Don't blend SoftLight patterns in realtime.

Telegram/SourceFiles/window/section_widget.cpp

@@ -91,36 +91,61 @@ void SectionWidget::PaintBackground(
 	Painter p(widget);
 
 	const auto background = Window::Theme::Background();
-	auto fill = QRect(0, 0, widget->width(), controller->content()->height());
+	const auto fullHeight = controller->content()->height();
 	if (const auto color = background->colorForFill()) {
-		p.fillRect(fill, *color);
-		return;
-	}
-	auto fromy = controller->content()->backgroundFromY();
-	auto cached = controller->cachedBackground(fill);
-	if (!cached.pixmap.isNull()) {
-		p.drawPixmap(cached.x, fromy + cached.y, cached.pixmap);
+		p.fillRect(clip, *color);
 		return;
 	}
 	const auto gradient = background->gradientForFill();
+	const auto fill = QSize(widget->width(), fullHeight);
+	auto fromy = controller->content()->backgroundFromY();
+	auto cached = controller->cachedBackground(fill);
+	const auto goodCache = (cached.area == fill);
+	const auto useCached = goodCache || !gradient.isNull();
+	if (!cached.pixmap.isNull()) {
+		const auto to = QRect(
+			QPoint(cached.x, fromy + cached.y),
+			cached.pixmap.size() / cIntRetinaFactor());
+		if (goodCache) {
+			p.drawPixmap(to, cached.pixmap);
+		} else {
+			const auto sx = fill.width() / float64(cached.area.width());
+			const auto sy = fill.height() / float64(cached.area.height());
+			const auto round = [](float64 value) -> int {
+				return (value >= 0.)
+					? int(std::ceil(value))
+					: int(std::floor(value));
+			};
+			const auto sto = QPoint(round(to.x() * sx), round(to.y() * sy));
+			p.drawPixmap(
+				sto.x(),
+				sto.y(),
+				round((to.x() + to.width()) * sx) - sto.x(),
+				round((to.y() + to.height()) * sy) - sto.y(),
+				cached.pixmap);
+		}
+		return;
+	}
 	const auto patternOpacity = background->paper().patternOpacity();
 	const auto &bg = background->pixmap();
 	if (!bg.isNull() && !background->tile()) {
 		auto hq = PainterHighQualityEnabler(p);
-		QRect to, from;
-		Window::Theme::ComputeBackgroundRects(fill, bg.size(), to, from);
+		const auto rects = Window::Theme::ComputeBackgroundRects(
+			fill,
+			bg.size());
 		if (!gradient.isNull()) {
-			p.drawImage(to, gradient);
+			p.drawImage(rects.to, gradient);
 			p.setCompositionMode(QPainter::CompositionMode_SoftLight);
 			p.setOpacity(patternOpacity);
 		}
+		auto to = rects.to;
 		to.moveTop(to.top() + fromy);
-		p.drawPixmap(to, bg, from);
+		p.drawPixmap(to, bg, rects.from);
 		return;
 	}
 	if (!gradient.isNull()) {
 		auto hq = PainterHighQualityEnabler(p);
-		p.drawImage(fill, gradient);
+		p.drawImage(QRect(QPoint(0, fromy), fill), gradient);
 		p.setCompositionMode(QPainter::CompositionMode_SoftLight);
 		p.setOpacity(patternOpacity);
 	}

Telegram/SourceFiles/window/themes/window_theme.cpp

@@ -1494,27 +1494,31 @@ QImage PreprocessBackgroundImage(QImage image) {
 	return image;
 }
 
-void ComputeBackgroundRects(QRect wholeFill, QSize imageSize, QRect &to, QRect &from) {
-	if (uint64(imageSize.width()) * wholeFill.height() > uint64(imageSize.height()) * wholeFill.width()) {
-		float64 pxsize = wholeFill.height() / float64(imageSize.height());
-		int takewidth = qCeil(wholeFill.width() / pxsize);
+BackgroundRects ComputeBackgroundRects(QSize fillSize, QSize imageSize) {
+	if (uint64(imageSize.width()) * fillSize.height() > uint64(imageSize.height()) * fillSize.width()) {
+		float64 pxsize = fillSize.height() / float64(imageSize.height());
+		int takewidth = qCeil(fillSize.width() / pxsize);
 		if (takewidth > imageSize.width()) {
 			takewidth = imageSize.width();
 		} else if ((imageSize.width() % 2) != (takewidth % 2)) {
 			++takewidth;
 		}
-		to = QRect(int((wholeFill.width() - takewidth * pxsize) / 2.), 0, qCeil(takewidth * pxsize), wholeFill.height());
-		from = QRect((imageSize.width() - takewidth) / 2, 0, takewidth, imageSize.height());
+		return {
+			.from = QRect((imageSize.width() - takewidth) / 2, 0, takewidth, imageSize.height()),
+			.to = QRect(int((fillSize.width() - takewidth * pxsize) / 2.), 0, qCeil(takewidth * pxsize), fillSize.height()),
+		};
 	} else {
-		float64 pxsize = wholeFill.width() / float64(imageSize.width());
-		int takeheight = qCeil(wholeFill.height() / pxsize);
+		float64 pxsize = fillSize.width() / float64(imageSize.width());
+		int takeheight = qCeil(fillSize.height() / pxsize);
 		if (takeheight > imageSize.height()) {
 			takeheight = imageSize.height();
 		} else if ((imageSize.height() % 2) != (takeheight % 2)) {
 			++takeheight;
 		}
-		to = QRect(0, int((wholeFill.height() - takeheight * pxsize) / 2.), wholeFill.width(), qCeil(takeheight * pxsize));
-		from = QRect(0, (imageSize.height() - takeheight) / 2, imageSize.width(), takeheight);
+		return {
+			.from = QRect(0, (imageSize.height() - takeheight) / 2, imageSize.width(), takeheight),
+			.to = QRect(0, int((fillSize.height() - takeheight * pxsize) / 2.), fillSize.width(), qCeil(takeheight * pxsize)),
+		};
 	}
 }
 

Telegram/SourceFiles/window/themes/window_theme.h

@@ -270,7 +270,13 @@ private:
 
 [[nodiscard]] ChatBackground *Background();
 
-void ComputeBackgroundRects(QRect wholeFill, QSize imageSize, QRect &to, QRect &from);
+struct BackgroundRects {
+	QRect from;
+	QRect to;
+};
+[[nodiscard]] BackgroundRects ComputeBackgroundRects(
+	QSize fillSize,
+	QSize imageSize);
 
 bool ReadPaletteValues(const QByteArray &content, Fn<bool(QLatin1String name, QLatin1String value)> callback);
 

Telegram/SourceFiles/window/themes/window_theme_preview.cpp

@@ -455,12 +455,12 @@ void Generator::paintHistoryBackground() {
 	} else {
 		PainterHighQualityEnabler hq(*_p);
 
-		auto fill = QRect(_topBar.x(), _topBar.y(), _topBar.width(), _body.height());
-		QRect to, from;
-		ComputeBackgroundRects(fill, background.size(), to, from);
+		auto fill = QSize(_topBar.width(), _body.height());
+		const auto rects = ComputeBackgroundRects(fill, background.size());
+		auto to = rects.to;
 		to.moveTop(to.top() + fromy);
 		to.moveTopLeft(to.topLeft() + _history.topLeft());
-		_p->drawImage(to, background, from);
+		_p->drawImage(to, background, rects.from);
 	}
 	_p->setClipping(false);
 }

Telegram/SourceFiles/window/window_main_menu.cpp

@@ -984,24 +984,24 @@ void MainMenu::refreshMenu() {
 }
 
 void MainMenu::refreshBackground() {
-	const auto fill = QRect(0, 0, st::mainMenuWidth, st::mainMenuCoverHeight);
+	const auto fill = QSize(st::mainMenuWidth, st::mainMenuCoverHeight);
 	const auto intensityText = IntensityOfColor(st::mainMenuCoverFg->c);
 	const auto background = Window::Theme::Background();
 	const auto &paper = background->paper();
 	const auto &pixmap = background->pixmap();
 
 	QRect to, from;
-	Window::Theme::ComputeBackgroundRects(fill, pixmap.size(), to, from);
+	const auto rects = Window::Theme::ComputeBackgroundRects(fill, pixmap.size());
 
 	auto backgroundImage = !paper.backgroundColors().empty()
 		? Data::GenerateWallPaper(
-			fill.size() * cIntRetinaFactor(),
+			fill * cIntRetinaFactor(),
 			paper.backgroundColors(),
 			paper.gradientRotation(),
 			paper.patternOpacity(),
 			[&](QPainter &p) { p.drawPixmap(to, pixmap, from); })
 		: QImage(
-			fill.size() * cIntRetinaFactor(),
+			fill * cIntRetinaFactor(),
 			QImage::Format_ARGB32_Premultiplied);
 	QPainter p(&backgroundImage);
 
@@ -1019,7 +1019,7 @@ void MainMenu::refreshBackground() {
 	// Solid color.
 	if (const auto color = background->colorForFill()) {
 		const auto intensity = IntensityOfColor(*color);
-		p.fillRect(fill, *color);
+		p.fillRect(QRect(QPoint(), fill), *color);
 		if (std::abs(intensity - intensityText) < kMinDiffIntensity) {
 			drawShadow(p);
 		}

Telegram/SourceFiles/window/window_session_controller.cpp

@@ -1318,17 +1318,15 @@ void SessionController::openDocument(
 		session().data().message(contextId));
 }
 
-CachedBackground SessionController::cachedBackground(QRect area) {
-	if (!_cachedBackground.pixmap.isNull()
-		&& area == _cachedBackground.area) {
-		return _cachedBackground;
+CachedBackground SessionController::cachedBackground(QSize area) {
+	if (_cachedBackground.area != area) {
+		if (_willCacheForArea != area || !_cacheBackgroundTimer.isActive()) {
+			_willCacheForArea = area;
+			_lastAreaChangeTime = crl::now();
+			_cacheBackgroundTimer.callOnce(kCacheBackgroundFastTimeout);
+		}
 	}
-	if (_willCacheForArea != area || !_cacheBackgroundTimer.isActive()) {
-		_willCacheForArea = area;
-		_lastAreaChangeTime = crl::now();
-		_cacheBackgroundTimer.callOnce(kCacheBackgroundFastTimeout);
-	}
-	return {};
+	return _cachedBackground;
 }
 
 void SessionController::cacheBackground() {
@@ -1348,10 +1346,10 @@ void SessionController::cacheBackground() {
 	if (background->tile() || bg.isNull()) {
 		auto result = gradient.isNull()
 			? QImage(
-				_willCacheForArea.size() * cIntRetinaFactor(),
+				_willCacheForArea * cIntRetinaFactor(),
 				QImage::Format_ARGB32_Premultiplied)
 			: gradient.scaled(
-				_willCacheForArea.size() * cIntRetinaFactor(),
+				_willCacheForArea * cIntRetinaFactor(),
 				Qt::IgnoreAspectRatio,
 				Qt::SmoothTransformation);
 		result.setDevicePixelRatio(cRetinaFactor());
@@ -1379,15 +1377,12 @@ void SessionController::cacheBackground() {
 			.area = _willCacheForArea,
 		};
 	} else {
-		QRect to, from;
-		Window::Theme::ComputeBackgroundRects(
+		const auto rects = Window::Theme::ComputeBackgroundRects(
 			_willCacheForArea,
-			bg.size(),
-			to,
-			from);
-		auto image = bg.toImage().copy(from).scaled(
-			to.width() * cIntRetinaFactor(),
-			to.height() * cIntRetinaFactor(),
+			bg.size());
+		auto image = bg.toImage().copy(rects.from).scaled(
+			rects.to.width() * cIntRetinaFactor(),
+			rects.to.height() * cIntRetinaFactor(),
 			Qt::IgnoreAspectRatio,
 			Qt::SmoothTransformation);
 		auto result = gradient.isNull()
@@ -1401,16 +1396,19 @@ void SessionController::cacheBackground() {
 			QPainter p(&result);
 			p.setCompositionMode(QPainter::CompositionMode_SoftLight);
 			p.setOpacity(patternOpacity);
-			p.drawImage(QRect(QPoint(), to.size()), image);
+			p.drawImage(QRect(QPoint(), rects.to.size()), image);
 		}
 		image = QImage();
 		_cachedBackground = {
 			.pixmap = Ui::PixmapFromImage(std::move(result)),
 			.area = _willCacheForArea,
-			.x = to.x(),
-			.y = to.y(),
+			.x = rects.to.x(),
+			.y = rects.to.y(),
 		};
 	}
+	if (!gradient.isNull()) {
+		content()->update();
+	}
 }
 
 void SessionController::clearCachedBackground() {

Telegram/SourceFiles/window/window_session_controller.h

@@ -58,7 +58,7 @@ class FiltersMenu;
 
 struct CachedBackground {
 	QPixmap pixmap;
-	QRect area;
+	QSize area;
 	int x = 0;
 	int y = 0;
 };
@@ -400,7 +400,7 @@ public:
 	void toggleFiltersMenu(bool enabled);
 	[[nodiscard]] rpl::producer<> filtersMenuChanged() const;
 
-	[[nodiscard]] CachedBackground cachedBackground(QRect area);
+	[[nodiscard]] CachedBackground cachedBackground(QSize area);
 
 	rpl::lifetime &lifetime() {
 		return _lifetime;
@@ -462,7 +462,7 @@ private:
 	rpl::event_stream<> _filtersMenuChanged;
 
 	CachedBackground _cachedBackground;
-	QRect _willCacheForArea;
+	QSize _willCacheForArea;
 	crl::time _lastAreaChangeTime = 0;
 	base::Timer _cacheBackgroundTimer;