UIImageHelpers.swift

//
//  UIImage+Blurs.swift
//
//  Created by Nate Armstrong on 12/2/15.
//  Copyright © 2015 Nate Armstrong. All rights reserved.
//
//
//  Compression uses RBResizer: https://gist.github.com/hcatlin/180e81cd961573e3c54d

import Foundation

extension UIImage {

    //
    // returns a copy of self with a blur applied at the given rect
    //
    func blr_imageWithBlurInRect(rect: CGRect, blurRadius: CGFloat) -> UIImage? {
        // crop
        guard var copy = blr_imageByCroppingInRect(rect) else {
            return nil
        }

        // blur
        copy = UIImageEffects.imageByApplyingBlurToImage(copy, withRadius: blurRadius, tintColor: nil, saturationDeltaFactor: 1, maskImage: nil)

        // merge
        copy = blr_imageByMergingImage(copy, atPoint: rect.origin)

        return copy
    }

    //
    // returns a copy of self cropped at the given rect
    //
    func blr_imageByCroppingInRect(rect: CGRect) -> UIImage? {
        guard let imageRef = CGImageCreateWithImageInRect(self.CGImage, rect) else {
            return nil
        }
        return UIImage(CGImage: imageRef)
    }

    //
    // returns a copy of self merged with the given image at the given rect
    //
    func blr_imageByMergingImage(image: UIImage, atPoint point: CGPoint) -> UIImage {
        UIGraphicsBeginImageContext(size)

        drawAtPoint(CGPointZero)
        image.drawAtPoint(point)

        let merged = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return merged
    }

    //
    // returns a copy of self resized and compressed as NSData
    //
    func blr_compressForWeb() -> NSData {
        let resized = RBResizeImage(self, targetSize: CGSize(width: 640, height: 1136))
        return UIImageJPEGRepresentation(resized, 0.5)!
    }
}