Badge on BottomNavigationView

Question

I am trying to add a badge to the BottomNavigationView Item without using any library, however somehow the BottomNavigationView is not showing the

Answer 1

I managed to make BottomNavigationView with the badge. Here is my code (Kotlin).

This is the panel (inherited from BottomNavigationView)

/** Bottom menu with badge */
class AdvancedBottomNavigationView(context: Context, attrs: AttributeSet) : BottomNavigationView(context, attrs) {

    private companion object {
        const val BADGE_MIN_WIDTH = 16          // [dp]
        const val BADGE_MARGIN_TOP = 5          // [dp]
        const val BADGE_MARGIN_LEFT = 15        // [dp]
    }

    @Inject internal lateinit var uiCalculator: UICalculatorInterface

    private val bottomMenuView: BottomNavigationMenuView

    init {
        //  Get access to internal menu
        val field = BottomNavigationView::class.java.getDeclaredField("mMenuView")
        field.isAccessible = true
        bottomMenuView = field.get(this) as BottomNavigationMenuView

        App.injections.presentationLayerComponent!!.inject(this)

        @SuppressLint("CustomViewStyleable")
        val a = context.obtainStyledAttributes(attrs, R.styleable.advanced_bottom_navigation_bar)
        val badgeLayoutId  = a.getResourceId(R.styleable.advanced_bottom_navigation_bar_badge_layout, -1)
        a.recycle()

        initBadges(badgeLayoutId)
    }

    /**
     * [position] index of menu item */
    fun setBadgeValue(position: Int, count: Int) {
        val menuView = bottomMenuView
        val menuItem = menuView.getChildAt(position) as BottomNavigationItemView

        val badge = menuItem.findViewById(R.id.bottom_bar_badge)
        val badgeText = menuItem.findViewById(R.id.bottom_bar_badge_text) as TextView

        if (count > 0) {
            badgeText.text = count.toString()
            badge.visibility = View.VISIBLE
        } else {
            badge.visibility = View.GONE
        }
    }

    /**
     * Select menu item
     * [position] index of menu item to select
     */
    fun setSelected(position: Int) = bottomMenuView.getChildAt(position).performClick()

    private fun initBadges(badgeLayoutId: Int) {
        // Adding badges to each Item
        val menuView = bottomMenuView
        val totalItems = menuView.childCount

        val oneItemAreaWidth = uiCalculator.getScreenSize(context).first / totalItems

        val marginTop = uiCalculator.dpToPixels(context, BADGE_MARGIN_TOP)
        val marginLeft = uiCalculator.dpToPixels(context, BADGE_MARGIN_LEFT)

        for (i in 0 until totalItems) {
            val menuItem = menuView.getChildAt(i) as BottomNavigationItemView

            // Add badge to every item
            val badge = View.inflate(context, badgeLayoutId, null) as FrameLayout
            badge.visibility = View.GONE
            badge.minimumWidth = uiCalculator.dpToPixels(context, BADGE_MIN_WIDTH)

            val layoutParam = FrameLayout.LayoutParams(
                FrameLayout.LayoutParams.WRAP_CONTENT,
                FrameLayout.LayoutParams.WRAP_CONTENT)
            layoutParam.gravity = Gravity.START

            layoutParam.setMargins(oneItemAreaWidth / 2 + marginLeft, marginTop, 0, 0)
            menuItem.addView(badge, layoutParam)
        }
    }
 }

It's attr.xml file with options for this component:

Background for badge from drawable folder:

Badge itself:

And this is an example how to use it in your code:

I hope this helps you.