themes.xml

<resources xmlns:tools="http://schemas.android.com/tools">
    <!-- Base application theme. -->
    <style name="Theme.Nafmii" parent="Theme.MaterialComponents.DayNight.NoActionBar">
        <item name="android:windowBackground">@mipmap/splash1</item>
        <!-- Customize your theme here. -->
    </style>

    <style name="Nafmii.Fullscreen" parent="Theme.Nafmii">
        <!-- 设置全屏-->
        <item name="android:windowFullscreen">true</item>
        <item name="android:windowBackground">@mipmap/splash1</item>
    </style>

    <style name="Nafmii.Fullscreen.NoTitleBar" parent="Nafmii.Fullscreen">
        <!-- 取消Actionbar-->
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
    </style>
</resources>