fix: reduce darkreader mode white flash further by using QWebEnginePa…

…ge::setBackgroundColor() (for Qt6.6.3+) (#1406)

* fix: reduce darkreader mode white flash further by using
QWebEnginePage::setBackgroundColor() (for Qt6.6.3+)

In previous Qt6.x versions, this function only set background once and
become invalidated if reload a page.

* [autofix.ci] apply automated fixes

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

src/ui/articleview.cc

@@ -155,6 +155,8 @@ ArticleView::ArticleView( QWidget * parent,
 
   webview->setUp( const_cast< Config::Class * >( &cfg ) );
 
+  syncBackgroundColorWithCfgDarkReader();
+
   goBackAction.setShortcut( QKeySequence( "Alt+Left" ) );
   webview->addAction( &goBackAction );
   connect( &goBackAction, &QAction::triggered, this, &ArticleView::back );
@@ -1360,6 +1362,20 @@ void ArticleView::setDelayedHighlightText( QString const & text )
   delayedHighlightText = text;
 }
 
+void ArticleView::syncBackgroundColorWithCfgDarkReader() const
+{
+// Only works Qt6.6.3+ https://bugreports.qt.io/browse/QTBUG-112013
+#if QT_VERSION >= QT_VERSION_CHECK( 6, 6, 3 )
+  if ( cfg.preferences.darkReaderMode ) {
+    webview->page()->setBackgroundColor( Qt::black );
+  }
+  else {
+    webview->page()->setBackgroundColor( Qt::white );
+  }
+#endif
+}
+
+
 void ArticleView::back()
 {
   // Don't allow navigating back to page 0, which is usually the initial

src/ui/articleview.hh

@@ -172,6 +172,9 @@ public:
 
   void setDelayedHighlightText( QString const & text );
 
+  /// \brief Set background as black if darkreader mode is enabled.
+  void syncBackgroundColorWithCfgDarkReader() const;
+
 private:
   // widgets
   ArticleWebView * webview;

src/ui/mainwindow.cc

@@ -2270,7 +2270,7 @@ void MainWindow::editPreferences()
       ArticleView & view = dynamic_cast< ArticleView & >( *( ui.tabWidget->widget( x ) ) );
 
       view.setSelectionBySingleClick( p.selectWordBySingleClick );
-
+      view.syncBackgroundColorWithCfgDarkReader();
       if ( needReload ) {
         view.reload();
       }

src/ui/scanpopup.cc

@@ -291,6 +291,8 @@ void ScanPopup::refresh()
 
   updateDictionaryBar();
 
+  definition->syncBackgroundColorWithCfgDarkReader();
+
   connect( ui.groupList, &GroupComboBox::currentIndexChanged, this, &ScanPopup::currentGroupChanged );
 #ifdef HAVE_X11
   selectionDelayTimer.setInterval( cfg.preferences.selectionChangeDelayTimer );