Plug memory leak when gestures are grabbed but never triggered

When a gesture is grabbed by QAbstractScrollArea but never triggered
then the deletion of the QAbstractScrollArea would mean that the gesture
created for it would not be deleted.  This ensures that it always
deletes the gestures waiting to be deleted even if no gesture event is
triggered

Task-number: QTBUG-25011

Change-Id: I36118b82baaa60ac4e014896159060e1af76b2d2
Reviewed-by: Denis Dzyubenko <denis.dzyubenko@nokia.com>
(cherry picked from commit 3ec88b355b5c9649d128fcf18cb2abc39ac0e770)

1 files changed, 91 insertions, 93 deletions

diff --git a/src/gui/kernel/qgesturemanager.cpp b/src/gui/kernel/qgesturemanager.cpp
index 4454ef2..37954fd 100644
--- a/src/gui/kernel/qgesturemanager.cpp
+++ b/src/gui/kernel/qgesturemanager.cpp
@@ -287,106 +287,104 @@ bool QGestureManager::filterEventThroughContexts(const QMultiMap<QObject *,
             }
         }
     }
-    if (triggeredGestures.isEmpty() && finishedGestures.isEmpty()
-        && newMaybeGestures.isEmpty() && notGestures.isEmpty())
-        return consumeEventHint;
-
-    QSet<QGesture *> startedGestures = triggeredGestures - m_activeGestures;
-    triggeredGestures &= m_activeGestures;
-
-    // check if a running gesture switched back to maybe state
-    QSet<QGesture *> activeToMaybeGestures = m_activeGestures & newMaybeGestures;
-
-    // check if a maybe gesture switched to canceled - reset it but don't send an event
-    QSet<QGesture *> maybeToCanceledGestures = m_maybeGestures & notGestures;
-
-    // check if a running gesture switched back to not gesture state,
-    // i.e. were canceled
-    QSet<QGesture *> canceledGestures = m_activeGestures & notGestures;
-
-    // new gestures in maybe state
-    m_maybeGestures += newMaybeGestures;
-
-    // gestures that were in maybe state
-    QSet<QGesture *> notMaybeGestures = (startedGestures | triggeredGestures
-                                         | finishedGestures | canceledGestures
-                                         | notGestures);
-    m_maybeGestures -= notMaybeGestures;
-
-    Q_ASSERT((startedGestures & finishedGestures).isEmpty());
-    Q_ASSERT((startedGestures & newMaybeGestures).isEmpty());
-    Q_ASSERT((startedGestures & canceledGestures).isEmpty());
-    Q_ASSERT((finishedGestures & newMaybeGestures).isEmpty());
-    Q_ASSERT((finishedGestures & canceledGestures).isEmpty());
-    Q_ASSERT((canceledGestures & newMaybeGestures).isEmpty());
-
-    QSet<QGesture *> notStarted = finishedGestures - m_activeGestures;
-    if (!notStarted.isEmpty()) {
-        // there are some gestures that claim to be finished, but never started.
-        // probably those are "singleshot" gestures so we'll fake the started state.
-        foreach (QGesture *gesture, notStarted)
+    if (!triggeredGestures.isEmpty() || !finishedGestures.isEmpty()
+        || !newMaybeGestures.isEmpty() || !notGestures.isEmpty()) {
+        QSet<QGesture *> startedGestures = triggeredGestures - m_activeGestures;
+        triggeredGestures &= m_activeGestures;
+
+        // check if a running gesture switched back to maybe state
+        QSet<QGesture *> activeToMaybeGestures = m_activeGestures & newMaybeGestures;
+
+        // check if a maybe gesture switched to canceled - reset it but don't send an event
+        QSet<QGesture *> maybeToCanceledGestures = m_maybeGestures & notGestures;
+
+        // check if a running gesture switched back to not gesture state,
+        // i.e. were canceled
+        QSet<QGesture *> canceledGestures = m_activeGestures & notGestures;
+
+        // new gestures in maybe state
+        m_maybeGestures += newMaybeGestures;
+
+        // gestures that were in maybe state
+        QSet<QGesture *> notMaybeGestures = (startedGestures | triggeredGestures
+                                             | finishedGestures | canceledGestures
+                                             | notGestures);
+        m_maybeGestures -= notMaybeGestures;
+
+        Q_ASSERT((startedGestures & finishedGestures).isEmpty());
+        Q_ASSERT((startedGestures & newMaybeGestures).isEmpty());
+        Q_ASSERT((startedGestures & canceledGestures).isEmpty());
+        Q_ASSERT((finishedGestures & newMaybeGestures).isEmpty());
+        Q_ASSERT((finishedGestures & canceledGestures).isEmpty());
+        Q_ASSERT((canceledGestures & newMaybeGestures).isEmpty());
+
+        QSet<QGesture *> notStarted = finishedGestures - m_activeGestures;
+        if (!notStarted.isEmpty()) {
+            // there are some gestures that claim to be finished, but never started.
+            // probably those are "singleshot" gestures so we'll fake the started state.
+            foreach (QGesture *gesture, notStarted)
+                gesture->d_func()->state = Qt::GestureStarted;
+            QSet<QGesture *> undeliveredGestures;
+            deliverEvents(notStarted, &undeliveredGestures);
+            finishedGestures -= undeliveredGestures;
+        }
+
+        m_activeGestures += startedGestures;
+        // sanity check: all triggered gestures should already be in active gestures list
+        Q_ASSERT((m_activeGestures & triggeredGestures).size() == triggeredGestures.size());
+        m_activeGestures -= finishedGestures;
+        m_activeGestures -= activeToMaybeGestures;
+        m_activeGestures -= canceledGestures;
+
+        // set the proper gesture state on each gesture
+        foreach (QGesture *gesture, startedGestures)
             gesture->d_func()->state = Qt::GestureStarted;
-        QSet<QGesture *> undeliveredGestures;
-        deliverEvents(notStarted, &undeliveredGestures);
-        finishedGestures -= undeliveredGestures;
-    }
+        foreach (QGesture *gesture, triggeredGestures)
+            gesture->d_func()->state = Qt::GestureUpdated;
+        foreach (QGesture *gesture, finishedGestures)
+            gesture->d_func()->state = Qt::GestureFinished;
+        foreach (QGesture *gesture, canceledGestures)
+            gesture->d_func()->state = Qt::GestureCanceled;
+        foreach (QGesture *gesture, activeToMaybeGestures)
+            gesture->d_func()->state = Qt::GestureFinished;
+
+        if (!m_activeGestures.isEmpty() || !m_maybeGestures.isEmpty() ||
+            !startedGestures.isEmpty() || !triggeredGestures.isEmpty() ||
+            !finishedGestures.isEmpty() || !canceledGestures.isEmpty()) {
+            DEBUG() << "QGestureManager::filterEventThroughContexts:"
+                    << "\n\tactiveGestures:" << m_activeGestures
+                    << "\n\tmaybeGestures:" << m_maybeGestures
+                    << "\n\tstarted:" << startedGestures
+                    << "\n\ttriggered:" << triggeredGestures
+                    << "\n\tfinished:" << finishedGestures
+                    << "\n\tcanceled:" << canceledGestures
+                    << "\n\tmaybe-canceled:" << maybeToCanceledGestures;
+        }
 
-    m_activeGestures += startedGestures;
-    // sanity check: all triggered gestures should already be in active gestures list
-    Q_ASSERT((m_activeGestures & triggeredGestures).size() == triggeredGestures.size());
-    m_activeGestures -= finishedGestures;
-    m_activeGestures -= activeToMaybeGestures;
-    m_activeGestures -= canceledGestures;
-
-    // set the proper gesture state on each gesture
-    foreach (QGesture *gesture, startedGestures)
-        gesture->d_func()->state = Qt::GestureStarted;
-    foreach (QGesture *gesture, triggeredGestures)
-        gesture->d_func()->state = Qt::GestureUpdated;
-    foreach (QGesture *gesture, finishedGestures)
-        gesture->d_func()->state = Qt::GestureFinished;
-    foreach (QGesture *gesture, canceledGestures)
-        gesture->d_func()->state = Qt::GestureCanceled;
-    foreach (QGesture *gesture, activeToMaybeGestures)
-        gesture->d_func()->state = Qt::GestureFinished;
-
-    if (!m_activeGestures.isEmpty() || !m_maybeGestures.isEmpty() ||
-        !startedGestures.isEmpty() || !triggeredGestures.isEmpty() ||
-        !finishedGestures.isEmpty() || !canceledGestures.isEmpty()) {
-        DEBUG() << "QGestureManager::filterEventThroughContexts:"
-                << "\n\tactiveGestures:" << m_activeGestures
-                << "\n\tmaybeGestures:" << m_maybeGestures
-                << "\n\tstarted:" << startedGestures
-                << "\n\ttriggered:" << triggeredGestures
-                << "\n\tfinished:" << finishedGestures
-                << "\n\tcanceled:" << canceledGestures
-                << "\n\tmaybe-canceled:" << maybeToCanceledGestures;
-    }
+        QSet<QGesture *> undeliveredGestures;
+        deliverEvents(startedGestures+triggeredGestures+finishedGestures+canceledGestures,
+                      &undeliveredGestures);
 
-    QSet<QGesture *> undeliveredGestures;
-    deliverEvents(startedGestures+triggeredGestures+finishedGestures+canceledGestures,
-                  &undeliveredGestures);
-
-    foreach (QGesture *g, startedGestures) {
-        if (undeliveredGestures.contains(g))
-            continue;
-        if (g->gestureCancelPolicy() == QGesture::CancelAllInContext) {
-            DEBUG() << "lets try to cancel some";
-            // find gestures in context in Qt::GestureStarted or Qt::GestureUpdated state and cancel them
-            cancelGesturesForChildren(g);
+        foreach (QGesture *g, startedGestures) {
+            if (undeliveredGestures.contains(g))
+                continue;
+            if (g->gestureCancelPolicy() == QGesture::CancelAllInContext) {
+                DEBUG() << "lets try to cancel some";
+                // find gestures in context in Qt::GestureStarted or Qt::GestureUpdated state and cancel them
+                cancelGesturesForChildren(g);
+            }
         }
-    }
 
-    m_activeGestures -= undeliveredGestures;
+        m_activeGestures -= undeliveredGestures;
 
-    // reset gestures that ended
-    QSet<QGesture *> endedGestures =
-            finishedGestures + canceledGestures + undeliveredGestures + maybeToCanceledGestures;
-    foreach (QGesture *gesture, endedGestures) {
-        recycle(gesture);
-        m_gestureTargets.remove(gesture);
+        // reset gestures that ended
+        QSet<QGesture *> endedGestures =
+                finishedGestures + canceledGestures + undeliveredGestures + maybeToCanceledGestures;
+        foreach (QGesture *gesture, endedGestures) {
+            recycle(gesture);
+            m_gestureTargets.remove(gesture);
+        }
     }
-
     //Clean up the Gestures
     qDeleteAll(m_gesturesToDelete);
     m_gesturesToDelete.clear();