rotate.swift

//
//  UIImageExtensions.swift
//  Dating
//
//  Created by Erison on 1/28/16.
//  Copyright © 2016 Yuriy Berdnikov. All rights reserved.
//

import UIKit

extension UIImage {
    /**
     Rotate the UIImage by x degrees and flips it.
     
     - Parameter degrees: Degrees to rotate the image
     - Parameter flip: Bool value that flips the image. False by default
     */
    func imageRotatedByDegrees(degrees: CGFloat, flip: Bool = false) -> UIImage {
        // calculate the size of the rotated view's containing box for our drawing space
        let rotatedViewBox = UIView(frame: CGRect(origin: CGPointZero, size: size))
        let transform = CGAffineTransformMakeRotation(degrees.fromDegreesToRadians());
        rotatedViewBox.transform = transform
        let rotatedSize = rotatedViewBox.frame.size

        // Create the bitmap context
        UIGraphicsBeginImageContext(rotatedSize)
        let bitmap = UIGraphicsGetCurrentContext()

        // Move the origin to the middle of the image so we will rotate and scale around the center.
        CGContextTranslateCTM(bitmap, rotatedSize.width / 2.0, rotatedSize.height / 2.0);

        // Rotate the image context
        CGContextRotateCTM(bitmap, degrees.fromDegreesToRadians());

        // Now, draw the rotated/scaled image into the context
        var yFlip: CGFloat

        if(flip){
            yFlip = CGFloat(-1.0)
        } else {
            yFlip = CGFloat(1.0)
        }

        CGContextScaleCTM(bitmap, yFlip, -1.0)
        CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)
        CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)

        let rotatedImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return rotatedImage
    }

    /**
     Takes an image and return the .Up orientation variant of it. Ignores mirrored cases.

     - Parameter image: Image to be fliped to .Up orientation
     */
    func imageToUpOrientation() -> UIImage {
        switch self.imageOrientation {
        case .Up:
            return self
        case .Down:
            return self.imageRotatedByDegrees(180)
        case .Left:
            return self.imageRotatedByDegrees(-90)
        case .Right:
            return self.imageRotatedByDegrees(0)
        default:
            return self
        }
    }
}