From 32bc723745393e63b68408d6d905a0a999f0f932 Mon Sep 17 00:00:00 2001
From: 23rd <23rd@vivaldi.net>
Date: Sun, 24 Feb 2019 20:19:16 +0300
Subject: [PATCH] Added scroll animation in dialogs list when it scrolls to
 top.

---
 .../SourceFiles/dialogs/dialogs_widget.cpp    | 20 ++++++++++++++++++-
 Telegram/SourceFiles/dialogs/dialogs_widget.h |  1 +
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/Telegram/SourceFiles/dialogs/dialogs_widget.cpp b/Telegram/SourceFiles/dialogs/dialogs_widget.cpp
index 884b8a055..161a4eb3b 100644
--- a/Telegram/SourceFiles/dialogs/dialogs_widget.cpp
+++ b/Telegram/SourceFiles/dialogs/dialogs_widget.cpp
@@ -333,7 +333,25 @@ void DialogsWidget::dialogsToUp() {
 		return;
 	}
 	if (_filter->getLastText().trimmed().isEmpty() && !_searchInChat) {
-		_scroll->scrollToY(0);
+		_scrollToAnimation.finish();
+		auto scrollTop = _scroll->scrollTop();
+		const auto scrollTo = 0;
+		const auto maxAnimatedDelta = _scroll->height();
+		if (scrollTo + maxAnimatedDelta < scrollTop) {
+			scrollTop = scrollTo + maxAnimatedDelta;
+			_scroll->scrollToY(scrollTop);
+		}
+
+		const auto scroll = [&] {
+			_scroll->scrollToY(qRound(_scrollToAnimation.current()));
+		};
+
+		_scrollToAnimation.start(
+			scroll,
+			scrollTop,
+			scrollTo,
+			st::slideDuration,
+			anim::sineInOut);
 	}
 }
 
diff --git a/Telegram/SourceFiles/dialogs/dialogs_widget.h b/Telegram/SourceFiles/dialogs/dialogs_widget.h
index df43b2bfc..faad0637c 100644
--- a/Telegram/SourceFiles/dialogs/dialogs_widget.h
+++ b/Telegram/SourceFiles/dialogs/dialogs_widget.h
@@ -199,6 +199,7 @@ private:
 	object_ptr<BottomButton> _loadMoreChats = { nullptr };
 	std::unique_ptr<Window::ConnectionState> _connecting;
 
+	Animation _scrollToAnimation;
 	Animation _a_show;
 	Window::SlideDirection _showDirection;
 	QPixmap _cacheUnder, _cacheOver;