Refactor: move change listener notification logic into helpers

A dozen loops doing more or less the same, all with the comment
"intentional copy (QTBUG-54732)", are best factored out into a helper.

Most of the loops call a different QQuickItemChangeListener member, so
provide a template that expects a pointer to a QQuickItemChangeListener
member function.
Some loops have some additional logic, so provide a second template that
just calls a functor.

No functional change, but needed for follow-up fixes to focus reason
handling in Qt Quick Controls.

Pick-to: 6.2
Change-Id: I6b11e06331da44b288315fc0732009d5f34f539a
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

3 files changed, 60 insertions, 121 deletions

diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index fffee1afa0..a6a14d7ce3 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -2355,31 +2355,22 @@ QQuickItem::~QQuickItem()
     while (!d->childItems.isEmpty())
         d->childItems.constFirst()->setParentItem(nullptr);
 
-    if (!d->changeListeners.isEmpty()) {
-        const auto listeners = d->changeListeners; // NOTE: intentional copy (QTBUG-54732)
-        for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-            QQuickAnchorsPrivate *anchor = change.listener->anchorPrivate();
-            if (anchor)
-                anchor->clearItem(this);
-        }
-
-        /*
+    d->notifyChangeListeners(QQuickItemPrivate::AllChanges, [this](const QQuickItemPrivate::ChangeListener &change){
+        QQuickAnchorsPrivate *anchor = change.listener->anchorPrivate();
+        if (anchor)
+            anchor->clearItem(this);
+    });
+    /*
         update item anchors that depended on us unless they are our child (and will also be destroyed),
         or our sibling, and our parent is also being destroyed.
     */
-        for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-            QQuickAnchorsPrivate *anchor = change.listener->anchorPrivate();
-            if (anchor && anchor->item && anchor->item->parentItem() && anchor->item->parentItem() != this)
-                anchor->update();
-        }
-
-        for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-            if (change.types & QQuickItemPrivate::Destroyed)
-                change.listener->itemDestroyed(this);
-        }
-
-        d->changeListeners.clear();
-    }
+    d->notifyChangeListeners(QQuickItemPrivate::AllChanges, [this](const QQuickItemPrivate::ChangeListener &change){
+        QQuickAnchorsPrivate *anchor = change.listener->anchorPrivate();
+        if (anchor && anchor->item && anchor->item->parentItem() && anchor->item->parentItem() != this)
+            anchor->update();
+    });
+    d->notifyChangeListeners(QQuickItemPrivate::Destroyed, &QQuickItemChangeListener::itemDestroyed, this);
+    d->changeListeners.clear();
 
     /*
        Remove any references our transforms have to us, in case they try to
@@ -3663,14 +3654,7 @@ QQuickAnchors *QQuickItemPrivate::anchors() const
 void QQuickItemPrivate::siblingOrderChanged()
 {
     Q_Q(QQuickItem);
-    if (!changeListeners.isEmpty()) {
-        const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-        for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-            if (change.types & QQuickItemPrivate::SiblingOrder) {
-                change.listener->itemSiblingOrderChanged(q);
-            }
-        }
-    }
+    notifyChangeListeners(QQuickItemPrivate::SiblingOrder, &QQuickItemChangeListener::itemSiblingOrderChanged, q);
 }
 
 QQmlListProperty<QObject> QQuickItemPrivate::data()
@@ -3801,15 +3785,10 @@ void QQuickItem::geometryChange(const QRectF &newGeometry, const QRectF &oldGeom
     change.setWidthChange(newGeometry.width() != oldGeometry.width());
     change.setHeightChange(newGeometry.height() != oldGeometry.height());
 
-    if (!d->changeListeners.isEmpty()) {
-        const auto listeners = d->changeListeners; // NOTE: intentional copy (QTBUG-54732)
-        for (const QQuickItemPrivate::ChangeListener &listener : listeners) {
-            if (listener.types & QQuickItemPrivate::Geometry) {
-                if (change.matches(listener.gTypes))
-                    listener.listener->itemGeometryChanged(this, change, oldGeometry);
-            }
-        }
-    }
+    d->notifyChangeListeners(QQuickItemPrivate::Geometry, [&](const QQuickItemPrivate::ChangeListener &listener){
+        if (change.matches(listener.gTypes))
+            listener.listener->itemGeometryChanged(this, change, oldGeometry);
+    });
 
     // The notify method takes care of emitting the signal, and also notifies any
     // property observers.
@@ -4439,16 +4418,11 @@ void QQuickItem::setBaselineOffset(qreal offset)
 
     d->baselineOffset = offset;
 
-    if (!d->changeListeners.isEmpty()) {
-        const auto listeners = d->changeListeners; // NOTE: intentional copy (QTBUG-54732)
-        for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-            if (change.types & QQuickItemPrivate::Geometry) {
-                QQuickAnchorsPrivate *anchor = change.listener->anchorPrivate();
-                if (anchor)
-                    anchor->updateVerticalAnchors();
-            }
-        }
-    }
+    d->notifyChangeListeners(QQuickItemPrivate::Geometry, [](const QQuickItemPrivate::ChangeListener &change){
+        QQuickAnchorsPrivate *anchor = change.listener->anchorPrivate();
+        if (anchor)
+            anchor->updateVerticalAnchors();
+    });
 
     if (d->_anchors && (d->_anchors->usedAnchors() & QQuickAnchors::BaselineAnchor))
         QQuickAnchorsPrivate::get(d->_anchors)->updateVerticalAnchors();
@@ -6617,26 +6591,12 @@ void QQuickItemPrivate::itemChange(QQuickItem::ItemChange change, const QQuickIt
         q->itemChange(change, data);
         if (!subtreeTransformChangedEnabled)
             subtreeTransformChangedEnabled = true;
-        if (!changeListeners.isEmpty()) {
-            const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-            for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-                if (change.types & QQuickItemPrivate::Children) {
-                    change.listener->itemChildAdded(q, data.item);
-                }
-            }
-        }
+        notifyChangeListeners(QQuickItemPrivate::Children, &QQuickItemChangeListener::itemChildAdded, q, data.item);
         break;
     }
     case QQuickItem::ItemChildRemovedChange: {
         q->itemChange(change, data);
-        if (!changeListeners.isEmpty()) {
-            const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-            for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-                if (change.types & QQuickItemPrivate::Children) {
-                    change.listener->itemChildRemoved(q, data.item);
-                }
-            }
-        }
+        notifyChangeListeners(QQuickItemPrivate::Children, &QQuickItemChangeListener::itemChildRemoved, q, data.item);
         break;
     }
     case QQuickItem::ItemSceneChange:
@@ -6644,50 +6604,22 @@ void QQuickItemPrivate::itemChange(QQuickItem::ItemChange change, const QQuickIt
         break;
     case QQuickItem::ItemVisibleHasChanged: {
         q->itemChange(change, data);
-        if (!changeListeners.isEmpty()) {
-            const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-            for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-                if (change.types & QQuickItemPrivate::Visibility) {
-                    change.listener->itemVisibilityChanged(q);
-                }
-            }
-        }
+        notifyChangeListeners(QQuickItemPrivate::Visibility, &QQuickItemChangeListener::itemVisibilityChanged, q);
         break;
     }
     case QQuickItem::ItemEnabledHasChanged: {
         q->itemChange(change, data);
-        if (!changeListeners.isEmpty()) {
-            const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-            for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-                if (change.types & QQuickItemPrivate::Enabled) {
-                    change.listener->itemEnabledChanged(q);
-                }
-            }
-        }
+        notifyChangeListeners(QQuickItemPrivate::Enabled, &QQuickItemChangeListener::itemEnabledChanged, q);
         break;
     }
     case QQuickItem::ItemParentHasChanged: {
         q->itemChange(change, data);
-        if (!changeListeners.isEmpty()) {
-            const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-            for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-                if (change.types & QQuickItemPrivate::Parent) {
-                    change.listener->itemParentChanged(q, data.item);
-                }
-            }
-        }
+        notifyChangeListeners(QQuickItemPrivate::Parent, &QQuickItemChangeListener::itemParentChanged, q, data.item);
         break;
     }
     case QQuickItem::ItemOpacityHasChanged: {
         q->itemChange(change, data);
-        if (!changeListeners.isEmpty()) {
-            const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-            for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-                if (change.types & QQuickItemPrivate::Opacity) {
-                    change.listener->itemOpacityChanged(q);
-                }
-            }
-        }
+        notifyChangeListeners(QQuickItemPrivate::Opacity, &QQuickItemChangeListener::itemOpacityChanged, q);
         break;
     }
     case QQuickItem::ItemActiveFocusHasChanged:
@@ -6695,14 +6627,7 @@ void QQuickItemPrivate::itemChange(QQuickItem::ItemChange change, const QQuickIt
         break;
     case QQuickItem::ItemRotationHasChanged: {
         q->itemChange(change, data);
-        if (!changeListeners.isEmpty()) {
-            const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-            for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-                if (change.types & QQuickItemPrivate::Rotation) {
-                    change.listener->itemRotationChanged(q);
-                }
-            }
-        }
+        notifyChangeListeners(QQuickItemPrivate::Rotation, &QQuickItemChangeListener::itemRotationChanged, q);
         break;
     }
     case QQuickItem::ItemAntialiasingHasChanged:
@@ -7114,14 +7039,7 @@ void QQuickItem::resetWidth()
 void QQuickItemPrivate::implicitWidthChanged()
 {
     Q_Q(QQuickItem);
-    if (!changeListeners.isEmpty()) {
-        const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-        for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-            if (change.types & QQuickItemPrivate::ImplicitWidth) {
-                change.listener->itemImplicitWidthChanged(q);
-            }
-        }
-    }
+    notifyChangeListeners(QQuickItemPrivate::ImplicitWidth, &QQuickItemChangeListener::itemImplicitWidthChanged, q);
     emit q->implicitWidthChanged();
 }
 
@@ -7330,14 +7248,7 @@ void QQuickItem::resetHeight()
 void QQuickItemPrivate::implicitHeightChanged()
 {
     Q_Q(QQuickItem);
-    if (!changeListeners.isEmpty()) {
-        const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
-        for (const QQuickItemPrivate::ChangeListener &change : listeners) {
-            if (change.types & QQuickItemPrivate::ImplicitHeight) {
-                change.listener->itemImplicitHeightChanged(q);
-            }
-        }
-    }
+    notifyChangeListeners(QQuickItemPrivate::ImplicitHeight, &QQuickItemChangeListener::itemImplicitHeightChanged, q);
     emit q->implicitHeightChanged();
 }
 
diff --git a/src/quick/items/qquickitem_p.h b/src/quick/items/qquickitem_p.h
index 51ef850d5f..576d392a26 100644
--- a/src/quick/items/qquickitem_p.h
+++ b/src/quick/items/qquickitem_p.h
@@ -331,6 +331,7 @@ public:
         ImplicitWidth = 0x100,
         ImplicitHeight = 0x200,
         Enabled = 0x400,
+        AllChanges = 0xFFFFFFFF
     };
 
     Q_DECLARE_FLAGS(ChangeTypes, ChangeType)
@@ -358,6 +359,32 @@ public:
         QQuickGeometryChange gTypes;  //NOTE: not used for ==
     };
 
+    // call QQuickItemChangeListener PMF
+    template <typename Fn, typename ...Args>
+    void notifyChangeListeners(QQuickItemPrivate::ChangeTypes changeTypes, Fn &&function, Args &&...args)
+    {
+        if (changeListeners.isEmpty())
+            return;
+
+        const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
+        for (const QQuickItemPrivate::ChangeListener &change : listeners) {
+            if (change.types & changeTypes)
+                (change.listener->*function)(args...);
+        }
+    }
+    // call functor
+    template <typename Fn>
+    void notifyChangeListeners(QQuickItemPrivate::ChangeTypes changeTypes, Fn &&function) {
+        if (changeListeners.isEmpty())
+            return;
+
+        const auto listeners = changeListeners; // NOTE: intentional copy (QTBUG-54732)
+        for (const QQuickItemPrivate::ChangeListener &change : listeners) {
+            if (change.types & changeTypes)
+                function(change);
+        }
+    }
+
     struct ExtraData {
         ExtraData();
 
diff --git a/src/quick/items/qquickitemchangelistener_p.h b/src/quick/items/qquickitemchangelistener_p.h
index 31d06c9983..91e2d69cc0 100644
--- a/src/quick/items/qquickitemchangelistener_p.h
+++ b/src/quick/items/qquickitemchangelistener_p.h
@@ -134,6 +134,7 @@ public:
     virtual void itemRotationChanged(QQuickItem *) {}
     virtual void itemImplicitWidthChanged(QQuickItem *) {}
     virtual void itemImplicitHeightChanged(QQuickItem *) {}
+    virtual void itemFocusChanged(QQuickItem *, Qt::FocusReason /* reason */) {}
 
     virtual QQuickAnchorsPrivate *anchorPrivate() { return nullptr; }
 };