NSView CARenderer Demo

NSView+RenderWithCARenderer.swift

extension NSView {
    func renderWithCARenderer() -> NSImage? {
        let width = Int(frame.width * 2)
        let height = Int(frame.height * 2)
        frame.origin = CGPoint(x: 0, y: 0)
        
        let descriptor = MTLTextureDescriptor.texture2DDescriptor(pixelFormat: .rgba8Unorm, width: width, height: height, mipmapped: true)
        descriptor.usage = [.shaderRead, .shaderWrite, .renderTarget]
        
        let device = MTLCreateSystemDefaultDevice()!
        let options = [CIContextOption.workingColorSpace: NSNull()]
        let context = CIContext(mtlDevice: device, options: options)
        let texture = device.makeTexture(descriptor: descriptor)!
        
        let renderer = CARenderer(mtlTexture: texture)
        renderer.layer = layer
        renderer.bounds = CGRect(x: 0, y: 0, width: width, height: height)
        renderer.layer?.transform = CGAffineTransform(scaleX: 2, y: 2)
        
        CATransaction.flush()
        
        renderer.beginFrame(atTime: .currentMediaTime)
        renderer.addUpdate(renderer.bounds)
        renderer.render()
        renderer.endFrame()
        
        let ciImage = CIImage(mtlTexture: texture)!
        let cgImage = context.createCGImage(ciImage, from: ciImage.extent)!
        let nsImage = NSImage(cgImage: cgImage, size: cgImage.size)
        
        return nsImage
    }
}