Main view for the Tomtelizer written in RubyMotion

tomtelizer_view_controller.rb

# Main controller for the Tomtelizer
#
class TomtelizerViewController < UIViewController

  # Load the view
  #
  def loadView
    self.view = UIImageView.alloc.init
    @debug_face = false
  end

  def viewDidLoad
    @images = %w{matz guido jmccolor}.reverse.map { |name|
      UIImage.imageNamed "#{name}.jpg"
    }

    view.image = @images.first
    view.contentMode = UIViewContentModeScaleAspectFit
    view.userInteractionEnabled = true

    add_gesture('swipe_previous:', UISwipeGestureRecognizerDirectionLeft)
    add_gesture('swipe_next:', UISwipeGestureRecognizerDirectionRight)
  end

  def add_gesture(action, direction)
    gesture = UISwipeGestureRecognizer.alloc.
      initWithTarget(self, action: action)
    gesture.direction = direction
    view.addGestureRecognizer(gesture)
  end

  def viewDidAppear(animated)
    hatify
  end

  def hatify
    # Remove previous hats.
    view.subviews.each { |v| v.removeFromSuperview }

    # CoreImage used a coordinate system which is flipped on the Y axis
    # compared to UIKit. Also, a UIImageView can return an image larger than
    # itself. To properly translate points, we use an affine transform.
    transform = CGAffineTransformMakeScale(view.bounds.size.width / view.image.size.width, -1 * (view.bounds.size.height / view.image.size.height))
    transform = CGAffineTransformTranslate(transform, 0, -view.image.size.height)

    image = CIImage.imageWithCGImage(view.image.CGImage)
    @detector ||= CIDetector.detectorOfType CIDetectorTypeFace, context:nil, options: { CIDetectorAccuracy: CIDetectorAccuracyHigh }
    @detector.featuresInImage(image).each do |feature|
      # We need the mouth and eyes positions to determine
      # where the hat should be added.
      next unless feature.hasMouthPosition    \
              and feature.hasLeftEyePosition  \
              and feature.hasRightEyePosition

      # Create the tomtelizer view.
      hatView = UIImageView.alloc.init
      hatView.image = UIImage.imageNamed('santa-hat.png')
      hatView.contentMode = UIViewContentModeScaleAspectFit

      # Compute its location and size, based on the position of the eyes and
      # mouth.
      w = feature.bounds.size.width * 1.6
      h = feature.bounds.size.height * 1.2
      x = (feature.mouthPosition.x + (feature.leftEyePosition.x + feature.rightEyePosition.x) / 2) / 2 - w / 2
      y = ((feature.rightEyePosition.y + feature.leftEyePosition.y) / 2) - w/11

      hatView.frame = CGRectApplyAffineTransform([[x, y], [w, h]], transform)

      # Apply a rotation on the hat, based on the face inclination.
      hatAngle = Math.atan2(feature.leftEyePosition.x -
                            feature.rightEyePosition.x,
                            feature.leftEyePosition.y -
                            feature.rightEyePosition.y) + Math::PI/2

      hatView.transform = CGAffineTransformMakeRotation(hatAngle)

      view.addSubview(hatView)
    end
  end

  def swipe_previous(gesture)
    idx = @images.index(view.image)
    view.image = (idx == 0) ? @images.last : @images[idx-1]
    hatify
  end

  def swipe_next(gesture)
    idx = @images.index(view.image)
    view.image = (idx == @images.size - 1) ? @images.first : @images[idx + 1]
    hatify
  end
end