Save scroll top state to media memento.

Telegram/SourceFiles/info/info.style

@@ -150,7 +150,7 @@ infoLayerTopBar: InfoTopBar {
 }
 
 infoMinimalWidth: 324px;
-infoDesiredWidth: 360px;
+infoDesiredWidth: 430px;
 infoMinimalLayerMargin: 48px;
 
 infoTabs: SettingsSlider(defaultTabsSlider) {

Telegram/SourceFiles/info/info_content_widget.cpp

@@ -57,6 +57,10 @@ ContentWidget::ContentWidget(
 }
 
 void ContentWidget::resizeEvent(QResizeEvent *e) {
+	updateControlsGeometry();
+}
+
+void ContentWidget::updateControlsGeometry() {
 	auto newScrollTop = _scroll->scrollTop() + _topDelta;
 	auto scrollGeometry = rect().marginsRemoved(
 		QMargins(0, _scrollTopSkip, 0, 0));
@@ -113,6 +117,10 @@ Ui::RpWidget *ContentWidget::doSetInnerWidget(
 				int desired) {
 			inner->setVisibleTopBottom(top, bottom);
 		}, _inner->lifetime());
+
+	_scrollTopSkip = scrollTopSkip;
+	updateControlsGeometry();
+
 	return _inner;
 }
 

Telegram/SourceFiles/info/info_content_widget.h

@@ -110,6 +110,7 @@ private:
 	RpWidget *doSetInnerWidget(
 		object_ptr<RpWidget> inner,
 		int scrollTopSkip);
+	void updateControlsGeometry();
 
 	const not_null<Window::Controller*> _controller;
 	const not_null<PeerData*> _peer;

Telegram/SourceFiles/info/media/info_media_inner_widget.cpp

@@ -252,9 +252,11 @@ object_ptr<ListWidget> InnerWidget::setupList(
 }
 
 void InnerWidget::saveState(not_null<Memento*> memento) {
+	_list->saveState(memento);
 }
 
 void InnerWidget::restoreState(not_null<Memento*> memento) {
+	_list->restoreState(memento);
 }
 
 rpl::producer<SelectedItems> InnerWidget::selectedListValue() const {

Telegram/SourceFiles/info/media/info_media_list_widget.cpp

@@ -720,6 +720,12 @@ bool ListWidget::isMyItem(not_null<const HistoryItem*> item) const {
 	return (_peer == peer || _peer == peer->migrateTo());
 }
 
+bool ListWidget::isPossiblyMyId(FullMsgId fullId) const {
+	return (fullId.channel != 0)
+		? (_peer->isChannel() && _peer->bareId() == fullId.channel)
+		: (!_peer->isChannel() || _peer->migrateFrom());
+}
+
 bool ListWidget::isItemLayout(
 		not_null<const HistoryItem*> item,
 		BaseLayout *layout) const {
@@ -878,6 +884,29 @@ void ListWidget::markLayoutsStale() {
 	}
 }
 
+void ListWidget::saveState(not_null<Memento*> memento) {
+	if (_universalAroundId != kDefaultAroundId) {
+		memento->setAroundId(computeFullId(_universalAroundId));
+		memento->setIdsLimit(_idsLimit);
+		auto state = countScrollState();
+		memento->setScrollTopItem(computeFullId(state.item));
+		memento->setScrollTopShift(state.shift);
+	}
+}
+
+void ListWidget::restoreState(not_null<Memento*> memento) {
+	if (auto limit = memento->idsLimit()) {
+		auto wasAroundId = memento->aroundId();
+		if (isPossiblyMyId(wasAroundId)) {
+			_idsLimit = limit;
+			_universalAroundId = GetUniversalId(wasAroundId);
+			_scrollTopState.item = GetUniversalId(memento->scrollTopItem());
+			_scrollTopState.shift = memento->scrollTopShift();
+			refreshViewer();
+		}
+	}
+}
+
 int ListWidget::resizeGetHeight(int newWidth) {
 	if (newWidth > 0) {
 		for (auto &section : _sections) {
@@ -887,7 +916,7 @@ int ListWidget::resizeGetHeight(int newWidth) {
 	return recountHeight();
 }
 
-auto ListWidget::findItemByPoint(QPoint point) -> FoundItem {
+auto ListWidget::findItemByPoint(QPoint point) const -> FoundItem {
 	Expects(!_sections.empty());
 	auto sectionIt = findSectionAfterTop(point.y());
 	if (sectionIt == _sections.end()) {
@@ -920,7 +949,7 @@ auto ListWidget::findItemDetails(
 
 auto ListWidget::foundItemInSection(
 		const FoundItem &item,
-		const Section &section) -> FoundItem {
+		const Section &section) const -> FoundItem {
 	return {
 		item.layout,
 		item.geometry.translated(0, section.top()),
@@ -941,7 +970,7 @@ void ListWidget::checkMoveToOtherViewer() {
 	if (width() <= 0
 		|| visibleHeight <= 0
 		|| _sections.empty()
-		|| _scrollTopId) {
+		|| _scrollTopState.item) {
 		return;
 	}
 
@@ -994,34 +1023,39 @@ void ListWidget::checkMoveToOtherViewer() {
 	}
 }
 
-void ListWidget::saveScrollState() {
+auto ListWidget::countScrollState() const -> ScrollTopState {
 	if (_sections.empty()) {
-		_scrollTopId = 0;
-		_scrollTopShift = 0;
-		return;
+		return { 0, 0 };
 	}
 	auto topItem = findItemByPoint({ 0, _visibleTop });
-	_scrollTopId = GetUniversalId(topItem.layout);
-	_scrollTopShift = _visibleTop - topItem.geometry.y();
+	return {
+		GetUniversalId(topItem.layout),
+		_visibleTop - topItem.geometry.y()
+	};
+}
+
+void ListWidget::saveScrollState() {
+	if (!_scrollTopState.item) {
+		_scrollTopState = countScrollState();
+	}
 }
 
 void ListWidget::restoreScrollState() {
-	auto scrollTopId = base::take(_scrollTopId);
-	auto scrollTopShift = base::take(_scrollTopShift);
-	if (_sections.empty() || !scrollTopId) {
+	if (_sections.empty() || !_scrollTopState.item) {
 		return;
 	}
-	auto sectionIt = findSectionByItem(scrollTopId);
+	auto sectionIt = findSectionByItem(_scrollTopState.item);
 	if (sectionIt == _sections.end()) {
 		--sectionIt;
 	}
 	auto item = foundItemInSection(
-		sectionIt->findItemNearId(scrollTopId),
+		sectionIt->findItemNearId(_scrollTopState.item),
 		*sectionIt);
-	auto newVisibleTop = item.geometry.y() + scrollTopShift;
+	auto newVisibleTop = item.geometry.y() + _scrollTopState.shift;
 	if (_visibleTop != newVisibleTop) {
 		_scrollToRequests.fire_copy(newVisibleTop);
 	}
+	_scrollTopState = ScrollTopState();
 }
 
 QMargins ListWidget::padding() const {

Telegram/SourceFiles/info/media/info_media_list_widget.h

@@ -74,6 +74,9 @@ public:
 		clearSelected();
 	}
 
+	void saveState(not_null<Memento*> memento);
+	void restoreState(not_null<Memento*> memento);
+
 	~ListWidget();
 
 protected:
@@ -150,6 +153,10 @@ private:
 		Touch,
 		Other,
 	};
+	struct ScrollTopState {
+		UniversalMsgId item = 0;
+		int shift = 0;
+	};
 
 	void start();
 	int recountHeight();
@@ -160,6 +167,7 @@ private:
 	bool isItemLayout(
 		not_null<const HistoryItem*> item,
 		BaseLayout *layout) const;
+	bool isPossiblyMyId(FullMsgId fullId) const;
 	void repaintItem(const HistoryItem *item);
 	void repaintItem(UniversalMsgId msgId);
 	void repaintItem(const BaseLayout *item);
@@ -229,13 +237,14 @@ private:
 	std::vector<Section>::const_iterator findSectionAfterBottom(
 		std::vector<Section>::const_iterator from,
 		int bottom) const;
-	FoundItem findItemByPoint(QPoint point);
+	FoundItem findItemByPoint(QPoint point) const;
 	base::optional<FoundItem> findItemById(UniversalMsgId universalId);
 	base::optional<FoundItem> findItemDetails(BaseLayout *item);
 	FoundItem foundItemInSection(
 		const FoundItem &item,
-		const Section &section);
+		const Section &section) const;
 
+	ScrollTopState countScrollState() const;
 	void saveScrollState();
 	void restoreScrollState();
 
@@ -268,7 +277,8 @@ private:
 	Type _type = Type::Photo;
 
 	static constexpr auto kMinimalIdsLimit = 16;
-	UniversalMsgId _universalAroundId = (ServerMaxMsgId - 1);
+	static constexpr auto kDefaultAroundId = (ServerMaxMsgId - 1);
+	UniversalMsgId _universalAroundId = kDefaultAroundId;
 	int _idsLimit = kMinimalIdsLimit;
 	SharedMediaMergedSlice _slice;
 
@@ -277,8 +287,7 @@ private:
 
 	int _visibleTop = 0;
 	int _visibleBottom = 0;
-	UniversalMsgId _scrollTopId = 0;
-	int _scrollTopShift = 0;
+	ScrollTopState _scrollTopState;
 	rpl::event_stream<int> _scrollToRequests;
 
 	MouseAction _mouseAction = MouseAction::None;

Telegram/SourceFiles/info/media/info_media_widget.cpp

@@ -104,7 +104,6 @@ void Widget::saveState(not_null<Memento*> memento) {
 
 void Widget::restoreState(not_null<Memento*> memento) {
 	_inner->restoreState(memento);
-	scrollTopRestore(memento->scrollTop());
 }
 
 } // namespace Media

Telegram/SourceFiles/info/media/info_media_widget.h

@@ -52,8 +52,37 @@ public:
 		return _type;
 	}
 
+	void setAroundId(FullMsgId aroundId) {
+		_aroundId = aroundId;
+	}
+	FullMsgId aroundId() const {
+		return _aroundId;
+	}
+	void setIdsLimit(int limit) {
+		_idsLimit = limit;
+	}
+	int idsLimit() const {
+		return _idsLimit;
+	}
+	void setScrollTopItem(FullMsgId item) {
+		_scrollTopItem = item;
+	}
+	FullMsgId scrollTopItem() const {
+		return _scrollTopItem;
+	}
+	void setScrollTopShift(int shift) {
+		_scrollTopShift = shift;
+	}
+	int scrollTopShift() const {
+		return _scrollTopShift;
+	}
+
 private:
 	Type _type = Type::Photo;
+	FullMsgId _aroundId;
+	int _idsLimit = 0;
+	FullMsgId _scrollTopItem;
+	int _scrollTopShift = 0;;
 
 };