Android Странное поведение нижнего индикатора навигации

Question

Я добавил индикатор в нижнюю панель навигации, чтобы получить ожидаемый результат, подобный этому изображение 1 , но он ведет себя странно, когда я нажимаю на вкладку в первый раз изображение 2 , но показываю ожидаемый результат при ретуши на вкладке изображение 3

Это код для BottomNavigationViewIndicator:

class BottomNavigationViewIndicator @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null,defStyleAttr: Int = 0) : View(context, attrs, defStyleAttr) {

private val targetId: Int
private var target: BottomNavigationMenuView? = null

private var rect = Rect()
private val backgroundDrawable: Drawable

private var index = 0
private var animator: AnimatorSet? = null

init {
    if (attrs == null) {
        targetId = NO_ID
        backgroundDrawable = ColorDrawable(Color.TRANSPARENT)
    } else {
        with(context.obtainStyledAttributes(attrs, R.styleable.BottomNavigationViewIndicator)) {
            targetId = getResourceId(R.styleable.BottomNavigationViewIndicator_targetBottomNavigation, NO_ID)
            val clipableId = getResourceId(R.styleable.BottomNavigationViewIndicator_clipableBackground, NO_ID)
            backgroundDrawable = if (clipableId != NO_ID) {
                getDrawable(context, clipableId) ?: ColorDrawable(Color.TRANSPARENT)
            } else {
                ColorDrawable(getColor(R.styleable.BottomNavigationViewIndicator_clipableBackground, Color.TRANSPARENT))
            }
            recycle()
        }
    }
}

override fun onAttachedToWindow() {
    super.onAttachedToWindow()
    if (targetId == NO_ID) return attachedError("invalid target id $targetId, did you set the app:targetBottomNavigation attribute?")
    val parentView = parent as? View ?: return attachedError("Impossible to find the view using $parent")
    val child = parentView.findViewById<View?>(targetId)
    if (child !is ListenableBottomNavigationView) return attachedError("Invalid view $child, the app:targetBottomNavigation has to be n ListenableBottomNavigationView")
    for (i in 0 until child.childCount) {
        val subView = child.getChildAt(i)
        if (subView is BottomNavigationMenuView) target = subView
    }
    if (SDK_INT >= LOLLIPOP) elevation = child.elevation
    child.addOnNavigationItemSelectedListener { updateRectByIndex(it, true) }
    post { updateRectByIndex(index, false) }
}

private fun attachedError(message: String) {
    Timber.e(message)
}

override fun onDetachedFromWindow() {
    super.onDetachedFromWindow()
    target = null
}

override fun onDraw(canvas: Canvas) {
    super.onDraw(canvas)
    canvas.clipRect(rect)
    backgroundDrawable.draw(canvas)
}

private fun updateRectByIndex(index: Int, animated: Boolean) {
    this.index = index
    target?.apply {
        if (childCount < 1 || index >= childCount) return
        val reference = getChildAt(index)

        val start = reference.left + left
        val end = reference.right + left

        backgroundDrawable.setBounds(left, top, right, bottom)
        val newRect = Rect(start, 0, end, height)
        if (animated) startUpdateRectAnimation(newRect) else updateRect(newRect)
    }
}

private fun startUpdateRectAnimation(rect: Rect) {
    animator?.cancel()
    animator = AnimatorSet().also {
        it.playTogether(
                ofInt(this, "rectLeft", this.rect.left, rect.left),
                ofInt(this, "rectRight", this.rect.right, rect.right),
                ofInt(this, "rectTop", this.rect.top, rect.top),
                ofInt(this, "rectBottom", this.rect.bottom, rect.bottom)
        )
        it.interpolator = FastOutSlowInInterpolator()
        it.duration = resources.getInteger(android.R.integer.config_shortAnimTime).toLong()
        it.start()
    }
}

private fun updateRect(rect: Rect) {
    this.rect = rect
    postInvalidate()
}

@Keep fun setRectLeft(left: Int) = updateRect(rect.apply { this.left = left })
@Keep fun setRectRight(right: Int) = updateRect(rect.apply { this.right = right })
@Keep fun setRectTop(top: Int) = updateRect(rect.apply { this.top = top })
@Keep fun setRectBottom(bottom: Int) = updateRect(rect.apply { this.bottom = bottom })

}

Я взял его из этого article https://medium.com/@ademar111190 / writing-a-custom-view-to-use-as-bottom-navigation-indicator-8cf63a737dab