Add scroll-to-down button to Feed.

Telegram/SourceFiles/core/event_filter.cpp

@@ -0,0 +1,30 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "core/event_filter.h"
+
+namespace Core {
+
+EventFilter::EventFilter(
+	not_null<QObject*> parent,
+	base::lambda<bool(not_null<QEvent*>)> filter)
+: QObject(parent)
+, _filter(std::move(filter)) {
+	parent->installEventFilter(this);
+}
+
+bool EventFilter::eventFilter(QObject *watched, QEvent *event) {
+	return _filter(event);
+}
+
+not_null<QObject*> InstallEventFilter(
+		not_null<QObject*> object,
+		base::lambda<bool(not_null<QEvent*>)> filter) {
+	return new EventFilter(object, std::move(filter));
+}
+
+} // namespace Core

Telegram/SourceFiles/core/event_filter.h

@@ -0,0 +1,30 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+namespace Core {
+
+class EventFilter : public QObject {
+public:
+	EventFilter(
+		not_null<QObject*> parent,
+		base::lambda<bool(not_null<QEvent*>)> filter);
+
+protected:
+	bool eventFilter(QObject *watched, QEvent *event);
+
+private:
+	base::lambda<bool(not_null<QEvent*>)> _filter;
+
+};
+
+not_null<QObject*> InstallEventFilter(
+	not_null<QObject*> object,
+	base::lambda<bool(not_null<QEvent*>)> filter);
+
+} // namespace Core

Telegram/SourceFiles/data/data_feed.cpp

@@ -279,6 +279,12 @@ int Feed::unreadCount() const {
 	return _unreadCount ? *_unreadCount : 0;
 }
 
+rpl::producer<int> Feed::unreadCountValue() const {
+	return rpl::single(
+		unreadCount()
+	) | rpl::then(_unreadCountChanges.events());
+}
+
 bool Feed::unreadCountKnown() const {
 	return !!_unreadCount;
 }
@@ -321,6 +327,8 @@ void Feed::setUnreadCounts(int unreadNonMutedCount, int unreadMutedCount) {
 	}
 	_unreadCount = unreadNonMutedCount + unreadMutedCount;
 	_unreadMutedCount = unreadMutedCount;
+
+	_unreadCountChanges.fire(unreadCount());
 	updateChatListEntry();
 }
 
@@ -333,7 +341,7 @@ void Feed::setUnreadPosition(const MessagePosition &position) {
 void Feed::unreadCountChanged(
 		base::optional<int> unreadCountDelta,
 		int mutedCountDelta) {
-	if (!unreadCountKnown()) {
+	if (!unreadCountKnown() || (unreadCountDelta && !*unreadCountDelta)) {
 		return;
 	}
 	if (unreadCountDelta) {
@@ -342,6 +350,8 @@ void Feed::unreadCountChanged(
 			_unreadMutedCount + mutedCountDelta,
 			0,
 			*_unreadCount);
+
+		_unreadCountChanges.fire(unreadCount());
 		updateChatListEntry();
 	} else {
 //		_parent->session().api().requestFeedDialogsEntries(this);

Telegram/SourceFiles/data/data_feed.h

@@ -50,6 +50,7 @@ public:
 	void unreadCountChanged(
 		base::optional<int> unreadCountDelta,
 		int mutedCountDelta);
+	rpl::producer<int> unreadCountValue() const;
 	MessagePosition unreadPosition() const;
 	rpl::producer<MessagePosition> unreadPositionChanges() const;
 
@@ -98,6 +99,7 @@ private:
 
 	rpl::variable<MessagePosition> _unreadPosition;
 	base::optional<int> _unreadCount;
+	rpl::event_stream<int> _unreadCountChanges;
 	int _unreadMutedCount = 0;
 
 };

Telegram/SourceFiles/data/data_messages.h

@@ -77,12 +77,18 @@ struct MessagesRange {
 };
 
 constexpr auto MaxDate = std::numeric_limits<TimeId>::max();
-constexpr auto MinMessagePosition = MessagePosition(TimeId(0), FullMsgId());
-constexpr auto MaxMessagePosition = MessagePosition(MaxDate, FullMsgId());
+constexpr auto MinMessagePosition = MessagePosition(
+	TimeId(0),
+	FullMsgId(0, 1));
+constexpr auto MaxMessagePosition = MessagePosition(
+	MaxDate,
+	FullMsgId(0, ServerMaxMsgId - 1));
 constexpr auto FullMessagesRange = MessagesRange(
 	MinMessagePosition,
 	MaxMessagePosition);
-constexpr auto UnreadMessagePosition = MinMessagePosition;
+constexpr auto UnreadMessagePosition = MessagePosition(
+	TimeId(0),
+	FullMsgId(0, 0));;
 
 struct MessagesSlice {
 	std::vector<FullMsgId> ids;

Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp

@@ -1833,15 +1833,23 @@ void DialogsInner::peerSearchReceived(
 		return;
 	}
 
+	const auto alreadyAdded = [&](not_null<PeerData*> peer) {
+		for (const auto &row : _filterResults) {
+			if (const auto history = row->history()) {
+				if (history->peer == peer) {
+					return true;
+				}
+			}
+		}
+		return false;
+	};
 	_peerSearchQuery = query.toLower().trimmed();
 	_peerSearchResults.clear();
 	_peerSearchResults.reserve(result.size());
 	for (const auto &mtpPeer : my) {
 		if (const auto peer = App::peerLoaded(peerFromMTP(mtpPeer))) {
-			if (const auto history = App::historyLoaded(peer)) {
-				if (history->inChatList(Dialogs::Mode::All)) {
-					continue; // skip existing chats
-				}
+			if (alreadyAdded(peer)) {
+				continue;
 			}
 			const auto prev = nullptr, next = nullptr;
 			const auto position = 0;

Telegram/SourceFiles/history/feed/history_feed_section.cpp

@@ -13,11 +13,13 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "history/view/history_view_message.h"
 #include "history/view/history_view_service_message.h"
 #include "history/history_item.h"
+#include "core/event_filter.h"
 #include "lang/lang_keys.h"
 #include "ui/widgets/buttons.h"
 #include "ui/widgets/shadow.h"
 #include "ui/widgets/scroll_area.h"
 #include "ui/widgets/popup_menu.h"
+#include "ui/special_buttons.h"
 #include "boxes/confirm_box.h"
 #include "window/window_controller.h"
 #include "window/window_peer_menu.h"
@@ -66,9 +68,10 @@ Widget::Widget(
 , _topBar(this, controller)
 , _topBarShadow(this)
 , _showNext(
-		this,
-		lang(lng_feed_show_next).toUpper(),
-		st::historyComposeButton) {
+	this,
+	lang(lng_feed_show_next).toUpper(),
+	st::historyComposeButton)
+, _scrollDown(_scroll, st::historyToDown) {
 	_topBar->setActiveChat(_feed);
 
 	_topBar->move(0, 0);
@@ -125,6 +128,107 @@ Widget::Widget(
 	) | rpl::start_with_next([=] {
 		crl::on_main(this, [=] { checkForSingleChannelFeed(); });
 	}, lifetime());
+
+	setupScrollDownButton();
+}
+
+void Widget::setupScrollDownButton() {
+	_scrollDown->setClickedCallback([=] {
+		scrollDownClicked();
+	});
+	Core::InstallEventFilter(_scrollDown, [=](not_null<QEvent*> event) {
+		if (event->type() == QEvent::Wheel) {
+			return _scroll->viewportEvent(event);
+		}
+		return false;
+	});
+	updateScrollDownVisibility();
+	_feed->unreadCountValue(
+	) | rpl::start_with_next([=](int count) {
+		_scrollDown->setUnreadCount(count);
+	}, _scrollDown->lifetime());
+}
+
+void Widget::scrollDownClicked() {
+	showAtPosition(Data::MaxMessagePosition);
+}
+
+void Widget::showAtPosition(Data::MessagePosition position) {
+	if (!showAtPositionNow(position)) {
+		_nextAnimatedScrollPosition = position;
+		_nextAnimatedScrollDelta = _inner->isBelowPosition(position)
+			? -_scroll->height()
+			: _inner->isAbovePosition(position)
+			? _scroll->height()
+			: 0;
+		auto memento = HistoryView::ListMemento(position);
+		_inner->restoreState(&memento);
+	}
+}
+
+bool Widget::showAtPositionNow(Data::MessagePosition position) {
+	if (const auto scrollTop = _inner->scrollTopForPosition(position)) {
+		const auto currentScrollTop = _scroll->scrollTop();
+		const auto wanted = snap(*scrollTop, 0, _scroll->scrollTopMax());
+		const auto fullDelta = (wanted - currentScrollTop);
+		const auto limit = _scroll->height();
+		const auto scrollDelta = snap(fullDelta, -limit, limit);
+		_inner->animatedScrollTo(
+			wanted,
+			position,
+			scrollDelta,
+			(std::abs(fullDelta) > limit
+				? HistoryView::ListWidget::AnimatedScroll::Part
+				: HistoryView::ListWidget::AnimatedScroll::Full));
+		return true;
+	}
+	return false;
+}
+
+void Widget::updateScrollDownVisibility() {
+	if (animating() || !_inner->loadedAtBottomKnown()) {
+		return;
+	}
+
+	const auto scrollDownIsVisible = [&] {
+		if (!_inner->loadedAtBottom()) {
+			return true;
+		}
+		const auto top = _scroll->scrollTop() + st::historyToDownShownAfter;
+		if (top < _scroll->scrollTopMax()) {
+			return true;
+		}
+		return false;
+	};
+	auto scrollDownIsShown = scrollDownIsVisible();
+	if (_scrollDownIsShown != scrollDownIsShown) {
+		_scrollDownIsShown = scrollDownIsShown;
+		_scrollDownShown.start(
+			[=] { updateScrollDownPosition(); },
+			_scrollDownIsShown ? 0. : 1.,
+			_scrollDownIsShown ? 1. : 0.,
+			st::historyToDownDuration);
+	}
+}
+
+void Widget::updateScrollDownPosition() {
+	// _scrollDown is a child widget of _scroll, not me.
+	auto top = anim::interpolate(
+		0,
+		_scrollDown->height() + st::historyToDownPosition.y(),
+		_scrollDownShown.current(_scrollDownIsShown ? 1. : 0.));
+	_scrollDown->moveToRight(
+		st::historyToDownPosition.x(),
+		_scroll->height() - top);
+	auto shouldBeHidden = !_scrollDownIsShown && !_scrollDownShown.animating();
+	if (shouldBeHidden != _scrollDown->isHidden()) {
+		_scrollDown->setVisible(!shouldBeHidden);
+	}
+}
+
+void Widget::scrollDownAnimationFinish() {
+	_scrollDownShown.finish();
+	updateScrollDownPosition();
 }
 
 void Widget::checkForSingleChannelFeed() {
@@ -255,7 +359,7 @@ void Widget::listVisibleItemsChanged(HistoryItemsList &&items) {
 base::optional<int> Widget::listUnreadBarView(
 		const std::vector<not_null<Element*>> &elements) {
 	const auto position = _feed->unreadPosition();
-	if (!position || elements.empty()) {
+	if (!position || elements.empty() || !_feed->unreadCount()) {
 		return base::none;
 	}
 	const auto minimal = ranges::upper_bound(
@@ -276,6 +380,21 @@ base::optional<int> Widget::listUnreadBarView(
 	return base::make_optional(int(minimal - begin(elements)));
 }
 
+void Widget::listContentRefreshed() {
+	if (!_nextAnimatedScrollPosition) {
+		return;
+	}
+	const auto position = *base::take(_nextAnimatedScrollPosition);
+	if (const auto scrollTop = _inner->scrollTopForPosition(position)) {
+		const auto wanted = snap(*scrollTop, 0, _scroll->scrollTopMax());
+		_inner->animatedScrollTo(
+			wanted,
+			position,
+			_nextAnimatedScrollDelta,
+			HistoryView::ListWidget::AnimatedScroll::Part);
+	}
+}
+
 std::unique_ptr<Window::SectionMemento> Widget::createMemento() {
 	auto result = std::make_unique<Memento>(_feed);
 	saveState(result.get());
@@ -330,6 +449,8 @@ void Widget::updateControlsGeometry() {
 		}
 		updateInnerVisibleArea();
 	}
+
+	updateScrollDownPosition();
 	const auto fullWidthButtonRect = myrtlrect(
 		0,
 		bottom - _showNext->height(),
@@ -350,8 +471,8 @@ void Widget::paintEvent(QPaintEvent *e) {
 	//	updateListSize();
 	//}
 
-	//auto ms = getms();
-	//_historyDownShown.step(ms);
+	const auto ms = getms();
+	_scrollDownShown.step(ms);
 
 	SectionWidget::PaintBackground(this, e);
 }
@@ -366,7 +487,7 @@ void Widget::onScroll() {
 void Widget::updateInnerVisibleArea() {
 	const auto scrollTop = _scroll->scrollTop();
 	_inner->setVisibleTopBottom(scrollTop, scrollTop + _scroll->height());
-
+	updateScrollDownVisibility();
 }
 
 void Widget::showAnimatedHook(

Telegram/SourceFiles/history/feed/history_feed_section.h

@@ -16,6 +16,7 @@ namespace Ui {
 class ScrollArea;
 class PlainShadow;
 class FlatButton;
+class HistoryDownButton;
 } // namespace Ui
 
 namespace HistoryView {
@@ -81,6 +82,7 @@ public:
 	void listVisibleItemsChanged(HistoryItemsList &&items) override;
 	base::optional<int> listUnreadBarView(
 		const std::vector<not_null<Element*>> &elements) override;
+	void listContentRefreshed() override;
 
 protected:
 	void resizeEvent(QResizeEvent *e) override;
@@ -99,6 +101,14 @@ private:
 	void updateAdaptiveLayout();
 	void saveState(not_null<Memento*> memento);
 	void restoreState(not_null<Memento*> memento);
+	void showAtPosition(Data::MessagePosition position);
+	bool showAtPositionNow(Data::MessagePosition position);
+
+	void setupScrollDownButton();
+	void scrollDownClicked();
+	void scrollDownAnimationFinish();
+	void updateScrollDownVisibility();
+	void updateScrollDownPosition();
 
 	void forwardSelected();
 	void confirmDeleteSelected();
@@ -113,6 +123,14 @@ private:
 	bool _skipScrollEvent = false;
 	bool _undefinedAroundPosition = false;
 
+	base::optional<Data::MessagePosition> _nextAnimatedScrollPosition;
+	int _nextAnimatedScrollDelta = 0;
+
+	Animation _scrollDownShown;
+	bool _scrollDownIsShown = false;
+	object_ptr<Ui::HistoryDownButton> _scrollDown;
+
+
 };
 
 class Memento : public Window::SectionMemento {

Telegram/SourceFiles/history/view/history_view_list_widget.cpp

@@ -324,6 +324,75 @@ void ListWidget::refreshRows() {
 	checkUnreadBarCreation();
 	restoreScrollState();
 	mouseActionUpdate(QCursor::pos());
+	_delegate->listContentRefreshed();
+}
+
+base::optional<int> ListWidget::scrollTopForPosition(
+		Data::MessagePosition position) const {
+	if (position == Data::MaxMessagePosition) {
+		if (loadedAtBottom()) {
+			return height();
+		}
+		return base::none;
+	}
+	// #TODO showAtPosition
+	return base::none;
+}
+
+void ListWidget::animatedScrollTo(
+		int scrollTop,
+		Data::MessagePosition attachPosition,
+		int delta,
+		AnimatedScroll type) {
+	_scrollToAnimation.finish();
+	if (!delta || _items.empty()) {
+		_delegate->listScrollTo(scrollTop);
+		return;
+	}
+	const auto index = findNearestItem(attachPosition);
+	Assert(index >= 0 && index < int(_items.size()));
+	const auto attachTo = _items[index];
+	const auto attachToId = attachTo->data()->fullId();
+	const auto transition = (type == AnimatedScroll::Full)
+		? anim::sineInOut
+		: anim::easeOutCubic;
+	const auto initial = scrollTop - delta;
+	_delegate->listScrollTo(initial);
+
+	const auto attachToTop = itemTop(attachTo);
+	const auto relativeStart = initial - attachToTop;
+	const auto relativeFinish = scrollTop - attachToTop;
+	_scrollToAnimation.start(
+		[=] { scrollToAnimationCallback(attachToId); },
+		relativeStart,
+		relativeFinish,
+		st::slideDuration,
+		transition);
+}
+
+void ListWidget::scrollToAnimationCallback(FullMsgId attachToId) {
+	const auto attachTo = App::histItemById(attachToId);
+	const auto attachToView = viewForItem(attachTo);
+	if (!attachToView) {
+		_scrollToAnimation.finish();
+	} else {
+		const auto current = int(std::round(_scrollToAnimation.current()));
+		_delegate->listScrollTo(itemTop(attachToView) + current);
+	}
+}
+
+bool ListWidget::isAbovePosition(Data::MessagePosition position) const {
+	if (_items.empty()) {
+		return false;
+	}
+	return _items.back()->data()->position() < position;
+}
+
+bool ListWidget::isBelowPosition(Data::MessagePosition position) const {
+	if (_items.empty()) {
+		return false;
+	}
+	return _items.front()->data()->position() > position;
 }
 
 void ListWidget::checkUnreadBarCreation() {
@@ -838,6 +907,22 @@ void ListWidget::setTextSelection(
 	}
 }
 
+bool ListWidget::loadedAtTopKnown() const {
+	return !!_slice.skippedBefore;
+}
+
+bool ListWidget::loadedAtTop() const {
+	return _slice.skippedBefore && (*_slice.skippedBefore == 0);
+}
+
+bool ListWidget::loadedAtBottomKnown() const {
+	return !!_slice.skippedAfter;
+}
+
+bool ListWidget::loadedAtBottom() const {
+	return _slice.skippedAfter && (*_slice.skippedAfter == 0);
+}
+
 int ListWidget::itemMinimalHeight() const {
 	return st::msgMarginTopAttached
 		+ st::msgPhotoSize

Telegram/SourceFiles/history/view/history_view_list_widget.h

@@ -64,6 +64,7 @@ public:
 	virtual void listVisibleItemsChanged(HistoryItemsList &&items) = 0;
 	virtual base::optional<int> listUnreadBarView(
 		const std::vector<not_null<Element*>> &elements) = 0;
+	virtual void listContentRefreshed() = 0;
 
 };
 
@@ -134,6 +135,19 @@ public:
 
 	void saveState(not_null<ListMemento*> memento);
 	void restoreState(not_null<ListMemento*> memento);
+	base::optional<int> scrollTopForPosition(
+		Data::MessagePosition position) const;
+	enum class AnimatedScroll {
+		Full,
+		Part,
+	};
+	void animatedScrollTo(
+		int scrollTop,
+		Data::MessagePosition attachPosition,
+		int delta,
+		AnimatedScroll type);
+	bool isAbovePosition(Data::MessagePosition position) const;
+	bool isBelowPosition(Data::MessagePosition position) const;
 
 	TextWithEntities getSelectedText() const;
 	MessageIdsList getSelectedItems() const;
@@ -141,6 +155,11 @@ public:
 	void selectItem(not_null<HistoryItem*> item);
 	void selectItemAsGroup(not_null<HistoryItem*> item);
 
+	bool loadedAtTopKnown() const;
+	bool loadedAtTop() const;
+	bool loadedAtBottomKnown() const;
+	bool loadedAtBottom() const;
+
 	// AbstractTooltipShower interface
 	QString tooltipText() const override;
 	QPoint tooltipPos() const override;
@@ -355,6 +374,7 @@ private:
 		not_null<const Element*> view) const;
 	void checkUnreadBarCreation();
 	void applyUpdatedScrollState();
+	void scrollToAnimationCallback(FullMsgId attachToId);
 
 	// This function finds all history items that are displayed and calls template method
 	// for each found message (in given direction) in the passed history with passed top offset.
@@ -385,6 +405,7 @@ private:
 	not_null<ListDelegate*> _delegate;
 	not_null<Window::Controller*> _controller;
 	Data::MessagePosition _aroundPosition;
+	Data::MessagePosition _shownAtPosition;
 	Context _context;
 	int _aroundIndex = -1;
 	int _idsLimit = kMinimalIdsLimit;
@@ -405,6 +426,7 @@ private:
 	Element *_visibleTopItem = nullptr;
 	int _visibleTopFromItem = 0;
 	ScrollTopState _scrollTopState;
+	Animation _scrollToAnimation;
 
 	bool _scrollDateShown = false;
 	Animation _scrollDateOpacity;

Telegram/gyp/telegram_sources.txt

@@ -147,6 +147,8 @@
 <(src_loc)/core/crash_report_window.h
 <(src_loc)/core/crash_reports.cpp
 <(src_loc)/core/crash_reports.h
+<(src_loc)/core/event_filter.cpp
+<(src_loc)/core/event_filter.h
 <(src_loc)/core/file_utilities.cpp
 <(src_loc)/core/file_utilities.h
 <(src_loc)/core/launcher.cpp