QQuickWindow: deliver updates to handlers even if they don't grab

The "weak grab" concept depends on this.
First we deliver to grabbers, then we deliver to non-grabbing handlers
(but not to non-grabbing items).  Avoid re-delivering to grabbing
handlers which already received the same event.

Change-Id: If51e1cd9372e3bed1daea3758e9ef8e37c0ba5e3
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

5 files changed, 79 insertions, 5 deletions

diff --git a/src/quick/items/qquickevents.cpp b/src/quick/items/qquickevents.cpp
index 0c18cb4104..a68e72b0b7 100644
--- a/src/quick/items/qquickevents.cpp
+++ b/src/quick/items/qquickevents.cpp
@@ -835,6 +835,11 @@ bool QQuickPointerMouseEvent::allPointsAccepted() const {
     return m_mousePoint->isAccepted();
 }
 
+bool QQuickPointerMouseEvent::allPointsGrabbed() const
+{
+    return m_mousePoint->grabber() != nullptr;
+}
+
 QMouseEvent *QQuickPointerMouseEvent::asMouseEvent(const QPointF &localPos) const
 {
     auto event = static_cast<QMouseEvent *>(m_event);
@@ -854,6 +859,11 @@ void QQuickPointerMouseEvent::clearGrabbers() const {
     m_mousePoint->setGrabberItem(nullptr);
 }
 
+bool QQuickPointerMouseEvent::hasGrabber(const QQuickPointerHandler *handler) const
+{
+    return m_mousePoint->grabber() == handler;
+}
+
 bool QQuickPointerMouseEvent::isPressEvent() const
 {
     auto me = static_cast<QMouseEvent*>(m_event);
@@ -869,6 +879,15 @@ bool QQuickPointerTouchEvent::allPointsAccepted() const {
     return true;
 }
 
+bool QQuickPointerTouchEvent::allPointsGrabbed() const
+{
+    for (int i = 0; i < m_pointCount; ++i) {
+        if (!m_touchPoints.at(i)->grabber())
+            return false;
+    }
+    return true;
+}
+
 QVector<QObject *> QQuickPointerTouchEvent::grabbers() const
 {
     QVector<QObject *> result;
@@ -887,6 +906,14 @@ void QQuickPointerTouchEvent::clearGrabbers() const {
         point->setGrabber(nullptr);
 }
 
+bool QQuickPointerTouchEvent::hasGrabber(const QQuickPointerHandler *handler) const
+{
+    for (auto point: m_touchPoints)
+        if (point->grabber() == handler)
+            return true;
+    return false;
+}
+
 bool QQuickPointerTouchEvent::isPressEvent() const
 {
     return static_cast<QTouchEvent*>(m_event)->touchPointStates() & Qt::TouchPointPressed;
diff --git a/src/quick/items/qquickevents_p_p.h b/src/quick/items/qquickevents_p_p.h
index 4a78e98705..bbfc34dacf 100644
--- a/src/quick/items/qquickevents_p_p.h
+++ b/src/quick/items/qquickevents_p_p.h
@@ -393,6 +393,7 @@ public: // helpers for C++ only (during event delivery)
     virtual const QQuickPointerTabletEvent *asPointerTabletEvent() const { return nullptr; }
     bool isValid() const { return m_event != nullptr; }
     virtual bool allPointsAccepted() const = 0;
+    virtual bool allPointsGrabbed() const = 0;
     bool isAccepted() { return m_event->isAccepted(); }
     void setAccepted(bool accepted) { m_event->setAccepted(accepted); }
     QVector<QPointF> unacceptedPressedPointScenePositions() const;
@@ -402,6 +403,7 @@ public: // helpers for C++ only (during event delivery)
     virtual QQuickEventPoint *pointById(quint64 pointId) const = 0;
     virtual QVector<QObject *> grabbers() const = 0;
     virtual void clearGrabbers() const = 0;
+    virtual bool hasGrabber(const QQuickPointerHandler *handler) const = 0;
 
     ulong timestamp() const { return m_event->timestamp(); }
 
@@ -430,8 +432,10 @@ public:
     QQuickEventPoint *point(int i) const override;
     QQuickEventPoint *pointById(quint64 pointId) const override;
     bool allPointsAccepted() const override;
+    bool allPointsGrabbed() const override;
     QVector<QObject *> grabbers() const override;
     void clearGrabbers() const override;
+    bool hasGrabber(const QQuickPointerHandler *handler) const override;
 
     QMouseEvent *asMouseEvent(const QPointF& localPos) const;
 
@@ -461,8 +465,10 @@ public:
     QQuickEventPoint *pointById(quint64 pointId) const override;
     const QTouchEvent::TouchPoint *touchPointById(int pointId) const;
     bool allPointsAccepted() const override;
+    bool allPointsGrabbed() const override;
     QVector<QObject *> grabbers() const override;
     void clearGrabbers() const override;
+    bool hasGrabber(const QQuickPointerHandler *handler) const override;
 
     QMouseEvent *syntheticMouseEvent(int pointID, QQuickItem *relativeTo) const;
     QTouchEvent *touchEventForItem(QQuickItem *item, bool isFiltering = false) const;
diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index 98cc3112df..46e381db7d 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -5091,15 +5091,20 @@ void QQuickItemPrivate::deliverShortcutOverrideEvent(QKeyEvent *event)
     }
 }
 
-void QQuickItemPrivate::handlePointerEvent(QQuickPointerEvent *event)
+bool QQuickItemPrivate::handlePointerEvent(QQuickPointerEvent *event, bool avoidGrabber)
 {
     Q_Q(QQuickItem);
+    bool delivered = false;
     if (extra.isAllocated()) {
         for (QQuickPointerHandler *handler : extra->pointerHandlers) {
             qCDebug(lcPointerHandlerDispatch) << "   delivering" << event << "to" << handler << "on" << q;
-            handler->handlePointerEvent(event);
+            if (!avoidGrabber || !event->hasGrabber(handler)) {
+                handler->handlePointerEvent(event);
+                delivered = true;
+            }
         }
     }
+    return delivered;
 }
 
 /*!
diff --git a/src/quick/items/qquickitem_p.h b/src/quick/items/qquickitem_p.h
index e7ead7fa87..b39c437da5 100644
--- a/src/quick/items/qquickitem_p.h
+++ b/src/quick/items/qquickitem_p.h
@@ -563,7 +563,7 @@ public:
 #endif
     void deliverShortcutOverrideEvent(QKeyEvent *);
 
-    virtual void handlePointerEvent(QQuickPointerEvent *);
+    virtual bool handlePointerEvent(QQuickPointerEvent *, bool avoidGrabber = false);
 
     bool isTransparentForPositioner() const;
     void setTransparentForPositioner(bool trans);
diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index 6897240fbd..f7d6b245b2 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -1685,11 +1685,23 @@ void QQuickWindowPrivate::deliverMouseEvent(QQuickPointerMouseEvent *pointerEven
         if (me->type() == QEvent::MouseButtonRelease && !me->buttons() && q->mouseGrabberItem())
             q->mouseGrabberItem()->ungrabMouse();
     } else {
-        // send initial press
         bool delivered = false;
         if (pointerEvent->isPressEvent()) {
+            // send initial press
             QSet<QQuickItem*> hasFiltered;
             delivered = deliverPressEvent(pointerEvent, &hasFiltered);
+        } else if (pointerEvent->device()->type() == QQuickPointerDevice::Mouse) {
+            // if this is an update or release from an actual mouse,
+            // and the point wasn't grabbed, deliver only to non-grabber PointerHandlers
+            QVector<QQuickItem *> targetItems = pointerTargets(contentItem, point->scenePos(), false);
+            for (QQuickItem *item : targetItems) {
+                QQuickItemPrivate *itemPrivate = QQuickItemPrivate::get(item);
+                pointerEvent->localize(item);
+                if (itemPrivate->handlePointerEvent(pointerEvent, true)) // avoid re-delivering to grabbers
+                    delivered = true;
+                if (point->grabber())
+                    break;
+            }
         }
 
         if (!delivered)
@@ -2082,7 +2094,6 @@ void QQuickWindowPrivate::handleMouseEvent(QMouseEvent *event)
                 accepted = clearHover(event->timestamp());
             }
             event->setAccepted(accepted);
-            return;
         }
         deliverPointerEvent(pointerEventInstance(event));
         break;
@@ -2271,6 +2282,31 @@ bool QQuickWindowPrivate::deliverUpdatedTouchPoints(QQuickPointerTouchEvent *eve
         deliverMatchingPointsToItem(receiver, event, hasFiltered);
     }
 
+    // If some points weren't grabbed, deliver only to non-grabber PointerHandlers
+    if (!event->allPointsGrabbed()) {
+        QVector<QQuickItem *> targetItems;
+        int pointCount = event->pointCount();
+        for (int i = 0; i < pointCount; ++i) {
+            QQuickEventPoint *point = event->point(i);
+            QVector<QQuickItem *> targetItemsForPoint = pointerTargets(contentItem, point->scenePos(), false);
+            if (targetItems.count()) {
+                targetItems = mergePointerTargets(targetItems, targetItemsForPoint);
+            } else {
+                targetItems = targetItemsForPoint;
+            }
+        }
+
+        for (QQuickItem *item: targetItems) {
+            if (grabbers.contains(item))
+                continue;
+            QQuickItemPrivate *itemPrivate = QQuickItemPrivate::get(item);
+            event->localize(item);
+            itemPrivate->handlePointerEvent(event, true); // avoid re-delivering to grabbers
+            if (event->allPointsGrabbed())
+                break;
+        }
+    }
+
     return false;
 }