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Fix QListView assert when the last row is moved in IconMode

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After the last row is moved, 0 will be returned when obtaining
row and column data. At this time, QListView::doitemslayout will
not call d->doitemslayout, so the QBspTree data structure will
not be cleaned up, leaving a stale tree structure behind. This
will trigger an assert during paintEvent handling if QListView is
set to IconMode

In QListView::ListMode the test for a valid model index doesn't
use an assert.

Call QListViewPrivate::clear explicitly if the column count is 0
so that the QBspTree and other data structures are cleared.

Add a test case that simulates this scenario by implementing a
model that returns a 0 column count for an index after the model
structure was changed through a move of rows.

Done-with: Volker Hilsheimer
Fixes: QTBUG-95463
Change-Id: I36419be5459b8ced930c619f538482ea1db4ad03
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit ca69e5aeef2fef540e687475ac00a4f332fdc5f3)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
ChunLin Wang 2021-08-26 21:15:31 +08:00 committed by Qt Cherry-pick Bot
parent eddf2adb29
commit ef0f04d1da
2 changed files with 221 additions and 2 deletions
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6
src/widgets/itemviews/qlistview.cpp
View File

@ -1575,12 +1575,14 @@ void QListView::doItemsLayout()
setState(ExpandingState);
if (d->model->columnCount(d->root) > 0) { // no columns means no contents
d->resetBatchStartRow();
if (layoutMode() == SinglePass)
if (layoutMode() == SinglePass) {
d->doItemsLayout(d->model->rowCount(d->root)); // layout everything
else if (!d->batchLayoutTimer.isActive()) {
} else if (!d->batchLayoutTimer.isActive()) {
if (!d->doItemsLayout(d->batchSize)) // layout is done
d->batchLayoutTimer.start(0, this); // do a new batch as fast as possible
}
} else { // clear the QBspTree generated by the last layout
d->clear();
}
QAbstractItemView::doItemsLayout();
setState(oldState); // restoring the oldState

217
tests/auto/widgets/itemviews/qlistview/tst_qlistview.cpp
View File

@ -168,6 +168,7 @@ private slots:
void taskQTBUG_7232_AllowUserToControlSingleStep();
void taskQTBUG_51086_skippingIndexesInSelectedIndexes();
void taskQTBUG_47694_indexOutOfBoundBatchLayout();
void moveLastRow();
void itemAlignment();
void internalDragDropMove_data();
void internalDragDropMove();
@ -2560,6 +2561,222 @@ void tst_QListView::taskQTBUG_47694_indexOutOfBoundBatchLayout()
view.scrollTo(model.index(batchSize - 1, 0));
}
class TstMoveItem
{
friend class TstMoveModel;
public:
TstMoveItem(TstMoveItem *parent = nullptr)
: parentItem(parent)
{
if (parentItem)
parentItem->childItems.append(this);
}
~TstMoveItem()
{
QList<TstMoveItem *> delItms;
delItms.swap(childItems);
qDeleteAll(delItms);
if (parentItem)
parentItem->childItems.removeAll(this);
}
int row()
{
if (parentItem)
return parentItem->childItems.indexOf(this);
return -1;
}
public:
TstMoveItem *parentItem = nullptr;
QList<TstMoveItem *> childItems;
QHash<int, QVariant> data;
};
/*!
Test that removing the last row in an IconView mode QListView
doesn't crash. The model is specifically crafted to provoke a
stale QBspTree by returning a 0 column count for indexes without
children, which changes the column count after moving the last row.
See QTBUG_95463.
*/
class TstMoveModel : public QAbstractItemModel
{
Q_OBJECT
public:
TstMoveModel(QObject *parent = nullptr)
: QAbstractItemModel(parent)
{
rootItem = new TstMoveItem;
rootItem->data.insert(Qt::DisplayRole, "root");
TstMoveItem *itm = new TstMoveItem(rootItem);
itm->data.insert(Qt::DisplayRole, "parentItem1");
TstMoveItem *itmCh = new TstMoveItem(itm);
itmCh->data.insert(Qt::DisplayRole, "childItem");
itm = new TstMoveItem(rootItem);
itm->data.insert(Qt::DisplayRole, "parentItem2");
}
~TstMoveModel()
{
delete rootItem;
}
QModelIndex index(int row, int column, const QModelIndex &idxPar = QModelIndex()) const override
{
QModelIndex idx;
if (hasIndex(row, column, idxPar)) {
TstMoveItem *parentItem = nullptr;
if (idxPar.isValid())
parentItem = static_cast<TstMoveItem *>(idxPar.internalPointer());
else
parentItem = rootItem;
Q_ASSERT(parentItem);
TstMoveItem *childItem = parentItem->childItems.at(row);
if (childItem)
idx = createIndex(row, column, childItem);
}
return idx;
}
QModelIndex parent(const QModelIndex &index) const override
{
QModelIndex idxPar;
if (index.isValid()) {
TstMoveItem *childItem = static_cast<TstMoveItem *>(index.internalPointer());
TstMoveItem *parentItem = childItem->parentItem;
if (parentItem != rootItem)
idxPar = createIndex(parentItem->row(), 0, parentItem);
}
return idxPar;
}
int columnCount(const QModelIndex &idxPar = QModelIndex()) const override
{
int cnt = 0;
if (idxPar.isValid()) {
TstMoveItem *parentItem = static_cast<TstMoveItem *>(idxPar.internalPointer());
Q_ASSERT(parentItem);
cnt = parentItem->childItems.isEmpty() ? 0 : 1;
} else {
cnt = rootItem->childItems.isEmpty() ? 0 : 1;
}
return cnt;
}
int rowCount(const QModelIndex &idxPar = QModelIndex()) const override
{
int cnt = 0;
if (idxPar.isValid()) {
TstMoveItem *parentItem = static_cast<TstMoveItem *>(idxPar.internalPointer());
Q_ASSERT(parentItem);
cnt = parentItem->childItems.count();
} else {
cnt = rootItem->childItems.count();
}
return cnt;
}
Qt::ItemFlags flags(const QModelIndex &index) const override
{
Q_UNUSED(index)
return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
}
bool hasChildren(const QModelIndex &parent = QModelIndex()) const override
{
bool ret = false;
if (parent.isValid()) {
TstMoveItem *parentItem = static_cast<TstMoveItem *>(parent.internalPointer());
Q_ASSERT(parentItem);
ret = parentItem->childItems.count() > 0;
} else {
ret = rootItem->childItems.count() > 0;
}
return ret;
}
QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override
{
QVariant dt;
if (index.isValid()) {
TstMoveItem *item = static_cast<TstMoveItem *>(index.internalPointer());
if (item)
dt = item->data.value(role);
}
return dt;
}
bool moveRows(const QModelIndex &sourceParent, int sourceRow, int count, const QModelIndex &destinationParent, int destinationChild) override
{
TstMoveItem *itmSrcParent = itemAt(sourceParent);
TstMoveItem *itmDestParent = itemAt(destinationParent);
if (itmSrcParent && sourceRow >= 0
&& sourceRow + count <= itmSrcParent->childItems.count()
&& itmDestParent && destinationChild <= itmDestParent->childItems.count()) {
beginMoveRows(sourceParent, sourceRow, sourceRow + count - 1,
destinationParent, destinationChild);
QList<TstMoveItem *> itemsToMove;
for (int i = 0; i < count; ++i) {
TstMoveItem *itm = itmSrcParent->childItems.at(sourceRow+i);
itemsToMove.append(itm);
}
for (int i = itemsToMove.count() -1; i >= 0; --i) {
TstMoveItem *itm = itemsToMove.at(i);
itm->parentItem->childItems.removeAll(itm);
itm->parentItem = itmDestParent;
itmDestParent->childItems.insert(destinationChild, itm);
}
endMoveRows();
return true;
}
return false;
}
private:
TstMoveItem *itemAt(const QModelIndex &index) const
{
TstMoveItem *item = nullptr;
if (index.isValid()) {
Q_ASSERT(index.model() == this);
item = static_cast<TstMoveItem *>(index.internalPointer());
} else {
item = rootItem;
}
return item;
}
private:
TstMoveItem *rootItem = nullptr;
};
void tst_QListView::moveLastRow()
{
TstMoveModel model;
QListView view;
view.setModel(&model);
view.setRootIndex(model.index(0, 0, QModelIndex()));
view.setViewMode(QListView::IconMode);
view.show();
QApplication::setActiveWindow(&view);
QVERIFY(QTest::qWaitForWindowActive(&view));
QModelIndex sourceParent = model.index(0, 0);
QModelIndex destinationParent = model.index(1, 0);
// must not crash when paint event is processed
model.moveRow(sourceParent, 0, destinationParent, 0);
QTest::qWait(100);
}
void tst_QListView::itemAlignment()
{
auto item1 = new QStandardItem("111");