Question

我尝试使用AppBottomBar，并且希望能够像setExpanded一样在AppBarLayout中以编程方式隐藏或显示它。

我的布局就像

<androidx.coordinatorlayout.widget.CoordinatorLayout
    android:id="@+id/coordinator"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
          ...
    </com.google.android.material.appbar.AppBarLayout>

    <androidx.core.widget.NestedScrollView
        android:id="@+id/nested"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <fragment
            android:id="@+id/navHost"
            android:name="androidx.navigation.fragment.NavHostFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:defaultNavHost="true"
            app:navGraph="@navigation/home_nav" />
    </androidx.core.widget.NestedScrollView>

    <com.google.android.material.bottomappbar.BottomAppBar
        android:id="@+id/bottomAppBar"
        style="@style/Widget.MaterialComponents.BottomAppBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:backgroundTint="@color/colorPrimary"
        app:fabAlignmentMode="center"
        app:hideOnScroll="true"
        app:layout_scrollFlags="scroll|enterAlways"
        app:navigationIcon="@drawable/ic_menu"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>

我尝试使用AppBottomBar的行为，但是它不起作用。

Answer 1

您可以从其行为类中使用slideUp(...)和slideDown(...)方法。例如：

科特林

 val bottomAppBar = ...
 val behavior = bottomAppBar.behavior as HideBottomViewOnScrollBehavior
 behavior.slideDown(bottomAppBar) // use this to hide it
 behavior.slideUp(bottomAppBar) // use this to show it

Java

 BottomAppBar bottomAppBar = ...
 HideBottomViewOnScrollBehavior behavior = (HideBottomViewOnScrollBehavior) bottomAppBar.behavior;
 behavior.slideDown(bottomAppBar) // use this to hide it
 behavior.slideUp(bottomAppBar) // use this to show it

Answer 2

科特林

class HideBottomNavigationOnScrollBehavior<V : View>(
        context: Context?,
        attrs: AttributeSet?
) : HideBottomViewOnScrollBehavior<V>(context, attrs) {

    public override fun slideDown(child: V) {
        super.slideDown(child)
    }

    public override fun slideUp(child: V) {
        super.slideUp(child)
    }   
}

Answer 3

在底部的应用栏上调用performShow()和performHide()即可满足您的需求。

如何以编程方式显示/隐藏AppBottomBar？

3 个答案: