1 files changed, 76 insertions, 0 deletions
diff --git a/app/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.java b/app/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.java
new file mode 100644
index 00000000..250cf0a7
--- /dev/null
+++ b/app/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright © 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+package com.wireguard.android.activity;
+
+import android.content.SharedPreferences;
+import android.content.res.Resources;
+import android.os.Bundle;
+import android.preference.PreferenceManager;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.app.AppCompatDelegate;
+import android.util.Log;
+
+import java.lang.reflect.Field;
+
+public abstract class ThemeChangeAwareActivity extends AppCompatActivity implements SharedPreferences.OnSharedPreferenceChangeListener {
+    private static final String TAG = "WireGuard/" + ThemeChangeAwareActivity.class.getSimpleName();
+
+    private static Resources lastResources;
+    private static boolean lastDarkMode;
+    private static synchronized void invalidateDrawableCache(final Resources resources, final boolean darkMode) {
+        if (resources == lastResources && darkMode == lastDarkMode)
+            return;
+
+        try {
+            Field f;
+            Object o = resources;
+            try {
+                f = o.getClass().getDeclaredField("mResourcesImpl");
+                f.setAccessible(true);
+                o = f.get(o);
+            } catch (final Exception ignored) { }
+            f = o.getClass().getDeclaredField("mDrawableCache");
+            f.setAccessible(true);
+            o = f.get(o);
+            try {
+                o.getClass().getMethod("onConfigurationChange", int.class).invoke(o, -1);
+            } catch (final Exception ignored) {
+                o.getClass().getMethod("clear").invoke(o);
+            }
+        } catch (final Exception e) {
+            Log.e(TAG, "Failed to flush drawable cache", e);
+        }
+
+        lastResources = resources;
+        lastDarkMode = darkMode;
+    }
+
+
+    @Override
+    protected void onCreate(final Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        PreferenceManager.getDefaultSharedPreferences(this).registerOnSharedPreferenceChangeListener(this);
+    }
+
+    @Override
+    protected void onDestroy() {
+        PreferenceManager.getDefaultSharedPreferences(this).unregisterOnSharedPreferenceChangeListener(this);
+        super.onDestroy();
+    }
+
+    @Override
+    public void onSharedPreferenceChanged(final SharedPreferences sharedPreferences, final String key) {
+        if ("dark_theme".equals(key)) {
+            final boolean darkMode = sharedPreferences.getBoolean(key, false);
+            AppCompatDelegate.setDefaultNightMode(
+                    sharedPreferences.getBoolean(key, false) ?
+                            AppCompatDelegate.MODE_NIGHT_YES :
+                            AppCompatDelegate.MODE_NIGHT_NO);
+            invalidateDrawableCache(getResources(), darkMode);
+            recreate();
+        }
+    }
+}