView控件, 只能放一张图//不存在多图层//要想在图上画画必须重新绘制图片
			self.myView2.image = okimage //更新UI
		}
		
		
	}
	
	//CVImageBuffer->CIImage->CGImage->UIImage
	func convert(pixelBuffer:CVImageBuffer) -> UIImage
	{
		let ciimage: CIImage = CIImage(cvImageBuffer: pixelBuffer)
		let context:CIContext = CIContext.init(options: nil)
		let cgImage:CGImage = context.createCGImage(ciimage, from: ciimage.extent)!
		let image:UIImage = UIImage.init(cgImage: cgImage)
		
		return image
	}
	
}
////readLine()读取用户输入返回可选类型