Added initial support of auto-scroll with middle click to history view.

Fixed #24518.

Telegram/SourceFiles/history/history_inner_widget.cpp

@@ -333,6 +333,11 @@ HistoryInner::HistoryInner(
 		[=](QRect updated) { update(updated); }))
 , _touchSelectTimer([=] { onTouchSelect(); })
 , _touchScrollTimer([=] { onTouchScrollTimer(); })
+, _middleClickAutoscroll(
+	[=](int d) { _scroll->scrollToY(_scroll->scrollTop() + d); },
+	[=](const QCursor &cursor) { setCursor(cursor); },
+	[=] { mouseActionUpdate(QCursor::pos()); setCursor(_cursor); },
+	[=] { return window()->isActiveWindow(); })
 , _scrollDateCheck([this] { scrollDateCheck(); })
 , _scrollDateHideTimer([this] { scrollDateHideByTimer(); }) {
 	_history->delegateMixin()->setCurrent(this);
@@ -1734,6 +1739,14 @@ void HistoryInner::touchEvent(QTouchEvent *e) {
 void HistoryInner::mouseMoveEvent(QMouseEvent *e) {
 	static auto lastGlobalPosition = e->globalPos();
 	auto reallyMoved = (lastGlobalPosition != e->globalPos());
+	if (_middleClickAutoscroll.active()) {
+		if (reallyMoved) {
+			_mouseActive = true;
+			lastGlobalPosition = e->globalPos();
+		}
+		e->accept();
+		return;
+	}
 	auto buttonsPressed = (e->buttons() & (Qt::LeftButton | Qt::MiddleButton));
 	if (!buttonsPressed && _mouseAction != MouseAction::None) {
 		mouseReleaseEvent(e);
@@ -1786,6 +1799,18 @@ void HistoryInner::mousePressEvent(QMouseEvent *e) {
 		e->accept();
 		return; // ignore mouse press, that was hiding context menu
 	}
+	if (_middleClickAutoscroll.active()) {
+		_middleClickAutoscroll.stop();
+		e->accept();
+		return;
+	}
+	if (e->button() == Qt::MiddleButton) {
+		mouseActionCancel();
+		ClickHandler::unpressed();
+		_middleClickAutoscroll.start(e->globalPos());
+		e->accept();
+		return;
+	}
 	_mouseActive = true;
 	mouseActionStart(e->globalPos(), e->button());
 }
@@ -2196,6 +2221,10 @@ void HistoryInner::mouseActionFinish(
 }
 
 void HistoryInner::mouseReleaseEvent(QMouseEvent *e) {
+	if (_middleClickAutoscroll.active()) {
+		e->accept();
+		return;
+	}
 	mouseActionFinish(e->globalPos(), e->button());
 	if (!rect().contains(e->pos())) {
 		leaveEvent(e);
@@ -3503,6 +3532,10 @@ TextForMimeData HistoryInner::getSelectedText() const {
 }
 
 void HistoryInner::keyPressEvent(QKeyEvent *e) {
+	if (_middleClickAutoscroll.active() && e->key() == Qt::Key_Escape) {
+		_middleClickAutoscroll.stop();
+		return;
+	}
 	if (e->key() == Qt::Key_Escape) {
 		_widget->escape();
 	} else if (e == QKeySequence::Copy && !_selected.empty()) {

Telegram/SourceFiles/history/history_inner_widget.h

@@ -13,6 +13,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/controls/swipe_handler_data.h"
 #include "ui/effects/animations.h"
 #include "ui/dragging_scroll_manager.h"
+#include "ui/widgets/middle_click_autoscroll.h"
 #include "ui/widgets/tooltip.h"
 #include "ui/widgets/scroll_area.h"
 #include "ui/userpic_view.h"
@@ -560,6 +561,7 @@ private:
 	crl::time _touchAccelerationTime = 0;
 	crl::time _touchTime = 0;
 	base::Timer _touchScrollTimer;
+	Ui::MiddleClickAutoscroll _middleClickAutoscroll;
 
 	Ui::Controls::SwipeContextData _gestureHorizontal;
 	Ui::Controls::SwipeBackResult _swipeBackData;

Telegram/SourceFiles/history/view/history_view_list_widget.cpp

@@ -413,7 +413,12 @@ ListWidget::ListWidget(
 	[=](const HistoryItem *item) { return viewForItem(item); },
 	[=](const Element *view) { repaintItem(view); })
 , _touchSelectTimer([=] { onTouchSelect(); })
-, _touchScrollTimer([=] { onTouchScrollTimer(); }) {
+, _touchScrollTimer([=] { onTouchScrollTimer(); })
+, _middleClickAutoscroll(
+	[=](int d) { _delegate->listScrollTo(_visibleTop + d, false); },
+	[=](const QCursor &cursor) { setCursor(cursor); },
+	[=] { mouseActionUpdate(QCursor::pos()); setCursor(_cursor); },
+	[=] { return window()->isActiveWindow(); }) {
 	setAttribute(Qt::WA_AcceptTouchEvents);
 	setMouseTracking(true);
 	_scrollDateHideTimer.setCallback([this] { scrollDateHideByTimer(); });
@@ -2699,6 +2704,10 @@ void ListWidget::keyPressEvent(QKeyEvent *e) {
 	const auto hasModifiers = (Qt::NoModifier !=
 		(e->modifiers()
 			& ~(Qt::KeypadModifier | Qt::GroupSwitchModifier)));
+	if (_middleClickAutoscroll.active() && key == Qt::Key_Escape) {
+		_middleClickAutoscroll.stop();
+		return;
+	}
 	if (key == Qt::Key_Escape || key == Qt::Key_Back) {
 		if (hasSelectedText() || hasSelectedItems()) {
 			cancelSelection();
@@ -3003,6 +3012,18 @@ void ListWidget::mousePressEvent(QMouseEvent *e) {
 		e->accept();
 		return; // ignore mouse press, that was hiding context menu
 	}
+	if (_middleClickAutoscroll.active()) {
+		_middleClickAutoscroll.stop();
+		e->accept();
+		return;
+	}
+	if (e->button() == Qt::MiddleButton) {
+		mouseActionCancel();
+		ClickHandler::unpressed();
+		_middleClickAutoscroll.start(e->globalPos());
+		e->accept();
+		return;
+	}
 	_mouseActive = true;
 	mouseActionStart(e->globalPos(), e->button());
 }
@@ -3206,6 +3227,14 @@ void ListWidget::touchEvent(QTouchEvent *e) {
 void ListWidget::mouseMoveEvent(QMouseEvent *e) {
 	static auto lastGlobalPosition = e->globalPos();
 	auto reallyMoved = (lastGlobalPosition != e->globalPos());
+	if (_middleClickAutoscroll.active()) {
+		if (reallyMoved) {
+			_mouseActive = true;
+			lastGlobalPosition = e->globalPos();
+		}
+		e->accept();
+		return;
+	}
 	auto buttonsPressed = (e->buttons() & (Qt::LeftButton | Qt::MiddleButton));
 	if (!buttonsPressed && _mouseAction != MouseAction::None) {
 		mouseReleaseEvent(e);
@@ -3223,6 +3252,10 @@ void ListWidget::mouseMoveEvent(QMouseEvent *e) {
 }
 
 void ListWidget::mouseReleaseEvent(QMouseEvent *e) {
+	if (_middleClickAutoscroll.active()) {
+		e->accept();
+		return;
+	}
 	mouseActionFinish(e->globalPos(), e->button());
 	if (!rect().contains(e->pos())) {
 		leaveEvent(e);

Telegram/SourceFiles/history/view/history_view_list_widget.h

@@ -11,6 +11,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/rp_widget.h"
 #include "ui/effects/animations.h"
 #include "ui/dragging_scroll_manager.h"
+#include "ui/widgets/middle_click_autoscroll.h"
 #include "ui/widgets/tooltip.h"
 #include "mtproto/sender.h"
 #include "data/data_messages.h"
@@ -867,6 +868,7 @@ private:
 	crl::time _touchAccelerationTime = 0;
 	crl::time _touchTime = 0;
 	base::Timer _touchScrollTimer;
+	Ui::MiddleClickAutoscroll _middleClickAutoscroll;
 
 	rpl::event_stream<FullMsgId> _requestedToEditMessage;
 	rpl::event_stream<ReplyToMessageRequest> _requestedToReplyToMessage;

Telegram/SourceFiles/ui/widgets/middle_click_autoscroll.cpp

@@ -0,0 +1,228 @@
+/*
+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 "ui/widgets/middle_click_autoscroll.h"
+
+#include "styles/style_widgets.h"
+#include "ui/effects/animation_value.h"
+#include "ui/rect.h"
+
+namespace Ui {
+namespace {
+
+constexpr auto kDelay = 15;
+
+[[nodiscard]] int Deadzone() {
+	return std::max(1, int(std::lround(style::ConvertFloatScale(6.))));
+}
+
+[[nodiscard]] float64 SpeedScale() {
+	return style::ConvertFloatScale(30.);
+}
+
+[[nodiscard]] float64 MaxSpeed() {
+	return style::ConvertFloatScale(3600.);
+}
+
+[[nodiscard]] QImage PaintCursorImage(
+		int size,
+		int factor,
+		bool drawOuter,
+		bool drawTopArrow,
+		bool drawBottomArrow,
+		const QColor &inner,
+		const QColor &indicator,
+		const QColor &topArrow,
+		const QColor &bottomArrow) {
+	auto image = QImage(
+		QSize(size, size) * factor,
+		QImage::Format_ARGB32_Premultiplied);
+	image.setDevicePixelRatio(factor);
+	image.fill(Qt::transparent);
+	auto p = QPainter(&image);
+	p.setRenderHint(QPainter::Antialiasing);
+	p.setPen(Qt::NoPen);
+
+	const auto outerRect = QRectF(QPointF(0.5, 0.5), Size(size - 1.));
+	if (drawOuter) {
+		const auto outerStroke = std::max(1., style::ConvertFloatScale(1.5));
+		auto pen = QPen(indicator);
+		pen.setWidthF(outerStroke);
+		p.setPen(pen);
+		p.setBrush(inner);
+		p.drawEllipse(outerRect.marginsRemoved(Margins(outerStroke * 0.5)));
+	}
+	p.setPen(Qt::NoPen);
+	const auto centerSkip = style::ConvertFloatScale(10.5);
+	const auto centerRect = outerRect - Margins(centerSkip);
+	p.setBrush(indicator);
+	p.drawEllipse(centerRect);
+
+	const auto middle = size * 0.5;
+	const auto arrowGap = style::ConvertFloatScale(5.);
+	const auto headHalfWidth = style::ConvertFloatScale(4.5);
+	const auto headHeight = style::ConvertFloatScale(3.5);
+	const auto stroke = std::max(1., style::ConvertFloatScale(2.));
+	const auto drawArrow = [&](bool up, const QColor &color) {
+		auto pen = QPen(color);
+		pen.setWidthF(stroke);
+		pen.setCapStyle(Qt::RoundCap);
+		pen.setJoinStyle(Qt::RoundJoin);
+		p.setPen(pen);
+		const auto dir = up ? -1. : 1.;
+		const auto tipY = middle + dir * (arrowGap + headHeight);
+		const auto neckY = tipY - dir * headHeight;
+		p.drawLine(
+			QPointF(middle, tipY),
+			QPointF(middle - headHalfWidth, neckY));
+		p.drawLine(
+			QPointF(middle, tipY),
+			QPointF(middle + headHalfWidth, neckY));
+	};
+	if (drawTopArrow) {
+		drawArrow(true, topArrow);
+	}
+	if (drawBottomArrow) {
+		drawArrow(false, bottomArrow);
+	}
+	return image;
+}
+
+} // namespace
+
+MiddleClickAutoscroll::MiddleClickAutoscroll(
+	Fn<void(int)> scrollBy,
+	Fn<void(const QCursor &)> applyCursor,
+	Fn<void()> restoreCursor,
+	Fn<bool()> shouldContinue)
+: _scrollBy(std::move(scrollBy))
+, _applyCursor(std::move(applyCursor))
+, _restoreCursor(std::move(restoreCursor))
+, _shouldContinue(std::move(shouldContinue))
+, _timer([=] { onTimer(); }) {
+}
+
+void MiddleClickAutoscroll::start(const QPoint &globalPosition) {
+	if (_active) {
+		stop();
+	}
+	_active = true;
+	_startPosition = globalPosition;
+	_time = crl::now();
+	updateCursor(QCursor::pos().y() - _startPosition.y());
+	_timer.callEach(kDelay);
+}
+
+void MiddleClickAutoscroll::stop() {
+	if (!_active) {
+		return;
+	}
+	_active = false;
+	_timer.cancel();
+	if (_restoreCursor) {
+		_restoreCursor();
+	}
+}
+
+void MiddleClickAutoscroll::updateCursor(int delta) {
+	if (!_applyCursor) {
+		return;
+	}
+	const auto mode = (std::abs(delta) <= Deadzone())
+		? CursorMode::Neutral
+		: (delta < 0)
+		? CursorMode::Up
+		: CursorMode::Down;
+	_applyCursor(makeCursor(mode));
+}
+
+QCursor MiddleClickAutoscroll::makeCursor(CursorMode mode) {
+	struct CachedCursor {
+		CursorMode mode = CursorMode::Neutral;
+		int size = 0;
+		int factor = 0;
+		QColor inner;
+		QColor indicator;
+		QCursor cursor;
+	};
+	const auto size = std::max(
+		1,
+		int(std::lround(style::ConvertFloatScale(27.))));
+	const auto factor = style::DevicePixelRatio();
+	const auto inner = anim::with_alpha(st::windowBg->c, (240. / 255.));
+	const auto active = anim::with_alpha(st::windowFg->c, (210. / 255.));
+	const auto passive = anim::with_alpha(
+		st::windowSubTextFg->c,
+		(210. / 255.));
+	const auto neutral = (mode == CursorMode::Neutral);
+	const auto indicator = neutral ? passive : active;
+	static auto cache = std::vector<CachedCursor>();
+	if (const auto i = ranges::find_if(
+			cache,
+			[&](const CachedCursor &entry) {
+				return (entry.mode == mode)
+					&& (entry.size == size)
+					&& (entry.factor == factor)
+					&& (entry.inner == inner)
+					&& (entry.indicator == indicator);
+			});
+		i != cache.end()) {
+		return i->cursor;
+	}
+	const auto image = PaintCursorImage(
+		size,
+		factor,
+		neutral,
+		mode != CursorMode::Down,
+		mode != CursorMode::Up,
+		inner,
+		indicator,
+		indicator,
+		indicator);
+	const auto hot = int(std::floor(size * 0.5));
+	auto cursor = QCursor(QPixmap::fromImage(image), hot, hot);
+	cache.push_back(CachedCursor{
+		.mode = mode,
+		.size = size,
+		.factor = factor,
+		.inner = inner,
+		.indicator = indicator,
+		.cursor = cursor,
+	});
+	return cursor;
+}
+
+void MiddleClickAutoscroll::onTimer() {
+	if (!_active) {
+		return;
+	} else if (_shouldContinue && !_shouldContinue()) {
+		stop();
+		return;
+	}
+	const auto now = crl::now();
+	const auto elapsed = std::max(now - _time, 1LL);
+	_time = now;
+	const auto delta = QCursor::pos().y() - _startPosition.y();
+	updateCursor(delta);
+	const auto absolute = std::abs(delta) - Deadzone();
+	if (absolute <= 0) {
+		return;
+	}
+	const auto speed = std::min(
+		absolute * SpeedScale(),
+		MaxSpeed());
+	auto scroll = int(std::lround((speed * elapsed) / 1000.));
+	if (scroll <= 0) {
+		scroll = 1;
+	}
+	if (delta < 0) {
+		scroll = -scroll;
+	}
+	_scrollBy(scroll);
+}
+
+} // namespace Ui

Telegram/SourceFiles/ui/widgets/middle_click_autoscroll.h

@@ -0,0 +1,53 @@
+/*
+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 "base/timer.h"
+
+class QCursor;
+
+namespace Ui {
+
+class MiddleClickAutoscroll final {
+public:
+	explicit MiddleClickAutoscroll(
+		Fn<void(int)> scrollBy,
+		Fn<void(const QCursor &)> applyCursor = nullptr,
+		Fn<void()> restoreCursor = nullptr,
+		Fn<bool()> shouldContinue = nullptr);
+
+	[[nodiscard]] bool active() const {
+		return _active;
+	}
+
+	void start(const QPoint &globalPosition);
+	void stop();
+
+private:
+	enum class CursorMode {
+		Neutral,
+		Up,
+		Down,
+	};
+
+	void updateCursor(int delta);
+	void onTimer();
+	[[nodiscard]] static QCursor makeCursor(CursorMode mode);
+
+	Fn<void(int)> _scrollBy;
+	Fn<void(const QCursor &)> _applyCursor;
+	Fn<void()> _restoreCursor;
+	Fn<bool()> _shouldContinue;
+	bool _active = false;
+	QPoint _startPosition;
+	crl::time _time = 0;
+	base::Timer _timer;
+
+};
+
+} // namespace Ui

Telegram/cmake/td_ui.cmake

@@ -513,6 +513,8 @@ PRIVATE
     ui/widgets/horizontal_fit_container.h
     ui/widgets/level_meter.cpp
     ui/widgets/level_meter.h
+    ui/widgets/middle_click_autoscroll.cpp
+    ui/widgets/middle_click_autoscroll.h
     ui/widgets/multi_select.cpp
     ui/widgets/multi_select.h
     ui/widgets/sent_code_field.cpp