Apply theme for webview

Sets the theme for the web view based on the application theme.
Uses WebKit to check whether the web view supports the
dark mode feature. If yes,
FORCE_DARK_ON - For Dark and True black theme
FORCE_DARK_OFF - Light mode.

ForceDarkStrategy is set as
DARK_STRATEGY_PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING.
In this mode WebView content will be darkened by a user agent
unless web page supports dark theme.


Former-commit-id: 29eb5b9

app/build.gradle

@@ -147,4 +147,8 @@ dependencies {
 
     //Work manager
     implementation 'android.arch.work:work-runtime-ktx:1.0.1'
+
+    //Webkit
+    implementation 'androidx.webkit:webkit:1.4.0'
+
 }

app/src/main/java/com/celzero/bravedns/ui/DNSConfigureWebViewActivity.kt

@@ -34,6 +34,9 @@ import android.widget.Toast
 import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatActivity
 import androidx.lifecycle.MutableLiveData
+import androidx.webkit.WebSettingsCompat
+import androidx.webkit.WebSettingsCompat.DARK_STRATEGY_PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING
+import androidx.webkit.WebViewFeature
 import by.kirich1409.viewbindingdelegate.viewBinding
 import com.celzero.bravedns.R
 import com.celzero.bravedns.database.DoHEndpointRepository
@@ -125,12 +128,47 @@ class DNSConfigureWebViewActivity : AppCompatActivity(R.layout.activity_faq_webv
             }
         })
 
+        setWebViewTheme()
     }
 
     private fun Context.isDarkThemeOn(): Boolean {
         return resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK == Configuration.UI_MODE_NIGHT_YES
     }
 
+    /**
+     * Sets the theme for the webview based on the application theme.
+     * FORCE_DARK_ON - For Dark and True black theme
+     * FORCE_DARK_OFF - Light mode.
+     */
+    private fun setWebViewTheme(){
+        if (persistentState.theme == 0) {
+            if (isDarkThemeOn()) {
+                if (WebViewFeature.isFeatureSupported(WebViewFeature.FORCE_DARK)) {
+                    WebSettingsCompat.setForceDark(b.configureWebview.settings, WebSettingsCompat.FORCE_DARK_ON)
+                }
+            } else {
+                if (WebViewFeature.isFeatureSupported(WebViewFeature.FORCE_DARK)) {
+                    WebSettingsCompat.setForceDark(b.configureWebview.settings, WebSettingsCompat.FORCE_DARK_OFF)
+                }
+            }
+        } else if (persistentState.theme == 1) {
+            if (WebViewFeature.isFeatureSupported(WebViewFeature.FORCE_DARK)) {
+                WebSettingsCompat.setForceDark(b.configureWebview.settings, WebSettingsCompat.FORCE_DARK_OFF)
+            }
+        } else if (persistentState.theme == 2) {
+            if (WebViewFeature.isFeatureSupported(WebViewFeature.FORCE_DARK)) {
+                WebSettingsCompat.setForceDark(b.configureWebview.settings, WebSettingsCompat.FORCE_DARK_ON)
+            }
+        } else {
+            if (WebViewFeature.isFeatureSupported(WebViewFeature.FORCE_DARK)) {
+                WebSettingsCompat.setForceDark(b.configureWebview.settings, WebSettingsCompat.FORCE_DARK_ON)
+            }
+        }
+        if (WebViewFeature.isFeatureSupported(WebViewFeature.FORCE_DARK_STRATEGY)) {
+            WebSettingsCompat.setForceDarkStrategy(b.configureWebview.settings, DARK_STRATEGY_PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING)
+        }
+    }
+
     override fun onDestroy() {
         if (receivedIntentFrom == LOCAL) {
             updateLocalStamp()