Animated transition on pattern-on-gradient resize.

Telegram/SourceFiles/chat_helpers/tabbed_section.cpp

@@ -26,7 +26,7 @@ object_ptr<Window::SectionWidget> TabbedMemento::createWidget(
 TabbedSection::TabbedSection(
 	QWidget *parent,
 	not_null<Window::SessionController*> controller)
-: Window::SectionWidget(parent, controller)
+: Window::SectionWidget(parent, controller, PaintedBackground::Custom)
 , _selector(controller->tabbedSelector()) {
 	_selector->setParent(this);
 	_selector->setRoundRadius(0);

Telegram/SourceFiles/dialogs/dialogs_widget.cpp

@@ -164,7 +164,7 @@ void Widget::BottomButton::paintEvent(QPaintEvent *e) {
 Widget::Widget(
 	QWidget *parent,
 	not_null<Window::SessionController*> controller)
-	: Window::AbstractSectionWidget(parent, controller)
+: Window::AbstractSectionWidget(parent, controller, PaintedBackground::Custom)
 , _api(&controller->session().mtp())
 , _searchControls(this)
 , _mainMenuToggle(_searchControls, st::dialogsMenuToggle)

Telegram/SourceFiles/history/admin_log/history_admin_log_section.cpp

@@ -275,11 +275,14 @@ Widget::Widget(
 	QWidget *parent,
 	not_null<Window::SessionController*> controller,
 	not_null<ChannelData*> channel)
-: Window::SectionWidget(parent, controller)
+: Window::SectionWidget(parent, controller, PaintedBackground::Section)
 , _scroll(this, st::historyScroll, false)
 , _fixedBar(this, controller, channel)
 , _fixedBarShadow(this)
-, _whatIsThis(this, tr::lng_admin_log_about(tr::now).toUpper(), st::historyComposeButton) {
+, _whatIsThis(
+		this,
+		tr::lng_admin_log_about(tr::now).toUpper(),
+		st::historyComposeButton) {
 	_fixedBar->move(0, 0);
 	_fixedBar->resizeToWidth(width());
 	_fixedBar->showFilterRequests(
@@ -303,6 +306,11 @@ Widget::Widget(
 		updateAdaptiveLayout();
 	}, lifetime());
 
+	controller->repaintBackgroundRequests(
+	) | rpl::start_with_next([=] {
+		update();
+	}, lifetime());
+
 	_inner = _scroll->setOwnedWidget(object_ptr<InnerWidget>(this, controller, channel));
 	_inner->showSearchSignal(
 	) | rpl::start_with_next([=] {

Telegram/SourceFiles/history/history_widget.cpp

@@ -171,7 +171,7 @@ const auto kPsaAboutPrefix = "cloud_lng_about_psa_";
 HistoryWidget::HistoryWidget(
 	QWidget *parent,
 	not_null<Window::SessionController*> controller)
-: Window::AbstractSectionWidget(parent, controller)
+: Window::AbstractSectionWidget(parent, controller, PaintedBackground::Section)
 , _api(&controller->session().mtp())
 , _updateEditTimeLeftDisplay([=] { updateField(); })
 , _fieldBarCancel(this, st::historyReplyCancel)
@@ -432,6 +432,11 @@ HistoryWidget::HistoryWidget(
 		}
 	}, lifetime());
 
+	controller->repaintBackgroundRequests(
+	) | rpl::start_with_next([=] {
+		update();
+	}, lifetime());
+
 	session().data().newItemAdded(
 	) | rpl::start_with_next([=](not_null<HistoryItem*> item) {
 		newItemAdded(item);

Telegram/SourceFiles/history/view/history_view_pinned_section.cpp

@@ -90,7 +90,7 @@ PinnedWidget::PinnedWidget(
 	QWidget *parent,
 	not_null<Window::SessionController*> controller,
 	not_null<History*> history)
-: Window::SectionWidget(parent, controller)
+: Window::SectionWidget(parent, controller, PaintedBackground::Section)
 , _history(history->migrateToOrMe())
 , _migratedPeer(_history->peer->migrateFrom())
 , _topBar(this, controller)

Telegram/SourceFiles/history/view/history_view_replies_section.cpp

@@ -146,7 +146,7 @@ RepliesWidget::RepliesWidget(
 	not_null<Window::SessionController*> controller,
 	not_null<History*> history,
 	MsgId rootId)
-: Window::SectionWidget(parent, controller)
+: Window::SectionWidget(parent, controller, PaintedBackground::Section)
 , _history(history)
 , _rootId(rootId)
 , _root(lookupRoot())

Telegram/SourceFiles/history/view/history_view_scheduled_section.cpp

@@ -90,7 +90,7 @@ ScheduledWidget::ScheduledWidget(
 	QWidget *parent,
 	not_null<Window::SessionController*> controller,
 	not_null<History*> history)
-: Window::SectionWidget(parent, controller)
+: Window::SectionWidget(parent, controller, PaintedBackground::Section)
 , _history(history)
 , _scroll(this, st::historyScroll, false)
 , _topBar(this, controller)

Telegram/SourceFiles/info/info_section_widget.cpp

@@ -24,7 +24,7 @@ SectionWidget::SectionWidget(
 	not_null<Window::SessionController*> window,
 	Wrap wrap,
 	not_null<Memento*> memento)
-: Window::SectionWidget(parent, window)
+: Window::SectionWidget(parent, window, PaintedBackground::Custom)
 , _content(this, window, wrap, memento) {
 	init();
 }
@@ -34,7 +34,7 @@ SectionWidget::SectionWidget(
 	not_null<Window::SessionController*> window,
 	Wrap wrap,
 	not_null<MoveMemento*> memento)
-: Window::SectionWidget(parent, window)
+: Window::SectionWidget(parent, window, PaintedBackground::Custom)
 , _content(memento->takeContent(this, wrap)) {
 	init();
 }

Telegram/SourceFiles/info/info_wrap_widget.cpp

@@ -59,7 +59,7 @@ WrapWidget::WrapWidget(
 	not_null<Window::SessionController*> window,
 	Wrap wrap,
 	not_null<Memento*> memento)
-: SectionWidget(parent, window)
+: SectionWidget(parent, window, PaintedBackground::Custom)
 , _wrap(wrap)
 , _controller(createController(window, memento->content()))
 , _topShadow(this) {

Telegram/SourceFiles/settings/settings_chat.cpp

@@ -571,18 +571,21 @@ void BackgroundRow::updateImage() {
 				p.setCompositionMode(QPainter::CompositionMode_SoftLight);
 				p.setOpacity(patternOpacity);
 			}
-			const auto &pix = background->pixmap();
+			const auto &prepared = background->prepared();
-			if (!pix.isNull()) {
+			if (!prepared.isNull()) {
-				const auto sx = (pix.width() > pix.height())
+				const auto sx = (prepared.width() > prepared.height())
-					? ((pix.width() - pix.height()) / 2)
+					? ((prepared.width() - prepared.height()) / 2)
 					: 0;
-				const auto sy = (pix.height() > pix.width())
+				const auto sy = (prepared.height() > prepared.width())
-					? ((pix.height() - pix.width()) / 2)
+					? ((prepared.height() - prepared.width()) / 2)
 					: 0;
-				const auto s = (pix.width() > pix.height())
+				const auto s = (prepared.width() > prepared.height())
-					? pix.height()
+					? prepared.height()
-					: pix.width();
+					: prepared.width();
-				p.drawPixmap(0, 0, size, size, pix, sx, sy, s, s);
+				p.drawImage(
+					QRect(0, 0, size, size),
+					prepared,
+					QRect(sx, sy, s, s));
 			}
 		}
 	}

Telegram/SourceFiles/window/section_widget.cpp

@@ -18,14 +18,29 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 namespace Window {
 
+AbstractSectionWidget::AbstractSectionWidget(
+	QWidget *parent,
+	not_null<SessionController*> controller,
+	PaintedBackground paintedBackground)
+: RpWidget(parent)
+, _controller(controller) {
+	if (paintedBackground == PaintedBackground::Section) {
+		controller->repaintBackgroundRequests(
+		) | rpl::start_with_next([=] {
+			update();
+		}, lifetime());
+	}
+}
+
 Main::Session &AbstractSectionWidget::session() const {
 	return _controller->session();
 }
 
 SectionWidget::SectionWidget(
 	QWidget *parent,
-	not_null<Window::SessionController*> controller)
+	not_null<Window::SessionController*> controller,
-: AbstractSectionWidget(parent, controller) {
+	PaintedBackground paintedBackground)
+: AbstractSectionWidget(parent, controller, paintedBackground) {
 }
 
 void SectionWidget::setGeometryWithTopMoved(
@@ -99,18 +114,16 @@ void SectionWidget::PaintBackground(
 	const auto gradient = background->gradientForFill();
 	const auto fill = QSize(widget->width(), fullHeight);
 	auto fromy = controller->content()->backgroundFromY();
-	auto cached = controller->cachedBackground(fill);
+	auto state = controller->backgroundState(fill);
-	const auto goodCache = (cached.area == fill);
+	const auto paintCache = [&](const CachedBackground &cache) {
-	const auto useCached = goodCache || !gradient.isNull();
-	if (!cached.pixmap.isNull()) {
 		const auto to = QRect(
-			QPoint(cached.x, fromy + cached.y),
+			QPoint(cache.x, fromy + cache.y),
-			cached.pixmap.size() / cIntRetinaFactor());
+			cache.pixmap.size() / cIntRetinaFactor());
-		if (goodCache) {
+		if (cache.area == fill) {
-			p.drawPixmap(to, cached.pixmap);
+			p.drawPixmap(to, cache.pixmap);
 		} else {
-			const auto sx = fill.width() / float64(cached.area.width());
+			const auto sx = fill.width() / float64(cache.area.width());
-			const auto sy = fill.height() / float64(cached.area.height());
+			const auto sy = fill.height() / float64(cache.area.height());
 			const auto round = [](float64 value) -> int {
 				return (value >= 0.)
 					? int(std::ceil(value))
@@ -122,17 +135,27 @@ void SectionWidget::PaintBackground(
 				sto.y(),
 				round((to.x() + to.width()) * sx) - sto.x(),
 				round((to.y() + to.height()) * sy) - sto.y(),
-				cached.pixmap);
+				cache.pixmap);
 		}
+	};
+	const auto goodNow = !state.now.pixmap.isNull()
+		&& (state.now.area == fill);
+	const auto useCache = goodNow || !gradient.isNull();
+	if (useCache) {
+		if (state.shown < 1. && !gradient.isNull()) {
+			paintCache(state.was);
+			p.setOpacity(state.shown);
+		}
+		paintCache(state.now);
 		return;
 	}
 	const auto patternOpacity = background->paper().patternOpacity();
-	const auto &bg = background->pixmap();
+	const auto &prepared = background->prepared();
-	if (!bg.isNull() && !background->tile()) {
+	if (!prepared.isNull() && !background->tile()) {
-		auto hq = PainterHighQualityEnabler(p);
+		const auto hq = PainterHighQualityEnabler(p);
 		const auto rects = Window::Theme::ComputeBackgroundRects(
 			fill,
-			bg.size());
+			prepared.size());
 		if (!gradient.isNull()) {
 			p.drawImage(rects.to, gradient);
 			p.setCompositionMode(QPainter::CompositionMode_SoftLight);
@@ -140,17 +163,17 @@ void SectionWidget::PaintBackground(
 		}
 		auto to = rects.to;
 		to.moveTop(to.top() + fromy);
-		p.drawPixmap(to, bg, rects.from);
+		p.drawImage(to, prepared, rects.from);
 		return;
 	}
 	if (!gradient.isNull()) {
-		auto hq = PainterHighQualityEnabler(p);
+		const auto hq = PainterHighQualityEnabler(p);
 		p.drawImage(QRect(QPoint(0, fromy), fill), gradient);
 		p.setCompositionMode(QPainter::CompositionMode_SoftLight);
 		p.setOpacity(patternOpacity);
 	}
-	if (!bg.isNull()) {
+	if (!prepared.isNull()) {
-		auto &tiled = background->pixmapForTiled();
+		const auto &tiled = background->preparedForTiled();
 		auto left = clip.left();
 		auto top = clip.top();
 		auto right = clip.left() + clip.width();
@@ -163,7 +186,7 @@ void SectionWidget::PaintBackground(
 		auto cy = qCeil((bottom - fromy) / h);
 		for (auto i = sx; i < cx; ++i) {
 			for (auto j = sy; j < cy; ++j) {
-				p.drawPixmap(QPointF(i * w, fromy + j * h), tiled);
+				p.drawImage(QPointF(i * w, fromy + j * h), tiled);
 			}
 		}
 	}

Telegram/SourceFiles/window/section_widget.h

@@ -40,12 +40,14 @@ class AbstractSectionWidget
 	, public Media::Player::FloatSectionDelegate
 	, protected base::Subscriber {
 public:
+	enum class PaintedBackground {
+		Section,
+		Custom,
+	};
 	AbstractSectionWidget(
 		QWidget *parent,
-		not_null<SessionController*> controller)
+		not_null<SessionController*> controller,
-	: RpWidget(parent)
+		PaintedBackground paintedBackground);
-	, _controller(controller) {
-	}
 
 	[[nodiscard]] Main::Session &session() const;
 	[[nodiscard]] not_null<SessionController*> controller() const {
@@ -84,7 +86,8 @@ class SectionWidget : public AbstractSectionWidget {
 public:
 	SectionWidget(
 		QWidget *parent,
-		not_null<SessionController*> controller);
+		not_null<SessionController*> controller,
+		PaintedBackground paintedBackground);
 
 	virtual Dialogs::RowDescriptor activeChat() const {
 		return {};

Telegram/SourceFiles/window/themes/window_theme.cpp

@@ -730,8 +730,8 @@ void ChatBackground::set(const Data::WallPaper &paper, QImage image) {
 	Assert(colorForFill()
 		|| !_gradient.isNull()
 		|| (!_original.isNull()
-			&& !_pixmap.isNull()
+			&& !_prepared.isNull()
-			&& !_pixmapForTiled.isNull()));
+			&& !_preparedForTiled.isNull()));
 
 	_updates.fire({ BackgroundUpdate::Type::New, tile() }); // delayed?
 	if (needResetAdjustable) {
@@ -763,46 +763,42 @@ void ChatBackground::setPrepared(
 	}
 
 	_original = std::move(original);
+	_prepared = std::move(prepared);
 	_gradient = std::move(gradient);
-	preparePixmaps(std::move(prepared));
+	_imageMonoColor = _gradient.isNull()
+		? CalculateImageMonoColor(_prepared)
+		: std::nullopt;
+	prepareImageForTiled();
 }
 
-void ChatBackground::preparePixmaps(QImage image) {
+void ChatBackground::prepareImageForTiled() {
-	const auto width = image.width();
+	const auto width = _prepared.width();
-	const auto height = image.height();
+	const auto height = _prepared.height();
 	const auto isSmallForTiled = (width > 0 && height > 0)
 		&& (width < kMinimumTiledSize || height < kMinimumTiledSize);
-	if (isSmallForTiled) {
-		const auto repeatTimesX = qCeil(kMinimumTiledSize / (1. * width));
-		const auto repeatTimesY = qCeil(kMinimumTiledSize / (1. * height));
-		auto imageForTiled = QImage(
-			width * repeatTimesX,
-			height * repeatTimesY,
-			QImage::Format_ARGB32_Premultiplied);
-		imageForTiled.setDevicePixelRatio(image.devicePixelRatio());
-		auto imageForTiledBytes = imageForTiled.bits();
-		auto bytesInLine = width * sizeof(uint32);
-		for (auto timesY = 0; timesY != repeatTimesY; ++timesY) {
-			auto imageBytes = image.constBits();
-			for (auto y = 0; y != height; ++y) {
-				for (auto timesX = 0; timesX != repeatTimesX; ++timesX) {
-					memcpy(imageForTiledBytes, imageBytes, bytesInLine);
-					imageForTiledBytes += bytesInLine;
-				}
-				imageBytes += image.bytesPerLine();
-				imageForTiledBytes += imageForTiled.bytesPerLine() - (repeatTimesX * bytesInLine);
-			}
-		}
-		_pixmapForTiled = Ui::PixmapFromImage(std::move(imageForTiled));
-	}
-	_imageMonoColor = _gradient.isNull()
-		? CalculateImageMonoColor(image)
-		: std::nullopt;
-	_pixmap = image.isNull()
-		? QPixmap()
-		: Ui::PixmapFromImage(std::move(image));
 	if (!isSmallForTiled) {
-		_pixmapForTiled = _pixmap;
+		_preparedForTiled = _prepared;
+		return;
+	}
+	const auto repeatTimesX = qCeil(kMinimumTiledSize / (1. * width));
+	const auto repeatTimesY = qCeil(kMinimumTiledSize / (1. * height));
+	_preparedForTiled = QImage(
+		width * repeatTimesX,
+		height * repeatTimesY,
+		QImage::Format_ARGB32_Premultiplied);
+	_preparedForTiled.setDevicePixelRatio(_prepared.devicePixelRatio());
+	auto imageForTiledBytes = _preparedForTiled.bits();
+	auto bytesInLine = width * sizeof(uint32);
+	for (auto timesY = 0; timesY != repeatTimesY; ++timesY) {
+		auto imageBytes = _prepared.constBits();
+		for (auto y = 0; y != height; ++y) {
+			for (auto timesX = 0; timesX != repeatTimesX; ++timesX) {
+				memcpy(imageForTiledBytes, imageBytes, bytesInLine);
+				imageForTiledBytes += bytesInLine;
+			}
+			imageBytes += _prepared.bytesPerLine();
+			imageForTiledBytes += _preparedForTiled.bytesPerLine() - (repeatTimesX * bytesInLine);
+		}
 	}
 }
 
@@ -868,7 +864,7 @@ void ChatBackground::adjustPaletteUsingColor(QColor color) {
 }
 
 std::optional<QColor> ChatBackground::colorForFill() const {
-	return !_pixmap.isNull()
+	return !_prepared.isNull()
 		? imageMonoColor()
 		: !_gradient.isNull()
 		? std::nullopt
@@ -888,13 +884,12 @@ QImage ChatBackground::createCurrentImage() const {
 		result.fill(*fill);
 		return result;
 	} else if (_gradient.isNull()) {
-		return pixmap().toImage();
+		return _prepared;
-	} else if (pixmap().isNull()) {
+	} else if (_prepared.isNull()) {
 		return _gradient;
 	}
-	const auto &pattern = pixmap();
 	auto result = _gradient.scaled(
-		pattern.size(),
+		_prepared.size(),
 		Qt::IgnoreAspectRatio,
 		Qt::SmoothTransformation);
 	result.setDevicePixelRatio(1.);
@@ -902,7 +897,7 @@ QImage ChatBackground::createCurrentImage() const {
 		auto p = QPainter(&result);
 		p.setCompositionMode(QPainter::CompositionMode_SoftLight);
 		p.setOpacity(paper().patternOpacity());
-		p.drawPixmap(QRect(QPoint(), pattern.size()), pattern);
+		p.drawImage(QRect(QPoint(), _prepared.size()), _prepared);
 	}
 	return result;
 }
@@ -1044,7 +1039,7 @@ void ChatBackground::setTestingTheme(Instance &&theme) {
 			saveForRevert();
 			set(
 				Data::details::TestingEditorWallPaper(),
-				std::move(_pixmap).toImage());
+				base::take(_prepared));
 		}
 	} else if (switchToThemeBackground) {
 		saveForRevert();

Telegram/SourceFiles/window/themes/window_theme.h

@@ -170,11 +170,11 @@ public:
 	[[nodiscard]] WallPaperId id() const {
 		return _paper.id();
 	}
-	[[nodiscard]] const QPixmap &pixmap() const {
+	[[nodiscard]] const QImage &prepared() const {
-		return _pixmap;
+		return _prepared;
 	}
-	[[nodiscard]] const QPixmap &pixmapForTiled() const {
+	[[nodiscard]] const QImage &preparedForTiled() const {
-		return _pixmapForTiled;
+		return _preparedForTiled;
 	}
 	[[nodiscard]] std::optional<QColor> colorForFill() const;
 	[[nodiscard]] QImage gradientForFill() const;
@@ -197,7 +197,7 @@ private:
 	void initialRead();
 	void saveForRevert();
 	void setPrepared(QImage original, QImage prepared, QImage gradient);
-	void preparePixmaps(QImage image);
+	void prepareImageForTiled();
 	void writeNewBackgroundSettings();
 	void setPaper(const Data::WallPaper &paper);
 
@@ -239,8 +239,8 @@ private:
 	std::optional<QColor> _paperColor;
 	QImage _gradient;
 	QImage _original;
-	QPixmap _pixmap;
+	QImage _prepared;
-	QPixmap _pixmapForTiled;
+	QImage _preparedForTiled;
 	bool _nightMode = false;
 	bool _tileDayValue = false;
 	bool _tileNightValue = true;

Telegram/SourceFiles/window/window_main_menu.cpp

@@ -988,10 +988,11 @@ void MainMenu::refreshBackground() {
 	const auto intensityText = IntensityOfColor(st::mainMenuCoverFg->c);
 	const auto background = Window::Theme::Background();
 	const auto &paper = background->paper();
-	const auto &pixmap = background->pixmap();
+	const auto &prepared = background->prepared();
 
-	QRect to, from;
+	const auto rects = Window::Theme::ComputeBackgroundRects(
-	const auto rects = Window::Theme::ComputeBackgroundRects(fill, pixmap.size());
+		fill,
+		prepared.size());
 
 	auto backgroundImage = !paper.backgroundColors().empty()
 		? Data::GenerateWallPaper(
@@ -999,7 +1000,7 @@ void MainMenu::refreshBackground() {
 			paper.backgroundColors(),
 			paper.gradientRotation(),
 			paper.patternOpacity(),
-			[&](QPainter &p) { p.drawPixmap(to, pixmap, from); })
+			[&](QPainter &p) { p.drawImage(rects.to, prepared, rects.from); })
 		: QImage(
 			fill * cIntRetinaFactor(),
 			QImage::Format_ARGB32_Premultiplied);
@@ -1029,7 +1030,7 @@ void MainMenu::refreshBackground() {
 
 	// Background image.
 	if (!paper.isPattern()) {
-		p.drawPixmap(to, pixmap, from);
+		p.drawImage(rects.to, prepared, rects.from);
 	}
 
 	// Cut off the part of the background that is under text.

Telegram/SourceFiles/window/window_session_controller.cpp

@@ -72,6 +72,7 @@ namespace {
 constexpr auto kMaxChatEntryHistorySize = 50;
 constexpr auto kCacheBackgroundTimeout = 3 * crl::time(1000);
 constexpr auto kCacheBackgroundFastTimeout = crl::time(200);
+constexpr auto kBackgroundFadeDuration = crl::time(200);
 
 } // namespace
 
@@ -1318,15 +1319,16 @@ void SessionController::openDocument(
 		session().data().message(contextId));
 }
 
-CachedBackground SessionController::cachedBackground(QSize area) {
+const BackgroundState &SessionController::backgroundState(QSize area) {
-	if (_cachedBackground.area != area) {
+	_backgroundState.shown = _backgroundFade.value(1.);
+	if (_backgroundState.now.area != area) {
 		if (_willCacheForArea != area || !_cacheBackgroundTimer.isActive()) {
 			_willCacheForArea = area;
 			_lastAreaChangeTime = crl::now();
 			_cacheBackgroundTimer.callOnce(kCacheBackgroundFastTimeout);
 		}
 	}
-	return _cachedBackground;
+	return _backgroundState;
 }
 
 void SessionController::cacheBackground() {
@@ -1342,8 +1344,8 @@ void SessionController::cacheBackground() {
 	}
 	const auto gradient = background->gradientForFill();
 	const auto patternOpacity = background->paper().patternOpacity();
-	const auto &bg = background->pixmap();
+	const auto &prepared = background->prepared();
-	if (background->tile() || bg.isNull()) {
+	if (background->tile() || prepared.isNull()) {
 		auto result = gradient.isNull()
 			? QImage(
 				_willCacheForArea * cIntRetinaFactor(),
@@ -1353,34 +1355,34 @@ void SessionController::cacheBackground() {
 				Qt::IgnoreAspectRatio,
 				Qt::SmoothTransformation);
 		result.setDevicePixelRatio(cRetinaFactor());
-		if (!bg.isNull()) {
+		if (!prepared.isNull()) {
 			QPainter p(&result);
 			if (!gradient.isNull()) {
 				p.setCompositionMode(QPainter::CompositionMode_SoftLight);
 				p.setOpacity(patternOpacity);
 			}
-			const auto &tiled = background->pixmapForTiled();
+			const auto &tiled = background->preparedForTiled();
-			auto w = tiled.width() / cRetinaFactor();
+			const auto w = tiled.width() / cRetinaFactor();
-			auto h = tiled.height() / cRetinaFactor();
+			const auto h = tiled.height() / cRetinaFactor();
 			auto sx = 0;
 			auto sy = 0;
-			auto cx = qCeil(_willCacheForArea.width() / w);
+			const auto cx = qCeil(_willCacheForArea.width() / w);
-			auto cy = qCeil(_willCacheForArea.height() / h);
+			const auto cy = qCeil(_willCacheForArea.height() / h);
 			for (int i = sx; i < cx; ++i) {
 				for (int j = sy; j < cy; ++j) {
-					p.drawPixmap(QPointF(i * w, j * h), tiled);
+					p.drawImage(QPointF(i * w, j * h), tiled);
 				}
 			}
 		}
-		_cachedBackground = CachedBackground{
+		setCachedBackground({
 			.pixmap = Ui::PixmapFromImage(std::move(result)),
 			.area = _willCacheForArea,
-		};
+		});
 	} else {
 		const auto rects = Window::Theme::ComputeBackgroundRects(
 			_willCacheForArea,
-			bg.size());
+			prepared.size());
-		auto image = bg.toImage().copy(rects.from).scaled(
+		auto image = prepared.copy(rects.from).scaled(
 			rects.to.width() * cIntRetinaFactor(),
 			rects.to.height() * cIntRetinaFactor(),
 			Qt::IgnoreAspectRatio,
@@ -1399,21 +1401,51 @@ void SessionController::cacheBackground() {
 			p.drawImage(QRect(QPoint(), rects.to.size()), image);
 		}
 		image = QImage();
-		_cachedBackground = {
+		setCachedBackground({
 			.pixmap = Ui::PixmapFromImage(std::move(result)),
 			.area = _willCacheForArea,
 			.x = rects.to.x(),
 			.y = rects.to.y(),
-		};
+		});
-	}
-	if (!gradient.isNull()) {
-		content()->update();
 	}
 }
 
+void SessionController::setCachedBackground(CachedBackground &&cached) {
+	const auto background = Window::Theme::Background();
+	if (background->gradientForFill().isNull()
+		|| _backgroundState.now.pixmap.isNull()) {
+		_backgroundFade.stop();
+		_backgroundState.shown = 1.;
+		_backgroundState.now = std::move(cached);
+		return;
+	}
+	// #TODO themes compose several transitions.
+	_backgroundState.was = std::move(_backgroundState.now);
+	_backgroundState.now = std::move(cached);
+	_backgroundState.shown = 0.;
+	const auto callback = [=] {
+		if (!_backgroundFade.animating()) {
+			_backgroundState.was = {};
+			_backgroundState.shown = 1.;
+		}
+		_repaintBackgroundRequests.fire({});
+	};
+	_backgroundFade.start(
+		callback,
+		0.,
+		1.,
+		kBackgroundFadeDuration);
+}
+
 void SessionController::clearCachedBackground() {
-	_cachedBackground = {};
+	_backgroundState = {};
+	_backgroundFade.stop();
 	_cacheBackgroundTimer.cancel();
+	_repaintBackgroundRequests.fire({});
+}
+
+rpl::producer<> SessionController::repaintBackgroundRequests() const {
+	return _repaintBackgroundRequests.events();
 }
 
 SessionController::~SessionController() {

Telegram/SourceFiles/window/window_session_controller.h

@@ -7,13 +7,12 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #pragma once
 
-#include <rpl/variable.h>
 #include "base/flags.h"
 #include "base/object_ptr.h"
 #include "base/weak_ptr.h"
 #include "base/timer.h"
 #include "dialogs/dialogs_key.h"
-#include "ui/effects/animation_value.h"
+#include "ui/effects/animations.h"
 #include "ui/layers/layer_widget.h"
 #include "window/window_adaptive.h"
 
@@ -63,6 +62,12 @@ struct CachedBackground {
 	int y = 0;
 };
 
+struct BackgroundState {
+	CachedBackground was;
+	CachedBackground now;
+	float64 shown = 1.;
+};
+
 enum class GifPauseReason {
 	Any           = 0,
 	InlineResults = (1 << 0),
@@ -232,7 +237,6 @@ private:
 	MsgId _showingRepliesRootId = 0;
 	mtpRequestId _showingRepliesRequestId = 0;
 
-
 };
 
 class SessionController : public SessionNavigation {
@@ -296,11 +300,11 @@ public:
 	void floatPlayerAreaUpdated();
 
 	struct ColumnLayout {
-		int bodyWidth;
+		int bodyWidth = 0;
-		int dialogsWidth;
+		int dialogsWidth = 0;
-		int chatWidth;
+		int chatWidth = 0;
-		int thirdWidth;
+		int thirdWidth = 0;
-		Adaptive::WindowLayout windowLayout;
+		Adaptive::WindowLayout windowLayout = Adaptive::WindowLayout();
 	};
 	[[nodiscard]] ColumnLayout computeColumnLayout() const;
 	int dialogsSmallColumnWidth() const;
@@ -400,7 +404,8 @@ public:
 	void toggleFiltersMenu(bool enabled);
 	[[nodiscard]] rpl::producer<> filtersMenuChanged() const;
 
-	[[nodiscard]] CachedBackground cachedBackground(QSize area);
+	[[nodiscard]] const BackgroundState &backgroundState(QSize area);
+	[[nodiscard]] rpl::producer<> repaintBackgroundRequests() const;
 
 	rpl::lifetime &lifetime() {
 		return _lifetime;
@@ -433,6 +438,7 @@ private:
 
 	void cacheBackground();
 	void clearCachedBackground();
+	void setCachedBackground(CachedBackground &&cached);
 
 	const not_null<Controller*> _window;
 
@@ -461,10 +467,12 @@ private:
 
 	rpl::event_stream<> _filtersMenuChanged;
 
-	CachedBackground _cachedBackground;
+	BackgroundState _backgroundState;
+	Ui::Animations::Simple _backgroundFade;
 	QSize _willCacheForArea;
 	crl::time _lastAreaChangeTime = 0;
 	base::Timer _cacheBackgroundTimer;
+	rpl::event_stream<> _repaintBackgroundRequests;
 
 	rpl::lifetime _lifetime;