BottomNavigationView 基础配置

xml的展现

 <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_navigation"
        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:background="?android:attr/windowBackground"
        android:longClickable="true"
        android:theme="@style/bottom_navigation_style"
        app:labelVisibilityMode="labeled"
        app:layout_constraintBottom_toBottomOf="parent"
        app:menu="@menu/bottom_navigation" />

app:menu

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/navigation_home"
        android:icon="@mipmap/ic_main_home"
        android:title="@string/main_home" />

    <item
        android:id="@+id/navigation_shop"
        android:icon="@mipmap/ic_main_shop"
        android:title="@string/main_shop" />

    <item
        android:id="@+id/navigation_msg"
        android:icon="@mipmap/ic_main_msg"
        android:title="@string/main_msg" />

    <item
        android:id="@+id/navigation_mine"
        android:icon="@mipmap/ic_main_mine"
        android:title="@string/main_mine" />

</menu>

上面的xml就是底部导航的菜单

问题1：选中和未选中的图标和文字颜色配置 

 需要设置主题android:theme

    <style name="bottom_navigation_style" parent="LctTheme">
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="android:textColorSecondary">@android:color/black</item>
    </style>

colorPrimary为图标和文字的选中颜色

android:textColorSecondary为图标和文字的未选中颜色

问题2：给某一个菜单增加小红点或者未读标识

MenuBadge.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:layout_marginTop="@dimen/space_h"
        android:layout_marginStart="@dimen/space_xh"
        android:id="@+id/msgCount"
        android:layout_width="5dp"
        android:layout_height="5dp"
        android:layout_gravity="center"
        android:gravity="center"
        android:textColor="@color/white"
        android:textSize="@dimen/text_m"
        app:bl_shape="oval"
        app:bl_solid_color="@color/colorPrimary" />

</LinearLayout>  

 
下面是在activity的使用

private val badgeView by lazy { MenuBadgeBinding.inflate(layoutInflater, null, false) }

   /**
     * 给BottomNavigationView 设置Badge 小红点
     */
    private fun setBadge() {
        //获取底部菜单view
        val menuView = binding.bottomNavigation.getChildAt(0) as BottomNavigationMenuView
        //获取第2个itemView
        val itemView = menuView.getChildAt(2) as BottomNavigationItemView
        //把badgeView添加到itemView中
        itemView.addView(badgeView.root)
    }

问题3：底部导航栏长按会吐司

参数就是 BottomNavigationView 的菜单ID 集合

fun BottomNavigationView.clearToast(ids: MutableList<Int>) {
    val bottomNavigationMenuView: ViewGroup = (this.getChildAt(0) as ViewGroup)
    //遍历子View,重写长按点击事
    for (position in 0 until ids.size) {
        bottomNavigationMenuView.getChildAt(position).findViewById<View>(ids[position])
            .setOnLongClickListener { true }

    }
}