Implement QEvent::GraphicsSceneTouchBegin propagation

This event will be propagated to all items under the first touch point,
otherwise it's the same as QEvent::TouchBegin propagation: the first
item to accept the event gets the remaining touch events. If none of
the GraphicsSceneTouchEvents sent to the items are sent, then the
GraphicsSceneTouchEvent that was sent to the seen will be ignored,
causing the QTouchEvent sent to the QGraphicsView to also be ignored,
meaning widget TouchBegin event propagation resumes.

2 files changed, 69 insertions, 6 deletions

diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 8140fea..3d4bb5c 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -3798,6 +3798,9 @@ bool QGraphicsScene::event(QEvent *event)
     case QEvent::GraphicsSceneHoverEnter:
     case QEvent::GraphicsSceneHoverLeave:
     case QEvent::GraphicsSceneHoverMove:
+    case QEvent::GraphicsSceneTouchBegin:
+    case QEvent::GraphicsSceneTouchUpdate:
+    case QEvent::GraphicsSceneTouchEnd:
         // Reset the under-mouse list to ensure that this event gets fresh
         // item-under-mouse data. Be careful about this list; if people delete
         // items from inside event handlers, this list can quickly end up
@@ -5722,8 +5725,6 @@ QEvent::Type QGraphicsScenePrivate::removeTouchPoint(QGraphicsSceneTouchEvent::T
 
 void QGraphicsScenePrivate::touchEventHandler(QGraphicsSceneTouchEvent *sceneTouchEvent)
 {
-    Q_Q(QGraphicsScene);
-
     QList<QGraphicsSceneTouchEvent::TouchPoint *> sceneActiveTouchPoints = sceneCurrentTouchPoints;
 
     QHash<QGraphicsItem *, QGraphicsSceneTouchEvent *> itemsNeedingEvents;
@@ -5735,8 +5736,11 @@ void QGraphicsScenePrivate::touchEventHandler(QGraphicsSceneTouchEvent *sceneTou
         QEvent::Type eventType = QEvent::None;
         QList<QGraphicsSceneTouchEvent::TouchPoint *> activeTouchPoints;
         if (touchPoint->state() == Qt::TouchPointPressed) {
-            // determine which widget this event will go to
-            item = q->itemAt(touchPoint->scenePos());
+            // determine which item this event will go to
+            cachedItemsUnderMouse = itemsAtPosition(touchPoint->screenPos().toPoint(),
+                                                    touchPoint->scenePos(),
+                                                    sceneTouchEvent->widget());
+            item = cachedItemsUnderMouse.isEmpty() ? 0 : cachedItemsUnderMouse.first();
             QGraphicsSceneTouchEvent::TouchPoint *closestTouchPoint = findClosestTouchPoint(sceneActiveTouchPoints, touchPoint->scenePos());
             if (closestTouchPoint) {
                 QGraphicsItem *closestItem = itemForTouchPointId.value(closestTouchPoint->id());
@@ -5781,6 +5785,7 @@ void QGraphicsScenePrivate::touchEventHandler(QGraphicsSceneTouchEvent *sceneTou
             QGraphicsSceneTouchEvent *&touchEvent = itemsNeedingEvents[item];
             if (!touchEvent) {
                 touchEvent = new QGraphicsSceneTouchEvent(eventType);
+                touchEvent->setWidget(sceneTouchEvent->widget());
                 touchEvent->setModifiers(sceneTouchEvent->modifiers());
             }
             Q_ASSERT(touchEvent->type() == eventType);
@@ -5800,7 +5805,6 @@ void QGraphicsScenePrivate::touchEventHandler(QGraphicsSceneTouchEvent *sceneTou
         QGraphicsItem *item = it.key();
 
         QGraphicsSceneTouchEvent *touchEvent = it.value();
-        updateTouchPointsForItem(item, touchEvent);
 
         switch (touchEvent->type()) {
         case QEvent::GraphicsSceneTouchBegin:
@@ -5808,7 +5812,7 @@ void QGraphicsScenePrivate::touchEventHandler(QGraphicsSceneTouchEvent *sceneTou
             // if the TouchBegin handler recurses, we assume that means the event
             // has been implicitly accepted and continue to send touch events
             item->d_ptr->acceptedTouchBeginEvent = true;
-            bool res = sendEvent(item, touchEvent)
+            bool res = sendTouchBeginEvent(item, touchEvent)
                        && touchEvent->isAccepted();
             acceptSceneTouchEvent = acceptSceneTouchEvent || res;
             break;
@@ -5823,6 +5827,7 @@ void QGraphicsScenePrivate::touchEventHandler(QGraphicsSceneTouchEvent *sceneTou
         }
         default:
             if (item->d_ptr->acceptedTouchBeginEvent) {
+                updateTouchPointsForItem(item, touchEvent);
                 (void) sendEvent(item, touchEvent);
                 acceptSceneTouchEvent = true;
             }
@@ -5834,6 +5839,63 @@ void QGraphicsScenePrivate::touchEventHandler(QGraphicsSceneTouchEvent *sceneTou
     sceneTouchEvent->setAccepted(acceptSceneTouchEvent);
 }
 
+bool QGraphicsScenePrivate::sendTouchBeginEvent(QGraphicsItem *origin, QGraphicsSceneTouchEvent *touchEvent)
+{
+    Q_Q(QGraphicsScene);
+
+    if (cachedItemsUnderMouse.isEmpty() || cachedItemsUnderMouse.first() != origin) {
+        QGraphicsSceneTouchEvent::TouchPoint *firstTouchPoint = touchEvent->touchPoints().first();
+        cachedItemsUnderMouse = itemsAtPosition(firstTouchPoint->screenPos().toPoint(),
+                                                firstTouchPoint->scenePos(),
+                                                touchEvent->widget());
+    }
+    Q_ASSERT(cachedItemsUnderMouse.first() == origin);
+
+    // Set focus on the topmost enabled item that can take focus.
+    bool setFocus = false;
+    foreach (QGraphicsItem *item, cachedItemsUnderMouse) {
+        if (item->isEnabled() && (item->flags() & QGraphicsItem::ItemIsFocusable)) {
+            if (!item->isWidget() || ((QGraphicsWidget *)item)->focusPolicy() & Qt::ClickFocus) {
+                setFocus = true;
+                if (item != q->focusItem())
+                    q->setFocusItem(item, Qt::MouseFocusReason);
+                break;
+            }
+        }
+    }
+
+    // If nobody could take focus, clear it.
+    if (!stickyFocus && !setFocus)
+        q->setFocusItem(0, Qt::MouseFocusReason);
+
+    bool res = false;
+    bool eventAccepted = touchEvent->isAccepted();
+    foreach (QGraphicsItem *item, cachedItemsUnderMouse) {
+        // first, try to deliver the touch event
+        updateTouchPointsForItem(item, touchEvent);
+        touchEvent->ignore();
+        res = item->acceptTouchEvents()
+              && sendEvent(item, touchEvent);
+        eventAccepted = touchEvent->isAccepted();
+        item->d_ptr->acceptedTouchBeginEvent = (res && eventAccepted);
+        touchEvent->spont = false;
+        if (res && eventAccepted) {
+            // the first item to accept the TouchBegin gets an implicit grab.
+            for (int i = 0; i < touchEvent->touchPoints().count(); ++i) {
+                QGraphicsSceneTouchEvent::TouchPoint *touchPoint = touchEvent->touchPoints().at(i);
+                itemForTouchPointId[touchPoint->id()] = item;
+            }
+            if (origin != item)
+                itemCurrentTouchPoints.remove(origin);
+            itemCurrentTouchPoints[item] = touchEvent->touchPoints();
+            break;
+        }
+    }
+
+    touchEvent->setAccepted(eventAccepted);
+    return res;
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qgraphicsscene.cpp"
diff --git a/src/gui/graphicsview/qgraphicsscene_p.h b/src/gui/graphicsview/qgraphicsscene_p.h
index 589ab75..7928a45 100644
--- a/src/gui/graphicsview/qgraphicsscene_p.h
+++ b/src/gui/graphicsview/qgraphicsscene_p.h
@@ -287,6 +287,7 @@ public:
     QEvent::Type removeTouchPoint(QGraphicsSceneTouchEvent::TouchPoint *touchPoint,
                                   QList<QGraphicsSceneTouchEvent::TouchPoint *> *currentTouchPoints);
     void touchEventHandler(QGraphicsSceneTouchEvent *touchEvent);
+    bool sendTouchBeginEvent(QGraphicsItem *item, QGraphicsSceneTouchEvent *touchEvent);
 };
 
 QT_END_NAMESPACE