Progress DialogFragment with only progress view on the dimmed screen

ProgressDimDialogFragment.kt

/**
 * Dialog fragment showing progress widget on dimmed screen.
 * @author Vasili Chyrvon (vasili.chyrvon@gmail.com)
 */
class ProgressDimDialogFragment : AppCompatDialogFragment() {

    companion object {
        val TAG = "ProgressDimDialogFragment"

        private val ARGS_DISPATCH_BACK_PRESS = "args_dispatches_back_press"

        fun newInstance(dispatchBackPress: Boolean = true): ProgressDimDialogFragment {
            val args = Bundle()
            args.putBoolean(ARGS_DISPATCH_BACK_PRESS, dispatchBackPress)

            val fragment = ProgressDimDialogFragment()
            fragment.arguments = args
            return fragment
        }
    }

    private val dispatchBackPress by lazy { arguments.getBoolean(ARGS_DISPATCH_BACK_PRESS) }

    private var listener: BackPressListener? = null

    interface BackPressListener {
        fun onProgressBackPressed()
    }

    override fun onAttach(context: Context?) {
        super.onAttach(context)

        if (parentFragment is BackPressListener) {
            listener = parentFragment as BackPressListener
        } else if (activity is BackPressListener) {
            listener = activity as BackPressListener
        } else {
            if (dispatchBackPress)
                throw IllegalStateException("Activity or parent fragment must implement BackPressListener to dispatch back presses.")
        }
    }

    override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        with(dialog) {
            window.setBackgroundDrawable(ColorDrawable(0)) // Remove the frame
            setCanceledOnTouchOutside(false)
        }

        return MaterialProgressBar(context)
    }

    override fun onCancel(dialog: DialogInterface?) {
        listener?.onProgressBackPressed()
    }
}