高程不适用于协调器布局内的BottomSheet

Question

I am trying to use a BottomSheet in my layout. The root view is an CoordinatorLayout and I want to set Elevation on top for the Bottom Sheet so i am setting it with a high value (50dp), however it is not showing when the app runs but it appears on android studio design tool.

I have tried to set background for the sheet with a solid color instead of gradient but it still did work. I also tried to use Shadow shapes but it does not give the same elevation appearance.

here is my XML

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.atefhares.StartActivity"
    android:clipToPadding="false">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <LinearLayout
            android:id="@+id/DetailsView"
            android:layout_width="match_parent"
            android:layout_height="100dp"
            android:orientation="vertical">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Details Should be shown here"
                android:id="@+id/textView"
                android:textSize="25sp"
                android:padding="20dp" />
        </LinearLayout>

        <fragment xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            android:id="@+id/map"
            android:name="com.google.android.gms.maps.SupportMapFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:context="com.atefhares.Start_Activity" />


    </LinearLayout>
    <android.support.v4.widget.SlidingPaneLayout
        android:id="@+id/bottom_sheet"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:behavior_peekHeight="70dp"
        app:layout_behavior="android.support.design.widget.BottomSheetBehavior"
        android:background="@drawable/gradiant"
        android:fillViewport="true"
        android:elevation="50dp">


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

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

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

Edit: bottom_sheet_layout.xml

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


    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:background="@color/colorPrimary"
        android:padding="10dp"
        android:id="@+id/inviteLL">

        <ImageView
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:id="@+id/imageView"
            android:background="@drawable/invite_icon"
            android:layout_margin="5dp"
            android:layout_gravity="center_vertical" />

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Invite Friends"
            android:textSize="22sp"
            android:textColor="#ffffff"
            android:padding="10dp"
            android:fontFamily="sans-serif-condensed"
            android:gravity="center_vertical"
            android:id="@+id/inviteTV"

            android:layout_gravity="center_vertical"
            android:layout_weight="1" />

        <ImageView
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:id="@+id/arrowIV"
            android:layout_gravity="center_vertical"
            android:background="@drawable/arrow_up" />
    </LinearLayout>


    <ListView
        android:layout_width="match_parent"
        android:layout_height="fill_parent"
        android:id="@+id/usersLV"
        android:dividerHeight="1dp"
        android:divider="#ffffff"
        android:background="#ffffff" />

</LinearLayout>

So how can I make the elevation shows on top of the Bottom Sheet

Any one can help, please ?

Answer 1

The answer is: no, it is not possible (unless you create your own view custom with an elevation feature on top).

Elevetion is not meant to be visible in the top of a view, but in the bottom, on the right and on the left.

If you see closely on the official Material Design guidelines, you can see that the bottom bar simply don't have it (do not confuse with the gray space between the card and the bottom bar).

For example: import Card View sample from Android Studio and play with it with emulator or your device. You will see that if you increment the elevation value, the view will have his shadow everywhere except on top (see second image below).

Another example is given by importing Elevation Basic .

EDIT

Following code is taken from Card View sample. There is a layout containing a CardView with elevation . Whenever you change the elevation, you will always see shadow everywhere, but not on top (the code was tested with Lollipop and Marshmallow).

<LinearLayout android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:orientation="vertical"
              android:paddingBottom="@dimen/activity_vertical_margin"
              android:paddingTop="@dimen/activity_vertical_margin"
              android:paddingLeft="@dimen/activity_horizontal_margin"
              android:paddingRight="@dimen/activity_horizontal_margin"
    >
    <android.support.v7.widget.CardView
        android:id="@+id/cardview"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:elevation="100dp"
        card_view:cardBackgroundColor="@color/cardview_initial_background"
        card_view:cardCornerRadius="8dp"
        android:layout_marginLeft="@dimen/margin_large"
        android:layout_marginRight="@dimen/margin_large"
        >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/margin_medium"
            android:text="@string/cardview_contents"
            />
    </android.support.v7.widget.CardView>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="@dimen/margin_large"
        android:orientation="horizontal"
        >
        <TextView
            android:layout_width="@dimen/seekbar_label_length"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:text="@string/cardview_radius_seekbar_text"
            />
        <SeekBar
            android:id="@+id/cardview_radius_seekbar"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/margin_medium"
            />
    </LinearLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        >
        <TextView
            android:layout_width="@dimen/seekbar_label_length"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:text="@string/cardview_elevation_seekbar_text"
            />
        <SeekBar
            android:id="@+id/cardview_elevation_seekbar"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/margin_medium"
            />
    </LinearLayout>
</LinearLayout>

Answer 2

According to the google guidelines with the android:elevation is not possible (Also you can read more about the keyligth ).

Anyway on the most common cases when you scroll up the "BottomSheet" a semitransparent layer appears behind the "BottomSheet", this helps to keep the user focus on the "BottomSheet" actions, like these examples .

If anyway you want a top shadow you can set a drawable background with gradient like this (shadow_top.xml):

<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<gradient
    android:angle="90"
    android:centerColor="#000000"
    android:endColor="@android:color/transparent"
    android:startColor="#000000"
    android:type="linear" />

And your SlidingPanelLayout will be:

<android.support.v4.widget.SlidingPaneLayout
    android:id="@+id/bottom_sheet"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:behavior_peekHeight="95dp"
    android:paddingTop="25dp"
    app:layout_behavior="android.support.design.widget.BottomSheetBehavior"
    android:background="@drawable/shadow_top"
    android:fillViewport="true"
    >

Best regards.

Answer 3

Do not forget that to draw shadow you must use hardwareAccelerated drawing

hardwareAccelerated = true

hardwareAccelerated = false

See Android Hardware Acceleration for details

Answer 4

Try this,

<android.support.v4.widget.SlidingPaneLayout
        android:id="@+id/bottom_sheet"
xmlns:slide_panel="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:behavior_peekHeight="70dp"
      app:layout_behavior="android.support.design.widget.BottomSheetBehavior"
        android:background="@drawable/gradiant"
        android:fillViewport="true"
        slide_panel:elevation="50dp">