enable dark-mode for licencePage

- add androidx.webkit dependency to support dark mode on webView
- set dark-mode setup for webView in licence page

Android.mk

@@ -34,5 +34,6 @@ LOCAL_STATIC_JAVA_LIBRARIES := cr
 LOCAL_STATIC_ANDROID_LIBRARIES += androidx.legacy_legacy-support-v4
 LOCAL_STATIC_ANDROID_LIBRARIES += androidx.gridlayout_gridlayout
 LOCAL_STATIC_ANDROID_LIBRARIES += androidx.recyclerview_recyclerview
+LOCAL_STATIC_ANDROID_LIBRARIES += androidx.webkit_webkit
 
 include $(BUILD_PACKAGE)

src/com/android/calculator2/Licenses.java

 package com.android.calculator2;
 
 import android.app.Activity;
+import android.content.res.Configuration;
+import android.os.Build;
 import android.os.Bundle;
 import android.view.MenuItem;
 import android.webkit.WebView;
 
+import androidx.webkit.WebViewFeature;
+import androidx.webkit.WebSettingsCompat;
+
 public class Licenses extends Activity {
 
     private static final String LICENSE_URL = "file:///android_asset/licenses.html";
@@ -17,6 +22,18 @@ public class Licenses extends Activity {
         webView.loadUrl(LICENSE_URL);
 
         setContentView(webView);
+
+        handleDayNightMode(webView);
+    }
+
+    private void handleDayNightMode(WebView webView) {
+        if (WebViewFeature.isFeatureSupported(WebViewFeature.FORCE_DARK)) {
+            if (isInDarkMode()) {
+                WebSettingsCompat.setForceDark(webView.getSettings(), WebSettingsCompat.FORCE_DARK_ON);
+            } else {
+                WebSettingsCompat.setForceDark(webView.getSettings(), WebSettingsCompat.FORCE_DARK_AUTO);
+            }
+        }
     }
 
     @Override
@@ -27,4 +44,12 @@ public class Licenses extends Activity {
         }
         return super.onOptionsItemSelected(item);
     }
+
+    private boolean isInDarkMode() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO) {
+            int nightModeFlags = getApplication().getApplicationContext().getResources().getConfiguration().uiMode & Configuration.UI_MODE_NIGHT_MASK;
+            return nightModeFlags == Configuration.UI_MODE_NIGHT_YES;
+        }
+        return false;
+    }
 }