From aa00f9bd3417ed5358c317ff178b7cb4c16d01d6 Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Mon, 11 Mar 2019 11:11:02 +0400
Subject: [PATCH] Fix new animations engine restarts.

---
 .../SourceFiles/ui/effects/animations.cpp     | 56 +++++++++++++------
 Telegram/SourceFiles/ui/effects/animations.h  | 52 ++++++++++++++++-
 2 files changed, 90 insertions(+), 18 deletions(-)

diff --git a/Telegram/SourceFiles/ui/effects/animations.cpp b/Telegram/SourceFiles/ui/effects/animations.cpp
index 389457e68c..ecc9e4c9cf 100644
--- a/Telegram/SourceFiles/ui/effects/animations.cpp
+++ b/Telegram/SourceFiles/ui/effects/animations.cpp
@@ -20,19 +20,37 @@ constexpr auto kIgnoreUpdatesTimeout = crl::time(4);
 } // namespace
 
 void Basic::start() {
-	if (!animating()) {
+	if (animating()) {
+		restart();
+	} else {
 		Core::App().animationManager().start(this);
 	}
-	_started = crl::now();
 }
 
 void Basic::stop() {
 	if (animating()) {
 		Core::App().animationManager().stop(this);
-		_started = -1;
 	}
 }
 
+void Basic::restart() {
+	Expects(_started >= 0);
+
+	_started = crl::now();
+}
+
+void Basic::markStarted() {
+	Expects(_started < 0);
+
+	_started = crl::now();
+}
+
+void Basic::markStopped() {
+	Expects(_started >= 0);
+
+	_started = -1;
+}
+
 Manager::Manager() {
 	Core::Sandbox::Instance().widgetUpdateRequests(
 	) | rpl::start_with_next([=] {
@@ -42,28 +60,30 @@ Manager::Manager() {
 
 void Manager::start(not_null<Basic*> animation) {
 	if (_updating) {
-		_starting.push_back(animation);
+		_starting.emplace_back(animation.get());
 	} else {
 		if (empty(_active)) {
 			updateQueued();
 		}
-		_active.push_back(animation);
+		_active.emplace_back(animation.get());
 	}
 }
 
 void Manager::stop(not_null<Basic*> animation) {
-	if (empty(_active)) {
+	if (empty(_active) && empty(_starting)) {
 		return;
 	}
+	const auto value = animation.get();
+	const auto proj = &ActiveBasicPointer::get;
+	auto &list = _updating ? _starting : _active;
+	list.erase(ranges::remove(list, value, proj), end(list));
+
 	if (_updating) {
-		const auto i = ranges::find(_active, animation.get());
+		const auto i = ranges::find(_active, value, proj);
 		if (i != end(_active)) {
 			*i = nullptr;
 		}
-		return;
-	}
-	_active.erase(ranges::remove(_active, animation.get()), end(_active));
-	if (empty(_active)) {
+	} else if (empty(_active)) {
 		stopTimer();
 	}
 }
@@ -82,13 +102,17 @@ void Manager::update() {
 	const auto guard = gsl::finally([&] { _updating = false; });
 
 	_lastUpdateTime = now;
-	_active.erase(ranges::remove_if(_active, [&](Basic *element) {
-		return !element || !element->call(now);
-	}), end(_active));
+	const auto isFinished = [&](const ActiveBasicPointer &element) {
+		return !element.call(now);
+	};
+	_active.erase(ranges::remove_if(_active, isFinished), end(_active));
 
 	if (!empty(_starting)) {
-		auto starting = std::move(_starting);
-		_active.insert(end(_active), begin(starting), end(starting));
+		_active.insert(
+			end(_active),
+			std::make_move_iterator(begin(_starting)),
+			std::make_move_iterator(end(_starting)));
+		_starting.clear();
 	}
 }
 
diff --git a/Telegram/SourceFiles/ui/effects/animations.h b/Telegram/SourceFiles/ui/effects/animations.h
index a65054e04b..5fdcb0bb90 100644
--- a/Telegram/SourceFiles/ui/effects/animations.h
+++ b/Telegram/SourceFiles/ui/effects/animations.h
@@ -37,6 +37,10 @@ private:
 	[[nodiscard]] static Fn<bool(crl::time)> Prepare(Callback &&callback);
 
 	[[nodiscard]] bool call(crl::time now) const;
+	void restart();
+
+	void markStarted();
+	void markStopped();
 
 	crl::time _started = -1;
 	Fn<bool(crl::time)> _callback;
@@ -98,6 +102,50 @@ public:
 	void update();
 
 private:
+	class ActiveBasicPointer {
+	public:
+		ActiveBasicPointer(Basic *value = nullptr) : _value(value) {
+			if (_value) {
+				_value->markStarted();
+			}
+		}
+		ActiveBasicPointer(ActiveBasicPointer &&other)
+		: _value(base::take(other._value)) {
+		}
+		ActiveBasicPointer &operator=(ActiveBasicPointer &&other) {
+			if (_value != other._value) {
+				if (_value) {
+					_value->markStopped();
+				}
+				_value = base::take(other._value);
+			}
+			return *this;
+		}
+		~ActiveBasicPointer() {
+			if (_value) {
+				_value->markStopped();
+			}
+		}
+
+		[[nodiscard]] bool call(crl::time now) const {
+			return _value && _value->call(now);
+		}
+
+		friend inline bool operator==(
+				const ActiveBasicPointer &a,
+				const ActiveBasicPointer &b) {
+			return a._value == b._value;
+		}
+
+		Basic *get() const {
+			return _value;
+		}
+
+	private:
+		Basic *_value = nullptr;
+
+	};
+
 	friend class Basic;
 
 	void timerEvent(QTimerEvent *e) override;
@@ -113,8 +161,8 @@ private:
 	int _timerId = 0;
 	bool _updating = false;
 	bool _scheduled = false;
-	std::vector<Basic*> _active;
-	std::vector<not_null<Basic*>> _starting;
+	std::vector<ActiveBasicPointer> _active;
+	std::vector<ActiveBasicPointer> _starting;
 	rpl::lifetime _lifetime;
 
 };