Move event delivery from QQWindow to QQuickDeliveryAgent

QQuickWindow owns QQuickRootItem which owns QQuickDeliveryAgent, so
for every window there's an object responsible for event delivery,
while the window itself is mainly responsible for rendering (separation
of concerns).  However, QQuickRootItem and QQuickDeliveryAgent can now
be used in cases where the scene doesn't directly belong to a window,
such as when a Qt Quick sub-scene is mapped somewhere into a Qt Quick 3D
scene.  In that case, we must remember which delivery agent was in use
at the time when a QEventPoint is grabbed and deliver subsequent updates
via the same DA.  There's also a QQuickDeliveryAgent::Transform
abstraction which subscene-management code (such as QQuick3DViewport)
can implement, to provide a formula to map the window's scene
coordinates to subscene coordinates; if defined, it will be used
during delivery of subsequent updates to existing grabbers.

Task-number: QTBUG-84870
Change-Id: I70b433f7ebb05d2e60214ff3192e05da0aa84a42
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
(cherry picked from commit 68c103225f4e8bd6c1b18ef547108fd60f398c0f)
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 92 insertions, 35 deletions

diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index 93512d70f8..f4eea2923a 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -91,6 +91,7 @@ QT_BEGIN_NAMESPACE
 
 Q_DECLARE_LOGGING_CATEGORY(lcMouseTarget)
 Q_DECLARE_LOGGING_CATEGORY(lcHoverTrace)
+Q_DECLARE_LOGGING_CATEGORY(lcPtr)
 Q_DECLARE_LOGGING_CATEGORY(lcTransient)
 Q_LOGGING_CATEGORY(lcHandlerParent, "qt.quick.handler.parent")
 
@@ -2684,8 +2685,9 @@ void QQuickItem::setParentItem(QQuickItem *parentItem)
             while (!scopeItem->isFocusScope() && scopeItem->parentItem())
                 scopeItem = scopeItem->parentItem();
             if (d->window) {
-                QQuickWindowPrivate::get(d->window)->clearFocusInScope(scopeItem, scopeFocusedItem, Qt::OtherFocusReason,
-                                                                QQuickWindowPrivate::DontChangeFocusProperty);
+                d->deliveryAgentPrivate()->
+                        clearFocusInScope(scopeItem, scopeFocusedItem, Qt::OtherFocusReason,
+                                          QQuickDeliveryAgentPrivate::DontChangeFocusProperty);
                 if (scopeFocusedItem != this)
                     QQuickItemPrivate::get(scopeFocusedItem)->updateSubFocusItem(this, true);
             } else {
@@ -2760,8 +2762,9 @@ void QQuickItem::setParentItem(QQuickItem *parentItem)
                 emit scopeFocusedItem->focusChanged(false);
             } else {
                 if (d->window) {
-                    QQuickWindowPrivate::get(d->window)->setFocusInScope(scopeItem, scopeFocusedItem, Qt::OtherFocusReason,
-                                                                  QQuickWindowPrivate::DontChangeFocusProperty);
+                    d->deliveryAgentPrivate()->
+                            setFocusInScope(scopeItem, scopeFocusedItem, Qt::OtherFocusReason,
+                                            QQuickDeliveryAgentPrivate::DontChangeFocusProperty);
                 } else {
                     QQuickItemPrivate::get(scopeFocusedItem)->updateSubFocusItem(scopeItem, true);
                 }
@@ -3037,7 +3040,6 @@ void QQuickItemPrivate::derefWindow()
         window->unsetCursor();
     }
 #endif
-    c->hoverItems.removeAll(q);
     if (itemNodeInstance)
         c->cleanup(itemNodeInstance);
     if (!parentItem)
@@ -3194,6 +3196,7 @@ QQuickItemPrivate::QQuickItemPrivate()
     , replayingPressEvent(false)
     , touchEnabled(false)
     , hasCursorHandler(false)
+    , hasSubsceneDeliveryAgent(false)
     , dirtyAttributes(0)
     , nextDirtyItem(nullptr)
     , prevDirtyItem(nullptr)
@@ -5195,6 +5198,57 @@ QPointF QQuickItemPrivate::adjustedPosForTransform(const QPointF &centroidParent
     return pos;
 }
 
+/*! \internal
+    Returns the delivery agent for the narrowest subscene containing this item,
+    but falls back to QQuickWindowPrivate::deliveryAgent if there are no subscenes.
+
+    \note When a Qt Quick scene is shown in the usual way in its own window,
+    subscenes are ignored, and QQuickWindowPrivate::deliveryAgent is used.
+    Subscene delivery agents are used only in QtQuick 3D so far.
+*/
+QQuickDeliveryAgent *QQuickItemPrivate::deliveryAgent()
+{
+    // optimization: don't go up the parent hierarchy if this item is not aware of being in a subscene
+    if (hasSubsceneDeliveryAgent) {
+        QQuickItemPrivate *p = this;
+        do {
+            if (p->extra.isAllocated()) {
+                if (auto da = p->extra->subsceneDeliveryAgent)
+                    return da;
+                p = p->parentItem ? QQuickItemPrivate::get(p->parentItem) : nullptr;
+            }
+        } while (p);
+    }
+    if (window)
+        return QQuickWindowPrivate::get(window)->deliveryAgent;
+    return nullptr;
+}
+
+QQuickDeliveryAgentPrivate *QQuickItemPrivate::deliveryAgentPrivate()
+{
+    auto da = deliveryAgent();
+    return da ? static_cast<QQuickDeliveryAgentPrivate *>(QQuickDeliveryAgentPrivate::get(da)) : nullptr;
+}
+
+/*! \internal
+    Ensures that this item, presumably the root of a sub-scene (e.g. because it
+    is mapped onto a 3D object in Qt Quick 3D), has a delivery agent to be used
+    when delivering events to the subscene: i.e. when the viewport delivers an
+    event to the subscene, or when the outer delivery agent delivers an update
+    to an item that grabbed during a previous subscene delivery.  Creates a new
+    agent if it was not already created, and returns a pointer to the instance.
+*/
+QQuickDeliveryAgent *QQuickItemPrivate::ensureSubsceneDeliveryAgent()
+{
+    Q_Q(QQuickItem);
+    hasSubsceneDeliveryAgent = true;
+    if (extra.isAllocated() && extra->subsceneDeliveryAgent)
+        return extra->subsceneDeliveryAgent;
+    extra.value().subsceneDeliveryAgent = new QQuickDeliveryAgent(q);
+    qCDebug(lcPtr) << "created new" << extra->subsceneDeliveryAgent;
+    return extra->subsceneDeliveryAgent;
+}
+
 bool QQuickItemPrivate::filterKeyEvent(QKeyEvent *e, bool post)
 {
     if (!extra.isAllocated() || !extra->keyHandler)
@@ -6089,12 +6143,10 @@ bool QQuickItemPrivate::setEffectiveVisibleRecur(bool newEffectiveVisible)
 
     effectiveVisible = newEffectiveVisible;
     dirty(Visible);
-    if (parentItem) QQuickItemPrivate::get(parentItem)->dirty(ChildrenStackingChanged);
-
-    if (window) {
-        QQuickWindowPrivate *windowPriv = QQuickWindowPrivate::get(window);
-        windowPriv->removeGrabber(q, true, true, true);
-    }
+    if (parentItem)
+        QQuickItemPrivate::get(parentItem)->dirty(ChildrenStackingChanged);
+    if (window)
+        deliveryAgentPrivate()->removeGrabber(q, true, true, true);
 
     bool childVisibilityChanged = false;
     for (int ii = 0; ii < childItems.count(); ++ii)
@@ -6138,12 +6190,13 @@ void QQuickItemPrivate::setEffectiveEnableRecur(QQuickItem *scope, bool newEffec
 
     effectiveEnable = newEffectiveEnable;
 
-    if (window) {
-        QQuickWindowPrivate *windowPriv = QQuickWindowPrivate::get(window);
-        windowPriv->removeGrabber(q, true, true, true);
+    QQuickDeliveryAgentPrivate *da = deliveryAgentPrivate();
+    if (da) {
+        da->removeGrabber(q, true, true, true);
         if (scope && !effectiveEnable && activeFocus) {
-            windowPriv->clearFocusInScope(
-                    scope, q, Qt::OtherFocusReason, QQuickWindowPrivate::DontChangeFocusProperty | QQuickWindowPrivate::DontChangeSubFocusItem);
+            da->clearFocusInScope(scope, q, Qt::OtherFocusReason,
+                                  QQuickDeliveryAgentPrivate::DontChangeFocusProperty |
+                                  QQuickDeliveryAgentPrivate::DontChangeSubFocusItem);
         }
     }
 
@@ -6152,9 +6205,10 @@ void QQuickItemPrivate::setEffectiveEnableRecur(QQuickItem *scope, bool newEffec
                 (flags & QQuickItem::ItemIsFocusScope) && scope ? q : scope, newEffectiveEnable);
     }
 
-    if (window && scope && effectiveEnable && focus) {
-        QQuickWindowPrivate::get(window)->setFocusInScope(
-                scope, q, Qt::OtherFocusReason, QQuickWindowPrivate::DontChangeFocusProperty | QQuickWindowPrivate::DontChangeSubFocusItem);
+    if (scope && effectiveEnable && focus && da) {
+        da->setFocusInScope(scope, q, Qt::OtherFocusReason,
+                            QQuickDeliveryAgentPrivate::DontChangeFocusProperty |
+                            QQuickDeliveryAgentPrivate::DontChangeSubFocusItem);
     }
 
     itemChange(QQuickItem::ItemEnabledHasChanged, effectiveEnable);
@@ -7252,10 +7306,12 @@ void QQuickItem::setFocus(bool focus, Qt::FocusReason reason)
             scope = scope->parentItem();
         if (d->window) {
             if (reason != Qt::PopupFocusReason) {
+                auto da = d->deliveryAgentPrivate();
+                Q_ASSERT(da);
                 if (focus)
-                    QQuickWindowPrivate::get(d->window)->setFocusInScope(scope, this, reason);
+                    da->setFocusInScope(scope, this, reason);
                 else
-                    QQuickWindowPrivate::get(d->window)->clearFocusInScope(scope, this, reason);
+                    da->clearFocusInScope(scope, this, reason);
             }
         } else {
             // do the focus changes from setFocusInScope/clearFocusInScope that are
@@ -7276,7 +7332,7 @@ void QQuickItem::setFocus(bool focus, Qt::FocusReason reason)
             changed << this;
             emit focusChanged(focus);
 
-            QQuickWindowPrivate::notifyFocusChangesRecur(changed.data(), changed.count() - 1);
+            QQuickDeliveryAgentPrivate::notifyFocusChangesRecur(changed.data(), changed.count() - 1);
         }
     } else {
         QVarLengthArray<QQuickItem *, 20> changed;
@@ -7291,7 +7347,7 @@ void QQuickItem::setFocus(bool focus, Qt::FocusReason reason)
         changed << this;
         emit focusChanged(focus);
 
-        QQuickWindowPrivate::notifyFocusChangesRecur(changed.data(), changed.count() - 1);
+        QQuickDeliveryAgentPrivate::notifyFocusChangesRecur(changed.data(), changed.count() - 1);
     }
 }
 
@@ -7418,7 +7474,7 @@ bool QQuickItem::isUnderMouse() const
     // QQuickWindow handles QEvent::Leave to reset the lastMousePosition
     // FIXME: Using QPointF() as the reset value means an item will not be
     // under the mouse if the mouse is at 0,0 of the window.
-    if (QQuickWindowPrivate::get(d->window)->lastMousePosition == QPointF())
+    if (const_cast<QQuickItemPrivate *>(d)->deliveryAgentPrivate()->lastMousePosition == QPointF())
         return false;
 
     QPointF cursorPos = QGuiApplicationPrivate::lastCursorPosition;
@@ -7703,13 +7759,14 @@ void QQuickItem::grabMouse()
     Q_D(QQuickItem);
     if (!d->window)
         return;
-    QQuickWindowPrivate *windowPriv = QQuickWindowPrivate::get(d->window);
-    auto eventInDelivery = windowPriv->eventInDelivery();
+    auto da = d->deliveryAgentPrivate();
+    Q_ASSERT(da);
+    auto eventInDelivery = da->eventInDelivery();
     if (!eventInDelivery) {
         qWarning() << "cannot grab mouse: no event is currently being delivered";
         return;
     }
-    auto epd = windowPriv->mousePointData();
+    auto epd = da->mousePointData();
     eventInDelivery->setExclusiveGrabber(epd->eventPoint, this);
 }
 
@@ -7729,14 +7786,15 @@ void QQuickItem::ungrabMouse()
     Q_D(QQuickItem);
     if (!d->window)
         return;
-    QQuickWindowPrivate *windowPriv = QQuickWindowPrivate::get(d->window);
-    auto eventInDelivery = windowPriv->eventInDelivery();
+    auto da = d->deliveryAgentPrivate();
+    Q_ASSERT(da);
+    auto eventInDelivery = da->eventInDelivery();
     if (!eventInDelivery) {
         // do it the expensive way
-        windowPriv->removeGrabber(this);
+        da->removeGrabber(this);
         return;
     }
-    const auto &eventPoint = windowPriv->mousePointData()->eventPoint;
+    const auto &eventPoint = da->mousePointData()->eventPoint;
     if (eventInDelivery->exclusiveGrabber(eventPoint) == this)
         eventInDelivery->setExclusiveGrabber(eventPoint, nullptr);
 }
@@ -7785,8 +7843,8 @@ void QQuickItem::setKeepMouseGrab(bool keep)
 */
 void QQuickItem::grabTouchPoints(const QList<int> &ids)
 {
-    QQuickWindowPrivate *windowPriv = QQuickWindowPrivate::get(window());
-    auto event = windowPriv->eventInDelivery();
+    Q_D(QQuickItem);
+    auto event = d->deliveryAgentPrivate()->eventInDelivery();
     if (Q_UNLIKELY(!event)) {
         qWarning() << "cannot grab: no event is currently being delivered";
         return;
@@ -7806,8 +7864,7 @@ void QQuickItem::ungrabTouchPoints()
     Q_D(QQuickItem);
     if (!d->window)
         return;
-    QQuickWindowPrivate *windowPriv = QQuickWindowPrivate::get(d->window);
-    windowPriv->removeGrabber(this, false, true);
+    d->deliveryAgentPrivate()->removeGrabber(this, false, true);
 }
 
 /*!