QTableView: fix selection with rows and cells in ExtendedSelection mode

QTableView stored the current row/column selection start in an own
variable instead using currentSelectionStartIndex. This leads to an
inconsistent behavior when the selection is done with a click on the
header and then in a cell (and the other way round)

Fixes: QTBUG-92561
Change-Id: I4c8bda3a938de451b6eff2819141e86a6870fbef
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit e8b3d35a18e7e4cf6543868d89d6060c90314f39)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/widgets/itemviews/qtableview.cpp

@@ -3388,7 +3388,7 @@ void QTableViewPrivate::selectRow(int row, bool anchor)
         selectionModel->setCurrentIndex(index, QItemSelectionModel::NoUpdate);
         if ((anchor && !(command & QItemSelectionModel::Current))
             || (q->selectionMode() == QTableView::SingleSelection))
-            rowSectionAnchor = row;
+            currentSelectionStartIndex = model->index(row, column, root);
 
         if (q->selectionMode() != QTableView::SingleSelection
             && command.testFlag(QItemSelectionModel::Toggle)) {
@@ -3401,6 +3401,7 @@ void QTableViewPrivate::selectRow(int row, bool anchor)
                 command |= QItemSelectionModel::Current;
         }
 
+        const auto rowSectionAnchor = currentSelectionStartIndex.row();
         QModelIndex upper = model->index(qMin(rowSectionAnchor, row), column, root);
         QModelIndex lower = model->index(qMax(rowSectionAnchor, row), column, root);
         if ((verticalHeader->sectionsMoved() && upper.row() != lower.row())) {
@@ -3427,7 +3428,7 @@ void QTableViewPrivate::selectColumn(int column, bool anchor)
         selectionModel->setCurrentIndex(index, QItemSelectionModel::NoUpdate);
         if ((anchor && !(command & QItemSelectionModel::Current))
             || (q->selectionMode() == QTableView::SingleSelection))
-            columnSectionAnchor = column;
+            currentSelectionStartIndex = model->index(row, column, root);
 
         if (q->selectionMode() != QTableView::SingleSelection
             && command.testFlag(QItemSelectionModel::Toggle)) {
@@ -3440,6 +3441,7 @@ void QTableViewPrivate::selectColumn(int column, bool anchor)
                 command |= QItemSelectionModel::Current;
         }
 
+        const auto columnSectionAnchor = currentSelectionStartIndex.column();
         QModelIndex left = model->index(row, qMin(columnSectionAnchor, column), root);
         QModelIndex right = model->index(row, qMax(columnSectionAnchor, column), root);
         if ((horizontalHeader->sectionsMoved() && left.column() != right.column())) {

src/widgets/itemviews/qtableview_p.h

@@ -136,7 +136,6 @@ class QTableViewPrivate : public QAbstractItemViewPrivate
 public:
     QTableViewPrivate()
         : showGrid(true), gridStyle(Qt::SolidLine),
-          rowSectionAnchor(-1), columnSectionAnchor(-1),
           columnResizeTimerID(0), rowResizeTimerID(0),
           horizontalHeader(nullptr), verticalHeader(nullptr),
           sortingEnabled(false), geometryRecursionBlock(false),
@@ -186,8 +185,6 @@ public:
 
     bool showGrid;
     Qt::PenStyle gridStyle;
-    int rowSectionAnchor;
-    int columnSectionAnchor;
     int columnResizeTimerID;
     int rowResizeTimerID;
     QList<int> columnsToUpdate;

tests/auto/widgets/itemviews/qtableview/tst_qtableview.cpp

@@ -437,6 +437,8 @@ private slots:
     void taskQTBUG_30653_doItemsLayout();
     void taskQTBUG_50171_selectRowAfterSwapColumns();
     void deselectRow();
+    void selectRowsAndCells();
+    void selectColumnsAndCells();
 
 #if QT_CONFIG(wheelevent)
     void mouseWheel_data();
@@ -4783,6 +4785,76 @@ void tst_QTableView::deselectRow()
     QVERIFY(!tw.selectionModel()->isRowSelected(1, QModelIndex()));
 }
 
+class QTableViewSelectCells : public QTableView
+{
+public:
+    QItemSelectionModel::SelectionFlags selectionCommand(const QModelIndex &index,
+                                                         const QEvent *) const override
+    {
+        return QTableView::selectionCommand(index, shiftPressed ? &mouseEvent : nullptr);
+    }
+    QMouseEvent mouseEvent = QMouseEvent(QEvent::MouseButtonPress, QPointF(), Qt::LeftButton, Qt::LeftButton, Qt::ShiftModifier);
+    bool shiftPressed = false;
+};
+
+void tst_QTableView::selectRowsAndCells()
+{
+    const auto checkRows = [](const QModelIndexList &mil)
+    {
+        QCOMPARE(mil.size(), 3);
+        for (const auto &mi : mil)
+            QVERIFY(mi.row() >= 1 && mi.row() <= 3);
+    };
+    QTableViewSelectCells tw;
+    QtTestTableModel model(5, 1);
+    tw.setSelectionBehavior(QAbstractItemView::SelectRows);
+    tw.setSelectionMode(QAbstractItemView::ExtendedSelection);
+    tw.setModel(&model);
+    tw.show();
+
+    tw.selectRow(1);
+    tw.shiftPressed = true;
+    tw.selectRow(2);
+    tw.shiftPressed = false;
+    QTest::mouseClick(tw.viewport(), Qt::LeftButton, Qt::ShiftModifier, tw.visualRect(model.index(3, 0)).center());
+    checkRows(tw.selectionModel()->selectedRows());
+
+    tw.clearSelection();
+    QTest::mouseClick(tw.viewport(), Qt::LeftButton, Qt::NoModifier, tw.visualRect(model.index(3, 0)).center());
+    tw.shiftPressed = true;
+    tw.selectRow(1);
+    checkRows(tw.selectionModel()->selectedRows());
+}
+
+void tst_QTableView::selectColumnsAndCells()
+{
+    const auto checkColumns = [](const QModelIndexList &mil)
+    {
+        QCOMPARE(mil.size(), 3);
+        for (const auto &mi : mil)
+            QVERIFY(mi.column() >= 1 && mi.column() <= 3);
+    };
+    QTableViewSelectCells tw;
+    QtTestTableModel model(1, 5);
+    tw.setSelectionBehavior(QAbstractItemView::SelectColumns);
+    tw.setSelectionMode(QAbstractItemView::ExtendedSelection);
+    tw.setModel(&model);
+    tw.show();
+
+    tw.selectColumn(1);
+    tw.shiftPressed = true;
+    tw.selectColumn(2);
+    tw.shiftPressed = false;
+    QTest::mouseClick(tw.viewport(), Qt::LeftButton, Qt::ShiftModifier, tw.visualRect(model.index(0, 3)).center());
+    checkColumns(tw.selectionModel()->selectedColumns());
+
+    tw.clearSelection();
+    QTest::mouseClick(tw.viewport(), Qt::LeftButton, Qt::NoModifier, tw.visualRect(model.index(0, 3)).center());
+    tw.shiftPressed = true;
+    tw.selectColumn(1);
+    checkColumns(tw.selectionModel()->selectedColumns());
+}
+
 // This has nothing to do with QTableView, but it's convenient to reuse the QtTestTableModel
 #if QT_CONFIG(textmarkdownwriter)