o2oa-ios/O2Platform/Extension/UIImageView+Extension.swift

//
//  UIImageView+Extension.swift
//  O2Platform
//
//  Created by FancyLou on 2019/10/30.
//  Copyright © 2019 zoneland. All rights reserved.
//

import UIKit


extension UIImageView {
    
    func o2AspectToFitFrame() -> CGRect {

        guard let image = image else {
            assertionFailure("No image found!")
            return CGRect.zero
        }
        
        let imageRatio: CGFloat = image.size.width / image.size.height
        let viewRatio: CGFloat = frame.size.width / frame.size.height
        
        if imageRatio < viewRatio {
            let scale: CGFloat = frame.size.height / image.size.height
            let width: CGFloat = scale * image.size.width
            let topLeftX: CGFloat = (frame.size.width - width) * 0.5
            return CGRect(x: topLeftX, y: 0, width: width, height: frame.size.height)
        } else {
            let scale: CGFloat = frame.size.width / image.size.width
            let height: CGFloat = scale * image.size.height
            let topLeftY: CGFloat = (frame.size.height - height) * 0.5
            return CGRect(x: 0, y: topLeftY, width: frame.size.width, height: height)
        }
    }
}