Add itemAtIndex to quick views

This patch adds itemAtIndex method to ItemView-derived views and
to PathView.

[ChangeLog][QtQuick][QQuickItemView] Added itemAtIndex() to
GridView, ListView and PathView to fetch a visible delegate by index.

Change-Id: Id8475d06c1481036984fe5109bb52cf2729b1c21
Fixes: QTBUG-72961
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

7 files changed, 67 insertions, 0 deletions

diff --git a/src/quick/items/qquickgridview.cpp b/src/quick/items/qquickgridview.cpp
index 272d4a4df5..6638fbd3e8 100644
--- a/src/quick/items/qquickgridview.cpp
+++ b/src/quick/items/qquickgridview.cpp
@@ -2636,6 +2636,19 @@ bool QQuickGridViewPrivate::needsRefillForAddedOrRemovedIndex(int modelIndex) co
     \b Note: methods should only be called after the Component has completed.
 */
 
+/*!
+    \qmlmethod Item QtQuick::GridView::itemAtIndex(int index)
+
+    Returns the item for \a index. If there is no item for that index, for example
+    because it has not been created yet, or because it has been panned out of
+    the visible area and removed from the cache, null is returned.
+
+    \b Note: this method should only be called after the Component has completed.
+    The returned value should also not be stored since it can turn to null
+    as soon as control goes out of the calling scope, if the view releases that item.
+
+    \since 5.13
+*/
 
 /*!
     \qmlmethod QtQuick::GridView::forceLayout()
diff --git a/src/quick/items/qquickitemsmodule.cpp b/src/quick/items/qquickitemsmodule.cpp
index b2fcfb4307..ddd438e56d 100644
--- a/src/quick/items/qquickitemsmodule.cpp
+++ b/src/quick/items/qquickitemsmodule.cpp
@@ -472,6 +472,10 @@ static void qt_quickitems_defineModule(const char *uri, int major, int minor)
 #if QT_CONFIG(quick_tableview)
     qmlRegisterType<QQuickTableView>(uri, 2, 12, "TableView");
 #endif
+
+    qmlRegisterUncreatableType<QQuickItemView, 13>(uri, 2, 13, itemViewName, itemViewMessage);
+    qmlRegisterType<QQuickPathView, 13>(uri, 2, 13, "PathView");
+    qmlRegisterType<QQuickGridView, 13>(uri, 2, 13, "GridView");
 }
 
 static void initResources()
diff --git a/src/quick/items/qquickitemview.cpp b/src/quick/items/qquickitemview.cpp
index 8dafc16cf4..1f8a0de72b 100644
--- a/src/quick/items/qquickitemview.cpp
+++ b/src/quick/items/qquickitemview.cpp
@@ -951,6 +951,13 @@ QQuickItem *QQuickItemView::itemAt(qreal x, qreal y) const
     return item ? item->item : nullptr;
 }
 
+QQuickItem *QQuickItemView::itemAtIndex(int index) const
+{
+    Q_D(const QQuickItemView);
+    const FxViewItem *item = d->visibleItem(index);
+    return item ? item->item : nullptr;
+}
+
 void QQuickItemView::forceLayout()
 {
     Q_D(QQuickItemView);
diff --git a/src/quick/items/qquickitemview_p.h b/src/quick/items/qquickitemview_p.h
index 483fc1a09f..0a0da587b4 100644
--- a/src/quick/items/qquickitemview_p.h
+++ b/src/quick/items/qquickitemview_p.h
@@ -228,6 +228,7 @@ public:
     Q_INVOKABLE void positionViewAtIndex(int index, int mode);
     Q_INVOKABLE int indexAt(qreal x, qreal y) const;
     Q_INVOKABLE QQuickItem *itemAt(qreal x, qreal y) const;
+    Q_REVISION(13) Q_INVOKABLE QQuickItem *itemAtIndex(int index) const;
     Q_INVOKABLE void positionViewAtBeginning();
     Q_INVOKABLE void positionViewAtEnd();
     Q_REVISION(1) Q_INVOKABLE void forceLayout();
diff --git a/src/quick/items/qquicklistview.cpp b/src/quick/items/qquicklistview.cpp
index 62cbfcef2b..2a59e50304 100644
--- a/src/quick/items/qquicklistview.cpp
+++ b/src/quick/items/qquicklistview.cpp
@@ -3513,6 +3513,20 @@ void QQuickListViewPrivate::translateAndTransitionItemsAfter(int afterModelIndex
 */
 
 /*!
+    \qmlmethod Item QtQuick::ListView::itemAtIndex(int index)
+
+    Returns the item for \a index. If there is no item for that index, for example
+    because it has not been created yet, or because it has been panned out of
+    the visible area and removed from the cache, null is returned.
+
+    \b Note: this method should only be called after the Component has completed.
+    The returned value should also not be stored since it can turn to null
+    as soon as control goes out of the calling scope, if the view releases that item.
+
+    \since 5.13
+*/
+
+/*!
     \qmlmethod QtQuick::ListView::forceLayout()
 
     Responding to changes in the model is usually batched to happen only once
diff --git a/src/quick/items/qquickpathview.cpp b/src/quick/items/qquickpathview.cpp
index 77ed8a659c..be8532bf64 100644
--- a/src/quick/items/qquickpathview.cpp
+++ b/src/quick/items/qquickpathview.cpp
@@ -1550,6 +1550,33 @@ QQuickItem *QQuickPathView::itemAt(qreal x, qreal y) const
     return nullptr;
 }
 
+/*!
+    \qmlmethod Item QtQuick::QQuickPathView::itemAtIndex(int index)
+
+    Returns the item for \a index. If there is no item for that index, for example
+    because it has not been created yet, or because it has been panned out of
+    the visible area and removed from the cache, null is returned.
+
+    \b Note: this method should only be called after the Component has completed.
+    The returned value should also not be stored since it can turn to null
+    as soon as control goes out of the calling scope, if the view releases that item.
+
+    \since 5.13
+*/
+QQuickItem *QQuickPathView::itemAtIndex(int index) const
+{
+    Q_D(const QQuickPathView);
+    if (!d->isValid())
+        return nullptr;
+
+    for (QQuickItem *item : d->items) {
+        if (index ==  d->model->indexOf(item, nullptr))
+            return item;
+    }
+
+    return nullptr;
+}
+
 QPointF QQuickPathViewPrivate::pointNear(const QPointF &point, qreal *nearPercent) const
 {
     const auto pathLength = path->path().length();
diff --git a/src/quick/items/qquickpathview_p.h b/src/quick/items/qquickpathview_p.h
index 0e237b7b74..66be7fa6ff 100644
--- a/src/quick/items/qquickpathview_p.h
+++ b/src/quick/items/qquickpathview_p.h
@@ -180,6 +180,7 @@ public:
     Q_INVOKABLE void positionViewAtIndex(int index, int mode);
     Q_INVOKABLE int indexAt(qreal x, qreal y) const;
     Q_INVOKABLE QQuickItem *itemAt(qreal x, qreal y) const;
+    Q_REVISION(13) Q_INVOKABLE QQuickItem *itemAtIndex(int index) const;
 
     static QQuickPathViewAttached *qmlAttachedProperties(QObject *);