test.swift

/*____  ___ 
 / ___)/ __)
 \___ ( (_ \
 (____/\___/
 */

import CoreGraphics
import PlaygroundSupport
import UIKit
import Foundation

let imageView = UIImageView()
imageView.contentMode = .scaleAspectFit
imageView.autoresizingMask = [ .flexibleHeight, .flexibleWidth]
imageView.layer.magnificationFilter = kCAFilterNearest

PlaygroundPage.current.liveView = imageView

let width = 128
let height = 196
var buffer : [UInt32] = Array(repeating: 0, count: width*height)

let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedFirst.rawValue | CGBitmapInfo.byteOrder32Little.rawValue)
let bmp: UnsafeMutablePointer<UInt32> = UnsafeMutablePointer(mutating: buffer)
let context = CGContext(data: bmp, width: width, height: height, bitsPerComponent: 8,
                        bytesPerRow: width*4, space: CGColorSpace(name: CGColorSpace.genericRGBLinear)!, bitmapInfo: bitmapInfo.rawValue)

var xpos = 0
var direction = 1

    func renderBuffer()
    {
        memset(bmp, 0, width*height*4)
        var xpos2 = xpos+32
        
        for y in 0 ..< height {
            for x in xpos ..< xpos2 {
                buffer[y*width+x] = UInt32(0xff<<24 + (x%255)<<16 + (y%255)<<8 + (xpos+x*y)%255)
            }
        }
        
        if (xpos2 >= width)
        {
            direction = -1
        }
        
        if (xpos <= 0)
        {
            direction = 1
        }
        
        
        xpos = xpos + direction
        
    }
    


func renderImage() -> CGImage
{
    
    var img = context?.makeImage()
    
    return img!
}

@objc class Renderer:NSObject
{
    @objc func render()
    {
        renderBuffer()
        imageView.image = UIImage(cgImage:renderImage())
    }
}

let me = Renderer()

let displayLink = CADisplayLink(target:me , selector: #selector(Renderer.render))
displayLink.preferredFramesPerSecond = 60
displayLink.add(to: RunLoop.current, forMode: .commonModes)