QAbstractItemView::dataChanged(): optimize call to QWidget::update()

When topLeft and bottomRight are different in QAIV::dataChanged(), the
current implementation simply calls QWidget::update() without checking
if the affected cells are visible. This results in a big performance hit
when cells are updated frequently.
Now try to compute the exact update rect by iterating through the
modified indexes.

Fixes: QTBUG-58580
Change-Id: I97de567d494e40ed8cdb1ea1f5b3cf3a2f60455e
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>

11 files changed, 436 insertions, 4 deletions

diff --git a/src/widgets/itemviews/qabstractitemview.cpp b/src/widgets/itemviews/qabstractitemview.cpp
index ebef36d033..b8c30321ff 100644
--- a/src/widgets/itemviews/qabstractitemview.cpp
+++ b/src/widgets/itemviews/qabstractitemview.cpp
@@ -3335,8 +3335,19 @@ void QAbstractItemView::dataChanged(const QModelIndex &topLeft, const QModelInde
         }
     } else {
         d->updateEditorData(topLeft, bottomRight);
-        if (isVisible() && !d->delayedPendingLayout)
-            d->viewport->update();
+        if (isVisible() && !d->delayedPendingLayout) {
+            if (!topLeft.isValid() ||
+                topLeft.parent() != bottomRight.parent() ||
+                topLeft.row() > bottomRight.row() ||
+                topLeft.column() > bottomRight.column()) {
+                // invalid parameter - call update() to redraw all
+                d->viewport->update();
+            } else {
+                const QRect updateRect = d->intersectedRect(d->viewport->rect(), topLeft, bottomRight);
+                if (!updateRect.isEmpty())
+                    d->viewport->update(updateRect);
+            }
+        }
     }
 
 #ifndef QT_NO_ACCESSIBILITY
@@ -3620,6 +3631,19 @@ void QAbstractItemViewPrivate::_q_columnsMoved(const QModelIndex &, int, int, co
   _q_layoutChanged();
 }
 
+QRect QAbstractItemViewPrivate::intersectedRect(const QRect rect, const QModelIndex &topLeft, const QModelIndex &bottomRight) const
+{
+    Q_Q(const QAbstractItemView);
+
+    const auto parentIdx = topLeft.parent();
+    QRect updateRect;
+    for (int r = topLeft.row(); r <= bottomRight.row(); ++r) {
+        for (int c = topLeft.column(); c <= bottomRight.column(); ++c)
+            updateRect |= q->visualRect(model->index(r, c, parentIdx));
+    }
+    return rect.intersected(updateRect);
+}
+
 /*!
     This slot is called when the selection is changed. The previous
     selection (which may be empty), is specified by \a deselected, and the
diff --git a/src/widgets/itemviews/qabstractitemview_p.h b/src/widgets/itemviews/qabstractitemview_p.h
index fe1c00248f..4b29b68b66 100644
--- a/src/widgets/itemviews/qabstractitemview_p.h
+++ b/src/widgets/itemviews/qabstractitemview_p.h
@@ -108,6 +108,7 @@ public:
     virtual void _q_layoutChanged();
     virtual void _q_rowsMoved(const QModelIndex &source, int sourceStart, int sourceEnd, const QModelIndex &destination, int destinationStart);
     virtual void _q_columnsMoved(const QModelIndex &source, int sourceStart, int sourceEnd, const QModelIndex &destination, int destinationStart);
+    virtual QRect intersectedRect(const QRect rect, const QModelIndex &topLeft, const QModelIndex &bottomRight) const;
 
     void _q_headerDataChanged() { doDelayedItemsLayout(); }
     void _q_scrollerStateChanged();
diff --git a/src/widgets/itemviews/qtableview.cpp b/src/widgets/itemviews/qtableview.cpp
index 81fceba8dc..c3ccfac5be 100644
--- a/src/widgets/itemviews/qtableview.cpp
+++ b/src/widgets/itemviews/qtableview.cpp
@@ -669,6 +669,52 @@ void QTableViewPrivate::trimHiddenSelections(QItemSelectionRange *range) const
     *range = QItemSelectionRange(topLeft, bottomRight);
 }
 
+QRect QTableViewPrivate::intersectedRect(const QRect rect, const QModelIndex &topLeft, const QModelIndex &bottomRight) const
+{
+    Q_Q(const QTableView);
+
+    using minMaxPair = std::pair<int, int>;
+    const auto calcMinMax = [q, rect](QHeaderView *hdr, int startIdx, int endIdx, minMaxPair bounds) -> minMaxPair
+    {
+        minMaxPair ret(std::numeric_limits<int>::max(), std::numeric_limits<int>::min());
+        if (hdr->sectionsMoved()) {
+            for (int i = startIdx; i <= endIdx; ++i) {
+                const int start = hdr->sectionViewportPosition(i);
+                const int end = start + hdr->sectionSize(i);
+                ret.first = std::min(start, ret.first);
+                ret.second = std::max(end, ret.second);
+                if (ret.first <= bounds.first && ret.second >= bounds.second)
+                    break;
+            }
+        } else {
+            if (q->isRightToLeft() && q->horizontalHeader() == hdr)
+                std::swap(startIdx, endIdx);
+            ret.first = hdr->sectionViewportPosition(startIdx);
+            ret.second = hdr->sectionViewportPosition(endIdx) +
+                         hdr->sectionSize(endIdx);
+        }
+        return ret;
+    };
+
+    const auto yVals = calcMinMax(verticalHeader, topLeft.row(), bottomRight.row(),
+                                  minMaxPair(rect.top(), rect.bottom()));
+    if (yVals.first == yVals.second) // all affected rows are hidden
+        return QRect();
+
+    // short circuit: check if no row is inside rect
+    const QRect colRect(QPoint(rect.left(), yVals.first),
+                        QPoint(rect.right(), yVals.second));
+    const QRect intersected = rect.intersected(colRect);
+    if (intersected.isNull())
+        return QRect();
+
+    const auto xVals = calcMinMax(horizontalHeader, topLeft.column(), bottomRight.column(),
+                                  minMaxPair(rect.left(), rect.right()));
+    const QRect updateRect(QPoint(xVals.first, yVals.first),
+                           QPoint(xVals.second, yVals.second));
+    return rect.intersected(updateRect);
+}
+
 /*!
   \internal
   Sets the span for the cell at (\a row, \a column).
diff --git a/src/widgets/itemviews/qtableview_p.h b/src/widgets/itemviews/qtableview_p.h
index 8f174351d2..e17773c4bd 100644
--- a/src/widgets/itemviews/qtableview_p.h
+++ b/src/widgets/itemviews/qtableview_p.h
@@ -149,6 +149,7 @@ public:
  }
     void init();
     void trimHiddenSelections(QItemSelectionRange *range) const;
+    QRect intersectedRect(const QRect rect, const QModelIndex &topLeft, const QModelIndex &bottomRight) const override;
 
     inline bool isHidden(int row, int col) const {
         return verticalHeader->isSectionHidden(row)
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index 9aba17be70..a3bebb8f3c 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -1396,6 +1396,24 @@ void QTreeViewPrivate::_q_modelDestroyed()
     QAbstractItemViewPrivate::_q_modelDestroyed();
 }
 
+QRect QTreeViewPrivate::intersectedRect(const QRect rect, const QModelIndex &topLeft, const QModelIndex &bottomRight) const
+{
+    Q_Q(const QTreeView);
+
+    const auto parentIdx = topLeft.parent();
+    executePostedLayout();
+    QRect updateRect;
+    for (int r = topLeft.row(); r <= bottomRight.row(); ++r) {
+        if (isRowHidden(model->index(r, 0, parentIdx)))
+            continue;
+        for (int c = topLeft.column(); c <= bottomRight.column(); ++c) {
+            const QModelIndex idx(model->index(r, c, parentIdx));
+            updateRect |= q->visualRect(idx);
+        }
+    }
+    return rect.intersected(updateRect);
+}
+
 /*!
   \reimp
 
diff --git a/src/widgets/itemviews/qtreeview_p.h b/src/widgets/itemviews/qtreeview_p.h
index 836d8f0c2d..1206850b71 100644
--- a/src/widgets/itemviews/qtreeview_p.h
+++ b/src/widgets/itemviews/qtreeview_p.h
@@ -135,6 +135,7 @@ public:
     void _q_modelAboutToBeReset();
     void _q_sortIndicatorChanged(int column, Qt::SortOrder order);
     void _q_modelDestroyed() override;
+    QRect intersectedRect(const QRect rect, const QModelIndex &topLeft, const QModelIndex &bottomRight) const override;
 
     void layout(int item, bool recusiveExpanding = false, bool afterIsUninitialized = false);
 
diff --git a/tests/auto/widgets/itemviews/qabstractitemview/CMakeLists.txt b/tests/auto/widgets/itemviews/qabstractitemview/CMakeLists.txt
index 520a0b4b98..2fc8c14eb6 100644
--- a/tests/auto/widgets/itemviews/qabstractitemview/CMakeLists.txt
+++ b/tests/auto/widgets/itemviews/qabstractitemview/CMakeLists.txt
@@ -12,4 +12,5 @@ add_qt_test(tst_qabstractitemview
         Qt::GuiPrivate
         Qt::TestPrivate
         Qt::Widgets
+        Qt::WidgetsPrivate
 )
diff --git a/tests/auto/widgets/itemviews/qabstractitemview/qabstractitemview.pro b/tests/auto/widgets/itemviews/qabstractitemview/qabstractitemview.pro
index 809a996324..b9091a134e 100644
--- a/tests/auto/widgets/itemviews/qabstractitemview/qabstractitemview.pro
+++ b/tests/auto/widgets/itemviews/qabstractitemview/qabstractitemview.pro
@@ -1,4 +1,4 @@
 CONFIG += testcase
 TARGET = tst_qabstractitemview
-QT += widgets testlib testlib-private gui-private
+QT += widgets testlib testlib-private gui-private widgets-private
 SOURCES         += tst_qabstractitemview.cpp
diff --git a/tests/auto/widgets/itemviews/qabstractitemview/tst_qabstractitemview.cpp b/tests/auto/widgets/itemviews/qabstractitemview/tst_qabstractitemview.cpp
index 0834d989e0..44b728a042 100644
--- a/tests/auto/widgets/itemviews/qabstractitemview/tst_qabstractitemview.cpp
+++ b/tests/auto/widgets/itemviews/qabstractitemview/tst_qabstractitemview.cpp
@@ -51,6 +51,7 @@
 #include <QTest>
 #include <QVBoxLayout>
 #include <QtTest/private/qtesthelpers_p.h>
+#include <private/qabstractitemview_p.h>
 
 Q_DECLARE_METATYPE(Qt::ItemFlags);
 
@@ -115,6 +116,9 @@ private slots:
     void setCurrentIndex_data();
     void setCurrentIndex();
 
+    void checkIntersectedRect_data();
+    void checkIntersectedRect();
+
     void task221955_selectedEditor();
     void task250754_fontChange();
     void task200665_itemEntered();
@@ -468,7 +472,8 @@ void tst_QAbstractItemView::basic_tests(QAbstractItemView *view)
     view->setCurrentIndex(QModelIndex());
 
     // protected methods
-    view->dataChanged(QModelIndex(), QModelIndex());
+    // will assert because an invalid index is passed
+    //view->dataChanged(QModelIndex(), QModelIndex());
     view->rowsInserted(QModelIndex(), -1, -1);
     view->rowsAboutToBeRemoved(QModelIndex(), -1, -1);
     view->selectionChanged(QItemSelection(), QItemSelection());
@@ -1098,6 +1103,101 @@ void tst_QAbstractItemView::setCurrentIndex()
     QVERIFY(view->currentIndex() == model->index(result ? 1 : 0, 0));
 }
 
+void tst_QAbstractItemView::checkIntersectedRect_data()
+{
+    auto createModel = [](int rowCount) -> QStandardItemModel*
+    {
+        QStandardItemModel *model = new QStandardItemModel;
+        for (int i = 0; i < rowCount; ++i) {
+            const QList<QStandardItem *> sil({new QStandardItem(QLatin1String("Row %1 Item").arg(i)),
+                                              new QStandardItem(QLatin1String("2nd column"))});
+            model->appendRow(sil);
+        }
+        return model;
+    };
+    QTest::addColumn<QStandardItemModel *>("model");
+    QTest::addColumn<QVector<QModelIndex>>("changedIndexes");
+    QTest::addColumn<bool>("isEmpty");
+    {
+        auto model = createModel(5);
+        QTest::newRow("multiple columns") << model
+                                          << QVector<QModelIndex>({model->index(0, 0),
+                                                                   model->index(0, 1)})
+                                          << false;
+    }
+    {
+        auto model = createModel(5);
+        QTest::newRow("multiple rows") << model
+                                       << QVector<QModelIndex>({model->index(0, 0),
+                                                                model->index(1, 0),
+                                                                model->index(2, 0)})
+                                       << false;
+    }
+    {
+        auto model = createModel(5);
+        QTest::newRow("hidden rows") << model
+                                     << QVector<QModelIndex>({model->index(3, 0),
+                                                              model->index(4, 0)})
+                                     << true;
+    }
+    {
+        auto model = createModel(500);
+        QTest::newRow("rows outside viewport") << model
+                                               << QVector<QModelIndex>({model->index(498, 0),
+                                                                        model->index(499, 0)})
+                                               << true;
+    }
+}
+
+void tst_QAbstractItemView::checkIntersectedRect()
+{
+    QFETCH(QStandardItemModel *, model);
+    QFETCH(const QVector<QModelIndex>, changedIndexes);
+    QFETCH(bool, isEmpty);
+
+    class TableView : public QTableView
+    {
+    public:
+        void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int>()) override
+        {
+            QTableView::dataChanged(topLeft, bottomRight, roles);
+            // we want to check the base class implementation here!
+            QAbstractItemViewPrivate *av = static_cast<QAbstractItemViewPrivate*>(qt_widget_private(this));
+            m_intersectecRect = av->intersectedRect(av->viewport->rect(), topLeft, bottomRight);
+        }
+        mutable QRect m_intersectecRect;
+    };
+
+    TableView view;
+    model->setParent(&view);
+    view.setModel(model);
+    view.resize(400, 400);
+    view.show();
+    view.setRowHidden(3, true);
+    view.setRowHidden(4, true);
+    QVERIFY(QTest::qWaitForWindowExposed(&view));
+
+    view.m_intersectecRect = QRect();
+    emit view.model()->dataChanged(changedIndexes.first(), changedIndexes.last());
+    if (isEmpty) {
+        QVERIFY(view.m_intersectecRect.isEmpty());
+    } else {
+        const auto parent = changedIndexes.first().parent();
+        const int rCount = view.model()->rowCount(parent);
+        const int cCount = view.model()->columnCount(parent);
+        for (int r = 0; r < rCount; ++r) {
+            for (int c = 0; c < cCount; ++c) {
+                const QModelIndex &idx = view.model()->index(r, c, parent);
+                const auto rect = view.visualRect(idx);
+                if (changedIndexes.contains(idx))
+                    QVERIFY(view.m_intersectecRect.contains(rect));
+                else
+                    QVERIFY(!view.m_intersectecRect.contains(rect));
+            }
+        }
+    }
+}
+
 void tst_QAbstractItemView::task221955_selectedEditor()
 {
     if (!QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::WindowActivation))
diff --git a/tests/auto/widgets/itemviews/qtableview/tst_qtableview.cpp b/tests/auto/widgets/itemviews/qtableview/tst_qtableview.cpp
index 544069243f..ccc6997f26 100644
--- a/tests/auto/widgets/itemviews/qtableview/tst_qtableview.cpp
+++ b/tests/auto/widgets/itemviews/qtableview/tst_qtableview.cpp
@@ -243,6 +243,14 @@ public:
         verticalHeader()->setMinimumSectionSize(0);
     }
 
+    void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int>()) override
+    {
+        QTableView::dataChanged(topLeft, bottomRight, roles);
+        QTableViewPrivate *av = static_cast<QTableViewPrivate*>(qt_widget_private(this));
+        m_intersectecRect = av->intersectedRect(av->viewport->rect(), topLeft, bottomRight);
+    }
+    mutable QRect m_intersectecRect;
+
     using QTableView::moveCursor;
     using QTableView::isIndexHidden;
     using QTableView::setSelection;
@@ -402,6 +410,9 @@ private slots:
     void selectionSignal();
     void setCurrentIndex();
 
+    void checkIntersectedRect_data();
+    void checkIntersectedRect();
+
     // task-specific tests:
     void task173773_updateVerticalHeader();
     void task227953_setRootIndex();
@@ -3842,6 +3853,121 @@ void tst_QTableView::setCurrentIndex()
     QCOMPARE(model.submit_count, 4);
 }
 
+void tst_QTableView::checkIntersectedRect_data()
+{
+    QTest::addColumn<QtTestTableModel *>("model");
+    QTest::addColumn<QVector<QModelIndex>>("changedIndexes");
+    QTest::addColumn<bool>("isEmpty");
+    QTest::addColumn<bool>("swapFirstAndLastIndexRow");  // for QHeaderView::sectionsMoved()
+    QTest::addColumn<bool>("swapFirstAndLastIndexColumn");  // for QHeaderView::sectionsMoved()
+    QTest::addColumn<Qt::LayoutDirection>("layoutDirection");
+    QTest::addColumn<int>("hiddenRow");
+    QTest::addColumn<int>("hiddenCol");
+    const auto testName = [](const QByteArray &prefix, Qt::LayoutDirection dir, bool r, bool c)
+    {
+        const char *strDir = dir == Qt::LeftToRight ? ", LeftToRight" : ", RightToLeft";
+        const char *strRow = r ? ", rowsSwapped" : "";
+        const char *strCol = c ? ", colsSwapped" : "";
+        return prefix + strDir + strRow + strCol;
+    };
+    for (int i = 0; i < 2; ++i) {
+        const Qt::LayoutDirection dir(i == 0 ? Qt::LeftToRight : Qt::RightToLeft);
+        for (int j = 0; j < 4; ++j) {
+            const bool swapRow = ((j & 1) == 1);
+            const bool swapColumn = ((j & 2) == 2);
+            {
+                QtTestTableModel *model = new QtTestTableModel(10, 3);
+                QTest::newRow(testName("multiple columns", dir, swapRow, swapColumn).data())
+                    << model
+                    << QVector<QModelIndex>({model->index(0, 0),
+                                             model->index(0, 1)})
+                    << false << swapRow << swapColumn << dir << -1 << -1;
+            }
+            {
+                QtTestTableModel *model = new QtTestTableModel(10, 3);
+                QTest::newRow(testName("multiple rows", dir, swapRow, swapColumn).data())
+                    << model
+                    << QVector<QModelIndex>({model->index(0, 0),
+                                             model->index(1, 0),
+                                             model->index(2, 0)})
+                    << false << swapRow << swapColumn << dir << -1 << -1;
+            }
+            {
+                QtTestTableModel *model = new QtTestTableModel(10, 3);
+                QTest::newRow(testName("hidden row", dir, swapRow, swapColumn).data())
+                    << model
+                    << QVector<QModelIndex>({model->index(3, 0),
+                                             model->index(3, 1)})
+                    << true << swapRow << swapColumn << dir << 3 << -1;
+            }
+            {
+                QtTestTableModel *model = new QtTestTableModel(50, 2);
+                QTest::newRow(testName("row outside viewport", dir, swapRow, swapColumn).data())
+                    << model
+                    << QVector<QModelIndex>({model->index(49, 0),
+                                             model->index(49, 1)})
+                    << true << swapRow << swapColumn << dir << -1 << -1;
+            }
+        }
+    }
+}
+
+void tst_QTableView::checkIntersectedRect()
+{
+    QFETCH(QtTestTableModel *, model);
+    QFETCH(const QVector<QModelIndex>, changedIndexes);
+    QFETCH(bool, isEmpty);
+    QFETCH(bool, swapFirstAndLastIndexRow);
+    QFETCH(bool, swapFirstAndLastIndexColumn);
+    QFETCH(Qt::LayoutDirection, layoutDirection);
+    QFETCH(int, hiddenRow);
+    QFETCH(int, hiddenCol);
+
+    QtTestTableView view;
+    model->setParent(&view);
+    view.setLayoutDirection(layoutDirection);
+    view.setModel(model);
+    view.resize(400, 400);
+    view.show();
+    if (hiddenRow >= 0)
+        view.hideRow(hiddenRow);
+    if (hiddenCol >= 0)
+        view.hideRow(hiddenCol);
+    if (swapFirstAndLastIndexRow)
+        view.verticalHeader()->swapSections(changedIndexes.first().row(), changedIndexes.last().row());
+    if (swapFirstAndLastIndexColumn)
+        view.horizontalHeader()->swapSections(changedIndexes.first().column(), changedIndexes.last().column());
+
+    QVERIFY(QTest::qWaitForWindowExposed(&view));
+
+    const auto toString = [](const QModelIndex &idx)
+    {
+        return QStringLiteral("idx: %1/%2").arg(idx.row()).arg(idx.column());
+    };
+
+    view.m_intersectecRect = QRect();
+    emit view.model()->dataChanged(changedIndexes.first(), changedIndexes.last());
+    if (isEmpty) {
+        QVERIFY(view.m_intersectecRect.isEmpty());
+    } else if (!changedIndexes.first().isValid()) {
+        QCOMPARE(view.m_intersectecRect, view.viewport()->rect());
+    } else {
+        const auto parent = changedIndexes.first().parent();
+        const int rCount = view.model()->rowCount(parent);
+        const int cCount = view.model()->columnCount(parent);
+        for (int r = 0; r < rCount; ++r) {
+            for (int c = 0; c < cCount; ++c) {
+                const QModelIndex &idx = view.model()->index(r, c, parent);
+                const auto rect = view.visualRect(idx);
+                if (changedIndexes.contains(idx))
+                    QVERIFY2(view.m_intersectecRect.contains(rect), qPrintable(toString(idx)));
+                else
+                    QVERIFY2(!view.m_intersectecRect.contains(rect), qPrintable(toString(idx)));
+            }
+        }
+    }
+}
+
 class task173773_EventFilter : public QObject
 {
     int paintEventCount_ = 0;
diff --git a/tests/auto/widgets/itemviews/qtreeview/tst_qtreeview.cpp b/tests/auto/widgets/itemviews/qtreeview/tst_qtreeview.cpp
index 7259fa1ab0..95501136cc 100644
--- a/tests/auto/widgets/itemviews/qtreeview/tst_qtreeview.cpp
+++ b/tests/auto/widgets/itemviews/qtreeview/tst_qtreeview.cpp
@@ -89,6 +89,13 @@ public:
         QTreeView::paintEvent(event);
         wasPainted = true;
     }
+    void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int>()) override
+    {
+        QTreeView::dataChanged(topLeft, bottomRight, roles);
+        QTreeViewPrivate *av = static_cast<QTreeViewPrivate*>(qt_widget_private(this));
+        m_intersectecRect = av->intersectedRect(av->viewport->rect(), topLeft, bottomRight);
+    }
+    mutable QRect m_intersectecRect;
     bool wasPainted = false;
 public slots:
     void handleSelectionChanged()
@@ -208,6 +215,8 @@ private slots:
     void statusTip_data();
     void statusTip();
     void fetchMoreOnScroll();
+    void checkIntersectedRect_data();
+    void checkIntersectedRect();
 
     // task-specific tests:
     void task174627_moveLeftToRoot();
@@ -4832,6 +4841,111 @@ void tst_QTreeView::fetchMoreOnScroll()
     QCOMPARE(im.item(19)->rowCount(), 20);
 }
 
+void tst_QTreeView::checkIntersectedRect_data()
+{
+    auto createModel = [](int rowCount)
+    {
+        QStandardItemModel *model = new QStandardItemModel;
+        for (int i = 0; i < rowCount; ++i) {
+            const QList<QStandardItem *> sil({new QStandardItem(QLatin1String("Row %1 Item").arg(i)),
+                                              new QStandardItem(QLatin1String("2nd column"))});
+            model->appendRow(sil);
+        }
+        for (int i = 2; i < 4; ++i) {
+            const QList<QStandardItem *> sil({new QStandardItem(QLatin1String("Row %1 Item").arg(i)),
+                                              new QStandardItem(QLatin1String("2nd column"))});
+            model->item(i)->appendRow(sil);
+        }
+        return model;
+    };
+    QTest::addColumn<QStandardItemModel *>("model");
+    QTest::addColumn<QVector<QModelIndex>>("changedIndexes");
+    QTest::addColumn<bool>("isEmpty");
+    {
+        auto model = createModel(5);
+        QTest::newRow("multiple columns") << model
+                                          << QVector<QModelIndex>({model->index(0, 0),
+                                                                   model->index(0, 1)})
+                                          << false;
+    }
+    {
+        auto model = createModel(5);
+        QTest::newRow("multiple rows") << model
+                                       << QVector<QModelIndex>({model->index(0, 0),
+                                                                model->index(1, 0),
+                                                                model->index(2, 0)})
+                                       << false;
+    }
+    {
+        auto model = createModel(5);
+        const QModelIndex idxRow2(model->indexFromItem(model->item(2)));
+        QTest::newRow("child row") << model
+                                   << QVector<QModelIndex>({model->index(0, 0, idxRow2),
+                                                            model->index(0, 1, idxRow2)})
+                                   << false;
+        }
+    {
+        auto model = createModel(5);
+        QTest::newRow("hidden row") << model
+                                    << QVector<QModelIndex>({model->index(3, 0),
+                                                             model->index(3, 1)})
+                                    << true;
+    }
+    {
+        auto model = createModel(5);
+        const QModelIndex idxRow3(model->indexFromItem(model->item(3)));
+        QTest::newRow("hidden child row") << model
+                                          << QVector<QModelIndex>({model->index(0, 0, idxRow3),
+                                                                   model->index(0, 1, idxRow3)})
+                                          << true;
+    }
+    {
+        auto model = createModel(50);
+        QTest::newRow("row outside viewport") << model
+                                              << QVector<QModelIndex>({model->index(49, 0),
+                                                                       model->index(49, 1)})
+                                              << true;
+    }
+}
+
+void tst_QTreeView::checkIntersectedRect()
+{
+    QFETCH(QStandardItemModel *, model);
+    QFETCH(const QVector<QModelIndex>, changedIndexes);
+    QFETCH(bool, isEmpty);
+
+    TreeView view;
+    model->setParent(&view);
+    view.setModel(model);
+    view.resize(400, 400);
+    view.show();
+    view.expandAll();
+    view.setRowHidden(3, QModelIndex(), true);
+    QVERIFY(QTest::qWaitForWindowExposed(&view));
+
+    view.m_intersectecRect = QRect();
+    emit view.model()->dataChanged(changedIndexes.first(), changedIndexes.last());
+    if (isEmpty) {
+        QVERIFY(view.m_intersectecRect.isEmpty());
+    } else if (!changedIndexes.first().isValid()) {
+        QCOMPARE(view.m_intersectecRect, view.viewport()->rect());
+    } else {
+        const auto parent = changedIndexes.first().parent();
+        const int rCount = view.model()->rowCount(parent);
+        const int cCount = view.model()->columnCount(parent);
+        for (int r = 0; r < rCount; ++r) {
+            for (int c = 0; c < cCount; ++c) {
+                const QModelIndex &idx = view.model()->index(r, c, parent);
+                const auto rect = view.visualRect(idx);
+                if (changedIndexes.contains(idx))
+                    QVERIFY(view.m_intersectecRect.contains(rect));
+                else
+                    QVERIFY(!view.m_intersectecRect.contains(rect));
+            }
+        }
+    }
+}
+
 static void fillModeltaskQTBUG_8376(QAbstractItemModel &model)
 {
     model.insertRow(0);