Add rpl::take(count).

Telegram/SourceFiles/ui/abstract_button.cpp

@@ -20,8 +20,20 @@ Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
 */
 #include "ui/abstract_button.h"
 
+#include <rpl/filter.h>
+#include <rpl/mappers.h>
+
 namespace Ui {
 
+AbstractButton::AbstractButton(QWidget *parent) : RpWidget(parent) {
+	setMouseTracking(true);
+
+	using namespace rpl::mappers;
+	shownValue()
+		| rpl::filter($1 == false)
+		| rpl::start_with_next([this] { clearState(); }, lifetime());
+}
+
 void AbstractButton::leaveEventHook(QEvent *e) {
 	if (_state & StateFlag::Down) return;
 

Telegram/SourceFiles/ui/abstract_button.h

@@ -30,9 +30,7 @@ class AbstractButton : public RpWidget {
 	Q_OBJECT
 
 public:
-	AbstractButton(QWidget *parent) : RpWidget(parent) {
-		setMouseTracking(true);
-	}
+	AbstractButton(QWidget *parent);
 
 	Qt::KeyboardModifiers clickModifiers() const {
 		return _modifiers;
@@ -58,13 +56,6 @@ public:
 		_clickedCallback = std::move(callback);
 	}
 
-	void setVisible(bool visible) override {
-		TWidget::setVisible(visible);
-		if (!visible) {
-			clearState();
-		}
-	}
-
 	auto clicks() const {
 		return _clicks.events();
 	}

Telegram/SourceFiles/ui/effects/fade_animation.cpp

@@ -100,7 +100,6 @@ void FadeAnimation::stopAnimation() {
 	_animation.finish();
 	if (!_cache.isNull()) {
 		_cache = QPixmap();
-		updateCallback();
 		if (_visible) {
 			_widget->showChildren();
 		}

Telegram/SourceFiles/ui/rp_widget.h

@@ -76,6 +76,10 @@ public:
 	virtual rpl::producer<int> desiredHeightValue() const {
 		return heightValue();
 	}
+	auto shownValue() const {
+		auto &stream = eventStreams().shown;
+		return stream.events_starting_with(!this->isHidden());
+	}
 
 	auto paintRequest() const {
 		return eventStreams().paint.events();
@@ -85,6 +89,17 @@ public:
 		return eventStreams().alive.events();
 	}
 
+	void setVisible(bool visible) final override {
+		auto wasVisible = !this->isHidden();
+		Parent::setVisible(visible);
+		auto nowVisible = !this->isHidden();
+		if (nowVisible != wasVisible) {
+			if (auto streams = _eventStreams.get()) {
+				streams->shown.fire_copy(nowVisible);
+			}
+		}
+	}
+
 	template <typename Error, typename Generator>
 	void showOn(rpl::producer<bool, Error, Generator> &&shown) {
 		std::move(shown)
@@ -133,6 +148,7 @@ private:
 	struct EventStreams {
 		rpl::event_stream<QRect> geometry;
 		rpl::event_stream<QRect> paint;
+		rpl::event_stream<bool> shown;
 		rpl::event_stream<> alive;
 	};
 	struct LifetimeHolder {