Manage unread bar using HistoryView::Element-s.

Telegram/SourceFiles/app.cpp

@@ -1225,6 +1225,9 @@ namespace {
 	}
 
 	History *historyLoaded(const PeerId &peer) {
+		if (!peer) {
+			return nullptr;
+		}
 		return ::histories.find(peer);
 	}
 

Telegram/SourceFiles/base/runtime_composer.h

@@ -190,27 +190,33 @@ public:
 	}
 
 protected:
-	void UpdateComponents(uint64 mask = 0) {
-		if (!_meta()->equals(mask)) {
-			RuntimeComposerBase tmp(mask);
-			tmp.swap(*this);
-			if (_data != zerodata() && tmp._data != zerodata()) {
-				auto meta = _meta(), wasmeta = tmp._meta();
-				for (int i = 0; i < meta->last; ++i) {
-					auto offset = meta->offsets[i];
-					auto wasoffset = wasmeta->offsets[i];
-					if (offset >= sizeof(_meta()) && wasoffset >= sizeof(_meta())) {
-						RuntimeComponentWraps[i].Move(_dataptrunsafe(offset), tmp._dataptrunsafe(wasoffset));
-					}
+	bool UpdateComponents(uint64 mask = 0) {
+		if (_meta()->equals(mask)) {
+			return false;
+		}
+		RuntimeComposerBase result(mask);
+		result.swap(*this);
+		if (_data != zerodata() && result._data != zerodata()) {
+			const auto meta = _meta();
+			const auto wasmeta = result._meta();
+			for (auto i = 0; i != meta->last; ++i) {
+				const auto offset = meta->offsets[i];
+				const auto wasoffset = wasmeta->offsets[i];
+				if (offset >= sizeof(_meta())
+					&& wasoffset >= sizeof(_meta())) {
+					RuntimeComponentWraps[i].Move(
+						_dataptrunsafe(offset),
+						result._dataptrunsafe(wasoffset));
 				}
 			}
 		}
+		return true;
 	}
-	void AddComponents(uint64 mask = 0) {
-		UpdateComponents(_meta()->maskadd(mask));
+	bool AddComponents(uint64 mask = 0) {
+		return UpdateComponents(_meta()->maskadd(mask));
 	}
-	void RemoveComponents(uint64 mask = 0) {
-		UpdateComponents(_meta()->maskremove(mask));
+	bool RemoveComponents(uint64 mask = 0) {
+		return UpdateComponents(_meta()->maskremove(mask));
 	}
 
 private:

Telegram/SourceFiles/history/admin_log/history_admin_log_inner.cpp

@@ -222,7 +222,7 @@ InnerWidget::InnerWidget(
 	Auth().data().viewResizeRequest(
 	) | rpl::start_with_next([this](auto view) {
 		if (view->delegate() == this) {
-			updateSize();
+			resizeItem(view);
 		}
 	}, lifetime());
 	Auth().data().itemViewRefreshRequest(
@@ -1618,6 +1618,10 @@ void InnerWidget::repaintItem(const Element *view) {
 	update(0, itemTop(view), width(), view->height());
 }
 
+void InnerWidget::resizeItem(not_null<Element*> view) {
+	updateSize();
+}
+
 void InnerWidget::refreshItem(not_null<const Element*> view) {
 	// No need to refresh views in admin log.
 }

Telegram/SourceFiles/history/admin_log/history_admin_log_inner.h

@@ -123,6 +123,7 @@ private:
 	int itemTop(not_null<const Element*> view) const;
 	void repaintItem(const Element *view);
 	void refreshItem(not_null<const Element*> view);
+	void resizeItem(not_null<Element*> view);
 	QPoint mapPointToItem(QPoint point, const Element *view) const;
 
 	void showContextMenu(QContextMenuEvent *e, bool showFromTouch = false);

Telegram/SourceFiles/history/history.cpp

@@ -79,13 +79,8 @@ void History::clearLastKeyboard() {
 	lastKeyboardFrom = 0;
 }
 
-bool History::canHaveFromPhotos() const {
-	if (peer->isUser() && !peer->isSelf() && !Adaptive::ChatWide()) {
-		return false;
-	} else if (isChannel() && !peer->isMegagroup()) {
-		return false;
-	}
-	return true;
+int History::height() const {
+	return _height;
 }
 
 void History::setHasPendingResizedItems() {
@@ -259,9 +254,22 @@ bool History::mySendActionUpdated(SendAction::Type type, bool doing) {
 	return true;
 }
 
-bool History::paintSendAction(Painter &p, int x, int y, int availableWidth, int outerWidth, style::color color, TimeMs ms) {
+bool History::paintSendAction(
+		Painter &p,
+		int x,
+		int y,
+		int availableWidth,
+		int outerWidth,
+		style::color color,
+		TimeMs ms) {
 	if (_sendActionAnimation) {
-		_sendActionAnimation.paint(p, color, x, y + st::normalFont->ascent, outerWidth, ms);
+		_sendActionAnimation.paint(
+			p,
+			color,
+			x,
+			y + st::normalFont->ascent,
+			outerWidth,
+			ms);
 		auto animationWidth = _sendActionAnimation.width();
 		x += animationWidth;
 		availableWidth -= animationWidth;
@@ -572,7 +580,11 @@ not_null<History*> Histories::findOrInsert(const PeerId &peerId) {
 	return i.value();
 }
 
-not_null<History*> Histories::findOrInsert(const PeerId &peerId, int32 unreadCount, int32 maxInboxRead, int32 maxOutboxRead) {
+not_null<History*> Histories::findOrInsert(
+		const PeerId &peerId,
+		int unreadCount,
+		MsgId maxInboxRead,
+		MsgId maxOutboxRead) {
 	auto i = map.constFind(peerId);
 	if (i == map.cend()) {
 		auto history = peerIsChannel(peerId)
@@ -1397,6 +1409,23 @@ void History::clearSendAction(not_null<UserData*> from) {
 	}
 }
 
+void History::mainViewRemoved(
+		not_null<HistoryBlock*> block,
+		not_null<HistoryView::Element*> view) {
+	if (lastSentMsg == view->data()) {
+		lastSentMsg = nullptr;
+	}
+	if (_firstUnreadView == view) {
+		getNextFirstUnreadMessage();
+	}
+	if (_unreadBarView == view) {
+		_unreadBarView = nullptr;
+	}
+	if (scrollTopItem == view) {
+		getNextScrollTopItem(block, view->indexInBlock());
+	}
+}
+
 void History::newItemAdded(not_null<HistoryItem*> item) {
 	App::checkImageCacheSize();
 	item->indexAsNewItem();
@@ -1408,9 +1437,7 @@ void History::newItemAdded(not_null<HistoryItem*> item) {
 		from->madeAction(itemServerTime.v);
 	}
 	if (item->out()) {
-		if (unreadBar) {
-			unreadBar->destroyUnreadBar();
-		}
+		destroyUnreadBar();
 		if (!item->unread()) {
 			outboxRead(item);
 		}
@@ -1739,18 +1766,23 @@ int History::countUnread(MsgId upTo) {
 	return result;
 }
 
-void History::updateShowFrom() {
-	if (showFrom) return;
+void History::calculateFirstUnreadMessage() {
+	if (_firstUnreadView) {
+		return;
+	}
 
 	for (auto i = blocks.cend(); i != blocks.cbegin();) {
 		--i;
 		const auto &messages = (*i)->messages;
 		for (auto j = messages.cend(); j != messages.cbegin();) {
 			--j;
-			const auto item = (*j)->data();
-			if (item->id > 0 && (!item->out() || !showFrom)) {
+			const auto view = j->get();
+			const auto item = view->data();
+			if (!IsServerMsgId(item->id)) {
+				continue;
+			} else if (!item->out() || !_firstUnreadView) {
 				if (item->id >= inboxReadBefore) {
-					showFrom = item;
+					_firstUnreadView = view;
 				} else {
 					return;
 				}
@@ -1776,7 +1808,7 @@ MsgId History::inboxRead(MsgId upTo) {
 		}
 	}
 
-	showFrom = nullptr;
+	_firstUnreadView = nullptr;
 	Auth().notifications().clearFromHistory(this);
 
 	return upTo;
@@ -1805,13 +1837,19 @@ HistoryItem *History::lastAvailableMessage() const {
 void History::setUnreadCount(int newUnreadCount) {
 	if (_unreadCount != newUnreadCount) {
 		if (newUnreadCount == 1) {
-			if (loadedAtBottom()) showFrom = lastAvailableMessage();
+			if (loadedAtBottom()) {
+				_firstUnreadView = !isEmpty()
+					? blocks.back()->messages.back().get()
+					: nullptr;
+			}
 			inboxReadBefore = qMax(inboxReadBefore, msgIdForRead());
 		} else if (!newUnreadCount) {
-			showFrom = nullptr;
+			_firstUnreadView = nullptr;
 			inboxReadBefore = qMax(inboxReadBefore, msgIdForRead() + 1);
 		} else {
-			if (!showFrom && !unreadBar && loadedAtBottom()) updateShowFrom();
+			if (!_firstUnreadView && !_unreadBarView && loadedAtBottom()) {
+				calculateFirstUnreadMessage();
+			}
 		}
 		if (inChatList(Dialogs::Mode::All)) {
 			App::histories().unreadIncrement(newUnreadCount - _unreadCount, mute());
@@ -1820,22 +1858,17 @@ void History::setUnreadCount(int newUnreadCount) {
 			}
 		}
 		_unreadCount = newUnreadCount;
-		if (auto main = App::main()) {
-			main->unreadCountChanged(this);
-		}
-		if (unreadBar) {
-			int32 count = _unreadCount;
-			if (peer->migrateTo()) {
-				if (History *h = App::historyLoaded(peer->migrateTo()->id)) {
-					count += h->unreadCount();
-				}
-			}
+		if (_unreadBarView) {
+			const auto count = chatListUnreadCount();
 			if (count > 0) {
-				unreadBar->setUnreadBarCount(count);
+				_unreadBarView->setUnreadBarCount(count);
 			} else {
-				unreadBar->setUnreadBarFreezed();
+				_unreadBarView->setUnreadBarFreezed();
 			}
 		}
+		if (const auto main = App::main()) {
+			main->unreadCountChanged(this);
+		}
 	}
 }
 
@@ -1858,18 +1891,21 @@ bool History::changeMute(bool newMute) {
 	return true;
 }
 
-void History::getNextShowFrom(HistoryBlock *block, int i) {
-	const auto setFromMessage = [&](const auto &message) {
-		const auto item = message->data();
-		if (item->id > 0) {
-			showFrom = item;
+void History::getNextFirstUnreadMessage() {
+	Expects(_firstUnreadView != nullptr);
+
+	const auto block = _firstUnreadView->block();
+	const auto index = _firstUnreadView->indexInBlock();
+	const auto setFromMessage = [&](const auto &view) {
+		if (IsServerMsgId(view->data()->id)) {
+			_firstUnreadView = view.get();
 			return true;
 		}
 		return false;
 	};
-	if (i >= 0) {
-		auto l = block->messages.size();
-		for (++i; i < l; ++i) {
+	if (index >= 0) {
+		const auto count = int(block->messages.size());
+		for (auto i = index + 1; i != count; ++i) {
 			const auto &message = block->messages[i];
 			if (setFromMessage(block->messages[i])) {
 				return;
@@ -1877,15 +1913,15 @@ void History::getNextShowFrom(HistoryBlock *block, int i) {
 		}
 	}
 
-	for (auto j = block->indexInHistory() + 1, s = int(blocks.size()); j < s; ++j) {
-		block = blocks[j].get();
-		for (const auto &message : block->messages) {
+	const auto count = int(blocks.size());
+	for (auto j = block->indexInHistory() + 1; j != count; ++j) {
+		for (const auto &message : blocks[j]->messages) {
 			if (setFromMessage(message)) {
 				return;
 			}
 		}
 	}
-	showFrom = nullptr;
+	_firstUnreadView = nullptr;
 }
 
 QDateTime History::adjustChatListDate() const {
@@ -1976,26 +2012,44 @@ void History::getNextScrollTopItem(HistoryBlock *block, int32 i) {
 }
 
 void History::addUnreadBar() {
-	if (unreadBar || !showFrom || !showFrom->mainView() || !unreadCount()) {
+	if (_unreadBarView || !_firstUnreadView || !unreadCount()) {
 		return;
 	}
-
-	int32 count = unreadCount();
-	if (peer->migrateTo()) {
-		if (History *h = App::historyLoaded(peer->migrateTo()->id)) {
-			count += h->unreadCount();
-		}
+	if (const auto count = chatListUnreadCount()) {
+		_unreadBarView = _firstUnreadView;
+		_unreadBarView->setUnreadBarCount(count);
 	}
-	showFrom->setUnreadBarCount(count);
-	unreadBar = showFrom;
 }
 
 void History::destroyUnreadBar() {
-	if (unreadBar) {
-		unreadBar->destroyUnreadBar();
+	if (const auto view = base::take(_unreadBarView)) {
+		view->destroyUnreadBar();
 	}
 }
 
+bool History::hasNotFreezedUnreadBar() const {
+	if (_firstUnreadView) {
+		if (const auto view = _unreadBarView) {
+			if (const auto bar = view->Get<HistoryView::UnreadBar>()) {
+				return !bar->freezed;
+			}
+		}
+	}
+	return false;
+}
+
+void History::unsetFirstUnreadMessage() {
+	_firstUnreadView = nullptr;
+}
+
+HistoryView::Element *History::unreadBar() const {
+	return _unreadBarView;
+}
+
+HistoryView::Element *History::firstUnreadMessage() const {
+	return _firstUnreadView;
+}
+
 not_null<HistoryItem*> History::addNewInTheMiddle(
 		not_null<HistoryItem*> item,
 		int blockIndex,
@@ -2028,10 +2082,16 @@ not_null<HistoryItem*> History::addNewInTheMiddle(
 
 int History::chatListUnreadCount() const {
 	const auto result = unreadCount();
-	if (const auto from = peer->migrateFrom()) {
-		if (const auto migrated = App::historyLoaded(from)) {
-			return result + migrated->unreadCount();
+	const auto addFromId = [&] {
+		if (const auto from = peer->migrateFrom()) {
+			return from->id;
+		} else if (const auto to = peer->migrateTo()) {
+			return to->id;
 		}
+		return PeerId(0);
+	}();
+	if (const auto migrated = App::historyLoaded(addFromId)) {
+		return result + migrated->unreadCount();
 	}
 	return result;
 }
@@ -2108,10 +2168,10 @@ bool History::isReadyFor(MsgId msgId) {
 		return loadedAtBottom();
 	}
 	if (msgId == ShowAtUnreadMsgId) {
-		if (peer->migrateFrom()) { // old group history
-			if (History *h = App::historyLoaded(peer->migrateFrom()->id)) {
-				if (h->unreadCount()) {
-					return h->isReadyFor(msgId);
+		if (const auto migratePeer = peer->migrateFrom()) {
+			if (const auto migrated = App::historyLoaded(migratePeer)) {
+				if (migrated->unreadCount()) {
+					return migrated->isReadyFor(msgId);
 				}
 			}
 		}
@@ -2136,12 +2196,14 @@ void History::getReadyFor(MsgId msgId) {
 		}
 		return;
 	}
-	if (msgId == ShowAtUnreadMsgId && peer->migrateFrom()) {
-		if (auto h = App::historyLoaded(peer->migrateFrom()->id)) {
-			if (h->unreadCount()) {
-				clear(true);
-				h->getReadyFor(msgId);
-				return;
+	if (msgId == ShowAtUnreadMsgId) {
+		if (const auto migratePeer = peer->migrateFrom()) {
+			if (const auto migrated = App::historyLoaded(migratePeer)) {
+				if (migrated->unreadCount()) {
+					clear(true);
+					migrated->getReadyFor(msgId);
+					return;
+				}
 			}
 		}
 	}
@@ -2194,7 +2256,7 @@ bool History::needUpdateInChatList() const {
 }
 
 void History::fixLastMessage(bool wasAtBottom) {
-	setLastMessage(wasAtBottom ? lastAvailableMessage() : 0);
+	setLastMessage(wasAtBottom ? lastAvailableMessage() : nullptr);
 }
 
 MsgId History::minMsgId() const {
@@ -2227,22 +2289,21 @@ MsgId History::msgIdForRead() const {
 	return result;
 }
 
-int History::resizeGetHeight(int newWidth) {
-	const auto resizeAllItems = (width != newWidth);
+void History::resizeToWidth(int newWidth) {
+	const auto resizeAllItems = (_width != newWidth);
 
 	if (!resizeAllItems && !hasPendingResizedItems()) {
-		return height;
+		return;
 	}
 	_flags &= ~(Flag::f_has_pending_resized_items);
 
-	width = newWidth;
+	_width = newWidth;
 	int y = 0;
 	for (const auto &block : blocks) {
 		block->setY(y);
 		y += block->resizeGetHeight(newWidth, resizeAllItems);
 	}
-	height = y;
-	return height;
+	_height = y;
 }
 
 ChannelHistory *History::asChannelHistory() {
@@ -2295,11 +2356,11 @@ bool History::removeOrphanMediaGroupPart() {
 }
 
 void History::clear(bool leaveItems) {
-	if (unreadBar) {
-		unreadBar = nullptr;
+	if (_unreadBarView) {
+		_unreadBarView = nullptr;
 	}
-	if (showFrom) {
-		showFrom = nullptr;
+	if (_firstUnreadView) {
+		_firstUnreadView = nullptr;
 	}
 	if (lastSentMsg) {
 		lastSentMsg = nullptr;
@@ -2475,22 +2536,11 @@ void HistoryBlock::clear(bool leaveItems) {
 void HistoryBlock::remove(not_null<Element*> view) {
 	Expects(view->block() == this);
 
-	const auto item = view->data();
-	auto blockIndex = indexInHistory();
-	auto itemIndex = view->indexInBlock();
-	if (_history->showFrom == item) {
-		_history->getNextShowFrom(this, itemIndex);
-	}
-	if (_history->lastSentMsg == item) {
-		_history->lastSentMsg = nullptr;
-	}
-	if (_history->unreadBar == item) {
-		_history->unreadBar = nullptr;
-	}
-	if (_history->scrollTopItem && _history->scrollTopItem->data() == item) {
-		_history->getNextScrollTopItem(this, itemIndex);
-	}
+	_history->mainViewRemoved(this, view);
 
+	const auto blockIndex = indexInHistory();
+	const auto itemIndex = view->indexInBlock();
+	const auto item = view->data();
 	item->clearMainView();
 	messages.erase(messages.begin() + itemIndex);
 	for (auto i = itemIndex, l = int(messages.size()); i < l; ++i) {

Telegram/SourceFiles/history/history.h

@@ -47,7 +47,11 @@ public:
 
 	History *find(const PeerId &peerId);
 	not_null<History*> findOrInsert(const PeerId &peerId);
-	not_null<History*> findOrInsert(const PeerId &peerId, int32 unreadCount, int32 maxInboxRead, int32 maxOutboxRead);
+	not_null<History*> findOrInsert(
+		const PeerId &peerId,
+		int unreadCount,
+		MsgId maxInboxRead,
+		MsgId maxOutboxRead);
 
 	void clear();
 	void remove(const PeerId &peer);
@@ -153,8 +157,6 @@ public:
 
 	void applyGroupAdminChanges(const base::flat_map<UserId, bool> &changes);
 
-	virtual ~History();
-
 	HistoryItem *addNewMessage(const MTPMessage &msg, NewMessageType type);
 	HistoryItem *addToHistory(const MTPMessage &msg);
 	not_null<HistoryItem*> addNewService(MsgId msgId, QDateTime date, const QString &text, MTPDmessage::Flags flags = 0, bool newMsg = true);
@@ -176,14 +178,11 @@ public:
 	void newItemAdded(not_null<HistoryItem*> item);
 
 	int countUnread(MsgId upTo);
-	void updateShowFrom();
 	MsgId inboxRead(MsgId upTo);
 	MsgId inboxRead(HistoryItem *wasRead);
 	MsgId outboxRead(MsgId upTo);
 	MsgId outboxRead(HistoryItem *wasRead);
 
-	HistoryItem *lastAvailableMessage() const;
-
 	int unreadCount() const {
 		return _unreadCount;
 	}
@@ -192,9 +191,13 @@ public:
 		return _mute;
 	}
 	bool changeMute(bool newMute);
-	void getNextShowFrom(HistoryBlock *block, int i);
 	void addUnreadBar();
 	void destroyUnreadBar();
+	bool hasNotFreezedUnreadBar() const;
+	HistoryView::Element *unreadBar() const;
+	void calculateFirstUnreadMessage();
+	void unsetFirstUnreadMessage();
+	HistoryView::Element *firstUnreadMessage() const;
 	void clearNotifications();
 
 	bool loadedAtBottom() const; // last message is in the list
@@ -210,7 +213,7 @@ public:
 	MsgId maxMsgId() const;
 	MsgId msgIdForRead() const;
 
-	int resizeGetHeight(int newWidth);
+	void resizeToWidth(int newWidth);
 
 	void removeNotification(HistoryItem *item) {
 		if (!notifies.isEmpty()) {
@@ -254,10 +257,6 @@ public:
 
 	void clearLastKeyboard();
 
-	// optimization for userpics displayed on the left
-	// if this returns false there is no need to even try to handle them
-	bool canHaveFromPhotos() const;
-
 	int getUnreadMentionsLoadedCount() const {
 		return _unreadMentions.size();
 	}
@@ -278,25 +277,6 @@ public:
 	void eraseFromUnreadMentions(MsgId msgId);
 	void addUnreadMentionsSlice(const MTPmessages_Messages &result);
 
-	std::deque<std::unique_ptr<HistoryBlock>> blocks;
-
-	int width = 0;
-	int height = 0;
-	int32 msgCount = 0;
-	MsgId inboxReadBefore = 1;
-	MsgId outboxReadBefore = 1;
-	HistoryItem *showFrom = nullptr;
-	HistoryItem *unreadBar = nullptr;
-
-	not_null<PeerData*> peer;
-	bool oldLoaded = false;
-	bool newLoaded = true;
-	HistoryItem *lastMsg = nullptr;
-	HistoryItem *lastSentMsg = nullptr;
-
-	typedef QList<HistoryItem*> NotifyQueue;
-	NotifyQueue notifies;
-
 	Data::Draft *localDraft() const {
 		return _localDraft.get();
 	}
@@ -340,9 +320,33 @@ public:
 		int y,
 		int size) const override;
 
-	// some fields below are a property of a currently displayed instance of this
-	// conversation history not a property of the conversation history itself
-public:
+	void forgetScrollState() {
+		scrollTopItem = nullptr;
+	}
+
+	// find the correct scrollTopItem and scrollTopOffset using given top
+	// of the displayed window relative to the history start coordinate
+	void countScrollState(int top);
+
+	virtual ~History();
+
+	// Still public data.
+	std::deque<std::unique_ptr<HistoryBlock>> blocks;
+
+	int height() const;
+	int32 msgCount = 0;
+	MsgId inboxReadBefore = 1;
+	MsgId outboxReadBefore = 1;
+
+	not_null<PeerData*> peer;
+	bool oldLoaded = false;
+	bool newLoaded = true;
+	HistoryItem *lastMsg = nullptr;
+	HistoryItem *lastSentMsg = nullptr;
+
+	typedef QList<HistoryItem*> NotifyQueue;
+	NotifyQueue notifies;
+
 	// we save the last showAtMsgId to restore the state when switching
 	// between different conversation histories
 	MsgId showAtMsgId = ShowAtUnreadMsgId;
@@ -352,25 +356,7 @@ public:
 	// resulting scrollTop = top(scrollTopItem) + scrollTopOffset
 	HistoryView::Element *scrollTopItem = nullptr;
 	int scrollTopOffset = 0;
-	void forgetScrollState() {
-		scrollTopItem = nullptr;
-	}
 
-	// find the correct scrollTopItem and scrollTopOffset using given top
-	// of the displayed window relative to the history start coord
-	void countScrollState(int top);
-
-protected:
-	// when this item is destroyed scrollTopItem just points to the next one
-	// and scrollTopOffset remains the same
-	// if we are at the bottom of the window scrollTopItem == nullptr and
-	// scrollTopOffset is undefined
-	void getNextScrollTopItem(HistoryBlock *block, int32 i);
-
-	// helper method for countScrollState(int top)
-	void countScrollTopItem(int top);
-
-public:
 	bool lastKeyboardInited = false;
 	bool lastKeyboardUsed = false;
 	MsgId lastKeyboardId = 0;
@@ -382,11 +368,18 @@ public:
 	Text cloudDraftTextCache;
 
 protected:
+	// when this item is destroyed scrollTopItem just points to the next one
+	// and scrollTopOffset remains the same
+	// if we are at the bottom of the window scrollTopItem == nullptr and
+	// scrollTopOffset is undefined
+	void getNextScrollTopItem(HistoryBlock *block, int32 i);
+
+	// helper method for countScrollState(int top)
+	void countScrollTopItem(int top);
+
 	void clearOnDestroy();
 	HistoryItem *addNewToLastBlock(const MTPMessage &msg, NewMessageType type);
 
-	friend class HistoryBlock;
-
 	// this method just removes a block from the blocks list
 	// when the last item from this block was detached and
 	// calls the required previousItemChanged()
@@ -425,6 +418,20 @@ protected:
 	}
 
 private:
+	friend class HistoryBlock;
+
+	enum class Flag {
+		f_has_pending_resized_items = (1 << 0),
+	};
+	using Flags = base::flags<Flag>;
+	friend inline constexpr auto is_flag_type(Flag) {
+		return true;
+	};
+
+	void mainViewRemoved(
+		not_null<HistoryBlock*> block,
+		not_null<HistoryView::Element*> view);
+
 	QDateTime adjustChatListDate() const override;
 	void removeDialog() override;
 	void changedInChatListHook(Dialogs::Mode list, bool added) override;
@@ -451,15 +458,20 @@ private:
 	void addItemsToLists(const std::vector<not_null<HistoryItem*>> &items);
 	void clearSendAction(not_null<UserData*> from);
 
-	enum class Flag {
-		f_has_pending_resized_items = (1 << 0),
-	};
-	using Flags = base::flags<Flag>;
-	friend inline constexpr auto is_flag_type(Flag) { return true; };
+	HistoryItem *lastAvailableMessage() const;
+	void getNextFirstUnreadMessage();
+
+	// Creates if necessary a new block for adding item.
+	// Depending on isBuildingFrontBlock() gets front or back block.
+	HistoryBlock *prepareBlockForAddingItem();
 
 	Flags _flags = 0;
 	bool _mute = false;
 	int _unreadCount = 0;
+	int _width = 0;
+	int _height = 0;
+	HistoryView::Element *_unreadBarView = nullptr;
+	HistoryView::Element *_firstUnreadView = nullptr;
 
 	base::optional<int> _unreadMentionsCount;
 	base::flat_set<MsgId> _unreadMentions;
@@ -473,10 +485,6 @@ private:
 	};
 	std::unique_ptr<BuildingBlock> _buildingFrontBlock;
 
-	// Creates if necessary a new block for adding item.
-	// Depending on isBuildingFrontBlock() gets front or back block.
-	HistoryBlock *prepareBlockForAddingItem();
-
 	std::unique_ptr<Data::Draft> _localDraft, _cloudDraft;
 	std::unique_ptr<Data::Draft> _editDraft;
 	MessageIdsList _forwardDraft;

Telegram/SourceFiles/history/history_inner_widget.cpp

@@ -217,7 +217,7 @@ void HistoryInner::enumerateItemsInHistory(History *history, int historytop, Met
 	if (historytop < 0 || history->isEmpty()) {
 		return;
 	}
-	if (_visibleAreaBottom <= historytop || historytop + history->height <= _visibleAreaTop) {
+	if (_visibleAreaBottom <= historytop || historytop + history->height() <= _visibleAreaTop) {
 		return;
 	}
 
@@ -302,9 +302,18 @@ void HistoryInner::enumerateItemsInHistory(History *history, int historytop, Met
 	}
 }
 
+bool HistoryInner::canHaveFromUserpics() const {
+	if (_peer->isUser() && !_peer->isSelf() && !Adaptive::ChatWide()) {
+		return false;
+	} else if (_peer->isChannel() && !_peer->isMegagroup()) {
+		return false;
+	}
+	return true;
+}
+
 template <typename Method>
 void HistoryInner::enumerateUserpics(Method method) {
-	if ((!_history || !_history->canHaveFromPhotos()) && (!_migrated || !_migrated->canHaveFromPhotos())) {
+	if (!canHaveFromUserpics()) {
 		return;
 	}
 
@@ -620,7 +629,7 @@ void HistoryInner::paintEvent(QPaintEvent *e) {
 						p,
 						st::historyPhotoLeft,
 						userpicTop,
-						message->history()->width,
+						width(),
 						st::msgPhotoSize);
 				}
 				return true;
@@ -635,6 +644,7 @@ void HistoryInner::paintEvent(QPaintEvent *e) {
 			//// if item top is before this value always show date as a floating date
 			//int showFloatingBefore = height() - 2 * (_visibleAreaBottom - _visibleAreaTop) - dateHeight;
 
+
 			auto scrollDateOpacity = _scrollDateOpacity.current(ms, _scrollDateShown ? 1. : 0.);
 			enumerateDates([&](not_null<Element*> view, int itemtop, int dateTop) {
 				// stop the enumeration if the date is above the painted rect
@@ -661,16 +671,17 @@ void HistoryInner::paintEvent(QPaintEvent *e) {
 					auto opacity = (dateInPlace/* || noFloatingDate*/) ? 1. : scrollDateOpacity;
 					if (opacity > 0.) {
 						p.setOpacity(opacity);
-						int dateY = /*noFloatingDate ? itemtop :*/ (dateTop - st::msgServiceMargin.top());
-						int width = item->history()->width;
+						const auto dateY = false // noFloatingDate
+							? itemtop
+							: (dateTop - st::msgServiceMargin.top());
 						if (const auto date = item->Get<HistoryMessageDate>()) {
-							date->paint(p, dateY, width);
+							date->paint(p, dateY, _contentWidth);
 						} else {
 							HistoryView::ServiceMessagePainter::paintDate(
 								p,
 								item->date,
 								dateY,
-								width);
+								_contentWidth);
 						}
 					}
 				}
@@ -1825,15 +1836,17 @@ void HistoryInner::keyPressEvent(QKeyEvent *e) {
 }
 
 void HistoryInner::recountHistoryGeometry() {
-	int visibleHeight = _scroll->height();
+	_contentWidth = _scroll->width();
+
+	const auto visibleHeight = _scroll->height();
 	int oldHistoryPaddingTop = qMax(visibleHeight - historyHeight() - st::historyPaddingBottom, 0);
 	if (_botAbout && !_botAbout->info->text.isEmpty()) {
 		accumulate_max(oldHistoryPaddingTop, st::msgMargin.top() + st::msgMargin.bottom() + st::msgPadding.top() + st::msgPadding.bottom() + st::msgNameFont->height + st::botDescSkip + _botAbout->height);
 	}
 
-	_history->resizeGetHeight(_scroll->width());
+	_history->resizeToWidth(_contentWidth);
 	if (_migrated) {
-		_migrated->resizeGetHeight(_scroll->width());
+		_migrated->resizeToWidth(_contentWidth);
 	}
 
 	// with migrated history we perhaps do not need to display first _history message
@@ -2339,7 +2352,7 @@ void HistoryInner::onUpdateSelected() {
 					}
 					dateWidth += st::msgServicePadding.left() + st::msgServicePadding.right();
 					auto dateLeft = st::msgServiceMargin.left();
-					auto maxwidth = item->history()->width;
+					auto maxwidth = _contentWidth;
 					if (Adaptive::ChatWide()) {
 						maxwidth = qMin(maxwidth, int32(st::msgMaxWidth + 2 * st::msgPhotoSkip + 2 * st::msgMargin.left()));
 					}
@@ -2549,9 +2562,9 @@ void HistoryInner::updateDragSelection(Element *dragSelFrom, Element *dragSelTo,
 int HistoryInner::historyHeight() const {
 	int result = 0;
 	if (!_history || _history->isEmpty()) {
-		result += _migrated ? _migrated->height : 0;
+		result += _migrated ? _migrated->height() : 0;
 	} else {
-		result += _history->height - _historySkipHeight + (_migrated ? _migrated->height : 0);
+		result += _history->height() - _historySkipHeight + (_migrated ? _migrated->height() : 0);
 	}
 	return result;
 }
@@ -2574,7 +2587,7 @@ int HistoryInner::migratedTop() const {
 
 int HistoryInner::historyTop() const {
 	int mig = migratedTop();
-	return (_history && !_history->isEmpty()) ? (mig >= 0 ? (mig + _migrated->height - _historySkipHeight) : _historyPaddingTop) : -1;
+	return (_history && !_history->isEmpty()) ? (mig >= 0 ? (mig + _migrated->height() - _historySkipHeight) : _historyPaddingTop) : -1;
 }
 
 int HistoryInner::historyDrawTop() const {

Telegram/SourceFiles/history/history_inner_widget.h

@@ -181,6 +181,7 @@ private:
 	template <typename Method>
 	void enumerateDates(Method method);
 
+	bool canHaveFromUserpics() const;
 	void mouseActionStart(const QPoint &screenPos, Qt::MouseButton button);
 	void mouseActionUpdate(const QPoint &screenPos);
 	void mouseActionFinish(const QPoint &screenPos, Qt::MouseButton button);
@@ -276,6 +277,7 @@ private:
 	not_null<PeerData*> _peer;
 	not_null<History*> _history;
 	History *_migrated = nullptr;
+	int _contentWidth = 0;
 	int _historyPaddingTop = 0;
 
 	// with migrated history we perhaps do not need to display first _history message

Telegram/SourceFiles/history/history_item.cpp

@@ -577,47 +577,6 @@ bool HistoryItem::unread() const {
 	return (_flags & MTPDmessage_ClientFlag::f_clientside_unread);
 }
 
-void HistoryItem::destroyUnreadBar() {
-	if (Has<HistoryMessageUnreadBar>()) {
-		Assert(!isLogEntry());
-
-		RemoveComponents(HistoryMessageUnreadBar::Bit());
-		Auth().data().requestItemResize(this);
-		if (_history->unreadBar == this) {
-			_history->unreadBar = nullptr;
-		}
-		// #TODO recount attach to previous
-	}
-}
-
-void HistoryItem::setUnreadBarCount(int count) {
-	Expects(!isLogEntry());
-
-	if (count > 0) {
-		if (!Has<HistoryMessageUnreadBar>()) {
-			AddComponents(HistoryMessageUnreadBar::Bit());
-			Auth().data().requestItemResize(this);
-			// #TODO recount attach to previous
-		}
-		const auto bar = Get<HistoryMessageUnreadBar>();
-		if (bar->_freezed) {
-			return;
-		}
-		bar->init(count);
-		Auth().data().requestItemRepaint(this);
-	} else {
-		destroyUnreadBar();
-	}
-}
-
-void HistoryItem::setUnreadBarFreezed() {
-	Expects(!isLogEntry());
-
-	if (const auto bar = Get<HistoryMessageUnreadBar>()) {
-		bar->_freezed = true;
-	}
-}
-
 MessageGroupId HistoryItem::groupId() const {
 	return _groupId;
 }

Telegram/SourceFiles/history/history_item.h

@@ -244,17 +244,6 @@ public:
 	QString authorOriginal() const;
 	MsgId idOriginal() const;
 
-	// count > 0 - creates the unread bar if necessary and
-	// sets unread messages count if bar is not freezed yet
-	// count <= 0 - destroys the unread bar
-	void setUnreadBarCount(int count);
-	void destroyUnreadBar();
-
-	// marks the unread bar as freezed so that unread
-	// messages count will not change for this bar
-	// when the new messages arrive in this chat history
-	void setUnreadBarFreezed();
-
 	int displayedDateHeight() const;
 	bool displayDate() const;
 

Telegram/SourceFiles/history/history_item_components.cpp

@@ -798,36 +798,6 @@ void HistoryMessageReplyMarkup::create(
 	}
 }
 
-void HistoryMessageUnreadBar::init(int count) {
-	if (_freezed) return;
-	_text = lng_unread_bar(lt_count, count);
-	_width = st::semiboldFont->width(_text);
-}
-
-int HistoryMessageUnreadBar::height() {
-	return st::historyUnreadBarHeight + st::historyUnreadBarMargin;
-}
-
-int HistoryMessageUnreadBar::marginTop() {
-	return st::lineWidth + st::historyUnreadBarMargin;
-}
-
-void HistoryMessageUnreadBar::paint(Painter &p, int y, int w) const {
-	p.fillRect(0, y + marginTop(), w, height() - marginTop() - st::lineWidth, st::historyUnreadBarBg);
-	p.fillRect(0, y + height() - st::lineWidth, w, st::lineWidth, st::historyUnreadBarBorder);
-	p.setFont(st::historyUnreadBarFont);
-	p.setPen(st::historyUnreadBarFg);
-
-	int left = st::msgServiceMargin.left();
-	int maxwidth = w;
-	if (Adaptive::ChatWide()) {
-		maxwidth = qMin(maxwidth, int32(st::msgMaxWidth + 2 * st::msgPhotoSkip + 2 * st::msgMargin.left()));
-	}
-	w = maxwidth;
-
-	p.drawText((w - _width) / 2, y + marginTop() + (st::historyUnreadBarHeight - 2 * st::lineWidth - st::historyUnreadBarFont->height) / 2 + st::historyUnreadBarFont->ascent, _text);
-}
-
 void HistoryMessageDate::init(const QDateTime &date) {
 	_text = langDayOfMonthFull(date.date());
 	_width = st::msgServiceFont->width(_text);

Telegram/SourceFiles/history/history_item_components.h

@@ -335,29 +335,6 @@ struct HistoryMessageDate : public RuntimeComponent<HistoryMessageDate, HistoryI
 	int _width = 0;
 };
 
-// Any HistoryItem can have this Component for
-// displaying the unread messages bar above the message.
-struct HistoryMessageUnreadBar : public RuntimeComponent<HistoryMessageUnreadBar, HistoryItem> {
-	void init(int count);
-
-	static int height();
-	static int marginTop();
-
-	void paint(Painter &p, int y, int w) const;
-
-	QString _text;
-	int _width = 0;
-
-	// If unread bar is freezed the new messages do not
-	// increment the counter displayed by this bar.
-	//
-	// It happens when we've opened the conversation and
-	// we've seen the bar and new messages are marked as read
-	// as soon as they are added to the chat history.
-	bool _freezed = false;
-
-};
-
 // Special type of Component for the channel actions log.
 struct HistoryMessageLogEntryOriginal
 	: public RuntimeComponent<HistoryMessageLogEntryOriginal, HistoryItem> {

Telegram/SourceFiles/history/history_media_types.cpp

@@ -2363,9 +2363,8 @@ void HistoryGif::draw(Painter &p, const QRect &r, TextSelection selection, TimeM
 	} else if (!inWebPage) {
 		auto fullRight = paintx + usex + usew;
 		auto fullBottom = painty + painth;
-		auto maxRight = item->history()->width - st::msgMargin.left();
-		// #TODO view media
-		if (item->history()->canHaveFromPhotos()) {
+		auto maxRight = _parent->width() - st::msgMargin.left();
+		if (_parent->hasFromPhoto()) {
 			maxRight -= st::msgMargin.right();
 		} else {
 			maxRight -= st::msgMargin.left();
@@ -2505,9 +2504,8 @@ HistoryTextState HistoryGif::getState(QPoint point, HistoryStateRequest request)
 	if (isRound || _caption.isEmpty()) {
 		auto fullRight = usex + paintx + usew;
 		auto fullBottom = painty + painth;
-		// #TODO view media
-		auto maxRight = _parent->data()->history()->width - st::msgMargin.left();
-		if (_parent->data()->history()->canHaveFromPhotos()) {
+		auto maxRight = _parent->width() - st::msgMargin.left();
+		if (_parent->hasFromPhoto()) {
 			maxRight -= st::msgMargin.right();
 		} else {
 			maxRight -= st::msgMargin.left();

Telegram/SourceFiles/history/history_widget.cpp

@@ -2204,6 +2204,13 @@ void HistoryWidget::destroyUnreadBar() {
 
 void HistoryWidget::newUnreadMsg(History *history, HistoryItem *item) {
 	if (_history == history) {
+		// If we get here in non-resized state we can't rely on results of
+		// doWeReadServerHistory() and mark chat as read.
+		// If we receive N messages being not at bottom:
+		// - on first message we set unreadcount += 1, firstUnreadMessage.
+		// - on second we get wrong doWeReadServerHistory() and read both.
+		Auth().data().sendHistoryChangeNotifications();
+
 		if (_scroll->scrollTop() + 1 > _scroll->scrollTopMax()) {
 			destroyUnreadBar();
 		}
@@ -2229,10 +2236,12 @@ void HistoryWidget::historyToDown(History *history) {
 	}
 }
 
-void HistoryWidget::unreadCountChanged(History *history) {
+void HistoryWidget::unreadCountChanged(not_null<History*> history) {
 	if (history == _history || history == _migrated) {
 		updateHistoryDownVisibility();
-		_historyDown->setUnreadCount(_history->unreadCount() + (_migrated ? _migrated->unreadCount() : 0));
+		_historyDown->setUnreadCount(
+			_history->unreadCount()
+			+ (_migrated ? _migrated->unreadCount() : 0));
 	}
 }
 
@@ -2452,16 +2461,15 @@ bool HistoryWidget::doWeReadServerHistory() const {
 		int scrollTop = _scroll->scrollTop();
 		if (scrollTop + 1 > _scroll->scrollTopMax()) return true;
 
-		auto showFrom = (_migrated && _migrated->showFrom) ? _migrated->showFrom : (_history ? _history->showFrom : nullptr);
-		if (showFrom && showFrom->mainView()) {
-			int scrollBottom = scrollTop + _scroll->height();
-			if (scrollBottom > _list->itemTop(showFrom)) return true;
+		if (const auto unread = firstUnreadMessage()) {
+			const auto scrollBottom = scrollTop + _scroll->height();
+			if (scrollBottom > _list->itemTop(unread)) {
+				return true;
+			}
 		}
 	}
-	if (historyHasNotFreezedUnreadBar(_history)) {
-		return true;
-	}
-	if (historyHasNotFreezedUnreadBar(_migrated)) {
+	if (_history->hasNotFreezedUnreadBar()
+		|| (_migrated && _migrated->hasNotFreezedUnreadBar())) {
 		return true;
 	}
 	return false;
@@ -2473,15 +2481,6 @@ bool HistoryWidget::doWeReadMentions() const {
 	return true;
 }
 
-bool HistoryWidget::historyHasNotFreezedUnreadBar(History *history) const {
-	if (history && history->showFrom && history->showFrom->mainView() && history->unreadBar) {
-		if (auto unreadBar = history->unreadBar->Get<HistoryMessageUnreadBar>()) {
-			return !unreadBar->_freezed;
-		}
-	}
-	return false;
-}
-
 void HistoryWidget::firstLoadMessages() {
 	if (!_history || _firstLoadRequest) return;
 
@@ -2707,10 +2706,12 @@ void HistoryWidget::visibleAreaUpdated() {
 		auto scrollBottom = scrollTop + _scroll->height();
 		_list->visibleAreaUpdated(scrollTop, scrollBottom);
 		if (_history->loadedAtBottom() && (_history->unreadCount() > 0 || (_migrated && _migrated->unreadCount() > 0))) {
-			auto showFrom = (_migrated && _migrated->showFrom) ? _migrated->showFrom : (_history ? _history->showFrom : nullptr);
-			auto showFromVisible = (showFrom && showFrom->mainView() && scrollBottom > _list->itemTop(showFrom));
-			auto atBottom = (scrollTop >= _scroll->scrollTopMax());
-			if ((showFromVisible || atBottom) && App::wnd()->doWeReadServerHistory()) {
+			const auto unread = firstUnreadMessage();
+			const auto unreadVisible = unread
+				&& (scrollBottom > _list->itemTop(unread));
+			const auto atBottom = (scrollTop >= _scroll->scrollTopMax());
+			if ((unreadVisible || atBottom)
+				 && App::wnd()->doWeReadServerHistory()) {
 				Auth().api().readServerHistory(_history);
 			}
 		}
@@ -4694,8 +4695,8 @@ int HistoryWidget::countInitialScrollTop() {
 			result = itemTopForHighlight(view);
 			enqueueMessageHighlight(view);
 		}
-	} else if (_history->unreadBar || (_migrated && _migrated->unreadBar)) {
-		result = unreadBarTop();
+	} else if (const auto top = unreadBarTop()) {
+		result = *top;
 	} else {
 		return countAutomaticScrollTop();
 	}
@@ -4704,28 +4705,18 @@ int HistoryWidget::countInitialScrollTop() {
 
 int HistoryWidget::countAutomaticScrollTop() {
 	auto result = ScrollMax;
-	if (_migrated && _migrated->showFrom) {
-		result = _list->itemTop(_migrated->showFrom);
-		if (result < _scroll->scrollTopMax() + HistoryMessageUnreadBar::height() - HistoryMessageUnreadBar::marginTop()) {
-			_migrated->addUnreadBar();
+	if (const auto unread = firstUnreadMessage()) {
+		result = _list->itemTop(unread);
+		const auto possibleUnreadBarTop = _scroll->scrollTopMax()
+			+ HistoryView::UnreadBar::height()
+			- HistoryView::UnreadBar::marginTop();
+		if (result < possibleUnreadBarTop) {
+			const auto history = unread->data()->history();
+			history->addUnreadBar();
 			if (hasPendingResizedItems()) {
 				updateListSize();
 			}
-			if (_migrated->unreadBar) {
-				setMsgId(ShowAtUnreadMsgId);
-				result = countInitialScrollTop();
-				App::wnd()->checkHistoryActivation();
-				return result;
-			}
-		}
-	} else if (_history->showFrom) {
-		result = _list->itemTop(_history->showFrom);
-		if (result < _scroll->scrollTopMax() + HistoryMessageUnreadBar::height() - HistoryMessageUnreadBar::marginTop()) {
-			_history->addUnreadBar();
-			if (hasPendingResizedItems()) {
-				updateListSize();
-			}
-			if (_history->unreadBar) {
+			if (history->unreadBar() != nullptr) {
 				setMsgId(ShowAtUnreadMsgId);
 				result = countInitialScrollTop();
 				App::wnd()->checkHistoryActivation();
@@ -4792,7 +4783,23 @@ void HistoryWidget::updateHistoryGeometry(bool initial, bool loadedDown, const S
 	updateListSize();
 	_updateHistoryGeometryRequired = false;
 
-	if ((!initial && !wasAtBottom) || (loadedDown && (!_history->showFrom || _history->unreadBar || _history->loadedAtBottom()) && (!_migrated || !_migrated->showFrom || _migrated->unreadBar || _history->loadedAtBottom()))) {
+	if ((!initial && !wasAtBottom)
+		|| (loadedDown
+			&& (!_history->firstUnreadMessage()
+				|| _history->unreadBar()
+				|| _history->loadedAtBottom())
+			&& (!_migrated
+				|| !_migrated->firstUnreadMessage()
+				|| _migrated->unreadBar()
+				|| _history->loadedAtBottom()))) {
+		const auto historyScrollTop = _list->historyScrollTop();
+		if (!wasAtBottom && historyScrollTop == ScrollMax) {
+			// History scroll top was not inited yet.
+			// If we're showing locally unread messages, we get here
+			// from destroyUnreadBar() before we have time to scroll
+			// to good initial position, like top of an unread bar.
+			return;
+		}
 		auto toY = qMin(_list->historyScrollTop(), _scroll->scrollTopMax());
 		if (change.type == ScrollChangeAdd) {
 			toY += change.value;
@@ -4815,7 +4822,9 @@ void HistoryWidget::updateHistoryGeometry(bool initial, bool loadedDown, const S
 		_historyInited = true;
 		_scrollToAnimation.finish();
 	}
-	auto newScrollTop = initial ? countInitialScrollTop() : countAutomaticScrollTop();
+	auto newScrollTop = initial
+		? countInitialScrollTop()
+		: countAutomaticScrollTop();
 	if (_scroll->scrollTop() == newScrollTop) {
 		visibleAreaUpdated();
 	} else {
@@ -4841,25 +4850,33 @@ bool HistoryWidget::hasPendingResizedItems() const {
 		|| (_migrated && _migrated->hasPendingResizedItems());
 }
 
-int HistoryWidget::unreadBarTop() const {
-	auto getUnreadBar = [this]() -> HistoryItem* {
-		if (_migrated && _migrated->unreadBar) {
-			return _migrated->unreadBar;
-		}
-		if (_history->unreadBar) {
-			return _history->unreadBar;
+base::optional<int> HistoryWidget::unreadBarTop() const {
+	auto getUnreadBar = [this]() -> HistoryView::Element* {
+		if (const auto bar = _migrated ? _migrated->unreadBar() : nullptr) {
+			return bar;
+		} else if (const auto bar = _history->unreadBar()) {
+			return bar;
 		}
 		return nullptr;
 	};
 	if (const auto bar = getUnreadBar()) {
-		auto result = _list->itemTop(bar)
-			+ HistoryMessageUnreadBar::marginTop();
-		if (bar->Has<HistoryMessageDate>()) {
-			result += bar->Get<HistoryMessageDate>()->height();
+		const auto result = _list->itemTop(bar)
+			+ HistoryView::UnreadBar::marginTop();
+		if (bar->data()->Has<HistoryMessageDate>()) {
+			return result + bar->data()->Get<HistoryMessageDate>()->height();
 		}
 		return result;
 	}
-	return -1;
+	return base::none;
+}
+
+HistoryView::Element *HistoryWidget::firstUnreadMessage() const {
+	if (_migrated) {
+		if (const auto result = _migrated->firstUnreadMessage()) {
+			return result;
+		}
+	}
+	return _history ? _history->firstUnreadMessage() : nullptr;
 }
 
 void HistoryWidget::addMessagesToFront(PeerData *peer, const QVector<MTPMessage> &messages) {
@@ -4879,14 +4896,18 @@ void HistoryWidget::addMessagesToBack(PeerData *peer, const QVector<MTPMessage>
 }
 
 void HistoryWidget::countHistoryShowFrom() {
-	if (_migrated && _showAtMsgId == ShowAtUnreadMsgId && _migrated->unreadCount()) {
-		_migrated->updateShowFrom();
+	if (_migrated
+		&& _showAtMsgId == ShowAtUnreadMsgId
+		&& _migrated->unreadCount()) {
+		_migrated->calculateFirstUnreadMessage();
 	}
-	if ((_migrated && _migrated->showFrom) || _showAtMsgId != ShowAtUnreadMsgId || !_history->unreadCount()) {
-		_history->showFrom = nullptr;
-		return;
+	if ((_migrated && _migrated->firstUnreadMessage())
+		|| (_showAtMsgId != ShowAtUnreadMsgId)
+		|| !_history->unreadCount()) {
+		_history->unsetFirstUnreadMessage();
+	} else {
+		_history->calculateFirstUnreadMessage();
 	}
-	_history->updateShowFrom();
 }
 
 void HistoryWidget::updateBotKeyboard(History *h, bool force) {
@@ -4989,26 +5010,30 @@ void HistoryWidget::updateHistoryDownPosition() {
 void HistoryWidget::updateHistoryDownVisibility() {
 	if (_a_show.animating()) return;
 
-	auto haveUnreadBelowBottom = [this](History *history) {
+	auto haveUnreadBelowBottom = [&](History *history) {
 		if (!_list || !history || history->unreadCount() <= 0) {
 			return false;
 		}
-		if (!history->showFrom || !history->showFrom->mainView()) {
+		const auto unread = history->firstUnreadMessage();
+		if (!unread) {
 			return false;
 		}
-		return (_list->itemTop(history->showFrom) >= _scroll->scrollTop() + _scroll->height());
+		const auto top = _list->itemTop(unread);
+		return (top >= _scroll->scrollTop() + _scroll->height());
 	};
-	auto historyDownIsVisible = [this, &haveUnreadBelowBottom] {
-		if (!_history || _firstLoadRequest) {
+	auto historyDownIsVisible = [&] {
+		if (!_list || _firstLoadRequest) {
 			return false;
 		}
 		if (!_history->loadedAtBottom() || _replyReturn) {
 			return true;
 		}
-		if (_scroll->scrollTop() + st::historyToDownShownAfter < _scroll->scrollTopMax()) {
+		const auto top = _scroll->scrollTop() + st::historyToDownShownAfter;
+		if (top < _scroll->scrollTopMax()) {
 			return true;
 		}
-		if (haveUnreadBelowBottom(_history) || haveUnreadBelowBottom(_migrated)) {
+		if (haveUnreadBelowBottom(_history)
+			|| haveUnreadBelowBottom(_migrated)) {
 			return true;
 		}
 		return false;
@@ -5338,7 +5363,8 @@ bool HistoryWidget::pinnedMsgVisibilityUpdated() {
 			updatePinnedBar();
 			result = true;
 
-			if (_scroll->scrollTop() != unreadBarTop()) {
+			const auto barTop = unreadBarTop();
+			if (!barTop || _scroll->scrollTop() != *barTop) {
 				synteticScrollToY(_scroll->scrollTop() + st::historyReplyHeight);
 			}
 		} else if (_pinnedBar->msgId != pinnedId) {
@@ -5356,7 +5382,8 @@ bool HistoryWidget::pinnedMsgVisibilityUpdated() {
 	} else if (_pinnedBar) {
 		destroyPinnedBar();
 		result = true;
-		if (_scroll->scrollTop() != unreadBarTop()) {
+		const auto barTop = unreadBarTop();
+		if (!barTop || _scroll->scrollTop() != *barTop) {
 			synteticScrollToY(_scroll->scrollTop() - st::historyReplyHeight);
 		}
 		updateControlsGeometry();

Telegram/SourceFiles/history/history_widget.h

@@ -203,7 +203,7 @@ public:
 
 	void newUnreadMsg(History *history, HistoryItem *item);
 	void historyToDown(History *history);
-	void unreadCountChanged(History *history);
+	void unreadCountChanged(not_null<History*> history);
 
 	QRect historyRect() const;
 	void pushTabbedSelectorToThirdSection(
@@ -534,7 +534,6 @@ private:
 	void updateTabbedSelectorToggleTooltipGeometry();
 	void checkTabbedSelectorToggleTooltip();
 
-	bool historyHasNotFreezedUnreadBar(History *history) const;
 	bool canWriteMessage() const;
 	bool isRestrictedWrite() const;
 	void orderWidgets();
@@ -670,9 +669,10 @@ private:
 
 	// Counts scrollTop for placing the scroll right at the unread
 	// messages bar, choosing from _history and _migrated unreadBar.
-	int unreadBarTop() const;
+	base::optional<int> unreadBarTop() const;
 	int itemTopForHighlight(not_null<HistoryView::Element*> view) const;
 	void scrollToCurrentVoiceMessage(FullMsgId fromId, FullMsgId toId);
+	HistoryView::Element *firstUnreadMessage() const;
 
 	// Scroll to current y without updating the _lastUserScrolled time.
 	// Used to distinguish between user scrolls and syntetic scrolls.

Telegram/SourceFiles/history/view/history_view_element.cpp

@@ -15,8 +15,10 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_session.h"
 #include "data/data_groups.h"
 #include "data/data_media_types.h"
+#include "lang/lang_keys.h"
 #include "auth_session.h"
 #include "layout.h"
+#include "styles/style_history.h"
 
 namespace HistoryView {
 namespace {
@@ -54,6 +56,60 @@ TextSelection ShiftItemSelection(
 	return ShiftItemSelection(selection, byText.length());
 }
 
+void UnreadBar::init(int count) {
+	if (freezed) {
+		return;
+	}
+	text = lng_unread_bar(lt_count, count);
+	width = st::semiboldFont->width(text);
+}
+
+int UnreadBar::height() {
+	return st::historyUnreadBarHeight + st::historyUnreadBarMargin;
+}
+
+int UnreadBar::marginTop() {
+	return st::lineWidth + st::historyUnreadBarMargin;
+}
+
+void UnreadBar::paint(Painter &p, int y, int w) const {
+	const auto bottom = y + height();
+	y += marginTop();
+	p.fillRect(
+		0,
+		y,
+		w,
+		height() - marginTop() - st::lineWidth,
+		st::historyUnreadBarBg);
+	p.fillRect(
+		0,
+		bottom - st::lineWidth,
+		w,
+		st::lineWidth,
+		st::historyUnreadBarBorder);
+	p.setFont(st::historyUnreadBarFont);
+	p.setPen(st::historyUnreadBarFg);
+
+	int left = st::msgServiceMargin.left();
+	int maxwidth = w;
+	if (Adaptive::ChatWide()) {
+		maxwidth = qMin(
+			maxwidth,
+			st::msgMaxWidth
+				+ 2 * st::msgPhotoSkip
+				+ 2 * st::msgMargin.left());
+	}
+	w = maxwidth;
+
+	const auto skip = st::historyUnreadBarHeight
+		- 2 * st::lineWidth
+		- st::historyUnreadBarFont->height;
+	p.drawText(
+		(w - width) / 2,
+		y + (skip / 2) + st::historyUnreadBarFont->ascent,
+		text);
+}
+
 Element::Element(
 	not_null<ElementDelegate*> delegate,
 	not_null<HistoryItem*> data)
@@ -99,8 +155,8 @@ int Element::marginTop() const {
 		}
 	}
 	result += item->displayedDateHeight();
-	if (const auto unreadbar = item->Get<HistoryMessageUnreadBar>()) {
-		result += unreadbar->height();
+	if (const auto bar = Get<UnreadBar>()) {
+		result += bar->height();
 	}
 	return result;
 }
@@ -198,7 +254,7 @@ void Element::refreshDataId() {
 
 bool Element::computeIsAttachToPrevious(not_null<Element*> previous) {
 	const auto item = data();
-	if (!item->Has<HistoryMessageDate>() && !item->Has<HistoryMessageUnreadBar>()) {
+	if (!item->Has<HistoryMessageDate>() && !Has<UnreadBar>()) {
 		const auto prev = previous->data();
 		const auto possible = !item->serviceMsg() && !prev->serviceMsg()
 			&& !item->isEmpty() && !prev->isEmpty()
@@ -217,6 +273,42 @@ bool Element::computeIsAttachToPrevious(not_null<Element*> previous) {
 	return false;
 }
 
+void Element::destroyUnreadBar() {
+	if (!Has<UnreadBar>()) {
+		return;
+	}
+	RemoveComponents(UnreadBar::Bit());
+	Auth().data().requestViewResize(this);
+	if (data()->mainView() == this) {
+		recountAttachToPreviousInBlocks();
+	}
+}
+
+void Element::setUnreadBarCount(int count) {
+	Expects(count > 0);
+
+	const auto changed = AddComponents(UnreadBar::Bit());
+	const auto bar = Get<UnreadBar>();
+	if (bar->freezed) {
+		return;
+	}
+	bar->init(count);
+	if (changed) {
+		if (data()->mainView() == this) {
+			recountAttachToPreviousInBlocks();
+		}
+		Auth().data().requestViewResize(this);
+	} else {
+		Auth().data().requestViewRepaint(this);
+	}
+}
+
+void Element::setUnreadBarFreezed() {
+	if (const auto bar = Get<UnreadBar>()) {
+		bar->freezed = true;
+	}
+}
+
 void Element::recountAttachToPreviousInBlocks() {
 	auto attachToPrevious = false;
 	if (const auto previous = previousInBlocks()) {

Telegram/SourceFiles/history/view/history_view_element.h

@@ -55,6 +55,29 @@ TextSelection ShiftItemSelection(
 	TextSelection selection,
 	const Text &byText);
 
+// Any HistoryView::Element can have this Component for
+// displaying the unread messages bar above the message.
+struct UnreadBar : public RuntimeComponent<UnreadBar, Element> {
+	void init(int count);
+
+	static int height();
+	static int marginTop();
+
+	void paint(Painter &p, int y, int w) const;
+
+	QString text;
+	int width = 0;
+
+	// If unread bar is freezed the new messages do not
+	// increment the counter displayed by this bar.
+	//
+	// It happens when we've opened the conversation and
+	// we've seen the bar and new messages are marked as read
+	// as soon as they are added to the chat history.
+	bool freezed = false;
+
+};
+
 class Element
 	: public Object
 	, public RuntimeComposer<Element>
@@ -110,6 +133,16 @@ public:
 
 	bool computeIsAttachToPrevious(not_null<Element*> previous);
 
+	// count > 0 - creates the unread bar if necessary and
+	// sets unread messages count if bar is not freezed yet
+	void setUnreadBarCount(int count);
+	void destroyUnreadBar();
+
+	// marks the unread bar as freezed so that unread
+	// messages count will not change for this bar
+	// when the new messages arrive in this chat history
+	void setUnreadBarFreezed();
+
 	virtual void draw(
 		Painter &p,
 		QRect clip,
@@ -195,7 +228,7 @@ private:
 	void recountDisplayDateInBlocks();
 
 	// This should be called only from previousInBlocksChanged() or when
-	// HistoryMessageDate or HistoryMessageUnreadBar bit is changed in the Composer mask
+	// HistoryMessageDate or UnreadBar bit is changed in the Composer mask
 	// then the result should be cached in a client side flag MTPDmessage_ClientFlag::f_attach_to_previous.
 	void recountAttachToPreviousInBlocks();
 

Telegram/SourceFiles/history/view/history_view_list_widget.cpp

@@ -231,7 +231,7 @@ ListWidget::ListWidget(
 	Auth().data().viewResizeRequest(
 	) | rpl::start_with_next([this](auto view) {
 		if (view->delegate() == this) {
-			updateSize();
+			resizeItem(view);
 		}
 	}, lifetime());
 	Auth().data().itemViewRefreshRequest(
@@ -572,24 +572,7 @@ void ListWidget::updateItemsGeometry() {
 		}
 		return count;
 	}();
-	if (first < count) {
-		auto view = _items[first].get();
-		for (auto i = first + 1; i != count; ++i) {
-			const auto next = _items[i].get();
-			if (next->isHiddenByGroup()) {
-				next->setDisplayDate(false);
-			} else {
-				const auto viewDate = view->data()->date;
-				const auto nextDate = next->data()->date;
-				next->setDisplayDate(nextDate.date() != viewDate.date());
-				auto attached = next->computeIsAttachToPrevious(view);
-				next->setAttachToPrevious(attached);
-				view->setAttachToNext(attached);
-				view = next;
-			}
-		}
-	}
-	updateSize();
+	refreshAttachmentsFromTill(first, count);
 }
 
 void ListWidget::updateSize() {
@@ -1452,6 +1435,61 @@ void ListWidget::repaintItem(const Element *view) {
 	update(0, itemTop(view), width(), view->height());
 }
 
+void ListWidget::resizeItem(not_null<Element*> view) {
+	const auto index = ranges::find(_items, view) - begin(_items);
+	if (index < int(_items.size())) {
+		refreshAttachmentsAtIndex(index);
+	}
+}
+
+void ListWidget::refreshAttachmentsAtIndex(int index) {
+	Expects(index >= 0 && index < _items.size());
+
+	const auto from = [&] {
+		if (index > 0) {
+			for (auto i = index - 1; i != 0; --i) {
+				if (!_items[i]->isHiddenByGroup()) {
+					return i;
+				}
+			}
+		}
+		return index;
+	}();
+	const auto till = [&] {
+		for (auto i = index + 1, count = int(_items.size()); i != count; ) {
+			if (!_items[i]->isHiddenByGroup()) {
+				return i + 1;
+			}
+		}
+		return index + 1;
+	}();
+	refreshAttachmentsFromTill(from, till);
+}
+
+void ListWidget::refreshAttachmentsFromTill(int from, int till) {
+	Expects(from >= 0 && from <= till && till <= int(_items.size()));
+
+	if (from == till) {
+		return;
+	}
+	auto view = _items[from].get();
+	for (auto i = from + 1; i != till; ++i) {
+		const auto next = _items[i].get();
+		if (next->isHiddenByGroup()) {
+			next->setDisplayDate(false);
+		} else {
+			const auto viewDate = view->data()->date;
+			const auto nextDate = next->data()->date;
+			next->setDisplayDate(nextDate.date() != viewDate.date());
+			auto attached = next->computeIsAttachToPrevious(view);
+			next->setAttachToPrevious(attached);
+			view->setAttachToNext(attached);
+			view = next;
+		}
+	}
+	updateSize();
+}
+
 void ListWidget::refreshItem(not_null<const Element*> view) {
 	const auto i = ranges::find(_items, view);
 	const auto index = i - begin(_items);
@@ -1467,7 +1505,7 @@ void ListWidget::refreshItem(not_null<const Element*> view) {
 
 		viewReplaced(view, i->second.get());
 
-		updateItemsGeometry();
+		refreshAttachmentsAtIndex(index);
 	}
 }
 

Telegram/SourceFiles/history/view/history_view_list_widget.h

@@ -165,6 +165,7 @@ private:
 	void performDrag();
 	int itemTop(not_null<const Element*> view) const;
 	void repaintItem(const Element *view);
+	void resizeItem(not_null<Element*> view);
 	void refreshItem(not_null<const Element*> view);
 	void itemRemoved(not_null<const HistoryItem*> item);
 	QPoint mapPointToItem(QPoint point, const Element *view) const;
@@ -194,6 +195,8 @@ private:
 	void updateVisibleTopItem();
 	void updateItemsGeometry();
 	void updateSize();
+	void refreshAttachmentsFromTill(int from, int till);
+	void refreshAttachmentsAtIndex(int index);
 
 	void toggleScrollDateShown();
 	void repaintScrollDateCallback();

Telegram/SourceFiles/history/view/history_view_message.cpp

@@ -360,14 +360,14 @@ void Message::draw(
 	}
 
 	auto dateh = 0;
-	if (auto date = item->Get<HistoryMessageDate>()) {
+	if (const auto date = item->Get<HistoryMessageDate>()) {
 		dateh = date->height();
 	}
-	if (auto unreadbar = item->Get<HistoryMessageUnreadBar>()) {
-		auto unreadbarh = unreadbar->height();
+	if (const auto bar = Get<UnreadBar>()) {
+		auto unreadbarh = bar->height();
 		if (clip.intersects(QRect(0, dateh, width(), unreadbarh))) {
 			p.translate(0, dateh);
-			unreadbar->paint(p, 0, width());
+			bar->paint(p, 0, width());
 			p.translate(0, -dateh);
 		}
 	}

Telegram/SourceFiles/history/view/history_view_service_message.cpp

@@ -315,8 +315,8 @@ QSize Service::performCountCurrentSize(int newWidth) {
 	const auto media = this->media();
 
 	auto newHeight = item->displayedDateHeight();
-	if (auto unreadbar = item->Get<HistoryMessageUnreadBar>()) {
-		newHeight += unreadbar->height();
+	if (const auto bar = Get<UnreadBar>()) {
+		newHeight += bar->height();
 	}
 
 	if (item->_text.isEmpty()) {
@@ -382,10 +382,10 @@ void Service::draw(
 		clip.translate(0, -dateh);
 		height -= dateh;
 	}
-	if (auto unreadbar = item->Get<HistoryMessageUnreadBar>()) {
-		unreadbarh = unreadbar->height();
+	if (const auto bar = Get<UnreadBar>()) {
+		unreadbarh = bar->height();
 		if (clip.intersects(QRect(0, 0, width(), unreadbarh))) {
-			unreadbar->paint(p, 0, width());
+			bar->paint(p, 0, width());
 		}
 		p.translate(0, unreadbarh);
 		clip.translate(0, -unreadbarh);
@@ -405,7 +405,7 @@ void Service::draw(
 			auto dt = (animms > st::activeFadeInDuration) ? (1. - (animms - st::activeFadeInDuration) / float64(st::activeFadeOutDuration)) : (animms / float64(st::activeFadeInDuration));
 			auto o = p.opacity();
 			p.setOpacity(o * dt);
-			p.fillRect(0, skiptop, item->history()->width, fillheight, st::defaultTextPalette.selectOverlay);
+			p.fillRect(0, skiptop, width(), fillheight, st::defaultTextPalette.selectOverlay);
 			p.setOpacity(o);
 		}
 	}
@@ -448,8 +448,8 @@ bool Service::hasPoint(QPoint point) const {
 	if (auto dateh = item->displayedDateHeight()) {
 		g.setTop(g.top() + dateh);
 	}
-	if (auto unreadbar = item->Get<HistoryMessageUnreadBar>()) {
-		g.setTop(g.top() + unreadbar->height());
+	if (const auto bar = Get<UnreadBar>()) {
+		g.setTop(g.top() + bar->height());
 	}
 	if (media) {
 		g.setHeight(g.height() - (st::msgServiceMargin.top() + media->height()));
@@ -472,8 +472,8 @@ HistoryTextState Service::getState(QPoint point, HistoryStateRequest request) co
 		point.setY(point.y() - dateh);
 		g.setHeight(g.height() - dateh);
 	}
-	if (auto unreadbar = item->Get<HistoryMessageUnreadBar>()) {
-		auto unreadbarh = unreadbar->height();
+	if (const auto bar = Get<UnreadBar>()) {
+		auto unreadbarh = bar->height();
 		point.setY(point.y() - unreadbarh);
 		g.setHeight(g.height() - unreadbarh);
 	}

Telegram/SourceFiles/mainwidget.cpp

@@ -1516,7 +1516,7 @@ void MainWidget::saveRecentHashtags(const QString &text) {
 	}
 }
 
-void MainWidget::unreadCountChanged(History *history) {
+void MainWidget::unreadCountChanged(not_null<History*> history) {
 	_history->unreadCountChanged(history);
 }
 

Telegram/SourceFiles/mainwidget.h

@@ -242,7 +242,7 @@ public:
 	void sendMessage(const MessageToSend &message);
 	void saveRecentHashtags(const QString &text);
 
-	void unreadCountChanged(History *history);
+	void unreadCountChanged(not_null<History*> history);
 
 	TimeMs highlightStartTime(not_null<const HistoryItem*> item) const;