Automatic day night theme in settings activity

There seems to be no "DayNight" theme compatible with older version of
android outside of the androidx library.

Using 'Theme.DeviceDefault' which is a dark theme, even if it doesn't
sounds like. Detect if a light theme should be used at activity
creation.

2 files changed, 16 insertions, 1 deletions

diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 4e29f0c..2489589 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -8,7 +8,7 @@
       </intent-filter>
       <meta-data android:name="android.view.im" android:resource="@xml/method"/>
     </service>
-    <activity android:name="juloo.keyboard2.SettingsActivity" android:icon="@drawable/ic_launcher" android:label="@string/settings_activity_label" android:theme="@style/android:Theme.Material">
+    <activity android:name="juloo.keyboard2.SettingsActivity" android:icon="@drawable/ic_launcher" android:label="@string/settings_activity_label" android:theme="@style/android:Theme.DeviceDefault">
       <intent-filter>
         <action android:name="android.intent.action.MAIN"/>
       </intent-filter>
diff --git a/srcs/juloo.keyboard2/SettingsActivity.java b/srcs/juloo.keyboard2/SettingsActivity.java
index 9ec82c5..98cd590 100644
--- a/srcs/juloo.keyboard2/SettingsActivity.java
+++ b/srcs/juloo.keyboard2/SettingsActivity.java
@@ -1,5 +1,7 @@
 package juloo.keyboard2;
 
+import android.content.res.Configuration;
+import android.os.Build;
 import android.os.Bundle;
 import android.preference.PreferenceActivity;
 
@@ -8,7 +10,20 @@ public class SettingsActivity extends PreferenceActivity
   @Override
   public void onCreate(Bundle savedInstanceState)
   {
+    detectSystemTheme();
     super.onCreate(savedInstanceState);
     addPreferencesFromResource(R.xml.settings);
   }
+
+  /** The default theme is [Theme.DeviceDefault], which is dark. Detect if the
+      system is using light theme. */
+  void detectSystemTheme()
+  {
+    if (Build.VERSION.SDK_INT >= 14)
+    {
+      int ui_mode = getResources().getConfiguration().uiMode;
+      if ((ui_mode & Configuration.UI_MODE_NIGHT_NO) != 0)
+        setTheme(android.R.style.Theme_DeviceDefault_Light);
+    }
+  }
 }