Centre Android GridLayout horizontalement

Je suis en train de créer un GridLayout avec 2 colonnes qui sera centré.

Mon avtual design est:

<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:custom="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    custom:rowCount="4"
    custom:columnCount="2"
    android:orientation="horizontal">
    <TimeTableKeeper.Tile
        android:layout_width="75dp"
        android:layout_height="75dp"
        android:gravity="top|left"
        android:background="#00FF00"
        custom:color="green"
        custom:layout_row="0"
        custom:layout_column="0" />
    <TimeTableKeeper.Tile
        android:layout_width="75dp"
        android:gravity="top|left"
        android:layout_height="75dp"
        android:background="#00FF00"
        custom:color="blue"
        custom:layout_row="0"
        custom:layout_column="1" />
</GridLayout>

Et il ressemble:

Centre Android GridLayout horizontalement

Et je voudrais avoir ce bouton, au centre et à la perfection avec un espacement entre eux.

Est-il possible?

--EDIT:

J'ai aussi essayé de mettre en LinearLayout, sans résultats:

<?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:gravity="center"
    android:orientation="vertical">
    <GridLayout xmlns:custom="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        custom:rowCount="4"
        custom:columnCount="2"
        android:orientation="horizontal"
        android:gravity="center"
        android:layout_gravity="center">
        <TimeTableKeeper.Tile
            android:layout_width="75dp"
            android:layout_height="75dp"
            android:background="#00FF00"
            custom:color="green"
            custom:layout_row="0"
            custom:layout_column="0" />
        <TimeTableKeeper.Tile
            android:layout_width="75dp"
            android:layout_height="75dp"
            android:background="#00FF00"
            custom:color="blue"
            custom:layout_row="0"
            custom:layout_column="1" />
    </GridLayout>
</LinearLayout>

source d'informationauteur Tomasz