Merge remote-tracking branch 'origin/5.15' into dev

 Conflicts:
	src/qml/types/qqmlbind.cpp

Change-Id: Ib992d1a7ac6c1a96d39819be6f23955dc31b44b2

1 files changed, 87 insertions, 7 deletions

diff --git a/src/quick/items/qquicklistview.cpp b/src/quick/items/qquicklistview.cpp
index 23925871e5..1615c9ecea 100644
--- a/src/quick/items/qquicklistview.cpp
+++ b/src/quick/items/qquicklistview.cpp
@@ -92,7 +92,7 @@ public:
 
     FxViewItem *newViewItem(int index, QQuickItem *item) override;
     void initializeViewItem(FxViewItem *item) override;
-    bool releaseItem(FxViewItem *item) override;
+    bool releaseItem(FxViewItem *item, QQmlInstanceModel::ReusableFlag reusableFlag) override;
     void repositionItemAt(FxViewItem *item, int index, qreal sizeBuffer) override;
     void repositionPackageItemAt(QQuickItem *item, int index) override;
     void resetFirstItemPosition(qreal pos = 0.0) override;
@@ -139,6 +139,8 @@ public:
     bool flick(QQuickItemViewPrivate::AxisData &data, qreal minExtent, qreal maxExtent, qreal vSize,
                QQuickTimeLineCallback::Callback fixupCallback, qreal velocity) override;
 
+    QQuickItemViewAttached *getAttachedObject(const QObject *object) const override;
+
     QQuickListView::Orientation orient;
     qreal visiblePos;
     qreal averageSize;
@@ -634,15 +636,15 @@ void QQuickListViewPrivate::initializeViewItem(FxViewItem *item)
     }
 }
 
-bool QQuickListViewPrivate::releaseItem(FxViewItem *item)
+bool QQuickListViewPrivate::releaseItem(FxViewItem *item, QQmlInstanceModel::ReusableFlag reusableFlag)
 {
     if (!item || !model)
-        return QQuickItemViewPrivate::releaseItem(item);
+        return QQuickItemViewPrivate::releaseItem(item, reusableFlag);
 
     QPointer<QQuickItem> it = item->item;
     QQuickListViewAttached *att = static_cast<QQuickListViewAttached*>(item->attached);
 
-    bool released = QQuickItemViewPrivate::releaseItem(item);
+    bool released = QQuickItemViewPrivate::releaseItem(item, reusableFlag);
     if (released && it && att && att->m_sectionItem) {
         // We hold no more references to this item
         int i = 0;
@@ -682,7 +684,7 @@ bool QQuickListViewPrivate::addVisibleItems(qreal fillFrom, qreal fillTo, qreal
         int newModelIdx = qBound(0, modelIndex + count, model->count());
         count = newModelIdx - modelIndex;
         if (count) {
-            releaseVisibleItems();
+            releaseVisibleItems(reusableFlag);
             modelIndex = newModelIdx;
             visibleIndex = modelIndex;
             visiblePos = itemEnd + count * (averageSize + spacing);
@@ -737,7 +739,7 @@ void QQuickListViewPrivate::removeItem(FxViewItem *item)
         releasePendingTransition.append(item);
     } else {
         qCDebug(lcItemViewDelegateLifecycle) << "\treleasing stationary item" << item->index << (QObject *)(item->item);
-        releaseItem(item);
+        releaseItem(item, reusableFlag);
     }
 }
 
@@ -808,6 +810,7 @@ void QQuickListViewPrivate::layoutVisibleItems(int fromModelIndex)
 
         FxViewItem *firstItem = *visibleItems.constBegin();
         bool fixedCurrent = currentItem && firstItem->item == currentItem->item;
+        firstVisibleItemPosition = firstItem->position();
         qreal sum = firstItem->size();
         qreal pos = firstItem->position() + firstItem->size() + spacing;
         firstItem->setVisible(firstItem->endPosition() >= from && firstItem->position() <= to);
@@ -1771,6 +1774,12 @@ void QQuickListViewPrivate::setSectionHelper(QQmlContext *context, QQuickItem *s
         sectionItem->setProperty("section", section);
 }
 
+QQuickItemViewAttached *QQuickListViewPrivate::getAttachedObject(const QObject *object) const
+{
+    QObject *attachedObject = qmlAttachedPropertiesObject<QQuickListView>(object);
+    return static_cast<QQuickItemViewAttached *>(attachedObject);
+}
+
 //----------------------------------------------------------------------------
 
 /*!
@@ -1919,6 +1928,39 @@ void QQuickListViewPrivate::setSectionHelper(QQmlContext *context, QQuickItem *s
     of type \l [QML] {real}, so it is possible to set fractional
     values like \c 0.1.
 
+    \section1 Reusing items
+
+    Since 5.15, ListView can be configured to recycle items instead of instantiating
+    from the \l delegate whenever new rows are flicked into view. This approach improves
+    performance, depending on the complexity of the delegate. Reusing
+    items is off by default (for backwards compatibility reasons), but can be switched
+    on by setting the \l reuseItems property to \c true.
+
+    When an item is flicked out, it moves to the \e{reuse pool}, which is an
+    internal cache of unused items. When this happens, the \l ListView::pooled
+    signal is emitted to inform the item about it. Likewise, when the item is
+    moved back from the pool, the \l ListView::reused signal is emitted.
+
+    Any item properties that come from the model are updated when the
+    item is reused. This includes \c index and \c row, but also
+    any model roles.
+
+    \note Avoid storing any state inside a delegate. If you do, reset it
+    manually on receiving the \l ListView::reused signal.
+
+    If an item has timers or animations, consider pausing them on receiving
+    the \l ListView::pooled signal. That way you avoid using the CPU resources
+    for items that are not visible. Likewise, if an item has resources that
+    cannot be reused, they could be freed up.
+
+    \note While an item is in the pool, it might still be alive and respond
+    to connected signals and bindings.
+
+    The following example shows a delegate that animates a spinning rectangle. When
+    it is pooled, the animation is temporarily paused:
+
+    \snippet qml/listview/reusabledelegate.qml 0
+
     \sa {QML Data Models}, GridView, PathView, {Qt Quick Examples - Views}
 */
 QQuickListView::QQuickListView(QQuickItem *parent)
@@ -2085,6 +2127,20 @@ QQuickListView::~QQuickListView()
 */
 
 /*!
+    \qmlproperty bool QtQuick::ListView::reuseItems
+
+    This property enables you to reuse items that are instantiated
+    from the \l delegate. If set to \c false, any currently
+    pooled items are destroyed.
+
+    This property is \c false by default.
+
+    \since 5.15
+
+    \sa {Reusing items}, ListView::pooled, ListView::reused
+*/
+
+/*!
     \qmlproperty Component QtQuick::ListView::highlight
     This property holds the component to use as the highlight.
 
@@ -2095,7 +2151,7 @@ QQuickListView::~QQuickListView()
     highlight item is \c 0.
 
     \sa highlightItem, highlightFollowsCurrentItem,
-    {Qt Quick Examples - Views#Highlight}{ListView highlight example},
+    {Qt Quick Examples - Views#Using Highlight}{ListView Highlight Example},
     {Stacking Order in ListView}
 */
 
@@ -3185,6 +3241,13 @@ void QQuickListView::keyPressEvent(QKeyEvent *event)
 void QQuickListView::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
 {
     Q_D(QQuickListView);
+
+    if (d->model) {
+        // When the view changes size, we force the pool to
+        // shrink by releasing all pooled items.
+        d->model->drainReusableItemsPool(0);
+    }
+
     if (d->isRightToLeft()) {
         // maintain position relative to the right edge
         qreal dx = newGeometry.width() - oldGeometry.width();
@@ -3592,6 +3655,23 @@ QQuickListViewAttached *QQuickListView::qmlAttachedProperties(QObject *obj)
     return new QQuickListViewAttached(obj);
 }
 
+bool QQuickListView::contains(const QPointF &point) const
+{
+    bool ret = QQuickItemView::contains(point);
+    // QTBUG-74046: if a mouse press "falls through" a floating header or footer, don't allow dragging the list from there
+    if (ret) {
+        if (auto header = headerItem()) {
+            if (headerPositioning() != QQuickListView::InlineHeader && header->contains(mapToItem(header, point)))
+                ret = false;
+        }
+        if (auto footer = footerItem()) {
+            if (footerPositioning() != QQuickListView::InlineFooter && footer->contains(mapToItem(footer, point)))
+                ret = false;
+        }
+    }
+    return ret;
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qquicklistview_p.cpp"