Re-implement splash theming

- Remove SplashActivity as we can dynamically change the theme in HomeActivity
  This should result in a nice improvement in app startup time.
- Add support fot platform splash themes on API 31+
- Renamed themes to have App namespace

app/src/main/AndroidManifest.xml

@@ -19,12 +19,12 @@
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
-        android:theme="@style/AppTheme">
+        android:theme="@style/App.Theme">
 
         <activity-alias
             android:name=".StartupActivity"
             android:exported="true"
-            android:targetActivity=".ui.home.SplashActivity">
+            android:targetActivity=".ui.home.HomeActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
@@ -47,10 +47,8 @@
         </activity-alias>
 
         <activity
-            android:name=".ui.home.SplashActivity"
-            android:theme="@style/SplashTheme" />
-
-        <activity android:name=".ui.home.HomeActivity" />
+            android:name=".ui.home.HomeActivity"
+            android:theme="@style/App.SplashTheme.Dark" />
 
         <activity
             android:name=".ui.home.UrlBarActivity"
@@ -66,7 +64,7 @@
 
         <activity
             android:name=".ui.vnc.IntentReceiverActivity"
-            android:theme="@style/SplashTheme" />
+            android:theme="@style/App.SplashTheme.Dark" />
 
         <activity android:name=".ui.prefs.PrefsActivity" />
 

app/src/main/java/com/gaurav/avnc/ui/home/HomeActivity.kt

@@ -11,6 +11,7 @@ package com.gaurav.avnc.ui.home
 import android.app.ActivityOptions
 import android.content.Intent
 import android.net.Uri
+import android.os.Build
 import android.os.Bundle
 import android.util.Log
 import android.view.Window
@@ -47,6 +48,7 @@ class HomeActivity : AppCompatActivity() {
     private val tabs = ServerTabs(this)
 
     override fun onCreate(savedInstanceState: Bundle?) {
+        setTheme(R.style.App_Theme)
         super.onCreate(savedInstanceState)
         window.requestFeature(Window.FEATURE_ACTIVITY_TRANSITIONS)
 
@@ -69,6 +71,7 @@ class HomeActivity : AppCompatActivity() {
         viewModel.discovery.servers.observe(this) { updateDiscoveryBadge(it) }
         viewModel.serverProfiles.observe(this) { updateShortcuts(it) }
 
+        setupSplashTheme()
         showWelcomeMsg()
     }
 
@@ -182,6 +185,22 @@ class HomeActivity : AppCompatActivity() {
         }.isSuccess
     }
 
+    /**
+     * Updates splash theme to match with app theme
+     */
+    private fun setupSplashTheme() {
+        if (Build.VERSION.SDK_INT < 31)
+            return
+
+        viewModel.pref.ui.theme.observe(this) {
+            when (it) {
+                "light" -> splashScreen.setSplashScreenTheme(R.style.App_SplashTheme_Light)
+                "dark" -> splashScreen.setSplashScreenTheme(R.style.App_SplashTheme_Dark)
+                else -> splashScreen.setSplashScreenTheme(R.style.App_SplashTheme)
+            }
+        }
+    }
+
     /************************************************************************************
      * Shortcuts
      ************************************************************************************/

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

@@ -8,7 +8,7 @@
 
 <resources>
 
-    <style name="AppThemeBase" parent="Theme.MaterialComponents.DayNight.NoActionBar">
+    <style name="App.BaseTheme" parent="Theme.MaterialComponents.DayNight.NoActionBar">
         <!-- This matches with appbar background at 4dp elevation-->
         <item name="android:statusBarColor">#272727</item>
     </style>

app/src/main/res/values-v23/styles.xml

@@ -8,7 +8,7 @@
 
 <resources>
 
-    <style name="AppThemeBase" parent="Theme.MaterialComponents.DayNight.NoActionBar">
+    <style name="App.BaseTheme" parent="Theme.MaterialComponents.DayNight.NoActionBar">
         <item name="android:windowLightStatusBar">true</item>
         <!-- Surface color is White-->
         <item name="android:statusBarColor">?colorSurface</item>

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

@@ -9,20 +9,35 @@
 <resources xmlns:tools="http://schemas.android.com/tools">
 
     <!--
-      This is used by startup activities and is intentionally a dark theme.
-      This way we get a dark window on app start irrespective of the theme chosen by user.
+      When app is launched, Android shows a temporary window until the app is ready.
+      The background color for this temporary window is selected from the theme specified
+      for the activity in app manifest. E.g. it will be white for a Light theme.
+
+      If we specify DayNight theme in manifest for startup activity, but user has selected
+      dark theme in AVNC, they may see a white flash before activity starts drawing. To
+      workaround this, we use App.SplashTheme.Dark in the manifest to get a dark window,
+      but switch to main theme in Activity's onCreate().
+
+      Since API 31, Android provides SplashScreen API to change splash theme at runtime,
+      which we use to match the splash theme with user's prefs (see HomeActivity).
+      Note: Some custom ROMs don't respect/support the splash theme introduced in API 31.
+      On such devices, we still rely on the above mentioned workaround.
     -->
-    <style name="SplashTheme" parent="Theme.MaterialComponents.NoActionBar" />
+    <style name="App.SplashTheme" parent="Theme.MaterialComponents.DayNight.NoActionBar" />
+
+    <style name="App.SplashTheme.Light" parent="Theme.MaterialComponents.Light.NoActionBar" />
+
+    <style name="App.SplashTheme.Dark" parent="Theme.MaterialComponents.NoActionBar" />
 
     <!--
       This base theme is used for configuration-specific styling (e.g. night mode, API 23)
     -->
-    <style name="AppThemeBase" parent="Theme.MaterialComponents.DayNight.NoActionBar" />
+    <style name="App.BaseTheme" parent="Theme.MaterialComponents.DayNight.NoActionBar" />
 
     <!--
       This is the main theme.
     -->
-    <style name="AppTheme" parent="AppThemeBase">
+    <style name="App.Theme" parent="App.BaseTheme">
         <item name="appBarLayoutStyle">@style/Widget.MaterialComponents.AppBarLayout.Surface</item>
     </style>