run with "macruby face_detector.rb" or "macruby face_detector.rb https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/304055_10150415385415891_522505890_10347873_1682210515_n.jpg?dl=1" for a photo of me with woody and buzz lightyear :p

face_detector.rb

framework 'Cocoa'

class NSColor
	def toCGColor
		color_RGB = colorUsingColorSpaceName(NSCalibratedRGBColorSpace)
		## approach #1
		# components = Array.new(4){Pointer.new(:double)}
		# color_RGB.getRed(components[0],
		#                 green: components[1],
		#                 blue: components[2],
		#                 alpha:components[3])
		# components.collect!{|x| x[0] }
		# approach #2
		components = [redComponent, greenComponent, blueComponent, alphaComponent]

		color_space = CGColorSpaceCreateWithName(KCGColorSpaceGenericRGB)
		color = CGColorCreate(color_space, components)
		CGColorSpaceRelease(color_space)
		color
	end
end

# NSVIew set background color & and set center
class NSView

	# set background like on IOS
	def background_color=(color)
		viewLayer = CALayer.layer
		viewLayer.backgroundColor = color.toCGColor
		self.wantsLayer = true # // view's backing store is using a Core Animation Layer
		self.layer = viewLayer
	end

	# helper to set nsview center like on IOS
	def center= (point)
		self.frameOrigin = [point.x-(self.frame.size.width/2), point.y-(self.frame.size.height/2)]
		self.needsDisplay = true
	end
end

# NSImage to CGImage
class NSImage
	def to_CGImage
		source = CGImageSourceCreateWithData(self.TIFFRepresentation, nil)
		maskRef = CGImageSourceCreateImageAtIndex(source, 0, nil)
	end
end

class FaceDetectionDelegate
	attr_accessor :window

	def initWithURL(url)
		case url
		when String
			@photo_url = NSURL.URLWithString(url)
		when NSURL
			@photo_url = url
		else
			raise "The FaceDetectionDelegate class was initiated with an unknown type object"
		end
		self
	end

	def applicationDidFinishLaunching(aNotification)
		window.delegate = self
		puts "Fetching and loading the image #{@photo_url.absoluteString}"
		image = NSImage.alloc.initWithContentsOfURL @photo_url
		@mustache = NSImage.alloc.initWithContentsOfURL NSURL.URLWithString("http://dl.dropbox.com/u/349788/mustache.png")
		@hat = NSImage.alloc.initWithContentsOfURL NSURL.URLWithString("http://dl.dropbox.com/u/349788/hat.png")
		@glasses = NSImage.alloc.initWithContentsOfURL NSURL.URLWithString("http://dl.dropbox.com/u/349788/glasses.png")

		# Helpers to set the NSImageView size
		bitmap = NSBitmapImageRep.imageRepWithData image.TIFFRepresentation
		puts "image size: w=#{bitmap.pixelsWide}, h=#{bitmap.pixelsHigh}" if bitmap

		imageView = NSImageView.alloc.init
		imageView.image = image
		imageView.wantsLayer = true
		imageView.imageScaling = NSImageScaleProportionallyUpOrDown
		imageView.layer.affineTransform = CGAffineTransformMakeScale(-1, 1)
		imageView.imageFrameStyle = NSImageFramePhoto

		window.setFrame([0.0, 0.0, (bitmap.pixelsWide+20), (bitmap.pixelsHigh+20)], display:true, animate:true)
		window.center

		window.contentView.wantsLayer = true
		window.contentView.layer.affineTransform = CGAffineTransformMakeScale(1, 1)

		imageView.frame = CGRectMake(0.0, 0.0, bitmap.pixelsWide, bitmap.pixelsHigh)
		window.contentView.addSubview(imageView)
		detect_faces
		window.orderFrontRegardless
	end


	def detect_faces
		ciImage = CIImage.imageWithCGImage window.contentView.subviews.last.image.to_CGImage
		detectorOptions = {CIDetectorAccuracy: CIDetectorAccuracyHigh }
		detector = CIDetector.detectorOfType "CIDetectorTypeFace", context:nil, options:detectorOptions
		features = detector.featuresInImage(ciImage)
		features.each do |feature|
			face = NSView.alloc.initWithFrame feature.bounds
			face.background_color = NSColor.yellowColor.colorWithAlphaComponent(0.4)
			#			window.contentView.addSubview(face)

			if(feature.hasLeftEyePosition)
				left_eye = NSView.alloc.initWithFrame CGRectMake(0, 0, 5, 5)
				left_eye.background_color = NSColor.blueColor.colorWithAlphaComponent(0.2)
				left_eye.center = feature.leftEyePosition
				#				window.contentView.addSubview(left_eye)
			end

			if(feature.hasRightEyePosition)
				right_eye = NSView.alloc.initWithFrame CGRectMake(0, 0, 5, 5)
				right_eye.background_color = NSColor.redColor.colorWithAlphaComponent(0.2)
				right_eye.center = feature.rightEyePosition
				#				window.contentView.addSubview(right_eye)
			end

			if(feature.hasMouthPosition)
				mouth = NSView.alloc.initWithFrame CGRectMake(0, 0, 10, 5)
				mouth.background_color = NSColor.greenColor.colorWithAlphaComponent(0.2)
				mouth.center = feature.mouthPosition
				#				window.contentView.addSubview(mouth)
			end

			if (feature.hasMouthPosition and feature.hasLeftEyePosition and feature.hasRightEyePosition)

				#mustache
				mustacheView = NSImageView.alloc.init
				mustacheView.image = @mustache
				mustacheView.imageFrameStyle = NSImageFrameNone
				mustacheView.imageScaling = NSScaleProportionally

				w = feature.bounds.size.width
				h = feature.bounds.size.height/5
				x = (feature.mouthPosition.x + (feature.leftEyePosition.x + feature.rightEyePosition.x)/2)/2 - w/2
				y = feature.mouthPosition.y
				mustacheView.frame = NSMakeRect(x, y, w, h)
				mustacheView.frameCenterRotation = Math.atan2(feature.rightEyePosition.y-feature.leftEyePosition.y,feature.rightEyePosition.x-feature.leftEyePosition.x)*180/Math::PI

				window.contentView.addSubview(mustacheView)

				hatView = NSImageView.alloc.init
				hatView.image = @hat
				hatView.imageFrameStyle = NSImageFrameNone
				hatView.imageScaling = NSScaleProportionally

				#hat
				w = feature.bounds.size.width*5/4
				h = feature.bounds.size.height*5/4
				x = (feature.rightEyePosition.x + feature.leftEyePosition.x + feature.mouthPosition.x)/3 - w/2
				y = (feature.rightEyePosition.y + feature.leftEyePosition.y)/2 - h/7
				hatView.frame = NSMakeRect(x, y, w, h)
				hatView.frameCenterRotation = 25 + Math.atan2(feature.rightEyePosition.y-feature.leftEyePosition.y,feature.rightEyePosition.x-feature.leftEyePosition.x)*180/Math::PI

				window.contentView.addSubview(hatView)

				#glasses
				glassesView = NSImageView.alloc.init
				glassesView.image = @glasses
				glassesView.imageFrameStyle = NSImageFrameNone
				glassesView.imageScaling = NSScaleProportionally

				w = feature.bounds.size.width
				h = feature.bounds.size.height/2
				x = (feature.rightEyePosition.x + feature.leftEyePosition.x)/2 - w/2
				y = (feature.rightEyePosition.y + feature.leftEyePosition.y)/2 - h/2
				glassesView.frame = NSMakeRect(x, y, w, h)
				glassesView.frameCenterRotation = Math.atan2(feature.rightEyePosition.y-feature.leftEyePosition.y,feature.rightEyePosition.x-feature.leftEyePosition.x)*180/Math::PI

				window.contentView.addSubview(glassesView)

			end
		end
	end

	def windowWillClose(sender); exit(1); end

end

# Create the Application
application = NSApplication.sharedApplication
NSApplication.sharedApplication.activationPolicy = NSApplicationActivationPolicyRegular
application.delegate = FaceDetectionDelegate.alloc.initWithURL(ARGV.shift || "http://merbist.com/wp-content/uploads/2010/03/matz_koichi_matt_aimonetti_sansonetti_jimmy.jpg")

# create the Application Window
frame = [0.0, 0.0, 330, 250]
window = NSWindow.alloc.initWithContentRect frame,
styleMask: NSTitledWindowMask | NSClosableWindowMask,
backing: NSBackingStoreBuffered,
defer: false

application.delegate.window = window
window.orderOut(nil)
window.display
puts "Starting the app..."
application.run