Challenge1: Efficient Thumbnail Load

Although this solution is similar to the ones below, I still put it out to show you that you can still setup the viewTreeObserver in other places like in onStart() because there is a confusion on where to put it. So this is just another way of doing it.

private var imageViewWidth = 0
private var imageViewHeight = 0

private fun updatePhotoView()  {
    if (photoFile.exists()) {
        val bitmap = getScaledBitmap(photoFile.path, imageViewWidth, imageViewHeight)
    }  else {

and then declaring it in onStart()

    photoView.apply {
        viewTreeObserver.addOnGlobalLayoutListener {
            imageViewWidth = width
            imageViewHeight = height