使用BottomNavigationView構造底部導航欄

2019.9.10 修改

取代RadioGroup和RadioButton建立底部選擇欄

使用AndroidStudio自動建立Activity，選擇

Bottom Navigation Activity

重點内容:

1. 布局:

   <android.support.design.widget.BottomNavigationView
       android:id="@+id/navigation"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:background="?android:attr/windowBackground"
       app:menu="@menu/navigation"/>
              

2. 建立menu檔案

   <menu xmlns:android="http://schemas.android.com/apk/res/android">
       <item
           android:id="@+id/navigation_home"
           android:icon="@drawable/ic_home_black_24dp"
           android:title="@string/title_home"/>
       <item
           android:id="@+id/navigation_dashboard"
           android:icon="@drawable/ic_dashboard_black_24dp"
           android:title="@string/title_dashboard"/>
       <item
           android:id="@+id/navigation_notifications"
           android:icon="@drawable/ic_notifications_black_24dp"
           android:title="@string/title_notifications"/>
   </menu>
              

3. 監聽事件
4. 設定圖檔大小

   //擴充方法,直接調用,傳入dp
   fun BottomNavigationView.setChildDimension(width: Float, height: Float) {
       val menuView = getChildAt(0) as BottomNavigationMenuView
       for (i in 0 until menuView.childCount) {
           val iconView = menuView.getChildAt(i).findViewById<View>(R.id.icon)
           val layoutParams = iconView.layoutParams
           val displayMetrics = resources.displayMetrics
           layoutParams.height = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, width, displayMetrics).toInt()
           layoutParams.width = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, height, displayMetrics).toInt()
           iconView.layoutParams = layoutParams
       }
   }
              

5. 設定小紅點

   BottomNavigationMenuView menuView = mNavView.getChildAt(0) as BottomNavigationMenuView
   val tab = menuView.getChildAt(1)
   val itemView = tab as BottomNavigationItemView
   val mDot = View(this)
   val params = BottomNavigationItemView.LayoutParams(dip(this, 8), dip(8))
   params.gravity = Gravity.END
   params.setMargins(0, dip(8), dip(45), 0)
   mDot.setLayoutParams(params)
   itemView.addView(mDot)
   mDot.setBackgroundResource(R.drawable.dot)