Correctly initialize ListView section attached properties.

During item insertion, indexes of items in the visibleItems list were
not adjusted before new items were created. Section initialization was
broken during insertion because section calculation relies on the
indexes of the items in the visibleItems list. The incorrect section
properties caused spurious section header creation, and layout issues.

Apply the index offset before creating the new items. This mirrors what
GridView already does.

Change-Id: I549a81825cf0e979bc5830840bf6cb75c7a82cac
Task-number: QTBUG-43873
Reviewed-by: Bea Lam <bea.lam@jollamobile.com>

2 files changed, 65 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicklistview/data/listview-sections_delegate.qml b/tests/auto/quick/qquicklistview/data/listview-sections_delegate.qml
index 7245025bac..11da286f4d 100644
--- a/tests/auto/quick/qquicklistview/data/listview-sections_delegate.qml
+++ b/tests/auto/quick/qquicklistview/data/listview-sections_delegate.qml
@@ -12,6 +12,9 @@ Rectangle {
             Item {
                 id: wrapper
                 objectName: "wrapper"
+                property string section: ListView.section
+                property string nextSection: ListView.nextSection
+                property string prevSection: ListView.previousSection
                 height: 20;
                 width: 240
                 Rectangle {
diff --git a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
index 3e19b005b7..c93aac456d 100644
--- a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
+++ b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
@@ -133,6 +133,7 @@ private slots:
     void sectionsDelegate_headerVisibility();
     void sectionPropertyChange();
     void sectionDelegateChange();
+    void sectionsItemInsertion();
     void cacheBuffer();
     void positionViewAtBeginningEnd();
     void positionViewAtIndex();
@@ -2540,6 +2541,67 @@ void tst_QQuickListView::sectionDelegateChange()
     delete window;
 }
 
+// QTBUG-43873
+void tst_QQuickListView::sectionsItemInsertion()
+{
+    QQuickView *window = createView();
+
+    QaimModel model;
+    for (int i = 0; i < 30; i++)
+        model.addItem("Item" + QString::number(i), QString::number(i/5));
+
+    QQmlContext *ctxt = window->rootContext();
+    ctxt->setContextProperty("testModel", &model);
+
+    window->setSource(testFileUrl("listview-sections_delegate.qml"));
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window));
+
+    QQuickListView *listview = findItem<QQuickListView>(window->rootObject(), "list");
+    QTRY_VERIFY(listview != 0);
+    QQuickItem *contentItem = listview->contentItem();
+    QTRY_VERIFY(contentItem != 0);
+    QTRY_COMPARE(QQuickItemPrivate::get(listview)->polishScheduled, false);
+
+    for (int i = 0; i < 3; ++i) {
+        QQuickItem *item = findItem<QQuickItem>(contentItem, "sect_" + QString::number(i));
+        QVERIFY(item);
+        QTRY_COMPARE(item->y(), qreal(i*20*6));
+    }
+
+    QQuickItem *topItem = findVisibleChild(contentItem, "sect_0"); // section header
+    QVERIFY(topItem);
+    QCOMPARE(topItem->y(), 0.);
+
+    // Insert a full screen of items at the beginning.
+    for (int i = 0; i < 10; i++)
+        model.insertItem(i, "Item" + QString::number(i), QLatin1String("A"));
+
+    QTRY_COMPARE(QQuickItemPrivate::get(listview)->polishScheduled, false);
+
+    int itemCount = findItems<QQuickItem>(contentItem, "wrapper").count();
+    QVERIFY(itemCount > 10);
+
+    // Verify that the new items are postioned correctly, and have the correct attached section properties
+    for (int i = 0; i < 10 && i < itemCount; ++i) {
+        QQuickItem *item = findItem<QQuickItem>(contentItem, "wrapper", i);
+        QVERIFY(item);
+        QTRY_COMPARE(item->y(), 20+i*20.0);
+        QCOMPARE(item->property("section").toString(), QLatin1String("A"));
+        QCOMPARE(item->property("nextSection").toString(), i < 9 ? QLatin1String("A") : QLatin1String("0"));
+        QCOMPARE(item->property("prevSection").toString(), i > 0 ? QLatin1String("A") : QLatin1String(""));
+    }
+    // Verify that the exiting items are postioned correctly, and have the correct attached section properties
+    for (int i = 10; i < 15 && i < itemCount; ++i) {
+        QQuickItem *item = findItem<QQuickItem>(contentItem, "wrapper", i);
+        QVERIFY(item);
+        QTRY_COMPARE(item->y(), 40+i*20.0);
+        QCOMPARE(item->property("section").toString(), QLatin1String("0"));
+        QCOMPARE(item->property("nextSection").toString(), i < 14 ? QLatin1String("0") : QLatin1String("1"));
+        QCOMPARE(item->property("prevSection").toString(), i > 10 ? QLatin1String("0") : QLatin1String("A"));
+    }
+}
+
 void tst_QQuickListView::currentIndex_delayedItemCreation()
 {
     QFETCH(bool, setCurrentToZero);