systray: Notify user once between two activations of the main window

This cannot be done without leaving some indication to the user that a
notification has been issued in the past, which may anyway appear as a
lack even when notifications are issued with every new message.

This is achieved by changing the icon semi-permanently (until the next
activation of the main window), and by silently updating the tooltip
when new notifications are issued with the total number of unread
messages.

This icon change is included in the minimal notification mode, as it is
very non-intrusive.

client/systemtrayicon.cpp

@@ -40,10 +40,14 @@ SystemTrayIcon::SystemTrayIcon(MainWindow* parent)
         showHideAction->setText(visible ? tr("Hide") : tr("Show"));
     });
 
-    setIcon(QIcon::fromTheme(appIconName(), QIcon(":/icon.png")));
+    m_appIcon = QIcon::fromTheme(appIconName(), QIcon(":/icon.png"));
+    m_unreadIcon = QIcon::fromTheme("mail-unread", m_appIcon);
+    m_notified = false;
+    setIcon(m_appIcon);
     setToolTip("Quaternion");
     setContextMenu(contextMenu);
     connect( this, &SystemTrayIcon::activated, this, &SystemTrayIcon::systemTrayIconAction);
+    connect(qApp, &QApplication::focusChanged, this, &SystemTrayIcon::focusChanged);
 }
 
 void SystemTrayIcon::newRoom(Quotient::Room* room)
@@ -57,9 +61,21 @@ void SystemTrayIcon::unreadStatsChanged(Quotient::Room* room)
 {
     using namespace Quotient;
     const auto mode = Settings().get<QString>("UI/notifications", "intrusive");
-    if (mode == "none")
+    int nNotifs = 0;
+
+    if (qApp->activeWindow() != nullptr || room->notificationCount() == 0)
         return;
-    if (qApp->activeWindow() != nullptr && room->notificationCount() > 0) {
+
+    for (auto* r: room->connection()->allRooms())
+        nNotifs += r->notificationCount();
+    setToolTip(tr("%Ln notification(s)", "", nNotifs));
+
+    if (!m_notified) {
+        setIcon(m_unreadIcon);
+        m_notified = true;
+        if (mode == "none")
+            return;
+
         showMessage(
             //: %1 is the room display name
             tr("Notification in %1").arg(room->displayName()),
@@ -90,3 +106,12 @@ void SystemTrayIcon::showHide()
         m_parent->setFocus();
     }
 }
+
+void SystemTrayIcon::focusChanged(QWidget* old, QWidget* now)
+{
+    if (m_notified && old == nullptr && qApp->activeWindow() != nullptr) {
+        setIcon(m_appIcon);
+        setToolTip("Quaternion");
+        m_notified = false;
+    }
+}

client/systemtrayicon.h

@@ -40,8 +40,12 @@ class SystemTrayIcon: public QSystemTrayIcon
     private slots:
         void unreadStatsChanged(Quotient::Room* room);
         void systemTrayIconAction(QSystemTrayIcon::ActivationReason reason);
+        void focusChanged(QWidget* old, QWidget* now);
 
     private:
         MainWindow* m_parent;
+        QIcon m_appIcon;
+        QIcon m_unreadIcon;
+        bool m_notified;
         void showHide();
 };