Add grabber context pointers

In Qt Quick we now need to keep track of which QQDeliveryAgent is
responsible when a point is grabbed, either passively or exclusively.
When we re-deliver to that grabber, we need to do it via the same agent,
so that the same scene transform is used, and the grabber will see the
event in the correct coordinate system.  It's easier to track this
mapping here instead of in a separate map in Qt Quick.

Task-number: QTBUG-92944
Change-Id: I69f769c694d0da24885cdf4087e5032022bff629
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 40330b8f0a717098982d1f54f34a18a8262b1f55)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

5 files changed, 18 insertions, 13 deletions

diff --git a/src/gui/kernel/qevent.cpp b/src/gui/kernel/qevent.cpp
index adc1029754..b5418347b4 100644
--- a/src/gui/kernel/qevent.cpp
+++ b/src/gui/kernel/qevent.cpp
@@ -400,7 +400,7 @@ QList<QPointer<QObject> > QPointerEvent::passiveGrabbers(const QEventPoint &poin
         qWarning() << "point is not in activePoints" << point;
         return {};
     }
-    return persistentPoint->passiveGrabbers;
+    return persistentPoint->passiveGrabbers.keys();
 }
 
 /*!
diff --git a/src/gui/kernel/qpointingdevice.cpp b/src/gui/kernel/qpointingdevice.cpp
index 6ef032098f..58f318f2f9 100644
--- a/src/gui/kernel/qpointingdevice.cpp
+++ b/src/gui/kernel/qpointingdevice.cpp
@@ -504,6 +504,8 @@ void QPointingDevicePrivate::setExclusiveGrabber(const QPointerEvent *event, con
     QMutableEventPoint::from(persistentPoint->eventPoint).setGlobalGrabPosition(point.globalPosition());
     if (exclusiveGrabber)
         emit q->grabChanged(exclusiveGrabber, QPointingDevice::GrabExclusive, event, point);
+    else
+        persistentPoint->exclusiveGrabberContext.clear();
 }
 
 /*!
@@ -536,7 +538,7 @@ bool QPointingDevicePrivate::addPassiveGrabber(const QPointerEvent *event, const
         qCDebug(lcPointerGrab) << name << "point" << point.id() << point.state()
                                << ": grab (passive)" << grabber;
     }
-    persistentPoint->passiveGrabbers << grabber;
+    persistentPoint->passiveGrabbers.insert(grabber, {});
     emit q->grabChanged(grabber, QPointingDevice::GrabPassive, event, point);
     return true;
 }
@@ -549,14 +551,14 @@ bool QPointingDevicePrivate::removePassiveGrabber(const QPointerEvent *event, co
         qWarning() << "point is not in activePoints" << point;
         return false;
     }
-    int i = persistentPoint->passiveGrabbers.indexOf(grabber);
-    if (i >= 0) {
+    auto pgit = persistentPoint->passiveGrabbers.find(grabber);
+    if (pgit != persistentPoint->passiveGrabbers.end()) {
         if (Q_UNLIKELY(lcPointerGrab().isDebugEnabled())) {
             qCDebug(lcPointerGrab) << name << "point" << point.id() << point.state()
                                    << ": removing passive grabber" << grabber;
         }
         emit q->grabChanged(grabber, QPointingDevice::UngrabPassive, event, point);
-        persistentPoint->passiveGrabbers.removeAt(i);
+        persistentPoint->passiveGrabbers.erase(pgit);
         return true;
     }
     return false;
@@ -574,9 +576,9 @@ void QPointingDevicePrivate::clearPassiveGrabbers(const QPointerEvent *event, co
         return;
     if (Q_UNLIKELY(lcPointerGrab().isDebugEnabled())) {
         qCDebug(lcPointerGrab) << name << "point" << point.id() << point.state()
-                               << ": clearing" << persistentPoint->passiveGrabbers;
+                               << ": clearing" << persistentPoint->passiveGrabbers.keys();
     }
-    for (auto g : persistentPoint->passiveGrabbers)
+    for (auto g : persistentPoint->passiveGrabbers.keys())
         emit q->grabChanged(g, QPointingDevice::UngrabPassive, event, point);
     persistentPoint->passiveGrabbers.clear();
 }
@@ -602,15 +604,16 @@ void QPointingDevicePrivate::removeGrabber(QObject *grabber, bool cancel)
                                    << "@" << epd.eventPoint.scenePosition()
                                    << ": grab" << grabber << "-> nullptr";
             epd.exclusiveGrabber.clear();
+            epd.exclusiveGrabberContext.clear();
             emit q->grabChanged(grabber,
                                 cancel ? QPointingDevice::CancelGrabExclusive : QPointingDevice::UngrabExclusive,
                                 nullptr, epd.eventPoint);
         }
-        int pi = epd.passiveGrabbers.indexOf(grabber);
-        if (pi >= 0) {
+        auto pgit = epd.passiveGrabbers.find(grabber);
+        if (pgit != epd.passiveGrabbers.end()) {
             qCDebug(lcPointerGrab) << name << "point" << epd.eventPoint.id() << epd.eventPoint.state()
                                    << ": removing passive grabber" << grabber;
-            epd.passiveGrabbers.removeAt(pi);
+            epd.passiveGrabbers.erase(pgit);
             emit q->grabChanged(grabber,
                                 cancel ? QPointingDevice::CancelGrabPassive : QPointingDevice::UngrabPassive,
                                 nullptr, epd.eventPoint);
diff --git a/src/gui/kernel/qpointingdevice_p.h b/src/gui/kernel/qpointingdevice_p.h
index 645c82673b..0198b0d142 100644
--- a/src/gui/kernel/qpointingdevice_p.h
+++ b/src/gui/kernel/qpointingdevice_p.h
@@ -85,10 +85,12 @@ public:
     /*! \internal
         This struct (stored in activePoints) holds persistent state between event deliveries.
     */
+    using PassiveGrabbersMap = QFlatMap<QPointer<QObject>, QPointer<QObject>>;
     struct EventPointData {
         QEventPoint eventPoint;
         QPointer<QObject> exclusiveGrabber;
-        QList<QPointer <QObject> > passiveGrabbers;
+        QPointer<QObject> exclusiveGrabberContext;  // extra info about where the grab happened
+        PassiveGrabbersMap passiveGrabbers;         // key: passive grabber; value: context (where the grab happened)
     };
     EventPointData *queryPointById(int id) const;
     EventPointData *pointById(int id) const;
diff --git a/tests/auto/gui/kernel/qmouseevent/tst_qmouseevent.cpp b/tests/auto/gui/kernel/qmouseevent/tst_qmouseevent.cpp
index d5174e0942..cdf11ec54a 100644
--- a/tests/auto/gui/kernel/qmouseevent/tst_qmouseevent.cpp
+++ b/tests/auto/gui/kernel/qmouseevent/tst_qmouseevent.cpp
@@ -290,7 +290,7 @@ void tst_QMouseEvent::grabbers()
     QCOMPARE(firstEPD->exclusiveGrabber, grabExclusive ? testMouseWidget : nullptr);
     QCOMPARE(firstEPD->passiveGrabbers.count(), grabPassive ? 1 : 0);
     if (grabPassive)
-        QCOMPARE(firstEPD->passiveGrabbers.first(), testMouseWidget);
+        QCOMPARE(firstEPD->passiveGrabbers.keys().first(), testMouseWidget);
 
     // Ensure that grabbers are forgotten after release delivery
     QTest::mouseRelease(testMouseWidget, Qt::LeftButton, Qt::KeyboardModifiers(), {10, 10});
diff --git a/tests/auto/gui/kernel/qtouchevent/tst_qtouchevent.cpp b/tests/auto/gui/kernel/qtouchevent/tst_qtouchevent.cpp
index 28c33e8226..fa3f495c23 100644
--- a/tests/auto/gui/kernel/qtouchevent/tst_qtouchevent.cpp
+++ b/tests/auto/gui/kernel/qtouchevent/tst_qtouchevent.cpp
@@ -1949,7 +1949,7 @@ void tst_QTouchEvent::grabbers()
     QCOMPARE(devPriv->pointById(0)->exclusiveGrabber, grabExclusive ? &w : nullptr);
     QCOMPARE(devPriv->pointById(0)->passiveGrabbers.count(), grabPassive ? 1 : 0);
     if (grabPassive)
-        QCOMPARE(devPriv->pointById(0)->passiveGrabbers.first(), &w);
+        QCOMPARE(devPriv->pointById(0)->passiveGrabbers.keys().first(), &w);
 
     // Ensure that eventpoints are forgotten after release delivery
     points.first().state = QEventPoint::State::Released;