From 763b3a37c34fd7819f9d553b94387c4fe16554ff Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Tue, 11 Jul 2023 12:21:33 +0400
Subject: [PATCH] Allow to change overscroll from outside.

---
 ui/widgets/elastic_scroll.cpp | 16 +++++++++++++---
 ui/widgets/elastic_scroll.h   |  2 +-
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/ui/widgets/elastic_scroll.cpp b/ui/widgets/elastic_scroll.cpp
index e9ef0f4..255ce12 100644
--- a/ui/widgets/elastic_scroll.cpp
+++ b/ui/widgets/elastic_scroll.cpp
@@ -1118,9 +1118,19 @@ void ElasticScroll::setOverscrollTypes(
 	}
 }
 
-void ElasticScroll::setOverscrollDefaults(int from, int till) {
+void ElasticScroll::setOverscrollDefaults(int from, int till, bool shift) {
 	Expects(from <= 0 && till >= 0);
 
+	if (_state.visibleFrom > 0
+		|| (!_state.visibleFrom
+			&& _overscrollTypeFrom != OverscrollType::Virtual)) {
+		from = 0;
+	}
+	if (_state.visibleTill < _state.fullSize
+		|| (_state.visibleTill == _state.fullSize
+			&& _overscrollTypeTill != OverscrollType::Virtual)) {
+		till = 0;
+	}
 	const auto fromChanged = (_overscrollDefaultFrom != from);
 	const auto tillChanged = (_overscrollDefaultTill != till);
 	const auto changed = (fromChanged && _overscroll < 0)
@@ -1133,8 +1143,8 @@ void ElasticScroll::setOverscrollDefaults(int from, int till) {
 	_overscrollDefaultTill = till;
 	if (changed) {
 		const auto delta = (_overscroll < 0)
-			? (_overscroll - _overscrollDefaultFrom)
-			: (_overscroll - _overscrollDefaultTill);
+			? (_overscroll - (shift ? 0 : _overscrollDefaultFrom))
+			: (_overscroll - (shift ? 0 : _overscrollDefaultTill));
 		_overscrollAccumulated = currentOverscrollDefaultAccumulated()
 			+ OverscrollToAccumulated(delta);
 	}
diff --git a/ui/widgets/elastic_scroll.h b/ui/widgets/elastic_scroll.h
index cba6c51..4a3434b 100644
--- a/ui/widgets/elastic_scroll.h
+++ b/ui/widgets/elastic_scroll.h
@@ -162,7 +162,7 @@ public:
 		Real,
 	};
 	void setOverscrollTypes(OverscrollType from, OverscrollType till);
-	void setOverscrollDefaults(int from, int till);
+	void setOverscrollDefaults(int from, int till, bool shift = false);
 	void setOverscrollBg(QColor bg);
 
 	[[nodiscard]] rpl::producer<> scrolls() const;