From 2b75b48919b08bc47e94151da021dbfdfc078568 Mon Sep 17 00:00:00 2001
From: 23rd <23rd@vivaldi.net>
Date: Fri, 10 Apr 2026 10:17:56 +0300
Subject: [PATCH] [thanos] Added scrollToY delegate callback for synthetic
 scroll support.

---
 Telegram/SourceFiles/history/history_inner_widget.cpp     | 3 +++
 Telegram/SourceFiles/history/history_widget.h             | 8 +++-----
 .../SourceFiles/history/view/history_view_list_widget.cpp | 3 +++
 .../SourceFiles/ui/effects/thanos_effect_controller.cpp   | 4 ++--
 .../SourceFiles/ui/effects/thanos_effect_controller.h     | 1 +
 5 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/Telegram/SourceFiles/history/history_inner_widget.cpp b/Telegram/SourceFiles/history/history_inner_widget.cpp
index 70031fba1c..e31421c1f3 100644
--- a/Telegram/SourceFiles/history/history_inner_widget.cpp
+++ b/Telegram/SourceFiles/history/history_inner_widget.cpp
@@ -4249,6 +4249,9 @@ void HistoryInner::setupThanosEffect() {
 			.scrollArea = [=]() -> not_null<Ui::ScrollArea*> {
 				return _scroll;
 			},
+			.scrollToY = [=](int y) {
+				_widget->synteticScrollToY(y);
+			},
 			.setCollapseGaps = [=](std::vector<CollapseGap> gaps) {
 				setCollapseGaps(std::move(gaps));
 			},
diff --git a/Telegram/SourceFiles/history/history_widget.h b/Telegram/SourceFiles/history/history_widget.h
index 6a48fa5e07..09ac181178 100644
--- a/Telegram/SourceFiles/history/history_widget.h
+++ b/Telegram/SourceFiles/history/history_widget.h
@@ -338,6 +338,9 @@ protected:
 	void mouseReleaseEvent(QMouseEvent *e) override;
 	void mouseMoveEvent(QMouseEvent *e) override;
 
+public:
+	void synteticScrollToY(int y);
+
 private:
 	using TabbedPanel = ChatHelpers::TabbedPanel;
 	using TabbedSelector = ChatHelpers::TabbedSelector;
@@ -651,11 +654,6 @@ private:
 	int itemTopForHighlight(not_null<HistoryView::Element*> view) const;
 	void scrollToCurrentVoiceMessage(FullMsgId fromId, FullMsgId toId);
 
-	// Scroll to current y without updating the _lastUserScrolled time.
-	// Used to distinguish between user scrolls and syntetic scrolls.
-	// This one is syntetic.
-	void synteticScrollToY(int y);
-
 	void writeDrafts();
 	void writeDraftTexts();
 	void writeDraftCursors();
diff --git a/Telegram/SourceFiles/history/view/history_view_list_widget.cpp b/Telegram/SourceFiles/history/view/history_view_list_widget.cpp
index 531d90cb59..ac6dc930dc 100644
--- a/Telegram/SourceFiles/history/view/history_view_list_widget.cpp
+++ b/Telegram/SourceFiles/history/view/history_view_list_widget.cpp
@@ -4411,6 +4411,9 @@ void ListWidget::setupThanosEffect() {
 			.scrollArea = [=]() -> not_null<Ui::ScrollArea*> {
 				return scroll;
 			},
+			.scrollToY = [=](int y) {
+				scroll->scrollToY(y);
+			},
 			.setCollapseGaps = [=](std::vector<Ui::CollapseGap> gaps) {
 				setCollapseGaps(std::move(gaps));
 			},
diff --git a/Telegram/SourceFiles/ui/effects/thanos_effect_controller.cpp b/Telegram/SourceFiles/ui/effects/thanos_effect_controller.cpp
index 8d8365893f..0261d8e63a 100644
--- a/Telegram/SourceFiles/ui/effects/thanos_effect_controller.cpp
+++ b/Telegram/SourceFiles/ui/effects/thanos_effect_controller.cpp
@@ -229,7 +229,7 @@ void ThanosEffectController::startCollapseAnimation(
 	const auto aboveViewport = std::max(0, scrollTop - itemTop);
 	const auto scrollAdjust = std::min(height, aboveViewport);
 	if (scrollAdjust > 0) {
-		scroll->scrollToY(scrollTop + scrollAdjust);
+		_delegate.scrollToY(scrollTop + scrollAdjust);
 	}
 
 	auto totalHeight = 0;
@@ -266,7 +266,7 @@ void ThanosEffectController::collapseAnimationCallback() {
 		const auto scroll = _delegate.scrollArea();
 		const auto scrollTop = scroll->scrollTop();
 		syncCollapseGapsToHost();
-		scroll->scrollToY(std::max(scrollTop - totalDelta, 0));
+		_delegate.scrollToY(std::max(scrollTop - totalDelta, 0));
 	}
 
 	if (!_collapseAnimation.animating()) {
diff --git a/Telegram/SourceFiles/ui/effects/thanos_effect_controller.h b/Telegram/SourceFiles/ui/effects/thanos_effect_controller.h
index d8e62b09e1..bee945003b 100644
--- a/Telegram/SourceFiles/ui/effects/thanos_effect_controller.h
+++ b/Telegram/SourceFiles/ui/effects/thanos_effect_controller.h
@@ -46,6 +46,7 @@ public:
 		Fn<ChatPaintContext(QRect)> preparePaintContext;
 		Fn<QWidget*()> window;
 		Fn<not_null<ScrollArea*>()> scrollArea;
+		Fn<void(int scrollTop)> scrollToY;
 		Fn<void(std::vector<CollapseGap>)> setCollapseGaps;
 	};