GMiOS/Gasteizko Margolariak/UIImageView.swift

//
//  UIImageView.swift
//  Gasteizko Margolariak
//
//  Created by Yuji Hato on 11/3/15.
//  Copyright © 2015 Yuji Hato. All rights reserved.
//

import UIKit


extension UIImageView {
    
    func setRandomDownloadImage(width: Int, height: Int) {
        if self.image != nil {
            self.alpha = 1
            return
        }
        self.alpha = 0
        let url = NSURL(string: "https://ssl.webpack.de/lorempixel.com/\(width)/\(height)/")!
        let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
        configuration.timeoutIntervalForRequest = 15
        configuration.timeoutIntervalForResource = 15
        configuration.requestCachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalCacheData
        let session = NSURLSession(configuration: configuration)
        let task = session.dataTaskWithURL(url, completionHandler: { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
            if error != nil {
                return
            }
            
            if let response = response as? NSHTTPURLResponse {
                if response.statusCode / 100 != 2 {
                    return
                }
                if let data = data, let image = UIImage(data: data) {
                    dispatch_async(dispatch_get_main_queue(), { () -> Void in
                        self.image = image
                        UIView.animateWithDuration(0.3, animations: { () -> Void in
                            self.alpha = 1
                            }) { (finished: Bool) -> Void in
                        }
                    })
                }
            }
        })
        task.resume()
    }
    
    func clipParallaxEffect(baseImage: UIImage?, screenSize: CGSize, displayHeight: CGFloat) {
        if let baseImage = baseImage {
            if displayHeight < 0 {
                return
            }
            let aspect: CGFloat = screenSize.width / screenSize.height
            let imageSize = baseImage.size
            let imageScale: CGFloat = imageSize.height / screenSize.height
            
            let cropWidth: CGFloat = floor(aspect < 1.0 ? imageSize.width * aspect : imageSize.width)
            let cropHeight: CGFloat = floor(displayHeight * imageScale)
            
            let left: CGFloat = (imageSize.width - cropWidth) / 2
            let top: CGFloat = (imageSize.height - cropHeight) / 2
            
            let trimRect : CGRect = CGRectMake(left, top, cropWidth, cropHeight)
            self.image = baseImage.trim(trimRect: trimRect)
            self.frame = CGRectMake(0, 0, screenSize.width, displayHeight)
        }
    }
}