Do not snapshot session when idle

There is no reason for a tab title to change if there is no QT event.
So, instead of snapshoting session regularly, we do it only if there is
some QT events. To catch all QT events an event handler is installed on the
QCoreApplication instance.

src/session/SessionController.cpp

@@ -114,7 +114,7 @@ SessionController::SessionController(Session *sessionParam, TerminalDisplay *vie
     , _findAction(nullptr)
     , _findNextAction(nullptr)
     , _findPreviousAction(nullptr)
-    , _interactionTimer(nullptr)
+    , _snapshotTimer(nullptr)
     , _searchStartLine(0)
     , _prevSearchResultLine(0)
     , _codecAction(nullptr)
@@ -209,28 +209,18 @@ SessionController::SessionController(Session *sessionParam, TerminalDisplay *vie
     connect(session(), &Konsole::Session::flowControlEnabledChanged, view(), &Konsole::TerminalDisplay::setFlowControlWarningEnabled);
     view()->setFlowControlWarningEnabled(session()->flowControlEnabled());
 
-    // take a snapshot of the session state every so often when
-    // user activity occurs
+    // take a snapshot of the session state shortly after any event occurs
     //
-    // the timer is owned by the session so that it will be destroyed along
-    // with the session
-    _interactionTimer = new QTimer(session());
-    _interactionTimer->setSingleShot(true);
-    _interactionTimer->setInterval(500);
-    connect(_interactionTimer, &QTimer::timeout, this, &Konsole::SessionController::snapshot);
-    connect(view(), &Konsole::TerminalDisplay::compositeFocusChanged, this, [this](bool focused) {
-        if (focused) {
-            interactionHandler();
-        }
-    });
-    connect(view(), &Konsole::TerminalDisplay::keyPressedSignal, this, &Konsole::SessionController::interactionHandler);
-
-    // take a snapshot of the session state periodically in the background
-    auto backgroundTimer = new QTimer(session());
-    backgroundTimer->setSingleShot(false);
-    backgroundTimer->setInterval(2000);
-    connect(backgroundTimer, &QTimer::timeout, this, &Konsole::SessionController::snapshot);
-    backgroundTimer->start();
+    // Don't link the timer with the session or we will have an use after
+    // free in SessionController::eventFilter
+    _snapshotTimer = new QTimer(nullptr);
+    _snapshotTimer->setSingleShot(true);
+    _snapshotTimer->setInterval(500);
+    connect(_snapshotTimer, &QTimer::timeout, this, &Konsole::SessionController::snapshot);
+    // Install an event handler on QCoreApplication
+    // This will catch all events: key strokes, mouse moves/clicks...
+    // but also all changes that occur in all tabs
+    QCoreApplication::instance()->installEventFilter(this);
 
     // xterm '10;?' request
     connect(session(), &Konsole::Session::getForegroundColor, this, &Konsole::SessionController::sendForegroundColor);
@@ -255,6 +245,8 @@ SessionController::SessionController(Session *sessionParam, TerminalDisplay *vie
 
 SessionController::~SessionController()
 {
+    QCoreApplication::instance()->removeEventFilter(this);
+    delete _snapshotTimer;
     _allControllers.remove(this);
 
     if (factory() != nullptr) {
@@ -317,11 +309,6 @@ void SessionController::viewFocusChangeHandler(bool focused)
     }
 }
 
-void SessionController::interactionHandler()
-{
-    _interactionTimer->start();
-}
-
 void SessionController::snapshot()
 {
     Q_ASSERT(!session().isNull());
@@ -1305,6 +1292,20 @@ void SessionController::searchClosed()
     searchHistory(false);
 }
 
+bool SessionController::eventFilter(QObject *obj, QEvent *event)
+{
+    // Forward event to super class
+    bool ret = ViewProperties::eventFilter(obj, event);
+
+    // Start the snapshot timer if:
+    // - it is not already started
+    // - the event is not a timer timeout
+    if(!_snapshotTimer->isActive() && event->type() != QEvent::Timer) {
+        _snapshotTimer->start();
+    }
+    return ret;
+}
+
 void SessionController::updateFilterList(const Profile::Ptr &profile)
 {
     if (profile != SessionManager::instance()->sessionProfile(session())) {

src/session/SessionController.h

@@ -219,6 +219,10 @@ public Q_SLOTS:
     /** Close the incremental search */
     void searchClosed(); // called when the user clicks on the
 
+protected:
+    /** Start snapshot timer if needed */
+    bool eventFilter(QObject *obj, QEvent *event) override;
+
 private Q_SLOTS:
     // menu item handlers
     void openBrowser();
@@ -277,7 +281,6 @@ private Q_SLOTS:
         const QExplicitlySharedDataPointer<Profile> &profile); // Called when the profile has changed, so we might need to change the list of filters
 
     void viewFocusChangeHandler(bool focused);
-    void interactionHandler();
     void snapshot(); // called periodically as the user types
     // to take a snapshot of the state of the
     // foreground process in the terminal
@@ -338,7 +341,7 @@ private:
     QAction *_findNextAction;
     QAction *_findPreviousAction;
 
-    QTimer *_interactionTimer;
+    QTimer *_snapshotTimer;
 
     int _searchStartLine;
     int _prevSearchResultLine;