Swift 4.2 自定义相机

自定义相机使用 AVFoundation 框架，简单的做了个demo，后面再更新，效果是这样的：

111543403082_.pic_hd.jpg

我们需要用到的几个对象

    var device: AVCaptureDevice! /// 获取设备：如摄像头
    var captureSession: AVCaptureSession! /// 会话，协调着input到output的数据传输，input和output的桥梁
    var previewLayer: AVCaptureVideoPreviewLayer! /// 图像预览层，实时显示捕获的图像
    var output:  AVCaptureVideoDataOutput! /// 图像流输出
    var beganTakePicture:Bool = false /// 相机开始拍照

创建一个会话Session

        // SessionPreset,用于设置output输出流的画面质量
        captureSession = AVCaptureSession()
        //captureSession.sessionPreset = AVCaptureSession.Preset.photo
        if UIDevice.current.userInterfaceIdiom == .phone {
            captureSession.sessionPreset = AVCaptureSession.Preset.vga640x480
        } else {
            captureSession.sessionPreset = AVCaptureSession.Preset.photo
        }
        // 设置为高分辨率
        if captureSession.canSetSessionPreset(AVCaptureSession.Preset(rawValue: "AVCaptureSessionPreset1280x720")) {
            captureSession.sessionPreset = AVCaptureSession.Preset(rawValue: "AVCaptureSessionPreset1280x720")
        }
        // 获取输入设备,builtInWideAngleCamera是通用相机,AVMediaType.video代表视频媒体,back表示前置摄像头,如果需要后置摄像头修改为front
        if #available(iOS 10.0, *)
        {
            let availbleDevices = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: .video, position: .back).devices
            device = availbleDevices.first
        }
        else
        {
            let devices = AVCaptureDevice.devices(for: .video)
            guard devices.count > 0 else { return } /// 初始化摄像头设备
            guard let device = devices.filter({  return $0.position == .back }).first else { return }
            self.device = device
        }

配置 session

        captureSession.beginConfiguration()
        do {
            // 将后置摄像头作为session的input 输入流
            let captureDeviceInput = try AVCaptureDeviceInput(device: device)
            captureSession.addInput(captureDeviceInput)
        } catch {
            print(error.localizedDescription)
        }
        // 设定视频预览层,也就是相机预览layer
        previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        sessionView.layer.addSublayer(previewLayer)    /// >>> sessionView 中
        previewLayer.frame = CGRect(x: 0, y: 0, width: JZScreenWidth, height: JZScreenHeigth-80)
        //previewLayer.videoGravity = AVLayerVideoGravity(rawValue: "AVLayerVideoGravityResizeAspectFill")
        previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill /// 相机页面展现形式-拉伸充满frame
        
        // 设定输出流
        output = AVCaptureVideoDataOutput()
        // 指定像素格式
        output.videoSettings = [(kCVPixelBufferPixelFormatTypeKey as NSString):NSNumber(value:kCVPixelFormatType_32BGRA)] as [String : Any]
        // 是否直接丢弃处理旧帧时捕获的新帧,默认为True,如果改为false会大幅提高内存使用
        output.alwaysDiscardsLateVideoFrames = true
        if captureSession.canAddOutput(output) {
            captureSession.addOutput(output)
        }
        // beginConfiguration()和commitConfiguration()方法中的修改将在commit时同时提交
        captureSession.commitConfiguration()
        captureSession.startRunning()
       // 开新线程进行输出流代理方法调用
        let queue = DispatchQueue(label: "com.brianadvent.captureQueue")
        output.setSampleBufferDelegate(self, queue: queue)
        
        let captureConnection = output.connection(with: .video)
        if captureConnection?.isVideoStabilizationSupported == true {
            /// 这个很重要 这个是为了拍照完成，防止图片旋转90度
            captureConnection?.videoOrientation = self.getCaptureVideoOrientation()
        }

遵循 AVCaptureVideoDataOutputSampleBufferDelegate
实现 delegate 方法

      func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
        if beganTakePicture == true {
            beganTakePicture = false
            /// 注意在主线程中执行
            DispatchQueue.main.async {
                #if false 
                self.photoImageView.image = self.imageConvert(sampleBuffer: sampleBuffer)
                self.captureSession.stopRunning()
                self.view.bringSubviewToFront(self.photoView)
                # else 
                self.captureSession.stopRunning()
                let image = self.imageConvert(sampleBuffer: sampleBuffer)
                // 导出照片
                let image1 = self.scaleToSize(image: image!, size: CGSize(width: JZScreenWidth, height: JZScreenHeigth - 40))
                // 放大二倍
                let resultImage = self.imageFromImage(imageFromImage: image1, inRext: CGRect(x: 0, y: 20 + (JZScreenHeigth - (JZScreenWidth * self.heightZoomPoint)), width: JZScreenWidth*2, height: (JZScreenWidth * self.heightZoomPoint)*2))
                self.photoImageView.image = resultImage
                self.view.bringSubviewToFront(self.photoView)
                #endif
            }
        }
    }

到此，基本就完成了简单的自定义相机拍照功能
此时，还需要几个帮助方法
拍照防止图片出来后旋转90度

    /// 旋转方向
    func getCaptureVideoOrientation() -> AVCaptureVideoOrientation {
        switch UIDevice.current.orientation {
        case .portrait,.faceUp,.faceDown:
            return .portrait
        case .portraitUpsideDown: // 如果这里设置成AVCaptureVideoOrientationPortraitUpsideDown,则视频方向和拍摄时的方向是相反的。
            return .portrait
        case .landscapeLeft:
            return .landscapeRight
        case .landscapeRight:
            return .landscapeLeft
        default:
            return .portrait
        }
    }

将CMSampleBufferRef流转为Image

    /// CMSampleBufferRef=>UIImage
    func imageConvert(sampleBuffer:CMSampleBuffer?) -> UIImage? {
        guard sampleBuffer != nil && CMSampleBufferIsValid(sampleBuffer!) == true else { return nil }
        let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer!)
        let ciImage = CIImage(cvPixelBuffer: pixelBuffer!)
        return UIImage(ciImage: ciImage)
    }

闪光灯-打开-关闭

        let device:AVCaptureDevice = AVCaptureDevice.default(for: .video)!
        // 呼叫控制硬件
        try! device.lockForConfiguration()
        if device.torchMode == .on {
            device.torchMode = .off
            sender.isSelected = false
        } else {
            device.torchMode = .on
            sender.isSelected = true
        }
        // 控制完毕需要关闭控制硬件
        device.unlockForConfiguration()

检查相机权限

    // MARK: - 检查相机权限
    func canUseCamera() -> Bool {
        let authStatus: AVAuthorizationStatus = AVCaptureDevice.authorizationStatus(for: .video)
         /*
          notDetermined: // 用户还没有关于这个应用程序做出了选择
          restricted: // 这个应用程序未被授权访问图片数据。用户不能更              改该应用程序的状态,可能是由于活动的限制,如家长控制到位。
          denied: // 用户已经明确否认了这个应用程序访问图片数据
          authorized: // 用户授权此应用程序访问图片数据
        */
        if authStatus == .denied {
            let alert = UIAlertView(title: "请打开相机权限", message: "设置-隐私-相机", delegate: nil, cancelButtonTitle: "取消", otherButtonTitles: "确定")
            alert.show()
            return false
        }
        return true
    }

图片的裁剪

        //1.先实现这个方法后得到返回的照片
        func scaleToSize(image:UIImage!,size:CGSize) -> UIImage{
        // 得到图片上下文，指定绘制范围
        //UIGraphicsBeginImageContext(size);
        
        /*
         *  UIGraphicsBeginImageContextWithOptions(CGSize size, BOOL opaque, CGFloat scale)
         *  CGSize size：指定将来创建出来的bitmap的大小
         *  BOOL opaque：设置透明YES代表透明，NO代表不透明
         *  CGFloat scale：代表缩放,0代表不缩放
         *  创建出来的bitmap就对应一个UIImage对象
         *  为了不影响像素，将图片放大了2倍
         */
        UIGraphicsBeginImageContextWithOptions(size, false, 2.0)
        // 将图片按照指定大小绘制
        image.draw(in: CGRect(x:0,y:0,width:size.width,height:size.height))
        // 从当前图片上下文中导出图片
        let img:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        // 当前图片上下文出栈
        UIGraphicsEndImageContext();
        // 返回新的改变大小后的图片
        return img
    }
    //2.实现这个方法,,就拿到了截取后的照片.
    func imageFromImage(imageFromImage:UIImage!,inRext:CGRect) ->UIImage{
        //将UIImage转换成CGImageRef
        let sourceImageRef:CGImage = imageFromImage.cgImage!
        // 按照给定的矩形区域进行剪裁
        // CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, rect);
        let newImageRef:CGImage = sourceImageRef.cropping(to: inRext)!
        // 将CGImageRef转换成UIImage
        // UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
        let img:UIImage = UIImage.init(cgImage: newImageRef)
        //返回剪裁后的图片
        return img
    }

此时，最关键的一步来了：拍照-按钮点击事件

    // 拍照
    @IBAction func startPhotoBtn(_ sender: UIButton) {
        beganTakePicture = true
    }

hhh