Auto Focus and Auto Exposure in AVFoundation on Cu

问题:

What is the best way to create an accurate Auto Focus and Exposure for AVFoundation custom layer camera?, for example, currently my camera preview layer is square, I would like the camera focus and exposure to be specify to that frame bound. I need this in Swift 2 if possible, if not please write your answer I would be able to convert it myself.

Current Auto Focus and Exposure: But as you can see this will evaluate the entire view when focusing.

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    //Get Touch Point
    let Point = touches.first!.locationInView(self.capture)
    //Assign Auto Focus and Auto Exposour
    if let device = currentCameraInput {
        do {
            try! device.lockForConfiguration()
            if device.focusPointOfInterestSupported{
                //Add Focus on Point
                device.focusPointOfInterest = Point
                device.focusMode = AVCaptureFocusMode.AutoFocus
            }

            if device.exposurePointOfInterestSupported{
                //Add Exposure on Point
                device.exposurePointOfInterest = Point
                device.exposureMode = AVCaptureExposureMode.AutoExpose
            }
            device.unlockForConfiguration()
        }
    }
}

Camera Layer: Anything in the 1:1 ratio should be considered as focus and exposure point, and anything outside this bound would not even be considered as a touch event for camera focus.

回答1:

 public func captureDevicePointOfInterestForPoint(pointInLayer: CGPoint) -> CGPoint

will give you the point for the device to focus on based on the settings of your AVCaptureVideoPreviewLayer. See the docs.

回答2:

Thanks to JLW here is how you do it in Swift 2. First, we need to setup Tap gesture you can do this programmatically or Storyboard.

    //Add UITap Gesture Capture Frame for Focus and Exposure
    let captureTapGesture: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: "AutoFocusGesture:")
    captureTapGesture.numberOfTapsRequired = 1
    captureTapGesture.numberOfTouchesRequired = 1
    self.captureFrame.addGestureRecognizer(captureTapGesture)

Create a function base on our selector in captureTapGesture.

/*=========================================
* FOCUS & EXPOSOUR
==========================================*/
var animateActivity: Bool!
internal func AutoFocusGesture(RecognizeGesture: UITapGestureRecognizer){
    let touchPoint: CGPoint = RecognizeGesture.locationInView(self.captureFrame)
    //GET PREVIEW LAYER POINT
    let convertedPoint = self.previewLayer.captureDevicePointOfInterestForPoint(touchPoint)

    //Assign Auto Focus and Auto Exposour
    if let device = currentCameraInput {
        do {
            try! device.lockForConfiguration()
            if device.focusPointOfInterestSupported{
                //Add Focus on Point
                device.focusPointOfInterest = convertedPoint
                device.focusMode = AVCaptureFocusMode.AutoFocus
            }

            if device.exposurePointOfInterestSupported{
                //Add Exposure on Point
                device.exposurePointOfInterest = convertedPoint
                device.exposureMode = AVCaptureExposureMode.AutoExpose
            }
            device.unlockForConfiguration()
        }
    }
}

Also, if you like to use your animation indicator, please use touchPoint at your touch of an event and assign it to your animated layer.

//Assign Indicator Position
touchIndicatorOutside.frame.origin.x = touchPoint.x - 10
touchIndicatorOutside.frame.origin.y = touchPoint.y - 10