Material TabLayout elevation not working

问题:

For some reason the elevation attribute does not seem to be working on the new TabLayout in the material design support library. Any ideas? XML:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<android.support.design.widget.TabLayout
    android:id="@+id/tab_layout"
    android:layout_width="match_parent"
    android:layout_height="?attr/actionBarSize"
    android:elevation="6dp" />

<android.support.v4.view.ViewPager
    android:id="@+id/view_pager"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1" />
</LinearLayout>

hooked up like this in a parent fragment:

ViewPager viewPager = (ViewPager) view.findViewById(R.id.view_pager);
TabLayout tabLayout = (TabLayout) view.findViewById(R.id.tab_layout);
AppPagerAdapter appPagerAdapter = new AppPagerAdapter(getChildFragmentManager());
viewPager.setAdapter(appPagerAdapter);
tabLayout.setupWithViewPager(viewPager);

image:

The activity has a toolbar but this is outside of the fragment and should not affect the tablayout's ability to have a shadow:

relevant activity xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.bluckapps.appinfomanager.ui.MainActivity">

<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?attr/colorPrimary"
    android:elevation="6dp"
    android:minHeight="?attr/actionBarSize"
    tools:ignore="UnusedAttribute" />

<FrameLayout
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1" />

</LinearLayout>

回答1:

To make the shadow show, you have to set a background on your TabLayout. It can be the same color as your window background (as long as it's a solid color with no alpha).

<android.support.design.widget.TabLayout
    android:id="@+id/tab_layout"
    android:layout_width="match_parent"
    android:layout_height="?attr/actionBarSize"
    android:elevation="6dp"
    android:background="@color/white" />

回答2:

You are supposed to use ToolBar with TabLayout. Then you can put them both inside an AppBarLayout and get a shadow. This only works on Lollipop+.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
            style="@style/ToolBarStyle"
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/colorPrimary"
            android:minHeight="@dimen/abc_action_bar_default_height_material"/>

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize" />
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />
</LinearLayout>

See http://inthecheesefactory.com/blog/android-design-support-library-codelab/en

回答3:

You'll need to use CoordinatorLayout as a container layout for your activity and then place your TabLayout right below AppBarLayout. According to Material Design specs you should use

android:elevation="4dp"

elevation and make your TabLayout be a part of AppBarLayout. Also note that elevation will only be visible on v21 (5.0) or higher.

回答4:

No need to use a Fragment. An Activity layout is enough. Like:

<android.support.design.widget.CoordinatorLayout
    android:id="@+id/home_coordinator_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/home_appbar_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        app:elevation="2dp"
        app:paddingEnd="0dp"
        app:paddingStart="0dp">

        <include layout="@layout/toolbar_appcompat"></include>

        <android.support.design.widget.TabLayout
            android:id="@+id/home_tab_layout"
            style="@style/TabLayoutStyle"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabContentStart="2dp"
            app:tabGravity="fill"
            app:tabIndicatorColor="@android:color/white"
            app:tabIndicatorHeight="2dp"
            app:tabMinWidth="24dp"
            app:tabMode="fixed"
            app:tabPadding="1dp"
            app:tabSelectedTextColor="@android:color/tab_indicator_text"
            app:tabTextColor="@android:color/darker_gray" />
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/home_view_pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        app:paddingEnd="0dp"
        app:paddingStart="0dp" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab_home"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="20dp"
        android:src="@drawable/arrow_toggle"
        app:borderWidth="1dp"
        app:elevation="3dp"
        app:fabSize="normal"
        app:layout_anchor="@+id/home_coordinator_layout"
        app:layout_anchorGravity="bottom|right|end"
        app:pressedTranslationZ="2dp"
        app:rippleColor="@color/swipe_refresh_color_scheme_green" />

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

Meanwhile, elevation is useful on Lollipop. If you want to be compatible backwards, you'd better use app:elevation. If app:elevation doesn't work, you'd better add a shadow below TabLayout manually, just like android:background="@drawable/myrect":

<!-- res/drawable/myrect.xml -->
<shape xmlns:android="http://schemas.android.com/apk/res/android"
       android:shape="rectangle">
    <solid android:color="#42000000" />
    <corners android:radius="5dp" />
</shape>

回答5:

Keep the tablayout inside appbarLayout. It'll work.

回答6:

All answers above didn't work for me ,so i found out this:

app:tabIndicatorHeight="4dp"
app:tabIndicatorColor="@color/colorAccent"

then allright!