Toggle ambient support in Android Wear 2.0 based on Drawer state (open or closed/peek)

ToggleAmbientBasedOnDrawerState.kt

private var mAmbientMode: AmbientMode? = null
private var mAmbientAttached = false
private val mDrawerStateCallback = object : WearableDrawerLayout.DrawerStateCallback() {
    override fun onDrawerStateChanged(layout: WearableDrawerLayout?, newState: Int) {
        super.onDrawerStateChanged(layout, newState)
        if (newState == 0) {
            if ((playback_drawer.isClosed || playback_drawer.isPeeking)) removeAmbientSupport()
            else if (playback_drawer.isOpened) addAmbientSupport()
        }
    }
}

private fun addAmbientSupport() {
    if (!mAmbientAttached) {
        mAmbientAttached = true
        if (mAmbientMode == null) AmbientMode.attachAmbientSupport(this@LibraryAltActivity)
        else fragmentManager
                .beginTransaction()
                .add(mAmbientMode, AmbientMode.FRAGMENT_TAG)
                .commit()
    }
}

private fun removeAmbientSupport() {
    if (mAmbientAttached) {
        mAmbientAttached = false
        if (mAmbientMode == null) {
            mAmbientMode = fragmentManager.findFragmentByTag(AmbientMode.FRAGMENT_TAG) as AmbientMode?
        }
        if (mAmbientMode != null) {
            fragmentManager
                    .beginTransaction()
                    .remove(mAmbientMode)
                    .commit()
        }
    }
}