iOS 点击对焦

问题描述 投票：0回答：9

我使用此代码在iOS自定义相机应用程序中实现点击对焦，但它不起作用。这是代码

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    let touchPer = touches.anyObject() as UITouch
    let screenSize = UIScreen.mainScreen().bounds.size
    var focus_x = touchPer.locationInView(self.view).x / screenSize.width
    var focus_y = touchPer.locationInView(self.view).y / screenSize.height

    if let device = captureDevice {
        if(device.lockForConfiguration(nil)) {
            device.focusMode = AVCaptureFocusMode.ContinuousAutoFocus

            device.focusPointOfInterest = CGPointMake(focus_x, focus_y)
            device.exposureMode = AVCaptureExposureMode.ContinuousAutoExposure
            device.unlockForConfiguration()
        }
    }
}
ios swift avcapturesession
9个回答
24
投票

随着 

videoView: UIView
显示视频和 
cameraDevice: AVCaptureDevice
，以下内容似乎对我有用：

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
    var touchPoint = touches.first as! UITouch
    var screenSize = videoView.bounds.size
    var focusPoint = CGPoint(x: touchPoint.locationInView(videoView).y / screenSize.height, y: 1.0 - touchPoint.locationInView(videoView.x / screenSize.width)

    if let device = cameraDevice {
        if(device.lockForConfiguration(nil)) {
            if device.focusPointOfInterestSupported {
                device.focusPointOfInterest = focusPoint
                device.focusMode = AVCaptureFocusMode.AutoFocus
            }
            if device.exposurePointOfInterestSupported {
                device.exposurePointOfInterest = focusPoint
                device.exposureMode = AVCaptureExposureMode.AutoExpose
            }
            device.unlockForConfiguration()
        }
    }
}

请注意，我必须交换 

x
和 
y
坐标，并将 
x
坐标从 1 重新映射到 0，而不是 0 到 1 — 不确定为什么会出现这种情况，但似乎有必要让它正常工作（尽管测试它也有点棘手）.

编辑：Apple的文档解释了坐标变换的原因。

此外，设备可能支持兴趣焦点。您可以使用 focusPointOfInterestSupported 测试支持。如果支持，您可以使用 focusPointOfInterest 设置焦点。您传递一个 CGPoint，其中 {0,0} 表示图片区域的左上角，{1,1} 表示横向模式下的右下角，主页按钮位于右侧 - 即使设备处于纵向模式，这也适用.

在我的示例中，我一直使用 

.ContinuousAutoFocus
和 
.ContinuousAutoExposure
，但文档表明 
.AutoFocus
是正确的选择。奇怪的是，文档没有提及 
.AutoExpose
，但我在代码中使用它并且工作正常。

我还修改了示例代码以包含 

.focusPointOfInterestSupported
和 
.exposurePointOfInterestSupported
测试 - 文档还提到对给定的焦点/曝光模式使用 
isFocusModeSupported:
和 
isExposureModeSupported:
方法来测试它是否在给定设备上可用。设置它，但我假设如果设备支持兴趣点模式，那么它也支持自动模式。这一切似乎在我的应用程序中运行良好。

11
投票

Swift 3.0 解决方案

使用 Swift 3 将 Cody 的答案转换为可行的解决方案。

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    let touchPoint = touches.first! as UITouch
    let screenSize = cameraView.bounds.size
    let focusPoint = CGPoint(x: touchPoint.location(in: cameraView).y / screenSize.height, y: 1.0 - touchPoint.location(in: cameraView).x / screenSize.width)

    if let device = captureDevice {
        do {
            try device.lockForConfiguration()
            if device.isFocusPointOfInterestSupported {
                device.focusPointOfInterest = focusPoint
                device.focusMode = AVCaptureFocusMode.autoFocus
            }
            if device.isExposurePointOfInterestSupported {
                device.exposurePointOfInterest = focusPoint
                device.exposureMode = AVCaptureExposureMode.autoExpose
            }
            device.unlockForConfiguration()

        } catch {
            // Handle errors here
        }
    }
}
9
投票

您应该阅读 Apple docs on 

focusPointOfInterest
，其中说了三件重要的事情：

  1. 为此属性设置值不会启动聚焦操作。要将相机聚焦在兴趣点上，请首先设置此属性的值，然后将 focusMode 属性设置为 autoFocus 或 ContinuousAutoFocus。

  2. 此属性的 CGPoint 值使用坐标系，其中 {0,0} 是图片区域的左上角，{1,1} 是右下角。 此坐标系始终相对于主页按钮位于右侧的横向设备方向，无论实际设备方向如何。您可以使用 AVCaptureVideoPreviewLayer 方法在此坐标系和视图坐标之间进行转换。

  3. 在更改此属性的值之前，必须调用 lockForConfiguration() 来获取对设备配置属性的独占访问权限。否则，设置此属性的值会引发异常。完成设备配置后，调用unlockForConfiguration()释放锁定并允许其他设备配置设置。

这是一个实现所有这些的实现：

// In your camera preview view    
@objc private func cameraViewTapped(with gestureRecognizer: UITapGestureRecognizer) {
    let location = gestureRecognizer.location(in: self)
    addFocusIndicatorView(at: location) // If you want to indicate it in the UI

    // This is the point you want to pass to your capture device
    let captureDeviceLocation = previewLayer.captureDevicePointConverted(fromLayerPoint: location)

    // Somehow pass the point to where your AVCaptureDevice is
    viewDelegate?.cameraPreviewView(self, didTapToFocusAt: captureDeviceLocation) 
}


// In your camera controller
func focus(at point: CGPoint) {
    guard let device = videoDevice else {
        return
    }

    guard device.isFocusPointOfInterestSupported, device.isExposurePointOfInterestSupported else {
        return
    }

    do {
        try device.lockForConfiguration()

        device.focusPointOfInterest = point
        device.exposurePointOfInterest = point

        device.focusMode = .continuousAutoFocus
        device.exposureMode = .continuousAutoExposure

        device.unlockForConfiguration()
    } catch {
        print(error)
    }
}
8
投票
 device.focusPointOfInterest = focusPoint
 device.focusMode = AVCaptureFocusMode.AutoFocus
 device.exposurePointOfInterest = focusPoint
 device.exposureMode = AVCaptureExposureMode.ContinuousAutoExposure

我不知道为什么会这样，但它确实有效。

5
投票

设置焦点兴趣点的更好方法：

  • 首先计算兴趣点：

     let devicePoint: CGPoint = (self.previewView.layer as!  AVCaptureVideoPreviewLayer).captureDevicePointOfInterestForPoint(gestureRecognizer.locationInView(gestureRecognizer.view))

  • 之后设置兴趣焦点：

    let device: AVCaptureDevice! = self.videoDeviceInput!.device

    do {
        try device.lockForConfiguration()

        if device.focusPointOfInterestSupported && device.isFocusModeSupported(focusMode){

            device.focusPointOfInterest = devicePoint
            device.focusMode = focusMode
        }

        device.unlockForConfiguration()

    }catch{
        print(error)
    }
2
投票

Swift 5.0版本

// The back camera as default device
var captureDevice: AVCaptureDevice? {
    return AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .back)
}

// The camera view.
var cameraView: UIView!

// The layer that contains the camera output
var previewLayer: AVCaptureVideoPreviewLayer

// The focus square view - the yellow one ;)
var squareFocusView: UIView

// User taps on screen to select focus
@IBAction func tapToFocus(_ sender: UITapGestureRecognizer) {
    // make sure we capture one tap only
    if (sender.state == .ended) {
        
        guard let captureDevice = captureDevice else {
            return
        }
        
        let tappedFocusPoint = sender.location(in: cameraView)
        
        // we need to move the focus point to be the center of the tap instead of (0.0, 0.0)
        let centerX = tappedFocusPoint.x - (squareFocusView.frame.size.width / 2.0)
        let centerY = tappedFocusPoint.y - (squareFocusView.frame.size.height / 2.0)

        let focusPoint = CGPoint(x: centerX, y: centerY)
        
        // we need to remap the point because of different coordination systems.
        let convertedFocusPoint = previewLayer.captureDevicePointConverted(fromLayerPoint: focusPoint)
        
        do {
            // changing focusMode and exposureMode requires the device config to be locked.
            try captureDevice.lockForConfiguration()
            
            if (captureDevice.isFocusModeSupported(.autoFocus) && captureDevice.isFocusPointOfInterestSupported) {
                captureDevice.focusPointOfInterest = convertedFocusPoint
                captureDevice.focusMode = .autoFocus
            }
            
            if (captureDevice.isExposureModeSupported(.autoExpose) && captureDevice.isExposurePointOfInterestSupported) {
                captureDevice.exposurePointOfInterest = convertedFocusPoint
                captureDevice.exposureMode = .autoExpose
            }
            
            // unlocks device config
            captureDevice.unlockForConfiguration()
            
        } catch {
            // handle error here
        }
    }
}
0
投票

您必须按正确的顺序调用方法：

if(device.lockForConfiguration(nil)) {

    device.focusPointOfInterest = CGPointMake(focus_x, focus_y)
    device.focusMode = AVCaptureFocusMode.ContinuousAutoFocus

    device.exposureMode = AVCaptureExposureMode.ContinuousAutoExposure
    device.unlockForConfiguration()
}

在设置对焦模式之前先设置兴趣点，否则焦点将聚焦在前一个兴趣点上。

同样适用于

exposurePointOfInterest
。

0
投票

斯威夫特 4：

   public override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    var touchPoint = touches.first as! UITouch
    let cameraView = cameraViewController.view
    var screenSize = cameraView!.bounds.size
    var focusPoint = CGPoint(x: touchPoint.location(in: cameraView).y / screenSize.height, y: 1.0 - touchPoint.location(in: cameraView).x / screenSize.width)
    
    
    
    
    if #available(iOS 10.0, *) {
        let device = AVCaptureDevice.default(.builtInWideAngleCamera,
                                             for: .video, position: .unspecified)
        
        do{
            try device?.lockForConfiguration()
            
            if device!.isFocusPointOfInterestSupported {
                        device!.focusPointOfInterest = focusPoint
                device!.focusMode = AVCaptureDevice.FocusMode.autoFocus
                    }
            if device!.isExposurePointOfInterestSupported {
                        device!.exposurePointOfInterest = focusPoint
                device!.exposureMode = AVCaptureDevice.ExposureMode.autoExpose
                    }
                    device!.unlockForConfiguration()
        }catch{
            
        }
           
  
            
        
    } else {
        // Fallback on earlier versions
    }
     
}
0
投票

除了提供的让您在特定点聚焦/曝光区域/对象的答案之外，如果该对象已移开，或者相机视图发生变化，此时我们需要将 focusMode 设置回 .continuousAutoFocus 并曝光模式返回 .ContinousAutoExposure 让系统处理焦点/曝光

首先，我们需要观察主题区域变更通知：

cameraDevice.isSubjectAreaChangeMonitoringEnabled = true
NotificationCenter.default.addObserver(self, selector: #selector(setDefaultFocusAndExposure), name: .AVCaptureDeviceSubjectAreaDidChange, object: nil)

并在收到通知时配置摄像头设备：

@objc private func setDefaultFocusAndExposure() {
        guard let cameraDevice else { return }
        try? cameraDevice.lockForConfiguration()
        if cameraDevice.isFocusModeSupported(.continuousAutoFocus) {
            cameraDevice.focusMode = .continuousAutoFocus
        }
        if cameraDevice.isExposureModeSupported(.continuousAutoExposure) {
            cameraDevice.exposureMode = .continuousAutoExposure
        }
        cameraDevice.unlockForConfiguration()
}

最后，不要忘记删除观察者，对我来说，我是在 deinit 中完成的：

deinit {
        NotificationCenter.default.removeObserver(self)
}
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