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.

(This is an alternative to 40330b8f0a717098982d1f54f34a18a8262b1f55:
it was not possible to use QFlatMap, because we need to keep the passive
grabbers in the same order as they were added.  We don't use a QList of
structs, because QPointerEvent::passiveGrabbers() needs to return a
QList of just the grabbers, and it's not as efficient to construct that
list in the accessor.)

Change-Id: I457114f816736749d2ea5ee48fa03524eb93d2d0
Pick-to: 6.1
Task-number: QTBUG-92944
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

2 files changed, 26 insertions, 0 deletions

diff --git a/src/gui/kernel/qpointingdevice.cpp b/src/gui/kernel/qpointingdevice.cpp
index 176a5fedf4..2a09ee3ca9 100644
--- a/src/gui/kernel/qpointingdevice.cpp
+++ b/src/gui/kernel/qpointingdevice.cpp
@@ -508,6 +508,8 @@ 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();
 }
 
 /*!
@@ -545,6 +547,17 @@ bool QPointingDevicePrivate::addPassiveGrabber(const QPointerEvent *event, const
     return true;
 }
 
+bool QPointingDevicePrivate::setPassiveGrabberContext(QPointingDevicePrivate::EventPointData *epd, QObject *grabber, QObject *context)
+{
+    int i = epd->passiveGrabbers.indexOf(grabber);
+    if (i < 0)
+        return false;
+    if (epd->passiveGrabbersContext.size() <= i)
+        epd->passiveGrabbersContext.resize(i + 1);
+    epd->passiveGrabbersContext[i] = context;
+    return true;
+}
+
 bool QPointingDevicePrivate::removePassiveGrabber(const QPointerEvent *event, const QEventPoint &point, QObject *grabber)
 {
     Q_Q(QPointingDevice);
@@ -561,6 +574,10 @@ bool QPointingDevicePrivate::removePassiveGrabber(const QPointerEvent *event, co
         }
         emit q->grabChanged(grabber, QPointingDevice::UngrabPassive, event, point);
         persistentPoint->passiveGrabbers.removeAt(i);
+        if (persistentPoint->passiveGrabbersContext.size()) {
+            Q_ASSERT(persistentPoint->passiveGrabbersContext.size() > i);
+            persistentPoint->passiveGrabbersContext.removeAt(i);
+        }
         return true;
     }
     return false;
@@ -583,6 +600,7 @@ void QPointingDevicePrivate::clearPassiveGrabbers(const QPointerEvent *event, co
     for (auto g : persistentPoint->passiveGrabbers)
         emit q->grabChanged(g, QPointingDevice::UngrabPassive, event, point);
     persistentPoint->passiveGrabbers.clear();
+    persistentPoint->passiveGrabbersContext.clear();
 }
 
 /*!
@@ -606,6 +624,7 @@ 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);
@@ -615,6 +634,10 @@ void QPointingDevicePrivate::removeGrabber(QObject *grabber, bool cancel)
             qCDebug(lcPointerGrab) << name << "point" << epd.eventPoint.id() << epd.eventPoint.state()
                                    << ": removing passive grabber" << grabber;
             epd.passiveGrabbers.removeAt(pi);
+            if (epd.passiveGrabbersContext.size()) {
+                Q_ASSERT(epd.passiveGrabbersContext.size() > pi);
+                epd.passiveGrabbersContext.removeAt(pi);
+            }
             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 04823a3e86..263bc91864 100644
--- a/src/gui/kernel/qpointingdevice_p.h
+++ b/src/gui/kernel/qpointingdevice_p.h
@@ -88,7 +88,9 @@ public:
     struct EventPointData {
         QEventPoint eventPoint;
         QPointer<QObject> exclusiveGrabber;
+        QPointer<QObject> exclusiveGrabberContext;          // extra info about where the grab happened
         QList<QPointer <QObject> > passiveGrabbers;
+        QList<QPointer <QObject> > passiveGrabbersContext;  // parallel list: extra info about where the grabs happened
     };
     EventPointData *queryPointById(int id) const;
     EventPointData *pointById(int id) const;
@@ -100,6 +102,7 @@ public:
     void setExclusiveGrabber(const QPointerEvent *event, const QEventPoint &point, QObject *exclusiveGrabber);
     bool removeExclusiveGrabber(const QPointerEvent *event, const QObject *grabber);
     bool addPassiveGrabber(const QPointerEvent *event, const QEventPoint &point, QObject *grabber);
+    static bool setPassiveGrabberContext(EventPointData *epd, QObject *grabber, QObject *context);
     bool removePassiveGrabber(const QPointerEvent *event, const QEventPoint &point, QObject *grabber);
     void clearPassiveGrabbers(const QPointerEvent *event, const QEventPoint &point);
     void removeGrabber(QObject *grabber, bool cancel = false);