Use non-exact image previews if available.

Telegram/SourceFiles/data/stickers/data_custom_emoji.cpp

@@ -380,7 +380,7 @@ std::unique_ptr<Ui::Text::CustomEmoji> CustomEmojiManager::create(
 			documentId,
 			std::make_unique<Ui::CustomEmoji::Instance>(Loading{
 				factory(),
-				Ui::CustomEmoji::Preview()
+				prepareNonExactPreview(documentId, tag)
 			}, std::move(repaint))).first;
 	}
 	return std::make_unique<Ui::CustomEmoji::Object>(
@@ -388,6 +388,27 @@ std::unique_ptr<Ui::Text::CustomEmoji> CustomEmojiManager::create(
 		std::move(update));
 }
 
+Ui::CustomEmoji::Preview CustomEmojiManager::prepareNonExactPreview(
+		DocumentId documentId,
+		SizeTag tag) const {
+	const auto &other = _instances[1 - SizeIndex(tag)];
+	const auto j = other.find(documentId);
+	if (j == end(other)) {
+		return {};
+	} else if (const auto nonExact = j->second->imagePreview()) {
+		const auto size = SizeFromTag(tag);
+		return {
+			nonExact.image().scaled(
+				size,
+				size,
+				Qt::IgnoreAspectRatio,
+				Qt::SmoothTransformation),
+			false,
+		};
+	}
+	return {};
+}
+
 std::unique_ptr<Ui::Text::CustomEmoji> CustomEmojiManager::create(
 		QStringView data,
 		Fn<void()> update,

Telegram/SourceFiles/data/stickers/data_custom_emoji.h

@@ -78,6 +78,9 @@ private:
 	void invokeRepaints();
 	void requestSetFor(not_null<DocumentData*> document);
 
+	[[nodiscard]] Ui::CustomEmoji::Preview prepareNonExactPreview(
+		DocumentId documentId,
+		SizeTag tag) const;
 	template <typename LoaderFactory>
 	[[nodiscard]] std::unique_ptr<Ui::Text::CustomEmoji> create(
 		DocumentId documentId,

Telegram/SourceFiles/ui/text/custom_emoji_instance.cpp

@@ -37,22 +37,38 @@ Preview::Preview(QPainterPath path, float64 scale)
 : _data(ScaledPath{ std::move(path), scale }) {
 }
 
-Preview::Preview(QImage image) : _data(std::move(image)) {
+Preview::Preview(QImage image, bool exact)
+: _data(Image{ .data = std::move(image), .exact = exact }) {
 }
 
 void Preview::paint(QPainter &p, int x, int y, const QColor &preview) {
 	if (const auto path = std::get_if<ScaledPath>(&_data)) {
 		paintPath(p, x, y, preview, *path);
-	} else if (const auto image = std::get_if<QImage>(&_data)) {
+	} else if (const auto image = std::get_if<Image>(&_data)) {
+		const auto &data = image->data;
 		const auto factor = style::DevicePixelRatio();
-		const auto width = image->width() / factor;
-		const auto height = image->height() / factor;
-		p.drawImage(QRect(x, y, width, height), *image);
+		const auto width = data.width() / factor;
+		const auto height = data.height() / factor;
+		p.drawImage(QRect(x, y, width, height), data);
 	}
 }
 
-bool Preview::image() const {
-	return v::is<QImage>(_data);
+bool Preview::isImage() const {
+	return v::is<Image>(_data);
+}
+
+bool Preview::isExactImage() const {
+	if (const auto image = std::get_if<Image>(&_data)) {
+		return image->exact;
+	}
+	return false;
+}
+
+QImage Preview::image() const {
+	if (const auto image = std::get_if<Image>(&_data)) {
+		return image->data;
+	}
+	return QImage();
 }
 
 void Preview::paintPath(
@@ -190,7 +206,7 @@ Preview Cache::makePreview() const {
 	Expects(_frames > 0);
 
 	const auto first = frame(0);
-	return { first.image->copy(first.source) };
+	return { first.image->copy(first.source), true };
 }
 
 void Cache::reserve(int frames) {
@@ -349,8 +365,12 @@ PaintFrameResult Cached::paint(QPainter &p, int x, int y, crl::time now) {
 	return _cache.paintCurrentFrame(p, x, y, now);
 }
 
+Preview Cached::makePreview() const {
+	return _cache.makePreview();
+}
+
 Loading Cached::unload() {
-	return Loading(_unloader(), _cache.makePreview());
+	return Loading(_unloader(), makePreview());
 }
 
 Renderer::Renderer(RendererDescriptor &&descriptor)
@@ -516,6 +536,10 @@ void Loading::paint(QPainter &p, int x, int y, const QColor &preview) {
 	_preview.paint(p, x, y, preview);
 }
 
+Preview Loading::imagePreview() const {
+	return _preview.isImage() ? _preview : Preview();
+}
+
 void Loading::cancel() {
 	_loader->cancel();
 	invalidate_weak_ptrs(this);
@@ -564,7 +588,7 @@ void Instance::paint(
 		if (!result.painted) {
 			caching->preview.paint(p, x, y, preview);
 		} else {
-			if (!caching->preview.image()) {
+			if (!caching->preview.isExactImage()) {
 				caching->preview = caching->renderer->makePreview();
 			}
 			if (result.next > now) {
@@ -582,6 +606,17 @@ void Instance::paint(
 	}
 }
 
+Preview Instance::imagePreview() const {
+	if (const auto loading = std::get_if<Loading>(&_state)) {
+		return loading->imagePreview();
+	} else if (const auto caching = std::get_if<Caching>(&_state)) {
+		return caching->preview.isImage() ? caching->preview : Preview();
+	} else if (const auto cached = std::get_if<Cached>(&_state)) {
+		return cached->makePreview();
+	}
+	return {};
+}
+
 void Instance::repaint() {
 	for (const auto &object : _usage) {
 		object->repaint();

Telegram/SourceFiles/ui/text/custom_emoji_instance.h

@@ -24,11 +24,13 @@ namespace Ui::CustomEmoji {
 class Preview final {
 public:
 	Preview() = default;
-	Preview(QImage image);
+	Preview(QImage image, bool exact);
 	Preview(QPainterPath path, float64 scale);
 
 	void paint(QPainter &p, int x, int y, const QColor &preview);
-	[[nodiscard]] bool image() const;
+	[[nodiscard]] bool isImage() const;
+	[[nodiscard]] bool isExactImage() const;
+	[[nodiscard]] QImage image() const;
 
 	[[nodiscard]] explicit operator bool() const {
 		return !v::is_null(_data);
@@ -39,6 +41,10 @@ private:
 		QPainterPath path;
 		float64 scale = 1.;
 	};
+	struct Image {
+		QImage data;
+		bool exact = false;
+	};
 
 	void paintPath(
 		QPainter &p,
@@ -47,7 +53,7 @@ private:
 		const QColor &preview,
 		const ScaledPath &path);
 
-	std::variant<v::null_t, ScaledPath, QImage> _data;
+	std::variant<v::null_t, ScaledPath, Image> _data;
 
 };
 
@@ -116,7 +122,7 @@ public:
 		Cache cache);
 
 	[[nodiscard]] QString entityData() const;
-
+	[[nodiscard]] Preview makePreview() const;
 	PaintFrameResult paint(QPainter &p, int x, int y, crl::time now);
 	[[nodiscard]] Loading unload();
 
@@ -194,6 +200,7 @@ public:
 	void load(Fn<void(Loader::LoadResult)> done);
 	[[nodiscard]] bool loading() const;
 	void paint(QPainter &p, int x, int y, const QColor &preview);
+	[[nodiscard]] Preview imagePreview() const;
 	void cancel();
 
 private:
@@ -224,6 +231,7 @@ public:
 		crl::time now,
 		const QColor &preview,
 		bool paused);
+	[[nodiscard]] Preview imagePreview() const;
 
 	void incrementUsage(not_null<Object*> object);
 	void decrementUsage(not_null<Object*> object);