layout_floating_widget.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <!--Root container-->
    <RelativeLayout
        android:id="@+id/root_container"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        tools:ignore="UselessParent">

        <!--View while view is collapsed-->
        <RelativeLayout
            android:id="@+id/collapse_view"
            android:layout_width="65dp"
            android:visibility="visible"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <!--Profile image for the chat head.-->
            <ImageView
                android:id="@+id/collapsed_iv"
                android:layout_width="60dp"
                android:layout_height="60dp"
                android:layout_marginTop="8dp"
                android:src="@drawable/ic_android_circle"
                tools:ignore="ContentDescription"/>

            <!--Close button-->
            <ImageView
                android:id="@+id/close_btn"
                android:layout_width="26dp"
                android:layout_height="26dp"
                android:layout_marginLeft="40dp"
                android:src="@drawable/ic_close"
                tools:ignore="ContentDescription"/>
        </RelativeLayout>

        <!--View while view is expanded-->
        <LinearLayout
            android:id="@+id/expanded_container"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="#EEEEEE"
            android:visibility="gone"
            android:orientation="horizontal"
            android:padding="8dp">

            <!--Album image for the sog currently playing.-->
            <ImageView
                android:layout_width="80dp"
                android:layout_height="80dp"
                android:src="@drawable/music_player"
                tools:ignore="ContentDescription"/>

            <!--Previous button-->
            <ImageView
                android:id="@+id/prev_btn"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_gravity="center_vertical"
                android:layout_marginLeft="20dp"
                android:src="@mipmap/ic_previous"
                tools:ignore="ContentDescription"/>

            <!--Play button-->
            <ImageView
                android:id="@+id/play_btn"
                android:layout_width="50dp"
                android:layout_height="50dp"
                android:layout_gravity="center_vertical"
                android:layout_marginLeft="10dp"
                android:src="@mipmap/ic_play"
                tools:ignore="ContentDescription"/>

            <!--Next button-->
            <ImageView
                android:id="@+id/next_btn"
                android:layout_width="30dp"
                android:layout_height="30dp"
                android:layout_gravity="center_vertical"
                android:layout_marginLeft="10dp"
                android:src="@mipmap/ic_play_next"
                tools:ignore="ContentDescription"/>

            <RelativeLayout
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:orientation="vertical">

                <ImageView
                    android:id="@+id/close_button"
                    android:layout_width="20dp"
                    android:layout_height="20dp"
                    android:src="@drawable/ic_close"/>

                <ImageView
                    android:id="@+id/open_button"
                    android:layout_width="20dp"
                    android:layout_height="20dp"
                    android:layout_alignParentBottom="true"
                    android:src="@drawable/ic_open"/>
            </RelativeLayout>
        </LinearLayout>
    </RelativeLayout>
</FrameLayout>