Gestures in GraphicsView do not require a viewport to subscribe to gestures.

When a graphicsitem subscribes to a gesture the viewport is implicitly
subscribed to it as well.

Task-number: QTBUG-9849
Reviewed-by: Olivier Goffart
Reviewed-by: Mikko Harju

6 files changed, 110 insertions, 25 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 5e0d46f..04d9075 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -7650,9 +7650,10 @@ QGraphicsObject::QGraphicsObject(QGraphicsItemPrivate &dd, QGraphicsItem *parent
 */
 void QGraphicsObject::grabGesture(Qt::GestureType gesture, Qt::GestureFlags flags)
 {
-    QGraphicsItemPrivate * const d = QGraphicsItem::d_func();
-    d->gestureContext.insert(gesture, flags);
-    (void)QGestureManager::instance(); // create a gesture manager
+    bool contains = QGraphicsItem::d_ptr->gestureContext.contains(gesture);
+    QGraphicsItem::d_ptr->gestureContext.insert(gesture, flags);
+    if (!contains && QGraphicsItem::d_ptr->scene)
+        QGraphicsItem::d_ptr->scene->d_func()->grabGesture(this, gesture);
 }
 
 /*!
@@ -7662,11 +7663,8 @@ void QGraphicsObject::grabGesture(Qt::GestureType gesture, Qt::GestureFlags flag
 */
 void QGraphicsObject::ungrabGesture(Qt::GestureType gesture)
 {
-    QGraphicsItemPrivate * const d = QGraphicsItem::d_func();
-    if (d->gestureContext.remove(gesture)) {
-        QGestureManager *manager = QGestureManager::instance();
-        manager->cleanupCachedGestures(this, gesture);
-    }
+    if (QGraphicsItem::d_ptr->gestureContext.remove(gesture) && QGraphicsItem::d_ptr->scene)
+        QGraphicsItem::d_ptr->scene->d_func()->ungrabGesture(this, gesture);
 }
 /*!
     Updates the item's micro focus. This is slot for convenience.
diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 9b7cf12..b7e2fda 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -710,6 +710,9 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
     cachedTargetItems.removeOne(dummy);
     cachedItemGestures.remove(dummy);
     cachedAlreadyDeliveredGestures.remove(dummy);
+
+    foreach (Qt::GestureType gesture, item->d_ptr->gestureContext.keys())
+        ungrabGesture(item, gesture);
 }
 
 /*!
@@ -2595,6 +2598,9 @@ void QGraphicsScene::addItem(QGraphicsItem *item)
         d->enableTouchEventsOnViews();
     }
 
+    foreach (Qt::GestureType gesture, item->d_ptr->gestureContext.keys())
+        d->grabGesture(item, gesture);
+
     // Update selection lists
     if (item->isSelected())
         d->selectedItems << item;
@@ -5609,6 +5615,8 @@ bool QGraphicsScene::sendEvent(QGraphicsItem *item, QEvent *event)
 void QGraphicsScenePrivate::addView(QGraphicsView *view)
 {
     views << view;
+    foreach (Qt::GestureType gesture, grabbedGestures.keys())
+        view->viewport()->grabGesture(gesture);
 }
 
 void QGraphicsScenePrivate::removeView(QGraphicsView *view)
@@ -6306,6 +6314,27 @@ void QGraphicsScenePrivate::cancelGesturesForChildren(QGesture *original)
     }
 }
 
+void QGraphicsScenePrivate::grabGesture(QGraphicsItem *, Qt::GestureType gesture)
+{
+    (void)QGestureManager::instance(); // create a gesture manager
+    if (!grabbedGestures[gesture]++) {
+        foreach (QGraphicsView *view, views)
+            view->viewport()->grabGesture(gesture);
+    }
+}
+
+void QGraphicsScenePrivate::ungrabGesture(QGraphicsItem *item, Qt::GestureType gesture)
+{
+    // we know this can only be an object
+    Q_ASSERT(item->d_ptr->isObject);
+    QGraphicsObject *obj = static_cast<QGraphicsObject *>(item);
+    QGestureManager::instance()->cleanupCachedGestures(obj, gesture);
+    if (!--grabbedGestures[gesture]) {
+        foreach (QGraphicsView *view, views)
+            view->viewport()->ungrabGesture(gesture);
+    }
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qgraphicsscene.cpp"
diff --git a/src/gui/graphicsview/qgraphicsscene.h b/src/gui/graphicsview/qgraphicsscene.h
index e5b15ef..c34a303 100644
--- a/src/gui/graphicsview/qgraphicsscene.h
+++ b/src/gui/graphicsview/qgraphicsscene.h
@@ -302,6 +302,7 @@ private:
     Q_PRIVATE_SLOT(d_func(), void _q_updateScenePosDescendants())
     friend class QGraphicsItem;
     friend class QGraphicsItemPrivate;
+    friend class QGraphicsObject;
     friend class QGraphicsView;
     friend class QGraphicsViewPrivate;
     friend class QGraphicsWidget;
diff --git a/src/gui/graphicsview/qgraphicsscene_p.h b/src/gui/graphicsview/qgraphicsscene_p.h
index 77bf450..8ad2a0a 100644
--- a/src/gui/graphicsview/qgraphicsscene_p.h
+++ b/src/gui/graphicsview/qgraphicsscene_p.h
@@ -302,6 +302,7 @@ public:
     QHash<QGraphicsObject *, QSet<QGesture *> > cachedItemGestures;
     QHash<QGraphicsObject *, QSet<QGesture *> > cachedAlreadyDeliveredGestures;
     QHash<QGesture *, QGraphicsObject *> gestureTargets;
+    QHash<Qt::GestureType, int>  grabbedGestures;
     void gestureEventHandler(QGestureEvent *event);
     void gestureTargetsAtHotSpots(const QSet<QGesture *> &gestures,
                            Qt::GestureFlag flag,
@@ -310,6 +311,8 @@ public:
                            QSet<QGesture *> *normal = 0,
                            QSet<QGesture *> *conflicts = 0);
     void cancelGesturesForChildren(QGesture *original);
+    void grabGesture(QGraphicsItem *, Qt::GestureType gesture);
+    void ungrabGesture(QGraphicsItem *, Qt::GestureType gesture);
 
     void updateInputMethodSensitivityInViews();
 
diff --git a/src/gui/graphicsview/qgraphicsview.cpp b/src/gui/graphicsview/qgraphicsview.cpp
index d2964ca..9dfcd2c 100644
--- a/src/gui/graphicsview/qgraphicsview.cpp
+++ b/src/gui/graphicsview/qgraphicsview.cpp
@@ -2688,6 +2688,11 @@ void QGraphicsView::setupViewport(QWidget *widget)
     if (d->scene && !d->scene->d_func()->allItemsIgnoreTouchEvents)
         widget->setAttribute(Qt::WA_AcceptTouchEvents);
 
+    if (d->scene) {
+        foreach (Qt::GestureType gesture, d->scene->d_func()->grabbedGestures.keys())
+            widget->grabGesture(gesture);
+    }
+
     widget->setAcceptDrops(acceptDrops());
 }
 
diff --git a/tests/auto/gestures/tst_gestures.cpp b/tests/auto/gestures/tst_gestures.cpp
index dfadf48..4a9f1d1 100644
--- a/tests/auto/gestures/tst_gestures.cpp
+++ b/tests/auto/gestures/tst_gestures.cpp
@@ -336,6 +336,7 @@ private slots:
     void finishedWithoutStarted();
     void unknownGesture();
     void graphicsItemGesture();
+    void graphicsView();
     void graphicsItemTreeGesture();
     void explicitGraphicsObjectTarget();
     void gestureOverChildGraphicsItem();
@@ -859,7 +860,6 @@ void tst_Gestures::graphicsItemGesture()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
     item->grabGesture(CustomGesture::GestureType);
 
     static const int TotalGestureEventsCount = CustomGesture::SerialFinishedThreshold - CustomGesture::SerialStartedThreshold + 1;
@@ -908,6 +908,71 @@ void tst_Gestures::graphicsItemGesture()
     QCOMPARE(item->gestureOverrideEventsReceived, 0);
 }
 
+void tst_Gestures::graphicsView()
+{
+    QGraphicsScene scene;
+    QGraphicsView view(&scene);
+    view.setWindowFlags(Qt::X11BypassWindowManagerHint);
+
+    GestureItem *item = new GestureItem("item");
+    scene.addItem(item);
+    item->setPos(100, 100);
+
+    view.show();
+    QTest::qWaitForWindowShown(&view);
+    view.ensureVisible(scene.sceneRect());
+
+    item->grabGesture(CustomGesture::GestureType);
+
+    static const int TotalGestureEventsCount = CustomGesture::SerialFinishedThreshold - CustomGesture::SerialStartedThreshold + 1;
+    static const int TotalCustomEventsCount = CustomGesture::SerialFinishedThreshold - CustomGesture::SerialMaybeThreshold + 1;
+
+    CustomEvent event;
+    // make sure the event is properly delivered if only the hotspot is set.
+    event.hotSpot = mapToGlobal(QPointF(10, 10), item, &view);
+    event.hasHotSpot = true;
+    sendCustomGesture(&event, item, &scene);
+
+    QCOMPARE(item->customEventsReceived, TotalCustomEventsCount);
+    QCOMPARE(item->gestureEventsReceived, TotalGestureEventsCount);
+    QCOMPARE(item->gestureOverrideEventsReceived, 0);
+
+    // change the viewport and try again
+    QWidget *newViewport = new QWidget;
+    view.setViewport(newViewport);
+
+    item->reset();
+    sendCustomGesture(&event, item, &scene);
+
+    QCOMPARE(item->customEventsReceived, TotalCustomEventsCount);
+    QCOMPARE(item->gestureEventsReceived, TotalGestureEventsCount);
+    QCOMPARE(item->gestureOverrideEventsReceived, 0);
+
+    // change the scene and try again
+    QGraphicsScene newScene;
+    item = new GestureItem("newItem");
+    newScene.addItem(item);
+    item->setPos(100, 100);
+    view.setScene(&newScene);
+
+    item->reset();
+    // first without a gesture
+    sendCustomGesture(&event, item, &newScene);
+
+    QCOMPARE(item->customEventsReceived, TotalCustomEventsCount);
+    QCOMPARE(item->gestureEventsReceived, 0);
+    QCOMPARE(item->gestureOverrideEventsReceived, 0);
+
+    // then grab the gesture and try again
+    item->reset();
+    item->grabGesture(CustomGesture::GestureType);
+    sendCustomGesture(&event, item, &newScene);
+
+    QCOMPARE(item->customEventsReceived, TotalCustomEventsCount);
+    QCOMPARE(item->gestureEventsReceived, TotalGestureEventsCount);
+    QCOMPARE(item->gestureOverrideEventsReceived, 0);
+}
+
 void tst_Gestures::graphicsItemTreeGesture()
 {
     QGraphicsScene scene;
@@ -933,7 +998,6 @@ void tst_Gestures::graphicsItemTreeGesture()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
     item1->grabGesture(CustomGesture::GestureType);
 
     static const int TotalGestureEventsCount = CustomGesture::SerialFinishedThreshold - CustomGesture::SerialStartedThreshold + 1;
@@ -991,7 +1055,6 @@ void tst_Gestures::explicitGraphicsObjectTarget()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
     item1->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
     item2->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
     item2_child1->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
@@ -1051,7 +1114,6 @@ void tst_Gestures::gestureOverChildGraphicsItem()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
     item1->grabGesture(CustomGesture::GestureType);
 
     static const int TotalGestureEventsCount = CustomGesture::SerialFinishedThreshold - CustomGesture::SerialStartedThreshold + 1;
@@ -1519,8 +1581,6 @@ void tst_Gestures::autoCancelGestures2()
     parent->setPos(0, 0);
     child->setPos(10, 10);
     scene.addItem(parent);
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
-    view.viewport()->grabGesture(secondGesture, Qt::DontStartGestureOnChildren);
     parent->grabGesture(CustomGesture::GestureType);
     child->grabGesture(secondGesture);
 
@@ -1573,7 +1633,6 @@ void tst_Gestures::graphicsViewParentPropagation()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
     item0->grabGesture(CustomGesture::GestureType, Qt::ReceivePartialGestures | Qt::IgnoredGesturesPropagateToParent);
     item1->grabGesture(CustomGesture::GestureType, Qt::ReceivePartialGestures | Qt::IgnoredGesturesPropagateToParent);
     item1_c1->grabGesture(CustomGesture::GestureType, Qt::IgnoredGesturesPropagateToParent);
@@ -1644,8 +1703,6 @@ void tst_Gestures::panelPropagation()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
-
     static const int TotalGestureEventsCount = CustomGesture::SerialFinishedThreshold - CustomGesture::SerialStartedThreshold + 1;
     static const int TotalCustomEventsCount = CustomGesture::SerialFinishedThreshold - CustomGesture::SerialMaybeThreshold + 1;
 
@@ -1757,8 +1814,6 @@ void tst_Gestures::panelStacksBehindParent()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
-
     static const int TotalGestureEventsCount = CustomGesture::SerialFinishedThreshold - CustomGesture::SerialStartedThreshold + 1;
 
     CustomEvent event;
@@ -1843,8 +1898,6 @@ void tst_Gestures::deleteGestureTargetItem()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
-
     if (propagateUpdateGesture)
         item2->ignoredUpdatedGestures << CustomGesture::GestureType;
     connect(items.value(emitter, 0), signalName, items.value(receiver, 0), slotName);
@@ -1890,8 +1943,6 @@ void tst_Gestures::viewportCoordinates()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
-
     CustomEvent event;
     event.hotSpot = mapToGlobal(item1->boundingRect().center(), item1, &view);
     event.hasHotSpot = true;
@@ -1929,8 +1980,6 @@ void tst_Gestures::partialGesturePropagation()
     QTest::qWaitForWindowShown(&view);
     view.ensureVisible(scene.sceneRect());
 
-    view.viewport()->grabGesture(CustomGesture::GestureType, Qt::DontStartGestureOnChildren);
-
     item1->ignoredUpdatedGestures << CustomGesture::GestureType;
 
     CustomEvent event;