CIImageView (Using Metal)

MTKCIImageView.swift

  //
//  MTKCIImageView.swift
//  Fil
//
//  Created by Muukii on 9/27/15.
//  Copyright © 2015 muukii. All rights reserved.
//

import Foundation
import Metal
import MetalKit
class MTKCIImageView: MTKView {
    
    var image: CIImage? {
        didSet {
            self.draw()
        }
    }
    
    var originalImageExtent: CGRect = CGRect.zero {
        didSet {
            
        }
    }
    
    var scale: CGFloat {
                
        return max(self.frame.width / originalImageExtent.width, self.frame.height / originalImageExtent.height)
    }
    
    func update() {
    
        guard let img = image where destRect.size.width <= img.extent.size.width && destRect.size.height <= img.extent.size.height else {
            return
        }
        
        self.draw()
    }
    
    let context: CIContext
    let commandQueue: MTLCommandQueue
    
    convenience init(frame: CGRect) {
        let device = MTLCreateSystemDefaultDevice()
        self.init(frame: frame, device: device)
    }
    
    override init(frame frameRect: CGRect, device: MTLDevice?) {
        guard let device = device else {
            fatalError("Can't use Metal")
        }
        commandQueue = device.newCommandQueueWithMaxCommandBufferCount(5)
        context = CIContext(MTLDevice: device, options: [kCIContextUseSoftwareRenderer:false])
        super.init(frame: frameRect, device: device)
        
        self.framebufferOnly = false
        self.enableSetNeedsDisplay = false
        self.paused = true
        self.clearColor = MTLClearColor(red: 0, green: 0, blue: 0, alpha: 0)
    }
    
    required init(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func drawRect(rect: CGRect) {
        
        JEDump(rect, "Draw Use Metal")
       
        
        guard let image = self.image else {
            return
        }
        
        let dRect = destRect
        
        let drawImage: CIImage
        
        if dRect == image.extent {
            drawImage = image
        } else {
            let scale = max(dRect.height / image.extent.height, dRect.width / image.extent.width)
            drawImage = image.imageByApplyingTransform(CGAffineTransformMakeScale(scale, scale))
        }
        
        let commandBuffer = commandQueue.commandBufferWithUnretainedReferences()
        guard let texture = self.currentDrawable?.texture else {
            return
        }
        guard let colorSpace = drawImage.colorSpace ?? CGColorSpaceCreateDeviceRGB() else {
            return
        }
        
        context.render(drawImage, toMTLTexture: texture, commandBuffer: commandBuffer, bounds: dRect, colorSpace: colorSpace)
        
        commandBuffer.presentDrawable(self.currentDrawable!)
        commandBuffer.commit()
    }
    
    private var destRect: CGRect {
        
        let scale: CGFloat
        if UIScreen.mainScreen().scale == 3 {
            // BUG?
            scale = 2.0 * (2.0 / UIScreen.mainScreen().scale) * 2
        } else {
            scale = UIScreen.mainScreen().scale
        }
        let destRect = CGRectApplyAffineTransform(self.bounds, CGAffineTransformMakeScale(scale, scale))
        
        return destRect
    }
}

Hi, i get orientation and flip issue in simulator. same like: https://stackoverflow.com/questions/60164536/flipped-picture-after-render-in-metal

Any solution?