Fix QQmlDelegateModel ignoring layoutChange in certain situations

Fix a regression introduced by commit a0aefe1 which caused the model to
ignore layout changes if d->m_adaptorModel.rootIndex was just a descendant
of any of the parent indexes, or when no parent indexes at all were provided
in the notification.

Task-number: QTBUG-39492
Change-Id: I4c97929d25ef75947ccfcbbe5bc234096689c58d
Reviewed-by: Alan Alpert <aalpert@blackberry.com>

4 files changed, 144 insertions, 4 deletions

diff --git a/src/qml/types/qqmldelegatemodel.cpp b/src/qml/types/qqmldelegatemodel.cpp
index 4591d42710..6029e277dd 100644
--- a/src/qml/types/qqmldelegatemodel.cpp
+++ b/src/qml/types/qqmldelegatemodel.cpp
@@ -1521,6 +1521,18 @@ void QQmlDelegateModel::_q_dataChanged(const QModelIndex &begin, const QModelInd
         _q_itemsChanged(begin.row(), end.row() - begin.row() + 1, roles);
 }
 
+bool QQmlDelegateModel::isDescendantOf(const QPersistentModelIndex& desc, const QList< QPersistentModelIndex >& parents) const
+{
+    for (int i = 0, c = parents.count(); i < c; ++i) {
+        for (QPersistentModelIndex parent = desc; parent.isValid(); parent = parent.parent()) {
+            if (parent == parents[i])
+                return true;
+        }
+    }
+
+    return false;
+}
+
 void QQmlDelegateModel::_q_layoutAboutToBeChanged(const QList<QPersistentModelIndex> &parents, QAbstractItemModel::LayoutChangeHint hint)
 {
     Q_D(QQmlDelegateModel);
@@ -1529,8 +1541,9 @@ void QQmlDelegateModel::_q_layoutAboutToBeChanged(const QList<QPersistentModelIn
 
     if (hint == QAbstractItemModel::VerticalSortHint) {
         d->m_storedPersistentIndexes.clear();
-        if (!parents.contains(d->m_adaptorModel.rootIndex))
+        if (!parents.isEmpty() && d->m_adaptorModel.rootIndex.isValid() &&  !isDescendantOf(d->m_adaptorModel.rootIndex, parents)) {
             return;
+        }
 
         for (int i = 0; i < d->m_count; ++i) {
             const QModelIndex index = d->m_adaptorModel.aim()->index(i, 0, d->m_adaptorModel.rootIndex);
@@ -1550,8 +1563,9 @@ void QQmlDelegateModel::_q_layoutChanged(const QList<QPersistentModelIndex> &par
         return;
 
     if (hint == QAbstractItemModel::VerticalSortHint) {
-        if (!parents.contains(d->m_adaptorModel.rootIndex))
+        if (!parents.isEmpty() && d->m_adaptorModel.rootIndex.isValid() && !isDescendantOf(d->m_adaptorModel.rootIndex, parents)) {
             return;
+        }
 
         for (int i = 0, c = d->m_storedPersistentIndexes.count(); i < c; ++i) {
             const QPersistentModelIndex &index = d->m_storedPersistentIndexes.at(i);
diff --git a/src/qml/types/qqmldelegatemodel_p.h b/src/qml/types/qqmldelegatemodel_p.h
index 0b67179163..53cc94bbdf 100644
--- a/src/qml/types/qqmldelegatemodel_p.h
+++ b/src/qml/types/qqmldelegatemodel_p.h
@@ -143,6 +143,8 @@ private Q_SLOTS:
     void _q_layoutChanged(const QList<QPersistentModelIndex>&, QAbstractItemModel::LayoutChangeHint);
 
 private:
+    bool isDescendantOf(const QPersistentModelIndex &desc, const QList<QPersistentModelIndex> &parents) const;
+
     Q_DISABLE_COPY(QQmlDelegateModel)
 };
 
diff --git a/tests/auto/quick/qquicklistview/data/qtbug39492.qml b/tests/auto/quick/qquicklistview/data/qtbug39492.qml
new file mode 100644
index 0000000000..4df3a080d7
--- /dev/null
+++ b/tests/auto/quick/qquicklistview/data/qtbug39492.qml
@@ -0,0 +1,40 @@
+import QtQuick 2.0
+import QtQml.Models 2.1
+
+Rectangle {
+    id: root
+    width: 240
+    height: 320
+    color: "#ffffff"
+
+
+    Component {
+        id: myDelegate
+        Rectangle {
+            id: wrapper
+            objectName: "wrapper"
+            height: 20
+            width: 240
+            Text {
+                objectName: "delegateText"
+                text: display
+            }
+            color: ListView.isCurrentItem ? "lightsteelblue" : "white"
+        }
+    }
+
+    DelegateModel {
+        id: delegateModel
+        objectName: "delegateModel"
+        model: testModel
+        delegate: myDelegate
+    }
+
+    ListView {
+        id: list
+        objectName: "listView"
+        model: delegateModel;
+        focus: true
+        anchors.fill: parent
+    }
+}
diff --git a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
index 2093265163..f267b93b26 100644
--- a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
+++ b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
@@ -41,6 +41,8 @@
 
 #include <QtTest/QtTest>
 #include <QtCore/QStringListModel>
+#include <QtCore/QSortFilterProxyModel>
+#include <QtGui/QStandardItemModel>
 #include <QtQuick/qquickview.h>
 #include <QtQml/qqmlengine.h>
 #include <QtQml/qqmlcontext.h>
@@ -50,6 +52,7 @@
 #include <QtQuick/private/qquicktext_p.h>
 #include <QtQml/private/qqmlobjectmodel_p.h>
 #include <QtQml/private/qqmllistmodel_p.h>
+#include <QtQml/private/qqmldelegatemodel_p.h>
 #include "../../shared/util.h"
 #include "../shared/viewtestutil.h"
 #include "../shared/visualtestutil.h"
@@ -62,6 +65,7 @@ Q_DECLARE_METATYPE(QQuickItemView::VerticalLayoutDirection)
 Q_DECLARE_METATYPE(QQuickItemView::PositionMode)
 Q_DECLARE_METATYPE(QQuickListView::Orientation)
 Q_DECLARE_METATYPE(Qt::Key)
+Q_DECLARE_METATYPE(QPersistentModelIndex)
 
 using namespace QQuickViewTestUtil;
 using namespace QQuickVisualTestUtil;
@@ -228,6 +232,9 @@ private slots:
     void roundingErrors();
     void roundingErrors_data();
 
+    void QTBUG_39492_data();
+    void QTBUG_39492();
+
 private:
     template <class T> void items(const QUrl &source);
     template <class T> void changed(const QUrl &source);
@@ -7309,8 +7316,85 @@ void tst_QQuickListView::roundingErrors_data()
     QTest::newRow("pixelAligned=false") << false;
 }
 
-QTEST_MAIN(tst_QQuickListView)
+void tst_QQuickListView::QTBUG_39492_data()
+{
+    QStandardItemModel *sourceModel = new QStandardItemModel(this);
+    for (int i = 0; i < 5; ++i) {
+        QStandardItem *item = new QStandardItem(QString::number(i));
+        for (int j = 0; j < 5; ++j) {
+            QStandardItem *subItem = new QStandardItem(QString("%1-%2").arg(i).arg(j));
+            item->appendRow(subItem);
+        }
+        sourceModel->appendRow(item);
+    }
 
-#include "tst_qquicklistview.moc"
+    QSortFilterProxyModel *sortModel = new QSortFilterProxyModel(this);
+    sortModel->setSourceModel(sourceModel);
+
+    QTest::addColumn<QSortFilterProxyModel*>("model");
+    QTest::addColumn<QPersistentModelIndex>("rootIndex");
+
+    QTest::newRow("invalid rootIndex")
+        << sortModel
+        << QPersistentModelIndex();
+
+    QTest::newRow("rootIndex 1")
+        << sortModel
+        << QPersistentModelIndex(sortModel->index(1, 0));
+
+    QTest::newRow("rootIndex 3")
+        << sortModel
+        << QPersistentModelIndex(sortModel->index(3, 0));
+
+    const QModelIndex rootIndex2 = sortModel->index(2, 0);
+    QTest::newRow("rootIndex 2-1")
+        << sortModel
+        << QPersistentModelIndex(sortModel->index(1, 0, rootIndex2));
+}
+
+void tst_QQuickListView::QTBUG_39492()
+{
+    QFETCH(QSortFilterProxyModel*, model);
+    QFETCH(QPersistentModelIndex, rootIndex);
+
+    QQuickView *window = getView();
+    window->rootContext()->setContextProperty("testModel", QVariant::fromValue(model));
+    window->setSource(testFileUrl("qtbug39492.qml"));
 
+    QQuickListView *listview = window->rootObject()->findChild<QQuickListView *>("listView");
+    QVERIFY(listview);
+
+    QQmlDelegateModel *delegateModel = window->rootObject()->findChild<QQmlDelegateModel *>("delegateModel");
+    QVERIFY(delegateModel);
+
+    delegateModel->setRootIndex(QVariant::fromValue(QModelIndex(rootIndex)));
+    model->sort(0, Qt::AscendingOrder);
+    listview->forceLayout();
+
+    for (int i = 0; i < model->rowCount(rootIndex); ++i) {
+        QQuickItem *delegateItem = listview->itemAt(10, 10 + i * 20);
+        QVERIFY(delegateItem);
+        QQuickItem *delegateText = delegateItem->findChild<QQuickItem *>("delegateText");
+        QVERIFY(delegateText);
+        QCOMPARE(delegateText->property("text").toString(),
+                 model->index(i, 0, rootIndex).data().toString());
+    }
+
+    model->sort(0, Qt::DescendingOrder);
+    listview->forceLayout();
 
+    for (int i = 0; i < model->rowCount(rootIndex); ++i) {
+        QQuickItem *delegateItem = listview->itemAt(10, 10 + i * 20);
+        QVERIFY(delegateItem);
+        QQuickItem *delegateText = delegateItem->findChild<QQuickItem *>("delegateText");
+        QVERIFY(delegateText);
+        QCOMPARE(delegateText->property("text").toString(),
+                 model->index(i, 0, rootIndex).data().toString());
+    }
+
+    releaseView(window);
+}
+
+QTEST_MAIN(tst_QQuickListView)
+
+#include "tst_qquicklistview.moc"