android design library toolbar shadow [closed]

Question

Trying new android design library I found a bug with toolbar shadow. When using CollapsingToolbarLayout the shadow below toolbar appears only when toolbar collapsed. When we expand it the shadow disappear. My layout looks like

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

<android.support.design.widget.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:fitsSystemWindows="true"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/collapsing_toolbar"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        app:contentScrim="?attr/colorPrimary"
        app:layout_scrollFlags="scroll|exitUntilCollapsed">

        <ImageView
            android:layout_width="match_parent"
            android:layout_height="@dimen/user_avatar_height"
            android:fitsSystemWindows="true"
            android:scaleType="centerCrop"
            app:layout_collapseMode="parallax" />

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:gravity="center_vertical"
            app:layout_collapseMode="pin"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

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

    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:background="@color/colorPrimary"
        android:minHeight="?attr/actionBarSize"
        app:tabGravity="fill"
        app:tabIndicatorColor="@android:color/white"
        app:tabMaxWidth="0dp"
        app:tabMode="fixed" />

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

<android.support.v4.view.ViewPager
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    app:layout_behavior="@string/appbar_scrolling_view_behavior" />

And results There is a shadow when toolbar collapsed.

But when expand it shadow disappear.

Is there any solutions to solve this problem? May be there is a way to handle shadow appearance/disappearance? Thanks.

Answer 1

Update

It seems that the support library team from Google introduced the behavior as part of 24.0.0 but it was kind of buggy so now there is a new workaround you need to do.

1 - Create appbar_always_elevated.xml in animator-v21 folder under res directory.

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item>
        <objectAnimator android:propertyName="elevation"
                        android:valueTo="8dp"
                        android:valueType="floatType"
                        android:duration="1"/>
    </item>

</selector>

2 - In AppBarLayout use:

<android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="300dp"
        android:fitsSystemWindows="true"
        android:stateListAnimator="@animator/appbar_always_elevated"
        android:theme="@style/AppTheme.AppBarOverlay">

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

---

Old answer

They fixed this as part of the new support library version (24) so you just need to upgrade and use the correct property.

watch https://youtu.be/w45y_w4skKs?t=31m52s

---

Old answer

I solved this issue by having a FrameLayout around the ViewPager and setting android:foreground.

Attached is the drawable that I am using, and here is the link to the gist