底部导航项图标背景大小

Question

我想改变底部导航菜单图标周围的背景大小，我试过了

   <?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"
    android:constantSize="true">
    <item android:drawable="@drawable/nav_selector" android:state_checked="true"/>
    <item android:drawable="@android:color/transparent"/>
</selector>

<com.google.android.material.bottomnavigation.BottomNavigationView
            android:id="@+id/bottomNavigation"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            app:itemBackground="@drawable/nav_background"
            app:itemIconTint="@drawable/bottom_navigation"
            app:labelVisibilityMode="unlabeled"
            app:menu="@menu/bottom_nav_menu"
            android:padding="@dimen/_5sdp"/>