Replaced dependence from scroll events in flexible scroll with custom.

Telegram/SourceFiles/info/info_flexible_scroll.cpp

@@ -66,7 +66,7 @@ void FlexibleScrollHelper::setupScrollAnimation() {
 			_scrollTopFrom,
 			_scrollTopTo,
 			std::clamp(eased, 0., 1.));
-		_scroll->scrollToY(scrollCurrent);
+		scrollToY(scrollCurrent);
 		_lastScrollApplied = scrollCurrent;
 		if (progress >= 1) {
 			clearScrollState();
@@ -122,7 +122,7 @@ void FlexibleScrollHelper::setupScrollHandling() {
 					: -1);
 			{
 				_applyingFakeScrollState = true;
-				_scroll->scrollToY(previousValue);
+				scrollToY(previousValue);
 				_applyingFakeScrollState = false;
 			}
 			if (_scrollAnimation.animating()
@@ -248,7 +248,8 @@ void FlexibleScrollHelper::setupScrollHandlingWithFilter() {
 		const auto wheel = static_cast<QWheelEvent*>(e.get());
 		const auto delta = wheel->angleDelta().y();
 		if (std::abs(delta) != 120) {
-			return base::EventFilterResult::Continue;
+			scrollToY(_scroll->scrollTop() - delta);
+			return base::EventFilterResult::Cancel;
 		}
 		const auto actualTop = _scroll->scrollTop();
 		const auto animationActive = _scrollAnimation.animating()
@@ -329,13 +330,8 @@ void FlexibleScrollHelper::setupScrollHandlingWithFilter() {
 		return base::EventFilterResult::Cancel;
 	}, _filterLifetime);
 
-	_scroll->scrollTopValue(
-	) | rpl::start_with_next([=](int top) {
-		const auto current = heightDiff() - top;
-		_inner->moveToLeft(0, std::min(0, current));
-		_pinnedToTop->resize(
-			_pinnedToTop->width(),
-			std::max(current + _pinnedToTop->minimumHeight(), 0));
+	_scroll->scrollTopValue() | rpl::start_with_next([=](int top) {
+		applyScrollToPinnedLayout(top);
 	}, _inner->lifetime());
 
 	_data.fillerWidthValue.events(
@@ -350,4 +346,21 @@ void FlexibleScrollHelper::setupScrollHandlingWithFilter() {
 	}));
 }
 
+void FlexibleScrollHelper::scrollToY(int scrollCurrent) {
+	applyScrollToPinnedLayout(scrollCurrent);
+	_scroll->scrollToY(scrollCurrent);
+}
+
+void FlexibleScrollHelper::applyScrollToPinnedLayout(int scrollCurrent) {
+	const auto top = std::min(scrollCurrent, _scroll->scrollTopMax());
+	const auto minimumHeight = _pinnedToTop->minimumHeight();
+	const auto current = _pinnedToTop->maximumHeight()
+		- minimumHeight
+		- top;
+	_inner->moveToLeft(0, std::min(0, current));
+	_pinnedToTop->resize(
+		_pinnedToTop->width(),
+		std::max(current + minimumHeight, 0));
+}
+
 } // namespace Info

Telegram/SourceFiles/info/info_flexible_scroll.h

@@ -35,6 +35,8 @@ private:
 	void setupScrollAnimation();
 	void setupScrollHandling();
 	void setupScrollHandlingWithFilter();
+	void scrollToY(int value);
+	void applyScrollToPinnedLayout(int scrollCurrent);
 
 	const not_null<Ui::ScrollArea*> _scroll;
 	const not_null<Ui::RpWidget*> _inner;