Fixed changing of button style between states within single intro step.

Telegram/SourceFiles/intro/intro_code.cpp

@@ -100,10 +100,13 @@ CodeWidget::CodeWidget(
 
 	_code->setDigitsCountMax(getData()->codeLength);
 
-	setTitleText(getData()->codeByFragmentUrl.isEmpty()
-		? rpl::single(Ui::FormatPhone(getData()->phone))
-		: tr::lng_intro_fragment_title());
 	updateDescText();
+	setTitleText(_isFragment.value(
+	) | rpl::map([=](bool isFragment) {
+		return !isFragment
+			? rpl::single(Ui::FormatPhone(getData()->phone))
+			: tr::lng_intro_fragment_title();
+	}) | rpl::flatten_latest());
 
 	account->setHandleLoginCode([=](const QString &code) {
 		_code->setText(code);
@@ -126,6 +129,7 @@ int CodeWidget::errorTop() const {
 void CodeWidget::updateDescText() {
 	const auto byTelegram = getData()->codeByTelegram;
 	const auto isFragment = !getData()->codeByFragmentUrl.isEmpty();
+	_isFragment = isFragment;
 	setDescriptionText(
 		isFragment
 			? tr::lng_intro_fragment_about(
@@ -136,8 +140,7 @@ void CodeWidget::updateDescText() {
 				Ui::Text::RichLangValue)
 			: (byTelegram ? tr::lng_code_from_telegram : tr::lng_code_desc)(
 				Ui::Text::RichLangValue));
-	if (isFragment) {
-	} else if (getData()->codeByTelegram) {
+	if (getData()->codeByTelegram) {
 		_noTelegramCode->show();
 		_callTimer.cancel();
 	} else {
@@ -420,15 +423,19 @@ void CodeWidget::submitCode() {
 }
 
 rpl::producer<QString> CodeWidget::nextButtonText() const {
-	return getData()->codeByFragmentUrl.isEmpty()
-		? Step::nextButtonText()
-		: tr::lng_intro_fragment_button();
+	return _isFragment.value(
+	) | rpl::map([=](bool isFragment) {
+		return isFragment
+			? tr::lng_intro_fragment_button()
+			: Step::nextButtonText();
+	}) | rpl::flatten_latest();
 }
 
-const style::RoundButton *CodeWidget::nextButtonStyle() const {
-	return !getData()->codeByFragmentUrl.isEmpty()
-		? &st::introFragmentButton
-		: nullptr;
+rpl::producer<const style::RoundButton*> CodeWidget::nextButtonStyle() const {
+	return _isFragment.value(
+	) | rpl::map([](bool isFragment) {
+		return isFragment ? &st::introFragmentButton : nullptr;
+	});
 }
 
 void CodeWidget::noTelegramCode() {

Telegram/SourceFiles/intro/intro_code.h

@@ -56,7 +56,7 @@ public:
 	void cancelled() override;
 	void submit() override;
 	rpl::producer<QString> nextButtonText() const override;
-	const style::RoundButton *nextButtonStyle() const override;
+	rpl::producer<const style::RoundButton*> nextButtonStyle() const override;
 
 	void updateDescText();
 
@@ -96,6 +96,8 @@ private:
 	QString _sentCode;
 	mtpRequestId _sentRequest = 0;
 
+	rpl::variable<bool> _isFragment = false;
+
 	base::Timer _callTimer;
 	CallStatus _callStatus = CallStatus();
 	int _callTimeout;

Telegram/SourceFiles/intro/intro_step.cpp

@@ -119,8 +119,8 @@ rpl::producer<QString> Step::nextButtonText() const {
 	return tr::lng_intro_next();
 }
 
-const style::RoundButton *Step::nextButtonStyle() const {
-	return nullptr;
+rpl::producer<const style::RoundButton*> Step::nextButtonStyle() const {
+	return rpl::single((const style::RoundButton*)(nullptr));
 }
 
 void Step::goBack() {

Telegram/SourceFiles/intro/intro_step.h

@@ -81,7 +81,8 @@ public:
 
 	virtual void submit() = 0;
 	[[nodiscard]] virtual rpl::producer<QString> nextButtonText() const;
-	[[nodiscard]] virtual const style::RoundButton *nextButtonStyle() const;
+	[[nodiscard]] virtual auto nextButtonStyle() const
+		-> rpl::producer<const style::RoundButton*>;
 
 	[[nodiscard]] int contentLeft() const;
 	[[nodiscard]] int contentTop() const;

Telegram/SourceFiles/intro/intro_widget.cpp

@@ -342,17 +342,21 @@ void Widget::historyMove(StackAction action, Animate animate) {
 		hideAndDestroy(std::exchange(_terms, { nullptr }));
 	}
 	{
-		const auto st = getStep()->nextButtonStyle();
-		const auto nextStyle = st ? st : &st::introNextButton;
-		if (_nextStyle != nextStyle) {
-			_nextStyle = nextStyle;
-			_next = nullptr;
-			_next.create(
-				this,
-				object_ptr<Ui::RoundButton>(this, nullptr, *nextStyle));
-			showControls();
-			updateControlsGeometry();
-		}
+		getStep()->nextButtonStyle(
+		) | rpl::start_with_next([=](const style::RoundButton *st) {
+			const auto nextStyle = st ? st : &st::introNextButton;
+			if (_nextStyle != nextStyle) {
+				_nextStyle = nextStyle;
+				const auto wasShown = _next->toggled();
+				_next.destroy();
+				_next.create(
+					this,
+					object_ptr<Ui::RoundButton>(this, nullptr, *nextStyle));
+				showControls();
+				updateControlsGeometry();
+				_next->toggle(wasShown, anim::type::instant);
+			}
+		}, _next->lifetime());
 	}
 
 	getStep()->finishInit();