QQmlDelegateModel: Refresh the view when a column is added at 0

It can happen that a model reports n>0 rows but columns=0 (See
QConcatenateTablesProxyModel). In those cases we would render glitchy
items until the elements are marked as dirty.

Pick-to: 6.2
Change-Id: I615c9cacbb1b6f9dee3898b03476605e5ac39d0a
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/qmlmodels/qqmldelegatemodel.cpp

@@ -389,6 +389,12 @@ void QQmlDelegateModelPrivate::connectToAbstractItemModel()
                       q,  QQmlDelegateModel, SLOT(_q_rowsRemoved(QModelIndex,int,int)));
     qmlobject_connect(aim, QAbstractItemModel, SIGNAL(rowsAboutToBeRemoved(QModelIndex,int,int)),
                       q,  QQmlDelegateModel, SLOT(_q_rowsAboutToBeRemoved(QModelIndex,int,int)));
+    qmlobject_connect(aim, QAbstractItemModel, SIGNAL(columnsInserted(QModelIndex,int,int)),
+                      q, QQmlDelegateModel, SLOT(_q_columnsInserted(QModelIndex,int,int)));
+    qmlobject_connect(aim, QAbstractItemModel, SIGNAL(columnsRemoved(QModelIndex,int,int)),
+                      q, QQmlDelegateModel, SLOT(_q_columnsRemoved(QModelIndex,int,int)));
+    qmlobject_connect(aim, QAbstractItemModel, SIGNAL(columnsMoved(QModelIndex,int,int,QModelIndex,int)),
+                      q, QQmlDelegateModel, SLOT(_q_columnsMoved(QModelIndex,int,int,QModelIndex,int)));
     qmlobject_connect(aim, QAbstractItemModel, SIGNAL(dataChanged(QModelIndex,QModelIndex,QVector<int>)),
                       q, QQmlDelegateModel, SLOT(_q_dataChanged(QModelIndex,QModelIndex,QVector<int>)));
     qmlobject_connect(aim, QAbstractItemModel, SIGNAL(rowsMoved(QModelIndex,int,int,QModelIndex,int)),
@@ -413,6 +419,12 @@ void QQmlDelegateModelPrivate::disconnectFromAbstractItemModel()
                         q, SLOT(_q_rowsAboutToBeRemoved(QModelIndex,int,int)));
     QObject::disconnect(aim, SIGNAL(rowsRemoved(QModelIndex,int,int)),
                         q, SLOT(_q_rowsRemoved(QModelIndex,int,int)));
+    QObject::disconnect(aim, SIGNAL(columnsInserted(QModelIndex,int,int)), q,
+                        SLOT(_q_columnsInserted(QModelIndex,int,int)));
+    QObject::disconnect(aim, SIGNAL(columnsRemoved(QModelIndex,int,int)), q,
+                        SLOT(_q_columnsRemoved(QModelIndex,int,int)));
+    QObject::disconnect(aim, SIGNAL(columnsMoved(QModelIndex,int,int,QModelIndex,int)), q,
+                        SLOT(_q_columnsMoved(QModelIndex,int,int,QModelIndex,int)));
     QObject::disconnect(aim, SIGNAL(dataChanged(QModelIndex,QModelIndex,QVector<int>)),
                         q, SLOT(_q_dataChanged(QModelIndex,QModelIndex,QVector<int>)));
     QObject::disconnect(aim, SIGNAL(rowsMoved(QModelIndex,int,int,QModelIndex,int)),
@@ -1970,6 +1982,38 @@ void QQmlDelegateModel::_q_rowsMoved(
     }
 }
 
+void QQmlDelegateModel::_q_columnsInserted(const QModelIndex &parent, int begin, int end)
+{
+    Q_D(QQmlDelegateModel);
+    Q_UNUSED(end);
+    if (parent == d->m_adaptorModel.rootIndex && begin == 0) {
+        // mark all items as changed
+        _q_itemsChanged(0, d->m_count, QVector<int>());
+    }
+}
+
+void QQmlDelegateModel::_q_columnsRemoved(const QModelIndex &parent, int begin, int end)
+{
+    Q_D(QQmlDelegateModel);
+    Q_UNUSED(end);
+    if (parent == d->m_adaptorModel.rootIndex && begin == 0) {
+        // mark all items as changed
+        _q_itemsChanged(0, d->m_count, QVector<int>());
+    }
+}
+
+void QQmlDelegateModel::_q_columnsMoved(const QModelIndex &parent, int start, int end,
+                                        const QModelIndex &destination, int column)
+{
+    Q_D(QQmlDelegateModel);
+    Q_UNUSED(end);
+    if ((parent == d->m_adaptorModel.rootIndex && start == 0)
+        || (destination == d->m_adaptorModel.rootIndex && column == 0)) {
+        // mark all items as changed
+        _q_itemsChanged(0, d->m_count, QVector<int>());
+    }
+}
+
 void QQmlDelegateModel::_q_dataChanged(const QModelIndex &begin, const QModelIndex &end, const QVector<int> &roles)
 {
     Q_D(QQmlDelegateModel);

src/qmlmodels/qqmldelegatemodel_p.h

@@ -152,6 +152,9 @@ private Q_SLOTS:
     void _q_itemsMoved(int from, int to, int count);
     void _q_modelReset();
     void _q_rowsInserted(const QModelIndex &,int,int);
+    void _q_columnsInserted(const QModelIndex &, int, int);
+    void _q_columnsRemoved(const QModelIndex &, int, int);
+    void _q_columnsMoved(const QModelIndex &, int, int, const QModelIndex &, int);
     void _q_rowsAboutToBeRemoved(const QModelIndex &parent, int begin, int end);
     void _q_rowsRemoved(const QModelIndex &,int,int);
     void _q_rowsMoved(const QModelIndex &, int, int, const QModelIndex &, int);

tests/auto/qml/qqmldelegatemodel/data/redrawUponColumnChange.qml

@@ -0,0 +1,11 @@
+import QtQuick 2.8
+
+ListView {
+    id: root
+    width: 200
+    height: 200
+
+    delegate: Text {
+        text: display
+    }
+}

tests/auto/qml/qqmldelegatemodel/tst_qqmldelegatemodel.cpp

@@ -27,11 +27,14 @@
 ****************************************************************************/
 
 #include <QtTest/qtest.h>
+#include <QtCore/QConcatenateTablesProxyModel>
+#include <QtGui/QStandardItemModel>
 #include <QtQml/qqmlcomponent.h>
 #include <QtQmlModels/private/qqmldelegatemodel_p.h>
 #include <QtQuick/qquickview.h>
 #include <QtQuick/qquickitem.h>
 #include <QtQuickTestUtils/private/qmlutils_p.h>
+#include <QtTest/QSignalSpy>
 
 class tst_QQmlDelegateModel : public QQmlDataTest
 {
@@ -46,6 +49,7 @@ private slots:
     void qtbug_86017();
     void filterOnGroup_removeWhenCompleted();
     void contextAccessedByHandler();
+    void redrawUponColumnChange();
 };
 
 class AbstractItemModel : public QAbstractItemModel
@@ -175,6 +179,30 @@ void tst_QQmlDelegateModel::contextAccessedByHandler()
     QVERIFY(root->property("works").toBool());
 }
 
+void tst_QQmlDelegateModel::redrawUponColumnChange()
+{
+    QStandardItemModel m1;
+    m1.appendRow({
+            new QStandardItem("Banana"),
+            new QStandardItem("Coconut"),
+    });
+
+    QQuickView view(testFileUrl("redrawUponColumnChange.qml"));
+    QCOMPARE(view.status(), QQuickView::Ready);
+    view.show();
+    QQuickItem *root = view.rootObject();
+    root->setProperty("model", QVariant::fromValue<QObject *>(&m1));
+
+    QObject *item = root->property("currentItem").value<QObject *>();
+    QVERIFY(item);
+    QCOMPARE(item->property("text").toString(), "Banana");
+
+    QVERIFY(root);
+    m1.removeColumn(0);
+
+    QCOMPARE(item->property("text").toString(), "Coconut");
+}
+
 QTEST_MAIN(tst_QQmlDelegateModel)
 
 #include "tst_qqmldelegatemodel.moc"