First attempt of Ctrl+Tab/Ctrl+Shift+Tab UI.

Telegram/CMakeLists.txt

@@ -1663,6 +1663,8 @@ PRIVATE
     window/window_adaptive.h
     window/window_chat_preview.cpp
     window/window_chat_preview.h
+    window/window_chat_switch_process.cpp
+    window/window_chat_switch_process.h
     window/window_connecting_widget.cpp
     window/window_connecting_widget.h
     window/window_controller.cpp

Telegram/SourceFiles/core/application.cpp

@@ -656,8 +656,20 @@ bool Application::eventFilter(QObject *object, QEvent *e) {
 		updateNonIdle();
 	} break;
 
+	case QEvent::KeyRelease: {
+		const auto event = static_cast<QKeyEvent*>(e);
+		if (Shortcuts::HandlePossibleChatSwitch(event)) {
+			return true;
+		}
+	} break;
+
 	case QEvent::ShortcutOverride: {
-		// handle shortcuts ourselves
+		// Ctrl+Tab/Ctrl+Shift+Tab chat switch is a special shortcut case,
+		// because it not only does an action on the shortcut activation,
+		// but also keeps the UI visible until you release the Ctrl key.
+		Shortcuts::HandlePossibleChatSwitch(static_cast<QKeyEvent*>(e));
+
+		// Handle all the shortcut management manually.
 		return true;
 	} break;
 

Telegram/SourceFiles/core/shortcuts.cpp

@@ -30,6 +30,10 @@ constexpr auto kCountLimit = 256; // How many shortcuts can be in json file.
 rpl::event_stream<not_null<Request*>> RequestsStream;
 bool Paused/* = false*/;
 
+Qt::Key ChatSwitchModifier/* = Qt::Key()*/;
+bool ChatSwitchStarted/* = false*/;
+rpl::event_stream<ChatSwitchRequest> ChatSwitchStream;
+
 const auto AutoRepeatCommands = base::flat_set<Command>{
 	Command::MediaPrevious,
 	Command::MediaNext,
@@ -156,6 +160,7 @@ public:
 	void toggleMedia(bool toggled);
 	void toggleSupport(bool toggled);
 	void listen(not_null<QWidget*> widget);
+	[[nodiscard]] bool handles(const QKeySequence &sequence) const;
 
 	[[nodiscard]] const QStringList &errors() const;
 
@@ -361,6 +366,10 @@ void Manager::listen(not_null<QWidget*> widget) {
 	}
 }
 
+bool Manager::handles(const QKeySequence &sequence) const {
+	return _shortcuts.contains(sequence);
+}
+
 void Manager::pruneListened() {
 	for (auto i = begin(_listened); i != end(_listened);) {
 		if (i->data()) {
@@ -470,10 +479,6 @@ void Manager::fillDefaults() {
 	set(u"ctrl+pgup"_q, Command::ChatPrevious);
 	set(u"alt+up"_q, Command::ChatPrevious);
 
-	set(u"%1+tab"_q.arg(ctrl), Command::ChatNext);
-	set(u"%1+shift+tab"_q.arg(ctrl), Command::ChatPrevious);
-	set(u"%1+backtab"_q.arg(ctrl), Command::ChatPrevious);
-
 	set(u"ctrl+alt+home"_q, Command::ChatFirst);
 	set(u"ctrl+alt+end"_q, Command::ChatLast);
 
@@ -800,6 +805,72 @@ bool HandleEvent(
 	return Launch(Data.lookup(object));
 }
 
+void CancelChatSwitch(Qt::Key result) {
+	ChatSwitchModifier = Qt::Key();
+	if (ChatSwitchStarted) {
+		ChatSwitchStarted = false;
+		ChatSwitchStream.fire({ .action = result });
+	}
+}
+
+rpl::producer<ChatSwitchRequest> ChatSwitchRequests() {
+	return ChatSwitchStream.events();
+}
+
+bool HandlePossibleChatSwitch(not_null<QKeyEvent*> event) {
+	const auto type = event->type();
+	if (Paused) {
+		return false;
+	} else if (type == QEvent::ShortcutOverride) {
+		const auto key = Qt::Key(event->key());
+		if (key == Qt::Key_Escape) {
+			CancelChatSwitch(Qt::Key_Escape);
+			return false;
+		} else if (key == Qt::Key_Return || key == Qt::Key_Enter) {
+			CancelChatSwitch(Qt::Key_Enter);
+			return false;
+		}
+		const auto ctrl = Platform::IsMac()
+			? Qt::MetaModifier
+			: Qt::ControlModifier;
+
+		if (Data.handles(ctrl | Qt::ShiftModifier | Qt::Key_Tab)
+			&& Data.handles(QKeySequence(ctrl | Qt::Key_Tab))
+			&& Data.handles(QKeySequence(ctrl | Qt::Key_Backtab))) {
+			return false;
+		} else if (key == Qt::Key_Control || key == Qt::Key_Meta) {
+			ChatSwitchModifier = key;
+		} else if (key == Qt::Key_Tab || key == Qt::Key_Backtab) {
+			const auto modifiers = event->modifiers();
+			if (modifiers & ctrl) {
+				if (Data.handles(modifiers | key)) {
+					return false;
+				}
+				if (ChatSwitchModifier == Qt::Key()) {
+					ChatSwitchModifier = Platform::IsMac()
+						? Qt::Key_Meta
+						: Qt::Key_Control;
+				}
+				const auto action = (modifiers & Qt::ShiftModifier)
+					? Qt::Key_Backtab
+					: key;
+				const auto started = !std::exchange(ChatSwitchStarted, true);
+				ChatSwitchStream.fire({
+					.action = action,
+					.started = started,
+				});
+				return true;
+			}
+		}
+	} else if (type == QEvent::KeyRelease) {
+		const auto key = Qt::Key(event->key());
+		if (key == ChatSwitchModifier) {
+			CancelChatSwitch(Qt::Key_Enter);
+		}
+	}
+	return false;
+}
+
 void ToggleMediaShortcuts(bool toggled) {
 	Data.toggleMedia(toggled);
 }

Telegram/SourceFiles/core/shortcuts.h

@@ -7,6 +7,9 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #pragma once
 
+class QKeyEvent;
+class QShortcutEvent;
+
 namespace Shortcuts {
 
 enum class Command {
@@ -122,7 +125,7 @@ private:
 
 };
 
-rpl::producer<not_null<Request*>> Requests();
+[[nodiscard]] rpl::producer<not_null<Request*>> Requests();
 
 void Start();
 void Finish();
@@ -132,7 +135,15 @@ void Listen(not_null<QWidget*> widget);
 bool Launch(Command command);
 bool HandleEvent(not_null<QObject*> object, not_null<QShortcutEvent*> event);
 
-const QStringList &Errors();
+bool HandlePossibleChatSwitch(not_null<QKeyEvent*> event);
+
+struct ChatSwitchRequest {
+	Qt::Key action = Qt::Key_Tab; // Key_Tab, Key_Backtab or Key_Escape.
+	bool started = false;
+};
+[[nodiscard]] rpl::producer<ChatSwitchRequest> ChatSwitchRequests();
+
+[[nodiscard]] const QStringList &Errors();
 
 // Media shortcuts are not enabled by default, because other
 // applications also use them. They are enabled only when

Telegram/SourceFiles/data/components/recent_peers.cpp

@@ -7,6 +7,9 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "data/components/recent_peers.h"
 
+#include "data/data_peer.h"
+#include "data/data_session.h"
+#include "history/history.h"
 #include "main/main_session.h"
 #include "storage/serialize_common.h"
 #include "storage/serialize_peer.h"
@@ -133,4 +136,28 @@ void RecentPeers::applyLocal(QByteArray serialized) {
 		("Suggestions: RecentPeers read OK, count: %1").arg(_list.size()));
 }
 
+std::vector<not_null<Thread*>> RecentPeers::collectChatOpenHistory() const {
+	_session->local().readSearchSuggestions();
+
+	auto result = _opens;
+	result.reserve(result.size() + _list.size());
+	for (const auto &peer : _list) {
+		const auto history = peer->owner().history(peer);
+		const auto thread = not_null<Data::Thread*>(history);
+		if (!ranges::contains(result, thread)) {
+			result.push_back(thread);
+		}
+	}
+	return result;
+}
+
+void RecentPeers::chatOpenPush(not_null<Thread*> thread) {
+	const auto i = ranges::find(_opens, thread);
+	if (i == end(_opens)) {
+		_opens.insert(begin(_opens), thread);
+	} else if (i != begin(_opens)) {
+		ranges::rotate(begin(_opens), i, i + 1);
+	}
+}
+
 } // namespace Data

Telegram/SourceFiles/data/components/recent_peers.h

@@ -13,6 +13,8 @@ class Session;
 
 namespace Data {
 
+class Thread;
+
 class RecentPeers final {
 public:
 	explicit RecentPeers(not_null<Main::Session*> session);
@@ -28,10 +30,16 @@ public:
 	[[nodiscard]] QByteArray serialize() const;
 	void applyLocal(QByteArray serialized);
 
+	[[nodiscard]] auto collectChatOpenHistory() const
+		-> std::vector<not_null<Thread*>>;
+	void chatOpenPush(not_null<Thread*> thread);
+
 private:
 	const not_null<Main::Session*> _session;
 
 	std::vector<not_null<PeerData*>> _list;
+	std::vector<not_null<Thread*>> _opens;
+
 	rpl::event_stream<> _updates;
 
 };

Telegram/SourceFiles/window/window.style

@@ -331,6 +331,14 @@ ivHeightDefault: 800px;
 
 maxWidthSharedMediaWindow: 419px;
 
+chatSwitchMargins: margins(16px, 16px, 16px, 16px);
+chatSwitchPadding: margins(12px, 12px, 12px, 12px);
+chatSwitchSize: size(72px, 72px);
+chatSwitchUserpic: UserpicButton(defaultUserpicButton) {
+	size: size(56px, 56px);
+	photoSize: 56px;
+}
+
 // Windows specific
 
 winQuitIcon: icon {{ "win_quit", windowFg }};

Telegram/SourceFiles/window/window_chat_switch_process.cpp

@@ -0,0 +1,225 @@
+/*
+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 "window/window_chat_switch_process.h"
+
+#include "core/shortcuts.h"
+#include "data/components/recent_peers.h"
+#include "data/data_thread.h"
+#include "main/main_session.h"
+#include "ui/widgets/shadow.h"
+#include "ui/controls/userpic_button.h"
+#include "ui/rp_widget.h"
+#include "styles/style_layers.h"
+#include "styles/style_window.h"
+
+namespace Window {
+
+ChatSwitchProcess::ChatSwitchProcess(
+	not_null<Ui::RpWidget*> geometry,
+	not_null<Main::Session*> session,
+	Data::Thread *opened)
+: _session(session)
+, _widget(std::make_unique<Ui::RpWidget>(
+	geometry->parentWidget() ? geometry->parentWidget() : geometry))
+, _view(Ui::CreateChild<Ui::RpWidget>(_widget.get()))\
+, _bg(st::boxRadius, st::boxBg)
+, _over(st::boxRadius, st::windowBgOver) {
+	setupWidget(geometry);
+	setupContent(opened);
+	setupView();
+}
+
+ChatSwitchProcess::~ChatSwitchProcess() = default;
+
+rpl::producer<not_null<Data::Thread*>> ChatSwitchProcess::chosen() const {
+	return _chosen.events();
+}
+
+rpl::producer<> ChatSwitchProcess::closeRequests() const {
+	return _closeRequests.events();
+}
+
+void ChatSwitchProcess::process(const Request &request) {
+	Expects(_selected < int(_list.size()));
+
+	const auto count = int(_list.size());
+	if (request.action == Qt::Key_Escape) {
+		_closeRequests.fire({});
+	} else if (request.action == Qt::Key_Enter) {
+		if (_selected >= 0) {
+			_chosen.fire_copy(_list[_selected]);
+		} else {
+			_closeRequests.fire({});
+		}
+	} else if (request.action == Qt::Key_Tab) {
+		if (_selected < 0 || _selected + 1 >= count) {
+			setSelected(0);
+		} else {
+			setSelected(_selected + 1);
+		}
+	} else if (request.action == Qt::Key_Backtab) {
+		if (_selected <= 0) {
+			setSelected(count - 1);
+		} else {
+			setSelected(_selected - 1);
+		}
+	}
+}
+
+void ChatSwitchProcess::setSelected(int index) {
+	if (_selected == index || _list.empty()) {
+		return;
+	}
+	if (_selected >= 0) {
+		_entries[_selected].button->update();
+	}
+	_selected = index;
+	if (_selected >= 0) {
+		_entries[_selected].button->update();
+	}
+}
+
+void ChatSwitchProcess::setupWidget(not_null<Ui::RpWidget*> geometry) {
+	geometry->geometryValue(
+	) | rpl::start_with_next([=](QRect value) {
+		const auto parent = geometry->parentWidget();
+		_widget->setGeometry((parent == _widget->parentWidget())
+			? value
+			: QRect(QPoint(), value.size()));
+	}, _widget->lifetime());
+
+	_widget->events() | rpl::start_with_next([=](not_null<QEvent*> e) {
+		if (e->type() == QEvent::MouseButtonPress) {
+			_closeRequests.fire({});
+		}
+	}, _widget->lifetime());
+
+	_widget->show();
+}
+
+void ChatSwitchProcess::setupContent(Data::Thread *opened) {
+	_list = _session->recentPeers().collectChatOpenHistory();
+	if (opened) {
+		const auto i = ranges::find(_list, not_null(opened));
+		if (i == end(_list)) {
+			_list.insert(begin(_list), opened);
+		} else if (i != begin(_list)) {
+			ranges::rotate(begin(_list), i, i + 1);
+		}
+		_selected = 0;
+	}
+
+	auto index = 0;
+	for (const auto &thread : _list) {
+		const auto button = Ui::CreateChild<Ui::AbstractButton>(_view.get());
+		button->resize(st::chatSwitchSize);
+		button->paintRequest() | rpl::start_with_next([=] {
+			if (index == _selected) {
+				auto p = QPainter(button);
+				_over.paint(p, button->rect());
+			}
+		}, button->lifetime());
+		button->setClickedCallback([=] {
+			_chosen.fire_copy(thread);
+		});
+		button->events() | rpl::start_with_next([=](not_null<QEvent*> e) {
+			if (e->type() == QEvent::MouseMove) {
+				setSelected(index);
+			}
+		}, button->lifetime());
+		button->show();
+
+		const auto userpic = Ui::CreateChild<Ui::UserpicButton>(
+			button,
+			thread->peer(),
+			st::chatSwitchUserpic);
+		userpic->show();
+		userpic->move(
+			((button->width() - userpic->width()) / 2),
+			((button->height() - userpic->height()) / 2));
+		userpic->setAttribute(Qt::WA_TransparentForMouseEvents);
+
+		_entries.push_back({ .button = button });
+
+		++index;
+	}
+}
+
+void ChatSwitchProcess::setupView() {
+	_widget->sizeValue() | rpl::start_with_next([=](QSize size) {
+		layout(size);
+	}, _view->lifetime());
+	_view->show();
+
+	_view->paintRequest() | rpl::start_with_next([=](QRect clip) {
+		if (_outer.isEmpty()) {
+			return;
+		}
+		auto p = QPainter(_view);
+		p.translate(-_shadowed.topLeft());
+		Ui::Shadow::paint(p, _outer, _view->width(), st::boxRoundShadow);
+		_bg.paint(p, _outer);
+	}, _view->lifetime());
+
+	_view->events() | rpl::start_with_next([=](not_null<QEvent*> e) {
+		if (e->type() == QEvent::MouseButtonPress) {
+			e->accept();
+		}
+	}, _view->lifetime());
+}
+
+void ChatSwitchProcess::layout(QSize size) {
+	const auto full = QRect(QPoint(), size);
+	const auto outer = full.marginsRemoved(st::chatSwitchMargins);
+	auto inner = outer.marginsRemoved(st::chatSwitchPadding);
+	const auto available = inner.width();
+	const auto canPerRow = (available / st::chatSwitchSize.width());
+	if (canPerRow < 1 || _list.empty()) {
+		return;
+	}
+	const auto count = int(_list.size());
+	const auto rows = (count + canPerRow - 1) / canPerRow;
+	const auto minPerRow = count / rows;
+	const auto wideRows = (count - (minPerRow * rows));
+	const auto maxPerRow = wideRows ? (minPerRow + 1) : minPerRow;
+	const auto narrowShift = wideRows ? (st::chatSwitchSize.width() / 2) : 0;
+	const auto width = maxPerRow * st::chatSwitchSize.width();
+	const auto height = rows * st::chatSwitchSize.height();
+
+	size = QSize(width, height);
+	_inner = QRect(
+		(full.width() - width) / 2,
+		(full.height() - height) / 2,
+		width,
+		height);
+	_outer = _inner.marginsAdded(st::chatSwitchPadding);
+
+	const auto padding = st::boxRoundShadow.extend + st::chatSwitchPadding;
+
+	auto index = 0;
+	auto top = padding.top();
+	for (auto row = 0; row != rows; ++row) {
+		const auto columns = (row < wideRows) ? maxPerRow : minPerRow;
+		auto left = padding.left() + ((row < wideRows) ? 0 : narrowShift);
+		for (auto column = 0; column != columns; ++column) {
+			auto &entry = _entries[index++];
+			entry.button->moveToLeft(left, top, _inner.width());
+			left += st::chatSwitchSize.width();
+		}
+		top += st::chatSwitchSize.height();
+	}
+
+	_shadowed = _outer.marginsAdded(st::boxRoundShadow.extend);
+	_view->setGeometry(_shadowed);
+}
+
+rpl::lifetime &ChatSwitchProcess::lifetime() {
+	return _lifetime;
+}
+
+} // namespace Window

Telegram/SourceFiles/window/window_chat_switch_process.h

@@ -0,0 +1,82 @@
+/*
+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
+
+#include "ui/round_rect.h"
+
+namespace Data {
+class Thread;
+} // namespace Data
+
+namespace Main {
+class Session;
+} // namespace Main
+
+namespace Shortcuts {
+struct ChatSwitchRequest;
+} // namespace Shortcuts
+
+namespace Ui {
+class AbstractButton;
+class RpWidget;
+} // namespace Ui
+
+namespace Window {
+
+class ChatSwitchProcess final {
+public:
+	// Create widget in geometry->parentWidget() and geometry->geometry().
+	ChatSwitchProcess(
+		not_null<Ui::RpWidget*> geometry,
+		not_null<Main::Session*> session,
+		Data::Thread *opened);
+	~ChatSwitchProcess();
+
+	[[nodiscard]] rpl::producer<not_null<Data::Thread*>> chosen() const;
+	[[nodiscard]] rpl::producer<> closeRequests() const;
+
+	using Request = Shortcuts::ChatSwitchRequest;
+	void process(const Request &request);
+
+	[[nodiscard]] rpl::lifetime &lifetime();
+
+private:
+	struct Entry {
+		not_null<Ui::AbstractButton*> button;
+	};
+	void setupWidget(not_null<Ui::RpWidget*> geometry);
+	void setupContent(Data::Thread *opened);
+	void setupView();
+
+	void layout(QSize size);
+
+	void setSelected(int index);
+
+	const not_null<Main::Session*> _session;
+	const std::unique_ptr<Ui::RpWidget> _widget;
+	const not_null<Ui::RpWidget*> _view;
+
+	QRect _shadowed;
+	QRect _outer;
+	QRect _inner;
+	Ui::RoundRect _bg;
+	Ui::RoundRect _over;
+
+	std::vector<not_null<Data::Thread*>> _list;
+	std::vector<Entry> _entries;
+
+	int _selected = -1;
+
+	rpl::event_stream<not_null<Data::Thread*>> _chosen;
+	rpl::event_stream<> _closeRequests;
+
+	rpl::lifetime _lifetime;
+
+};
+
+} // namespace Window

Telegram/SourceFiles/window/window_session_controller.cpp

@@ -14,6 +14,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "boxes/peers/replace_boost_box.h"
 #include "boxes/delete_messages_box.h"
 #include "window/window_chat_preview.h"
+#include "window/window_chat_switch_process.h"
 #include "window/window_controller.h"
 #include "window/window_filters_menu.h"
 #include "window/window_separate_id.h"
@@ -32,6 +33,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "history/view/history_view_subsection_tabs.h"
 #include "media/player/media_player_instance.h"
 #include "media/view/media_view_open_common.h"
+#include "data/components/recent_peers.h"
 #include "data/stickers/data_custom_emoji.h"
 #include "data/data_document_resolver.h"
 #include "data/data_download_manager.h"
@@ -1735,18 +1737,50 @@ void SessionController::init() {
 }
 
 void SessionController::setupShortcuts() {
-	Shortcuts::Requests(
+	using namespace Shortcuts;
+
+	ChatSwitchRequests(
+	) | rpl::filter([=](const ChatSwitchRequest &request) {
+		return !window().locked()
+			&& (_chatSwitchProcess
+				|| (request.started
+					&& (Core::App().activeWindow() == &window())));
+	}) | rpl::start_with_next([=](const ChatSwitchRequest &request) {
+		if (!_chatSwitchProcess) {
+			_chatSwitchProcess = std::make_unique<ChatSwitchProcess>(
+				widget()->bodyWidget(),
+				&session(),
+				activeChatCurrent().thread());
+			const auto close = [this, raw = _chatSwitchProcess.get()] {
+				if (_chatSwitchProcess.get() == raw) {
+					base::take(_chatSwitchProcess);
+				}
+			};
+
+			_chatSwitchProcess->chosen(
+			) | rpl::start_with_next([=](not_null<Data::Thread*> thread) {
+				close();
+				jumpToChatListEntry({ Dialogs::Key(thread), FullMsgId() });
+			}, _chatSwitchProcess->lifetime());
+
+			_chatSwitchProcess->closeRequests(
+			) | rpl::start_with_next(close, _chatSwitchProcess->lifetime());
+		}
+		_chatSwitchProcess->process(request);
+	}, _lifetime);
+
+	Requests(
 	) | rpl::filter([=] {
 		return (Core::App().activeWindow() == &window())
 			&& !isLayerShown()
 			&& !window().locked();
-	}) | rpl::start_with_next([=](not_null<Shortcuts::Request*> request) {
-		using C = Shortcuts::Command;
+	}) | rpl::start_with_next([=](not_null<Request*> request) {
+		using C = Command;
 
 		const auto app = &Core::App();
 		const auto accountsCount = int(app->domain().accounts().size());
 		auto &&accounts = ranges::views::zip(
-			Shortcuts::kShowAccount,
+			kShowAccount,
 			ranges::views::ints(0, accountsCount));
 		for (const auto &[command, index] : accounts) {
 			request->check(command) && request->handle([=] {
@@ -2033,6 +2067,10 @@ void SessionController::setActiveChatEntry(Dialogs::RowDescriptor row) {
 					{ anim::type::normal, anim::activation::background });
 			}, _activeHistoryLifetime);
 		}
+
+		if (const auto thread = row.key.thread()) {
+			session().recentPeers().chatOpenPush(thread);
+		}
 	}
 	if (session().supportMode()) {
 		pushToChatEntryHistory(row);

Telegram/SourceFiles/window/window_session_controller.h

@@ -99,6 +99,7 @@ class SectionMemento;
 class Controller;
 class FiltersMenu;
 class ChatPreviewManager;
+class ChatSwitchProcess;
 
 struct PeerByLinkInfo;
 struct SeparateId;
@@ -784,6 +785,8 @@ private:
 	std::deque<std::shared_ptr<Ui::ChatTheme>> _lastUsedCustomChatThemes;
 	rpl::variable<PeerThemeOverride> _peerThemeOverride;
 
+	std::unique_ptr<ChatSwitchProcess> _chatSwitchProcess;
+
 	base::has_weak_ptr _storyOpenGuard;
 
 	QString _premiumRef;