Paint expanded topics indicator.

Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp

@@ -546,6 +546,7 @@ void InnerWidget::paintEvent(QPaintEvent *e) {
 	auto fullWidth = width();
 	auto dialogsClip = r;
 	const auto ms = crl::now();
+	const auto shownForum = _controller->shownForum().current();
 	const auto paintRow = [&](
 			not_null<Row*> row,
 			bool selected,
@@ -557,6 +558,10 @@ void InnerWidget::paintEvent(QPaintEvent *e) {
 		if (forum && !_topicJumpCache) {
 			_topicJumpCache = std::make_unique<Ui::TopicJumpCache>();
 		}
+		const auto expanded = !active
+			&& forum
+			&& !_openedForum
+			&& (key.history()->peer->forum() == shownForum);
 		Ui::RowPainter::Paint(p, row, validateVideoUserpic(row), {
 			.st = (forum ? &st::forumDialogRow : _st.get()),
 			.topicJumpCache = _topicJumpCache.get(),
@@ -569,6 +574,7 @@ void InnerWidget::paintEvent(QPaintEvent *e) {
 			.selected = (_menuRow.key
 				? (row->key() == _menuRow.key)
 				: selected),
+			.topicsExpanded = expanded,
 			.topicJumpSelected = (selected
 				&& _selectedTopicJump
 				&& (!_pressed || _pressedTopicJump)),

Telegram/SourceFiles/dialogs/ui/dialogs_layout.cpp

@@ -186,6 +186,21 @@ int PaintBadges(
 	return (initial - right);
 }
 
+void PaintExpandedTopicsBar(QPainter &p) {
+	auto hq = PainterHighQualityEnabler(p);
+	const auto radius = st::roundRadiusLarge;
+	const auto width = st::forumDialogRow.padding.left() / 2;
+	p.setPen(Qt::NoPen);
+	p.setBrush(st::dialogsBgActive);
+	p.drawRoundedRect(
+		-3 * radius,
+		st::forumDialogRow.padding.top(),
+		3 * radius + width,
+		st::forumDialogRow.photoSize,
+		radius,
+		radius);
+}
+
 void PaintNarrowCounter(
 		QPainter &p,
 		const PaintContext &context,
@@ -338,6 +353,9 @@ void PaintRow(
 		if (!draft && item && !item->isEmpty()) {
 			PaintNarrowCounter(p, context, badgesState);
 		}
+		if (context.topicsExpanded) {
+			PaintExpandedTopicsBar(p);
+		}
 		return;
 	}
 

Telegram/SourceFiles/dialogs/ui/dialogs_layout.h

@@ -62,6 +62,7 @@ struct PaintContext {
 	int width = 0;
 	bool active = false;
 	bool selected = false;
+	bool topicsExpanded = false;
 	bool topicJumpSelected = false;
 	bool paused = false;
 	bool search = false;