feat: 优化代码

app/src/main/java/io/legado/app/ui/widget/SelectActionBar.kt

@@ -9,6 +9,7 @@ import androidx.annotation.MenuRes
 import androidx.annotation.StringRes
 import androidx.appcompat.widget.PopupMenu
 import io.legado.app.R
+import io.legado.app.utils.dp
 import io.legado.app.utils.visible
 import kotlinx.android.synthetic.main.view_select_action_bar.view.*
 import org.jetbrains.anko.sdk27.listeners.onClick
@@ -19,6 +20,7 @@ class SelectActionBar(context: Context, attrs: AttributeSet?) : FrameLayout(cont
 
     init {
         setBackgroundResource(R.color.background_menu)
+        elevation = 10.dp.toFloat()
         View.inflate(context, R.layout.view_select_action_bar, this)
         cb_selected_all.setOnCheckedChangeListener { buttonView, isChecked ->
             if (buttonView.isPressed) {

app/src/main/res/layout/activity_main.xml

@@ -8,7 +8,7 @@
         android:id="@+id/bottom_navigation_view"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:elevation="6dp"
+        android:elevation="10dp"
         android:background="@color/background"
         app:labelVisibilityMode="labeled"
         app:menu="@menu/main_bnv"