pre-accept the mouse event before childMouseEventFilter; grab after

In 5.9 a typical filtering sequence would be

deliverPressEvent -> deliverMatchingPointsToItem -> QQuickWindow::sendEvent ->
sendFilteredMouseEvent -> Test::childMouseEventFilter, let's say it returns true;
then because the event is accepted, deliverMatchingPointsToItem grabs the mouse.

In 5.10, we rather do

deliverPressOrReleaseEvent -> sendFilteredPointerEvent -> sendFilteredPointerEventImpl ->
Test::childMouseEventFilter, which returns true; and in this case, setGrabberItem
was missing until now.

In case of touch rather than mouse, it grabs the touchpoints in this
kind of scenario.

Also made the failsafe more reliable to ensure that no grabs are retained
after release (after seeing that one failing autotest can cause failures
in subsequent tests).

Done-with: Jan-Arve Sæther
Task-number: QTBUG-62631
Task-number: QTBUG-62549
Task-number: QTBUG-62628
Change-Id: I16dafc9aa0de2fc163c524f7f5b109f82d7e84fd
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 18 insertions, 6 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index 9f3f8531e4..c15079b3d7 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -1745,9 +1745,6 @@ void QQuickWindowPrivate::deliverMouseEvent(QQuickPointerMouseEvent *pointerEven
             // make sure not to accept unhandled events
             pointerEvent->setAccepted(false);
     }
-    // failsafe: never allow any kind of grab to persist after release
-    if (mouseIsReleased)
-        pointerEvent->clearGrabbers();
 }
 
 bool QQuickWindowPrivate::sendHoverEvent(QEvent::Type type, QQuickItem *item,
@@ -2263,6 +2260,9 @@ void QQuickWindowPrivate::deliverPointerEvent(QQuickPointerEvent *event)
     skipDelivery.clear();
     if (event->asPointerMouseEvent()) {
         deliverMouseEvent(event->asPointerMouseEvent());
+        // failsafe: never allow any kind of grab to persist after release
+        if (event->isReleaseEvent() && event->buttons() == Qt::NoButton)
+            event->clearGrabbers();
     } else if (event->asPointerTouchEvent()) {
         deliverTouchEvent(event->asPointerTouchEvent());
     } else {
@@ -2768,10 +2768,20 @@ bool QQuickWindowPrivate::sendFilteredPointerEventImpl(QQuickPointerEvent *event
             if (receiver->acceptedMouseButtons()) {
                 QPointF localPos = receiver->mapFromScene(pme->point(0)->scenePosition());
                 QMouseEvent *me = pme->asMouseEvent(localPos);
+                me->setAccepted(true);
+                auto oldMouseGrabber = pme->point(0)->grabberItem();
                 if (filteringParent->childMouseEventFilter(receiver, me)) {
                     qCDebug(DBG_MOUSE) << "mouse event intercepted by childMouseEventFilter of " << filteringParent;
                     skipDelivery.append(filteringParent);
                     filtered = true;
+                    if (me->isAccepted() && pme->isPressEvent()) {
+                        auto mouseGrabber = pme->point(0)->grabberItem();
+                        if (mouseGrabber && mouseGrabber != receiver && mouseGrabber != oldMouseGrabber) {
+                            receiver->mouseUngrabEvent();
+                        } else {
+                            pme->point(0)->setGrabberItem(receiver);
+                        }
+                    }
                 }
             }
         } else if (QQuickPointerTouchEvent *pte = event->asPointerTouchEvent()) {
@@ -2789,7 +2799,6 @@ bool QQuickWindowPrivate::sendFilteredPointerEventImpl(QQuickPointerEvent *event
                     if (filteringParent->childMouseEventFilter(receiver, filteringParentTouchEvent.data())) {
                         qCDebug(DBG_TOUCH) << "touch event intercepted by childMouseEventFilter of " << filteringParent;
                         skipDelivery.append(filteringParent);
-                        filteringParent->grabMouse();
                         for (auto point: qAsConst(filteringParentTouchEvent->touchPoints())) {
                             auto pointerEventPoint = pte->pointById(point.id());
                             for (auto handler : pointerEventPoint->passiveGrabbers()) {
@@ -2797,7 +2806,9 @@ bool QQuickWindowPrivate::sendFilteredPointerEventImpl(QQuickPointerEvent *event
                                 if (!passiveGrabsToCancel.contains(grab))
                                     passiveGrabsToCancel.append(grab);
                             }
-                            event->pointById(point.id())->setAccepted();
+                            QQuickEventPoint *pt = event->pointById(point.id());
+                            pt->setAccepted();
+                            pt->setGrabberItem(filteringParent);
                         }
                         return true;
                     } else {
@@ -2838,7 +2849,8 @@ bool QQuickWindowPrivate::sendFilteredPointerEventImpl(QQuickPointerEvent *event
                                         qCDebug(DBG_TOUCH_TARGET) << "TP (mouse)" << hex << tp.id() << "->" << filteringParent;
                                         pointerEventInstance(touchMouseDevice)->pointById(tp.id())->setGrabberItem(filteringParent);
                                         touchMouseUnset = false; // We want to leave touchMouseId and touchMouseDevice set
-                                        filteringParent->grabMouse();
+                                        if (mouseEvent->isAccepted())
+                                            filteringParent->grabMouse();
                                         auto pointerEventPoint = pte->pointById(tp.id());
                                         for (auto handler : pointerEventPoint->passiveGrabbers()) {
                                             QPair<QQuickPointerHandler *, QQuickEventPoint *> grab(handler, pointerEventPoint);