FEAT(client): Implement tray icon highlighting

Previously, only "window highlighting" was supported
by Mumble. However, when Mumble was minimized to tray,
there was no way to observe that highlighting.

As requested in mumble-voip#4584, this commit introduces highlighting
to the tray icon. When a highlight message is received, the
tray icon will flash the "information icon" every two seconds
until the MainWindow of Mumble receives focus again.

To enable this for a specific message type, the user needs to
check the "highlight" box in the "Messages" configuration dialog.

Fixes mumble-voip#4584

src/mumble/Log.cpp

@@ -421,6 +421,8 @@ Log::Log(QObject *p) : QObject(p) {
 #endif
 	uiLastId = 0;
 	qdDate   = QDate::currentDate();
+
+	QObject::connect(this, &Log::highlightSpawned, Global::get().mw, &MainWindow::highlightWindow);
 }
 
 // Display order in settingsscreen, allows to insert new events without breaking config-compatibility with older
@@ -812,7 +814,7 @@ void Log::log(MsgType mt, const QString &console, const QString &terse, bool own
 		if (!(Global::get().mw->isActiveWindow() && Global::get().mw->qdwLog->isVisible())) {
 			// Message notification with window highlight
 			if (flags & Settings::LogHighlight) {
-				QApplication::alert(Global::get().mw);
+				emit highlightSpawned();
 			}
 
 			// Message notification with balloon tooltips

src/mumble/Log.h

@@ -161,6 +161,9 @@ public slots:
 signals:
 	/// Signal emitted when there was a message received whose type was configured to spawn a notification
 	void notificationSpawned(QString title, QString body, QSystemTrayIcon::MessageIcon icon);
+
+	/// Signal emitted when there was a message received whose type was configured to highlight the application
+	void highlightSpawned();
 };
 
 class LogMessage {

src/mumble/MainWindow.cpp

@@ -111,6 +111,7 @@ MainWindow::MainWindow(QWidget *p)
 	SvgIcon::addSvgPixmapsToIcon(qiTalkingOn, QLatin1String("skin:talking_on.svg"));
 	SvgIcon::addSvgPixmapsToIcon(qiTalkingShout, QLatin1String("skin:talking_alt.svg"));
 	SvgIcon::addSvgPixmapsToIcon(qiTalkingWhisper, QLatin1String("skin:talking_whisper.svg"));
+	SvgIcon::addSvgPixmapsToIcon(m_iconInformation, QLatin1String("skin:Information_icon.svg"));
 
 #ifdef Q_OS_MAC
 	if (QFile::exists(QLatin1String("skin:mumble.icns")))
@@ -718,6 +719,14 @@ void MainWindow::changeEvent(QEvent *e) {
 		}
 	}
 
+	// Unhighlight the tray icon when receiving focus
+	if (e->type() == QEvent::ActivationChange) {
+		if (isActiveWindow() && Global::get().trayIcon != nullptr) {
+			emit windowActivated();
+		}
+		return;
+	}
+
 	QWidget::changeEvent(e);
 }
 
@@ -3633,6 +3642,10 @@ void MainWindow::showRaiseWindow() {
 	});
 }
 
+void MainWindow::highlightWindow() {
+	QApplication::alert(this);
+}
+
 void MainWindow::on_qaTalkingUIToggle_triggered() {
 	if (!Global::get().talkingUI) {
 		qCritical("MainWindow: Attempting to show Talking UI before it has been created!");

src/mumble/MainWindow.h

@@ -80,6 +80,7 @@ class MainWindow : public QMainWindow, public Ui::MainWindow {
 	QIcon qiIcon, qiIconMutePushToMute, qiIconMuteSelf, qiIconMuteServer, qiIconDeafSelf, qiIconDeafServer,
 		qiIconMuteSuppressed;
 	QIcon qiTalkingOn, qiTalkingWhisper, qiTalkingShout, qiTalkingOff;
+	QIcon m_iconInformation;
 	std::unordered_map< unsigned int, qt_unique_ptr< UserLocalNicknameDialog > > qmUserNicknameTracker;
 
 	/// "Action" for when there are no actions available
@@ -387,6 +388,8 @@ public slots:
 	void toggleSearchDialogVisibility();
 	/// Enables or disables the recording feature
 	void enableRecording(bool recordingAllowed);
+	/// Invokes OS native window highlighting
+	void highlightWindow();
 signals:
 	/// Signal emitted when the server and the client have finished
 	/// synchronizing (after a new connection).
@@ -404,6 +407,8 @@ public slots:
 
 	/// Signal emitted when the window manager notifies the Mumble MainWindow that the application was just minimized
 	void windowMinimized();
+	/// Signal emitted whenever the Mumble MainWindow regains the active state from the window manager
+	void windowActivated();
 
 public:
 	MainWindow(QWidget *parent);

src/mumble/widgets/TrayIcon.cpp

@@ -13,7 +13,7 @@
 #include <QApplication>
 
 TrayIcon::TrayIcon() : QSystemTrayIcon(Global::get().mw), m_statusIcon(Global::get().mw->qiIcon) {
-	setIcon(m_statusIcon);
+	applyIcon(m_statusIcon);
 
 	setToolTip("Mumble");
 
@@ -27,6 +27,13 @@ TrayIcon::TrayIcon() : QSystemTrayIcon(Global::get().mw), m_statusIcon(Global::g
 		Global::get().l, &Log::notificationSpawned, this,
 		[this](QString title, QString body, QSystemTrayIcon::MessageIcon icon) { showMessage(title, body, icon); });
 
+	QObject::connect(Global::get().l, &Log::highlightSpawned, this, &TrayIcon::on_timer_triggered);
+	QObject::connect(Global::get().mw, &MainWindow::windowActivated, this, &TrayIcon::on_tray_unhighlight);
+
+	m_highlightTimer = new QTimer(this);
+	m_highlightTimer->setSingleShot(true);
+	QObject::connect(m_highlightTimer, &QTimer::timeout, this, &TrayIcon::on_timer_triggered);
+
 	QObject::connect(this, &QSystemTrayIcon::activated, this, &TrayIcon::on_icon_clicked);
 
 	// messageClicked is buggy in Qt on some platforms and we can not do anything about this (QTBUG-87329)
@@ -88,7 +95,7 @@ void TrayIcon::on_icon_update() {
 
 	if (&newIcon.get() != &m_statusIcon.get()) {
 		m_statusIcon = newIcon;
-		setIcon(m_statusIcon);
+		applyIcon(m_statusIcon);
 	}
 }
 
@@ -129,6 +136,11 @@ void TrayIcon::updateContextMenu() {
 	m_contextMenu->addAction(Global::get().mw->qaQuit);
 }
 
+void TrayIcon::applyIcon(QIcon &icon) {
+	setIcon(icon);
+	m_currentIcon = &icon;
+}
+
 void TrayIcon::toggleShowHide() {
 	if (Global::get().mw->isVisible() && !Global::get().mw->isMinimized()) {
 		on_hideAction_triggered();
@@ -175,3 +187,31 @@ void TrayIcon::on_windowMinimized() {
 
 	on_hideAction_triggered();
 }
+
+void TrayIcon::on_tray_unhighlight() {
+	if (m_highlightTimer == nullptr || !m_highlightTimer->isActive()) {
+		return;
+	}
+
+	m_highlightTimer->stop();
+	applyIcon(m_statusIcon);
+}
+
+void TrayIcon::on_timer_triggered() {
+	// We implement tray icon "highlighting" by blinking the
+	// current status icon every few seconds until the MainWindow
+	// receives focus.
+	// This will only be happening, if the user selects "highlight"
+	// for a specific message in the messages settings table.
+	// Normal window highlighting - which desktops usually implement
+	// by blinking the application in the task bar - is invisible
+	// if the application is hidden to tray.
+
+	if (m_currentIcon == &m_statusIcon.get()) {
+		applyIcon(Global::get().mw->m_iconInformation);
+		m_highlightTimer->start(500);
+	} else {
+		applyIcon(m_statusIcon);
+		m_highlightTimer->start(2000);
+	}
+}

src/mumble/widgets/TrayIcon.h

@@ -9,6 +9,7 @@
 #include <functional>
 
 #include <QAction>
+#include <QTimer>
 #include <QtWidgets/QMenu>
 #include <QtWidgets/QSystemTrayIcon>
 
@@ -24,17 +25,24 @@ public slots:
 	void on_hideAction_triggered();
 	void on_showAction_triggered();
 
+	void on_icon_update();
+	void on_tray_unhighlight();
+
 private:
 	std::reference_wrapper< QIcon > m_statusIcon;
-	QMenu *m_contextMenu  = nullptr;
-	QAction *m_showAction = nullptr;
-	QAction *m_hideAction = nullptr;
+	QIcon *m_currentIcon     = nullptr;
+	QMenu *m_contextMenu     = nullptr;
+	QAction *m_showAction    = nullptr;
+	QAction *m_hideAction    = nullptr;
+	QTimer *m_highlightTimer = nullptr;
 
 	void updateContextMenu();
+	void applyIcon(QIcon &icon);
 
 private slots:
 	void on_icon_clicked(QSystemTrayIcon::ActivationReason reason);
 	void on_windowMinimized();
+	void on_timer_triggered();
 };
 
 #endif // MUMBLE_MUMBLE_WIDGETS_TRAYICON_H_