Cropping image

import UIKit

class AdvancedCroppingViewController: UIViewController {
    var imageContainer:UIView!
    var image:UIImage!
    var topImage:UIImage!
    var imageView:ZoomRotatePanImageView!
    var topImageView:UIImageView!
    var fillerView1:UIView!
    var fillerView2:UIView!
    var centerPoint:CGPoint!
    var tw:CGFloat!
    var th:CGFloat!
    var tx:CGFloat!
    var ty:CGFloat!
    var iw:CGFloat!
    var ih:CGFloat!
    var ix:CGFloat!
    var iy:CGFloat!
    var iratio:CGFloat!

    override func viewDidLoad() {
        super.viewDidLoad()
        loadImages()
    }

    func loadImages(){
        topImage = UIImage(named: topImageName)
        topImageView = UIImageView(image: topImage)
        imageView = ZoomRotatePanImageView(image: image)

        let w = self.view.frame.width
        let h = self.view.frame.height

        //TOP IMAGE

        let ratioW:CGFloat = w / topImage.size.width
        let ratioH:CGFloat = h / topImage.size.height
        let ratio:CGFloat = ratioW < ratioH ? ratioW : ratioH //Aspect Fit

        tw = topImage.size.width * ratio
        th = topImage.size.height * ratio
        tx = (w - tw) / 2.0
        ty = (h - th) / 2.0

        topImageView.frame = CGRectMake(tx, ty, tw, th)

        //FILLER VIEWS

        if(tx > 0){
            fillerView1 = UIView(frame: CGRectMake(0, 0, tx, th))
            fillerView2 = UIView(frame: CGRectMake(w - tx, 0, tx, th))
        }
        else{
            fillerView1 = UIView(frame: CGRectMake(0, 0, w, ty))
            fillerView2 = UIView(frame: CGRectMake(0, h - ty, w, ty))
        }

        fillerView1.backgroundColor = UIColor.whiteColor()
        fillerView2.backgroundColor = UIColor.whiteColor()

        //IMAGE

        imageContainer = UIView(frame: CGRectMake(0, 0, w, h))
        imageContainer.backgroundColor = UIColor.whiteColor()

        let iratioW:CGFloat = w / image.size.width
        let iratioH:CGFloat = h / image.size.height
        iratio = iratioW > iratioH ? iratioW : iratioH //Aspect Fill

        iw = image.size.width * iratio
        ih = image.size.height * iratio
        ix = (w - iw) / 2.0
        iy = (h - ih) / 2.0

        imageView.frame = CGRectMake(ix, iy, iw, ih)

        centerPoint = imageView.center

        imageContainer.addSubview(imageView)
        self.view.addSubview(imageContainer)
        self.view.addSubview(topImageView)
        self.view.addSubview(fillerView1)
        self.view.addSubview(fillerView2)

        print("Loaded image size: \(image.size)")
    }

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        let boundsScale = imageView.bounds.size.width / imageView.bounds.size.height
        let imageScale = image!.size.width / image!.size.height

        let size = (image?.size)!

        var canvasSize = size

        if boundsScale > imageScale {
            canvasSize.width =  canvasSize.height * boundsScale
        }
        else{
            canvasSize.height =  canvasSize.width / boundsScale
        }

        let xScale = canvasSize.width / imageView.bounds.width
        let yScale = canvasSize.height / imageView.bounds.height

        let center = CGPointApplyAffineTransform(imageView.center, CGAffineTransformScale(CGAffineTransformIdentity, xScale, yScale))

        let xCenter = center.x
        let yCenter = center.y

        UIGraphicsBeginImageContextWithOptions(canvasSize, false, 0);
        let context = UIGraphicsGetCurrentContext()!

        //Apply transformation
        CGContextTranslateCTM(context, xCenter, yCenter)

        CGContextConcatCTM(context, imageView.transform)

        CGContextTranslateCTM(context, -xCenter, -yCenter)

        var drawingRect : CGRect = CGRectZero
        drawingRect.size = canvasSize

        //Transaltion
        drawingRect.origin.x = (xCenter - size.width*0.5)
        drawingRect.origin.y = (yCenter - size.height*0.5)

        //Aspectfit calculation
        if boundsScale > imageScale {
            drawingRect.size.width =  drawingRect.size.height * imageScale
        }else{
            drawingRect.size.height = drawingRect.size.width / imageScale
        }

        image!.drawInRect(drawingRect)

        let preview = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        let previewVC = segue.destinationViewController as! PreviewViewController
        previewVC.preview = preview

//OLD METHOD

//        UIGraphicsBeginImageContextWithOptions(imageContainer.bounds.size, false, 0)
//        self.imageContainer.drawViewHierarchyInRect(imageContainer.bounds, afterScreenUpdates: true)
//        let screenshot = UIGraphicsGetImageFromCurrentImageContext()!
//        UIGraphicsEndImageContext()

//        let cropRect = CGRectMake(tx, ty, tw, th)
//        let preview = getSubImageFrom(screenshot, rect: cropRect)
//        let previewVC = segue.destinationViewController as! PreviewViewController
//        previewVC.preview = preview
    }

    func getSubImageFrom(img:UIImage!, rect:CGRect) -> UIImage! {
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()
        let drawRect = CGRectMake(-rect.origin.x, -rect.origin.y, img.size.width, img.size.height)
        CGContextClipToRect(context, CGRectMake(0, 0, rect.size.width, rect.size.height))
        img.drawInRect(drawRect)
        let subImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return subImage
    }

}