Question

我使用此代码在iOS自定义相机应用程序中实现Tap-to-Focus，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()
        }
    }
}

Answer 1

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

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坐标重新映射为1而不是0到1 - ~~不知道为什么应该是这样的，但似乎有必要让它正常工作（虽然测试它也有点棘手）~~。

编辑：Apple's documentation解释了坐标转换的原因。

此外，设备可以支持关注焦点。您使用focusPointOfInterestSupported测试支持。如果支持，则使用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}表示横向模式的右下角，右侧的主页按钮 - 即使设备处于纵向模式，这也适用

在我的示例中，我一直在使用.ContinuousAutoFocus和.ContinuousAutoExposure，但文档指出.AutoFocus是正确的选择。奇怪的是，文档没有提及.AutoExpose，但我在我的代码中使用它并且它工作正常。

我还修改了我的示例代码以包含.focusPointOfInterestSupported和.exposurePointOfInterestSupported测试 - 文档还提到了使用isFocusModeSupported:和isExposureModeSupported:方法进行给定的焦点/曝光模式在设置之前测试它是否在给定设备上可用，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。这一切似乎都在我的应用程序中正常工作。

Answer 2

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。

<line x1="40" y1="40" x2="100" y2="100" desc="directional line" />
<line x1="54.1" y1="54.1" x2="85.9" y2="85.9" desc="actual part of line" />

Answer 3

 device.focusPointOfInterest = focusPoint
 device.focusMode = AVCaptureFocusMode.AutoFocus
 device.exposurePointOfInterest = focusPoint
 device.exposureMode = AVCaptureExposureMode.ContinuousAutoExposure

我不知道为什么会这样，但确实如此。

Answer 4

设置焦点的更好方法是：

首先计算兴趣点：

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

之后设置了焦点：

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)
    }

Answer 5

您应该在focusPointOfInterest上阅读Apple docs，其中包含三个重要内容：

为此属性设置值不会启动聚焦操作。要将相机对焦于感兴趣的点，请先设置此属性的值，然后将focusMode属性设置为autoFocus或continuousAutoFocus。



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。无论实际的设备方向如何，此坐标系始终相对于横向设备方向，主菜单按钮位于右侧。您可以使用AVCaptureVideoPreviewLayer方法在此坐标系和视图坐标之间进行转换。



在更改此属性的值之前，必须调用lockForConfiguration（）以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。完成配置设备后，请调用unlockForConfiguration（）以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)
    }
}

Answer 6

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设置关注点，否则焦点将在之前的兴趣点上进行。

同样适用于exposurePointOfInterest。

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6 个答案: