Wie erweitere ich AppBarLayout, wenn ich nach unten scrolle? Erreicht den oberen Rand der RecyclerView

Ich arbeite an einer Android-App, in der ich @ verwenCoordinatorLayout,AppBarLayout undCollapsingToolbarLayout, um die Funktion der erweiterten Ausblendleiste zu verwenden.

Ich verwende recyclerview, um die Anzahl der Elemente im Fragment anzuzeigen. Wenn ich in recyclerview nach oben scrolle, wird es reibungslos ausgeblendet.AppBarLayout aber wenn ich nach unten scrolle und auf den ersten Punkt des @ greirecyclerview Der Bildlauf wird automatisch gestoppt, ohne "AppBarLayout" zu erweitern.

Dann muss ich nochmal runterscrollen um @ zu machAppBarLayout sichtbar. Meine Anforderung ist also, dass beim Scrollen nach unten, wenn ich zum Anfang der Recyclingübersicht komme, AppBarLayout erweitert werden muss.

Wie können wir das machen? Irgendeine Idee ? Bitte siehe Video von samehttps: //www.dropbox.com/s/va5jk27ikytk5ax/app_collapsebar_issue.mp4? dl = 0

Hier ist mein Layout gleich: -

<?xml version="1.0" encoding="utf-8"?>

<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/drawerLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"

    android:fitsSystemWindows="true">

    <FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/coordinator"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:adjustViewBounds="true"
        android:fitsSystemWindows="true"
        app:layout_scrollFlags="scroll|exitUntilCollapsed"
        >

        <android.support.design.widget.AppBarLayout
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="220dp"
        android:background="@drawable/offer_image"
        android:fitsSystemWindows="true"
        android:theme="@style/AppTheme.AppBarOverlay"
        app:layout_scrollFlags="scroll|exitUntilCollapsed">

        <!--    <com.flaviofaria.kenburnsview.KenBurnsView
            android:id="@+id/image"
            android:layout_width="match_parent"
            android:layout_height="220dp"
            android:src="@drawable/offer_image" />-->
        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/toolbar_layout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:expandedTitleMarginEnd="64dp"
            app:expandedTitleMarginStart="48dp"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">


            <com.flaviofaria.kenburnsview.KenBurnsView
            android:id="@+id/image"
            android:layout_width="match_parent"
            android:layout_height="220dp"

            android:src="@drawable/offer_image" />

            <FrameLayout
            android:id="@+id/collapse_frame"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="#B3c85a00">

            </FrameLayout>

            <FrameLayout
            android:id="@+id/centerCircle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center">

            <ImageView
                android:id="@+id/imageViewCenter"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:src="@drawable/offer" />
            </FrameLayout>

            <include
            android:id="@+id/toolbar"
            layout="@layout/toolbar" />

            <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom"
            android:layout_marginBottom="15dp"
            app:tabIndicatorColor="#FFFFFF"
            app:tabMode="scrollable" />
            <!--</FrameLayout>-->
        </android.support.design.widget.CollapsingToolbarLayout>
        </android.support.design.widget.AppBarLayout>

        <!--<FrameLayout-->

        <!--android:layout_width="match_parent"-->
        <!--android:layout_height="match_parent"-->
        <!-- -->
        <!--android:visibility="visible">-->

        <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        style="@style/floating_action_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:src="@drawable/ic_share_white_24dp"
        android:visibility="gone"
        app:backgroundTint="#FF9800"
        app:elevation="6dp"
        app:pressedTranslationZ="12dp" />

        <android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="left|bottom|fill_vertical"
        android:layout_marginTop="0dp"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"></android.support.v4.view.ViewPager>
        <!--</FrameLayout>-->

        <!--<include layout="@layout/content_scrolling" />-->

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

    <RelativeLayout
        android:id="@+id/bannerView"
        android:layout_width="match_parent"
        android:layout_height="58dp"
        android:layout_gravity="bottom|center"
        android:background="@drawable/curved_white_with_blue_border"
        android:visibility="gone">

        <TextView
        android:id="@+id/bannerText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerInParent="true"
        android:layout_centerVertical="true"
        android:gravity="center"
        android:padding="3dp"
        android:text="Banner"
        android:visibility="gone" />

        <ImageView
        android:id="@+id/bannerImage"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentLeft="true"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:gravity="center"
        android:padding="3dp"
        android:scaleType="fitXY"
        android:visibility="gone" />

        <ImageView
        android:id="@+id/bannerClose"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_centerVertical="true"
        android:src="@drawable/cross_icon" />
    </RelativeLayout>


    <LinearLayout
        android:id="@+id/socialTabs"
        android:layout_width="match_parent"
        android:layout_height="46dp"
        android:layout_gravity="bottom|center"
        android:layout_marginBottom="5dp"
        android:background="@color/White"
        android:orientation="horizontal"
        android:visibility="gone">

        <ImageView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:adjustViewBounds="true"
        android:src="@drawable/follow" />

        <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:background="@color/White">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="46dp"
            android:layout_gravity="center"
            android:gravity="center"
            android:paddingLeft="10dp"
            android:paddingRight="10dp"
            android:weightSum="3">

            <ImageView
            android:id="@+id/facebookImageView"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_weight="1"
            android:src="@drawable/fb_follow" />

            <ImageView
            android:id="@+id/googlePlusImageView"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_marginLeft="5dp"
            android:layout_marginRight="5dp"
            android:layout_weight="1"
            android:adjustViewBounds="true"
            android:src="@drawable/google_follow" />

            <ImageView
            android:id="@+id/twitterImageView"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_weight="1"
            android:adjustViewBounds="true"
            android:src="@drawable/twitter_follow" />
        </LinearLayout>
        </FrameLayout>
    </LinearLayout>
    </FrameLayout>

    <ExpandableListView
    android:id="@+id/left_drawer"
    android:layout_width="265dp"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:background="#fff"
    android:choiceMode="singleChoice"
    android:divider="@null"
    android:dividerHeight="0dp"
    android:drawSelectorOnTop="true"
    android:groupIndicator="@null"
    android:scrollbars="@null" />

</android.support.v4.widget.DrawerLayout>

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