Show / hide BottomNavigationView on scroll in CoordinatorLayout using AppBarLayout

Question

I try to use both AppBarLayout, and BottomNavigationLayoutin one CoordinatorLayout, and it is difficult for me to hide BottomNavigationLayouthow the material guide is required .

I mean something like this:

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="false">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_insetEdge="top"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:popupTheme="@style/AppTheme.PopupOverlay"
            app:layout_scrollFlags="scroll|enterAlways"/>
    </android.support.design.widget.AppBarLayout>


    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottom_nav"
        android:layout_width="match_parent"
        android:layout_height="56dp"
        android:layout_gravity="bottom"
        app:menu="@menu/menu_bottom_navigation"/>

    <FrameLayout
        android:id="@+id/content_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="top"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>

</android.support.design.widget.CoordinatorLayout>

As you can see, I also have FrameLayoutthat contained a snippet with the actual content. Currently, BottomNavigationViewthere are no standard / built-in behaviors - neither for the presentation itself, nor for its brothers and sisters. The existing one appbar_scrolling_view_behaviorhandles the presentation of the content in coordination with the application panel, but ignores the other siblings.

I am looking for a solution to hide and show both the application panel and the bottom scroll view of the navigation.

Answer 1

< <21 > Behavior. , , BottomNavigationView, BottomNavigationView. - :

public class BottomNavigationBehavior extends CoordinatorLayout.Behavior<BottomNavigationView> {

    public BottomNavigationBehavior() {
        super();
    }

    public BottomNavigationBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, BottomNavigationView child, View dependency) {
        boolean dependsOn = dependency instanceof FrameLayout;
        return dependsOn;
    }

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, BottomNavigationView child, View directTargetChild, View target, int nestedScrollAxes) {
        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL;
    }

    @Override
    public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, BottomNavigationView child, View target, int dx, int dy, int[] consumed) {
        if(dy < 0) {
            showBottomNavigationView(child);
        }
        else if(dy > 0) {
            hideBottomNavigationView(child);
        }
    }

    private void hideBottomNavigationView(BottomNavigationView view) {
        view.animate().translationY(view.getHeight());
    }

    private void showBottomNavigationView(BottomNavigationView view) {
        view.animate().translationY(0);
    }
}

, ViewPropertyAnimator, animate. , AppBarLayout, , .

, - Android BottomNavigationView , , , AppBarLayout.

( 2018): . onStartNestedScroll onNestedPreScroll .