Fix problems with extended selection after changing the model contents

Storing the position of the first selected item in the view can lead to
wrong extended selections if the contents of the model change. Future
Shift-clicks will always use the previous position of the first selected
item, which may not be correct any more, to calculate the current
selection.

To fix this problem, a QPersistentModelIndex is used to keep track of
the first selected item.

A new unit test is added. Moreover, one function of the QTableView unit
test is changed such that it shows the view prior to performing the
test. Without this change, this test may fail. That the test, which
simulates mouse presses without showing the view, worked at all seems
to be a coincidence, as pointed out in QTBUG-18009.

Task-number: QTBUG-18009
Change-Id: I0d844fbd1a994c279a7c8ee5d9b5b9fccecd25bf
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

2 files changed, 122 insertions, 0 deletions

diff --git a/tests/auto/widgets/itemviews/qabstractitemview/tst_qabstractitemview.cpp b/tests/auto/widgets/itemviews/qabstractitemview/tst_qabstractitemview.cpp
index 79f51d27c7..90580aea05 100644
--- a/tests/auto/widgets/itemviews/qabstractitemview/tst_qabstractitemview.cpp
+++ b/tests/auto/widgets/itemviews/qabstractitemview/tst_qabstractitemview.cpp
@@ -53,6 +53,8 @@
 #include <qscreen.h>
 #include <qscopedpointer.h>
 #include <qstyleditemdelegate.h>
+#include <qstringlistmodel.h>
+#include <qsortfilterproxymodel.h>
 
 static inline void setFrameless(QWidget *w)
 {
@@ -252,6 +254,7 @@ private slots:
     void QTBUG31411_noSelection();
     void QTBUG39324_settingSameInstanceOfIndexWidget();
     void sizeHintChangeTriggersLayout();
+    void shiftSelectionAfterChangingModelContents();
 };
 
 class MyAbstractItemDelegate : public QAbstractItemDelegate
@@ -1884,5 +1887,121 @@ void tst_QAbstractItemView::QTBUG39324_settingSameInstanceOfIndexWidget()
     table->show();
 }
 
+void tst_QAbstractItemView::shiftSelectionAfterChangingModelContents()
+{
+    QStringList list;
+    list << "A" << "B" << "C" << "D" << "E" << "F";
+    QStringListModel model(list);
+    QSortFilterProxyModel proxyModel;
+    proxyModel.setSourceModel(&model);
+    proxyModel.sort(0, Qt::AscendingOrder);
+    proxyModel.setDynamicSortFilter(true);
+
+    QPersistentModelIndex indexA(proxyModel.index(0, 0));
+    QPersistentModelIndex indexB(proxyModel.index(1, 0));
+    QPersistentModelIndex indexC(proxyModel.index(2, 0));
+    QPersistentModelIndex indexD(proxyModel.index(3, 0));
+    QPersistentModelIndex indexE(proxyModel.index(4, 0));
+    QPersistentModelIndex indexF(proxyModel.index(5, 0));
+
+    QListView view;
+    view.setModel(&proxyModel);
+    view.setSelectionMode(QAbstractItemView::ExtendedSelection);
+    view.show();
+    QTest::qWaitForWindowExposed(&view);
+
+    // Click "C"
+    QTest::mouseClick(view.viewport(), Qt::LeftButton, Qt::NoModifier, view.visualRect(indexC).center());
+    QModelIndexList selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), 1);
+    QVERIFY(selected.contains(indexC));
+
+    // Insert new item "B1"
+    model.insertRow(0);
+    model.setData(model.index(0, 0), "B1");
+
+    // Shift-click "D" -> we expect that "C" and "D" are selected
+    QTest::mouseClick(view.viewport(), Qt::LeftButton, Qt::ShiftModifier, view.visualRect(indexD).center());
+    selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), 2);
+    QVERIFY(selected.contains(indexC));
+    QVERIFY(selected.contains(indexD));
+
+    // Click "D"
+    QTest::mouseClick(view.viewport(), Qt::LeftButton, Qt::NoModifier, view.visualRect(indexD).center());
+    selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), 1);
+    QVERIFY(selected.contains(indexD));
+
+    // Remove items "B" and "C"
+    model.removeRows(proxyModel.mapToSource(indexB).row(), 1);
+    model.removeRows(proxyModel.mapToSource(indexC).row(), 1);
+    QVERIFY(!indexB.isValid());
+    QVERIFY(!indexC.isValid());
+
+    // Shift-click "F" -> we expect that "D", "E", and "F" are selected
+    QTest::mouseClick(view.viewport(), Qt::LeftButton, Qt::ShiftModifier, view.visualRect(indexF).center());
+    selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), 3);
+    QVERIFY(selected.contains(indexD));
+    QVERIFY(selected.contains(indexE));
+    QVERIFY(selected.contains(indexF));
+
+    // Move to "A" by pressing "Up" repeatedly
+    while (view.currentIndex() != indexA) {
+        QTest::keyClick(&view, Qt::Key_Up);
+    }
+    selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), 1);
+    QVERIFY(selected.contains(indexA));
+
+    // Change the sort order
+    proxyModel.sort(0, Qt::DescendingOrder);
+
+    // Shift-click "F" -> All items should be selected
+    QTest::mouseClick(view.viewport(), Qt::LeftButton, Qt::ShiftModifier, view.visualRect(indexF).center());
+    selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), model.rowCount());
+
+    // Restore the old sort order
+    proxyModel.sort(0, Qt::AscendingOrder);
+
+    // Click "D"
+    QTest::mouseClick(view.viewport(), Qt::LeftButton, Qt::NoModifier, view.visualRect(indexD).center());
+    selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), 1);
+    QVERIFY(selected.contains(indexD));
+
+    // Insert new item "B2"
+    model.insertRow(0);
+    model.setData(model.index(0, 0), "B2");
+
+    // Press Shift+Down -> "D" and "E" should be selected.
+    QTest::keyClick(&view, Qt::Key_Down, Qt::ShiftModifier);
+    selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), 2);
+    QVERIFY(selected.contains(indexD));
+    QVERIFY(selected.contains(indexE));
+
+    // Click "A" to reset the current selection starting point;
+    //then select "D" via QAbstractItemView::setCurrentIndex(const QModelIndex&).
+    QTest::mouseClick(view.viewport(), Qt::LeftButton, Qt::NoModifier, view.visualRect(indexA).center());
+    view.setCurrentIndex(indexD);
+    selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), 1);
+    QVERIFY(selected.contains(indexD));
+
+    // Insert new item "B3"
+    model.insertRow(0);
+    model.setData(model.index(0, 0), "B3");
+
+    // Press Shift+Down -> "D" and "E" should be selected.
+    QTest::keyClick(&view, Qt::Key_Down, Qt::ShiftModifier);
+    selected = view.selectionModel()->selectedIndexes();
+    QCOMPARE(selected.count(), 2);
+    QVERIFY(selected.contains(indexD));
+    QVERIFY(selected.contains(indexE));
+}
+
 QTEST_MAIN(tst_QAbstractItemView)
 #include "tst_qabstractitemview.moc"
diff --git a/tests/auto/widgets/itemviews/qtableview/tst_qtableview.cpp b/tests/auto/widgets/itemviews/qtableview/tst_qtableview.cpp
index a11d423896..75f77f8107 100644
--- a/tests/auto/widgets/itemviews/qtableview/tst_qtableview.cpp
+++ b/tests/auto/widgets/itemviews/qtableview/tst_qtableview.cpp
@@ -4288,6 +4288,9 @@ void tst_QTableView::taskQTBUG_4516_clickOnRichTextLabel()
     QLabel label("rich text");
     label.setTextFormat(Qt::RichText);
     view.setIndexWidget(model.index(1,1), &label);
+    view.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&view));
+
     view.setCurrentIndex(model.index(0,0));
     QCOMPARE(view.currentIndex(), model.index(0,0));