Gravity in LinearLayout - android?

I created bellow Layout :

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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/relativeStart"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/back"
    tools:context=".SongsActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/header"
        android:orientation="vertical">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:orientation="horizontal">

            <ImageButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@null"
                android:src="@drawable/felesh_m" />

            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_gravity="center_horizontal|center_vertical"
                android:gravity="center_horizontal|center_vertical"
                android:orientation="vertical">

                <ImageButton
                    android:id="@+id/imbCenter"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center_horizontal|center_vertical"
                    android:background="@null"
                    android:src="@drawable/hosein_hlarge" />
            </LinearLayout>

            <ImageButton
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@null"
                android:src="@drawable/felesh_m" />
        </LinearLayout>

        <android.support.v7.widget.RecyclerView
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="4" />
    </LinearLayout>
</RelativeLayout>

See bellow Image :

Change your layout like this. You don't need to take multiple Linear Layouts. That is bad for performance. So I have changed it to single Linear Layout with some Weight properties.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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/relativeStart"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/common_ic_googleplayservices">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/common_ic_googleplayservices"
        android:orientation="vertical">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="3"
            android:orientation="horizontal">

            <ImageButton
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="0.50"
                android:background="@null"
                android:src="@drawable/common_ic_googleplayservices" />


            <ImageButton
                android:id="@+id/imbCenter"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="2"
                android:background="@null"
                android:src="@drawable/common_ic_googleplayservices" />

            <ImageButton
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="0.50"
                android:background="@null"
                android:src="@drawable/common_ic_googleplayservices" />
        </LinearLayout>

        <android.support.v7.widget.RecyclerView
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="4" />
    </LinearLayout>
</RelativeLayout>