> REQ Swift refactor / code layout / review - swift

Question

I have made a mess of my translation from Obj-C to Swift so I'd really appreciate a refactor/code layout review. The curly braces are really throwing me. Are there any Xcode plugins or something to help me better manage my code blocks?
Some of my functions and calculations may not be so efficient as well so if you have any suggestions for those areas that would be great too. For example if you have used or seen better filter algorithms etc.
p.s. thanks Martin.
import UIKit
import Foundation
import AVFoundation
import CoreMedia
import CoreVideo
let minFramesForFilterToSettle = 10
class ViewController: UIViewController, AVCaptureVideoDataOutputSampleBufferDelegate {
let captureSession = AVCaptureSession()
// If we find a device we'll store it here for later use
var captureDevice : AVCaptureDevice?
var validFrameCounter: Int = 0
var detector: Detector!
var filter: Filter!
// var currentState = CurrentState.stateSampling // Is this initialized correctly?
override func viewDidLoad() {
super.viewDidLoad()
self.detector = Detector()
self.filter = Filter()
// startCameraCapture() // call to un-used function.
captureSession.sessionPreset = AVCaptureSessionPresetHigh
let devices = AVCaptureDevice.devices()
// Loop through all the capture devices on this phone
for device in devices {
// Make sure this particular device supports video
if (device.hasMediaType(AVMediaTypeVideo)) {
// Finally check the position and confirm we've got the back camera
if(device.position == AVCaptureDevicePosition.Front) {
captureDevice = device as? AVCaptureDevice
if captureDevice != nil {
//println("Capture device found")
beginSession()
}
}
}
}
} // end of viewDidLoad ???
// configure device for camera and focus mode // maybe not needed since we dont use focuc?
func configureDevice() {
if let device = captureDevice {
device.lockForConfiguration(nil)
//device.focusMode = .Locked
device.unlockForConfiguration()
}
}
// start capturing frames
func beginSession() {
// Create the AVCapture Session
configureDevice()
var err : NSError? = nil
captureSession.addInput(AVCaptureDeviceInput(device: captureDevice, error: &err))
if err != nil {
println("error: \(err?.localizedDescription)")
}
// Automatic Switch ON torch mode
if captureDevice!.hasTorch {
// lock your device for configuration
captureDevice!.lockForConfiguration(nil)
// check if your torchMode is on or off. If on turns it off otherwise turns it on
captureDevice!.torchMode = captureDevice!.torchActive ? AVCaptureTorchMode.Off : AVCaptureTorchMode.On
// sets the torch intensity to 100%
captureDevice!.setTorchModeOnWithLevel(1.0, error: nil)
// unlock your device
captureDevice!.unlockForConfiguration()
}
// Create a AVCaptureInput with the camera device
var deviceInput : AVCaptureInput = AVCaptureDeviceInput.deviceInputWithDevice(captureDevice, error: &err) as! AVCaptureInput
if deviceInput == nil! {
println("error: \(err?.localizedDescription)")
}
// Set the output
var videoOutput : AVCaptureVideoDataOutput = AVCaptureVideoDataOutput()
// create a queue to run the capture on
var captureQueue : dispatch_queue_t = dispatch_queue_create("captureQueue", nil)
// setup ourself up as the capture delegate
videoOutput.setSampleBufferDelegate(self, queue: captureQueue)
// configure the pixel format
videoOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as String : Int(kCVPixelFormatType_32BGRA)] // kCVPixelBufferPixelFormatTypeKey is a CFString btw.
// set the minimum acceptable frame rate to 10 fps
captureDevice!.activeVideoMinFrameDuration = CMTimeMake(1, 10)
// and the size of the frames we want - we'll use the smallest frame size available
captureSession.sessionPreset = AVCaptureSessionPresetLow
// Add the input and output
captureSession.addInput(deviceInput)
captureSession.addOutput(videoOutput)
// Start the session
captureSession.startRunning()
// we're now sampling from the camera
enum CurrentState {
case statePaused
case stateSampling
}
var currentState = CurrentState.statePaused
func setState(state: CurrentState){
switch state
{
case .statePaused:
// what goes here? Something like this?
UIApplication.sharedApplication().idleTimerDisabled = false
case .stateSampling:
// what goes here? Something like this?
UIApplication.sharedApplication().idleTimerDisabled = true // singletons
}
}
// we're now sampling from the camera
currentState = CurrentState.stateSampling
// stop the app from sleeping
UIApplication.sharedApplication().idleTimerDisabled = true
// update our UI on a timer every 0.1 seconds
NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: Selector("update"), userInfo: nil, repeats: true)
func stopCameraCapture() {
captureSession.stopRunning()
captureSession = nil
}
// pragma mark Pause and Resume of detection
func pause() {
if currentState == CurrentState.statePaused {
return
}
// switch off the torch
if captureDevice!.isTorchModeSupported(AVCaptureTorchMode.On) {
captureDevice!.lockForConfiguration(nil)
captureDevice!.torchMode = AVCaptureTorchMode.Off
captureDevice!.unlockForConfiguration()
}
currentState = CurrentState.statePaused
// let the application go to sleep if the phone is idle
UIApplication.sharedApplication().idleTimerDisabled = false
}
func resume() {
if currentState != CurrentState.statePaused {
return
}
// switch on the torch
if captureDevice!.isTorchModeSupported(AVCaptureTorchMode.On) {
captureDevice!.lockForConfiguration(nil)
captureDevice!.torchMode = AVCaptureTorchMode.On
captureDevice!.unlockForConfiguration()
}
currentState = CurrentState.stateSampling
// stop the app from sleeping
UIApplication.sharedApplication().idleTimerDisabled = true
}
// beginning of paste
// r,g,b values are from 0 to 1 // h = [0,360], s = [0,1], v = [0,1]
// if s == 0, then h = -1 (undefined)
func RGBtoHSV(r : Float, g : Float, b : Float, inout h : Float, inout s : Float, inout v : Float) {
let rgbMin = min(r, g, b)
let rgbMax = max(r, g, b)
let delta = rgbMax - rgbMin
v = rgbMax
s = delta/rgbMax
h = Float(0.0)
// start of calculation
if (rgbMax != 0) {
s = delta / rgbMax
}
else{
// r = g = b = 0
s = 0
h = -1
return
}
if r == rgbMax {
h = (g - b) / delta
}
else if (g == rgbMax) {
h = 2 + (b - r ) / delta
}
else{
h = 4 + (r - g) / delta
h = 60
}
if (h < 0) {
h += 360
}
}
// process the frame of video
func captureOutput(captureOutput:AVCaptureOutput, didOutputSampleBuffer sampleBuffer:CMSampleBuffer, fromConnection connection:AVCaptureConnection) {
// if we're paused don't do anything
if currentState == CurrentState.statePaused {
// reset our frame counter
self.validFrameCounter = 0
return
}
// this is the image buffer
var cvimgRef:CVImageBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer)
// Lock the image buffer
CVPixelBufferLockBaseAddress(cvimgRef, 0)
// access the data
var width: size_t = CVPixelBufferGetWidth(cvimgRef)
var height:size_t = CVPixelBufferGetHeight(cvimgRef)
// get the raw image bytes
let buf = UnsafeMutablePointer<UInt8>(CVPixelBufferGetBaseAddress(cvimgRef))
var bprow: size_t = CVPixelBufferGetBytesPerRow(cvimgRef)
var r = 0
var g = 0
var b = 0
for var y = 0; y < height; y++ {
for var x = 0; x < width * 4; x += 4 {
b+=buf[x](UnsafeMutablePointer(UInt8)) // fix
g+=buf[x + 1](UnsafeMutablePointer(Float)) // fix
r+=buf[x + 2](UnsafeMutablePointer(Int)) // fix
}
buf += bprow()
}
r /= 255 * (width*height)
g /= 255 * (width*height)
b /= 255 * (width*height)
}
// convert from rgb to hsv colourspace
var h = Float()
var s = Float()
var v = Float()
RGBtoHSV(r, g, b, &h, &s, &v)
// do a sanity check for blackness
if s > 0.5 && v > 0.5 {
// increment the valid frame count
validFrameCounter++
// filter the hue value - the filter is a simple band pass filter that removes any DC component and any high frequency noise
var filtered: Float = filter.processValue(h)
// have we collected enough frames for the filter to settle?
if validFrameCounter > minFramesForFilterToSettle {
// add the new value to the detector
detector.addNewValue(filtered, atTime: CACurrentMediaTime())
}
} else {
validFrameCounter = 0
// clear the detector - we only really need to do this once, just before we start adding valid samples
detector.reset()
}
}

Answer 1

You can actually do that
RGBtoHSV(r: r, g: g, b: b, h: &h, s: &s, v: &v)