Drawing images with CGContext and NSGraphicsContext in Swift

cocoa-drawing.swift

//: Playground - noun: a place where people can play

import Cocoa

let bounds = CGRectMake(0, 0, 100, 100);

func DrawImageInCGContext(size: CGSize, drawFunc: (context: CGContextRef, rect: CGRect) -> Void) -> NSImage? {
    let colorSpace = CGColorSpaceCreateDeviceRGB()
    let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.PremultipliedLast.rawValue)
    if let context = CGBitmapContextCreate(
        nil,
        Int(size.width),
        Int(size.height),
        8,
        0,
        colorSpace,
        bitmapInfo.rawValue) {
            drawFunc(context: context, rect: CGRect(origin: CGPoint.zero, size: size))
            if let image = CGBitmapContextCreateImage(context) {
                return NSImage(CGImage: image, size: size)
            }
            
    }
    return nil
}

func DrawImageInNSGraphicsContext(size: CGSize, drawFunc: (rect: CGRect) -> Void) -> NSImage? {
    guard let rep = NSBitmapImageRep(
        bitmapDataPlanes: nil,
        pixelsWide: Int(size.width),
        pixelsHigh: Int(size.height),
        bitsPerSample: 8,
        samplesPerPixel: 4,
        hasAlpha: true,
        isPlanar: false,
        colorSpaceName: NSCalibratedRGBColorSpace,
        bytesPerRow: 0,
        bitsPerPixel: 0) else {
            return nil
    }
    
    let context = NSGraphicsContext(bitmapImageRep: rep)
    
    NSGraphicsContext.saveGraphicsState()
    NSGraphicsContext.setCurrentContext(context)
    
    drawFunc(rect: CGRect(origin: CGPoint.zero, size: size))
    
    NSGraphicsContext.restoreGraphicsState()
    
    let image = NSImage(size: size)
    image.addRepresentation(rep)
    
    return image
}


let rect = CGRectMake(0, 0, 100, 20)

let image1 = DrawImageInCGContext(size: rect.size) { context, rect in
    CGContextSetFillColorWithColor(context, NSColor.redColor().CGColor)
    CGContextFillRect(context, rect);
}

let image2 = DrawImageInNSGraphicsContext(size: rect.size) { rect in
    NSColor.blueColor().set()
    NSRectFill(rect)
}