add a black splash screen

app/src/main/AndroidManifest.xml

@@ -12,14 +12,20 @@
         android:label="@string/app_launcher_name"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
+
         <activity
-            android:name=".activities.MainActivity"
-            android:resizeableActivity="true">
+            android:name=".activities.SplashActivity"
+            android:theme="@style/SplashTheme">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>
 
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
+        </activity>
+
+        <activity
+            android:name=".activities.MainActivity"
+            android:resizeableActivity="true">
 
             <intent-filter>
                 <action android:name="android.intent.action.PICK"/>

app/src/main/kotlin/com/simplemobiletools/gallery/activities/SplashActivity.kt

@@ -0,0 +1,13 @@
+package com.simplemobiletools.gallery.activities
+
+import android.content.Intent
+import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
+
+class SplashActivity : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        startActivity(Intent(this, MainActivity::class.java))
+        finish()
+    }
+}

app/src/main/res/layout/activity_splash.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/splash_layout"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"/>

app/src/main/res/values/styles.xml

@@ -11,6 +11,10 @@
         <item name="android:spinnerDropDownItemStyle">@style/SpinnerItem.DropDownItem</item>
     </style>
 
+    <style name="SplashTheme" parent="Theme.AppCompat.NoActionBar">
+        <item name="android:windowBackground">@android:color/black</item>
+    </style>
+
     <style name="FullScreenTheme.Base" parent="AppTheme">
         <item name="android:windowContentOverlay">@null</item>
         <item name="actionBarStyle">@style/MyFullScreenActionBar</item>