Rubymotion version of scaleAndRotate for iOS

util.rb

def scaleAndRotateImage(image)
  scaleAndRotateImage(image, maxResolution: 640)
end

def scaleAndRotateImage(image, maxResolution: maxResolution)
  imgRef = image.CGImage
  width, height = CGImageGetWidth(imgRef), CGImageGetHeight(imgRef)

  bounds = CGRectMake(0, 0, width, height)
  if (width > maxResolution || height > maxResolution)
    ratio = width/height
    if ratio > 1
      bounds.size.width = maxResolution
      bounds.size.height = (bounds.size.width / ratio).round
    else
      bounds.size.height = maxResolution
      bounds.size.width = (bounds.size.height * ratio).round
    end
  end

  scaleRatio = bounds.size.width / width
  imageSize = CGSizeMake(width, height)
  orientation = image.imageOrientation
  transformation = case orientation
  when UIImageOrientationUp then
    CGAffineTransformIdentity
  when UIImageOrientationUpMirrored then
    CGAffineTransformScale(CGAffineTransformMakeTranslation(imageSize.width, 0.0), -1.0, 0.0)
  when UIImageOrientationDown then
    CGAffineTransformRotate(CGAffineTransformMakeTranslation(imageSize.width, imageSize.height), Math::PI)
  when UIImageOrientationDownMirrored then
    CGAffineTransformScale(CGAffineTransformMakeTranslation(0.0, imageSize.height), 0.0, -1.0)
  when UIImageOrientationLeftMirrored then
    bounds = swapBounds(bounds)
    CGAffineTransformRotate(CGAffineTransformScale(CGAggineTransformMakeTranslation(imageSize.height, imageSize.width), 0.0, imageSize.width), 3.0 * Math::PI / 2.0)
  when UIImageOrientationLeft then
    bounds = swapBounds(bounds)
    CGAffineTransformRotate(CGAffineTransformMakeTranslation(0.0, imageSize.width), 3.0 * Math::PI / 2.0)
  when UIImageOrientationRightMirrored then
    bounds = swapBounds(bounds)
    CGAffineTransformRotate(CGAffineTransformMakeScale(-1.0, 1.0), Math::PI / 2.0)
  when UIImageOrientationRight then
    bounds = swapBounds(bounds)
    CGAffineTransformRotate(CGAggineTransformMakeTranslation(imageSize.height, 0.0), Math::PI / 2.0)
  else
    CGAffineTransformIdentity
  end

  UIGraphicsBeginImageContext(bounds.size)
  context = UIGraphicsGetCurrentContext()
  if [UIImageOrientationRight, UIImageOrientationLeft].include?(orientation)
    CGContextScaleCTM(context, -scaleRatio, scaleRatio)
    CGContextTranslateCTM(context, -height, 0)
  else
    CGContextScaleCTM(context, scaleRatio, -scaleRatio)
    CGContextTranslateCTM(context, 0, -height)
  end

  CGContextConcatCTM(context, transformation)
  CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef)
  imageCopy = UIGraphicsGetImageFromCurrentImageContext()
  UIGraphicsEndImageContext()

  imageCopy
end

def swapBounds(bounds)
  CGRectMake(0, 0, bounds.size.height, bounds.size.width)
end