qmdiarea.cpp

Go to the documentation of this file.

// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qmdiarea_p.h"
 
#include <QApplication>
#include <QStyle>
#include <QChildEvent>
#include <QResizeEvent>
#include <QScrollBar>
#include <QtAlgorithms>
#include <QPainter>
#include <QFontMetrics>
#include <QStyleOption>
#include <QDebug>
#include <qmath.h>
#if QT_CONFIG(menu)
#include <qmenu.h>
#endif
#include <private/qlayoutengine_p.h>
 
#include <algorithm>
 
QT_BEGIN_NAMESPACE
 
using namespace Qt::StringLiterals;
using namespace QMdi;
 
// Asserts in debug mode, gives warning otherwise.
static bool sanityCheck(const QMdiSubWindow * const child, const char *where)
{
    if (Q_UNLIKELY(!child)) {
        const char error[] = "null pointer";
        Q_ASSERT_X(false, where, error);
        qWarning("%s:%s", where, error);
        return false;
    }
    return true;
}
 
static bool sanityCheck(const QList<QWidget *> &widgets, const int index, const char *where)
{
    if (Q_UNLIKELY(index < 0 || index >= widgets.size())) {
        const char error[] = "index out of range";
        Q_ASSERT_X(false, where, error);
        qWarning("%s:%s", where, error);
        return false;
    }
    if (Q_UNLIKELY(!widgets.at(index))) {
        const char error[] = "null pointer";
        Q_ASSERT_X(false, where, error);
        qWarning("%s:%s", where, error);
        return false;
    }
    return true;
}
 
static void setIndex(int *index, int candidate, int min, int max, bool isIncreasing)
{
    if (!index)
        return;
 
    if (isIncreasing) {
        if (candidate > max)
            *index = min;
        else
            *index = qMax(candidate, min);
    } else {
        if (candidate < min)
            *index = max;
        else
            *index = qMin(candidate, max);
    }
    Q_ASSERT(*index >= min && *index <= max);
}
 
static inline bool useScrollBar(const QRect &childrenRect, const QSize &maxViewportSize,
                                Qt::Orientation orientation)
{
    if (orientation == Qt::Horizontal)
        return  childrenRect.width() > maxViewportSize.width()
                || childrenRect.left() < 0
                || childrenRect.right() >= maxViewportSize.width();
    else
        return childrenRect.height() > maxViewportSize.height()
               || childrenRect.top() < 0
               || childrenRect.bottom() >= maxViewportSize.height();
}
 
// Returns the closest mdi area containing the widget (if any).
static inline QMdiArea *mdiAreaParent(QWidget *widget)
{
    if (!widget)
        return nullptr;
 
    QWidget *parent = widget->parentWidget();
    while (parent) {
        if (QMdiArea *area = qobject_cast<QMdiArea *>(parent))
            return area;
        parent = parent->parentWidget();
    }
    return nullptr;
}
 
#if QT_CONFIG(tabwidget)
QTabBar::Shape _q_tb_tabBarShapeFrom(QTabWidget::TabShape shape, QTabWidget::TabPosition position);
#endif // QT_CONFIG(tabwidget)
 
static inline QString tabTextFor(QMdiSubWindow *subWindow)
{
    if (!subWindow)
        return QString();
 
    QString title = subWindow->windowTitle();
    if (subWindow->isWindowModified()) {
        title.replace("[*]"_L1, "*"_L1);
    } else {
        extern QString qt_setWindowTitle_helperHelper(const QString&, const QWidget*);
        title = qt_setWindowTitle_helperHelper(title, subWindow);
    }
 
    return title.isEmpty() ? QMdiArea::tr("(Untitled)") : title;
}
 
void RegularTiler::rearrange(QList<QWidget *> &widgets, const QRect &domain) const
{
    if (widgets.isEmpty())
        return;
 
    const int n = widgets.size();
    const int ncols = qMax(qCeil(qSqrt(qreal(n))), 1);
    const int nrows = qMax((n % ncols) ? (n / ncols + 1) : (n / ncols), 1);
    const int nspecial = (n % ncols) ? (ncols - n % ncols) : 0;
    const int dx = domain.width()  / ncols;
    const int dy = domain.height() / nrows;
 
    int i = 0;
    for (int row = 0; row < nrows; ++row) {
        const int y1 = int(row * (dy + 1));
        for (int col = 0; col < ncols; ++col) {
            if (row == 1 && col < nspecial)
                continue;
            const int x1 = int(col * (dx + 1));
            int x2 = int(x1 + dx);
            int y2 = int(y1 + dy);
            if (row == 0 && col < nspecial) {
                y2 *= 2;
                if (nrows != 2)
                    y2 += 1;
                else
                    y2 = domain.bottom();
            }
            if (col == ncols - 1 && x2 != domain.right())
                x2 = domain.right();
            if (row == nrows - 1 && y2 != domain.bottom())
                y2 = domain.bottom();
            if (!sanityCheck(widgets, i, "RegularTiler"))
                continue;
            QWidget *widget = widgets.at(i++);
            QRect newGeometry = QRect(QPoint(x1, y1), QPoint(x2, y2));
            widget->setGeometry(QStyle::visualRect(widget->layoutDirection(), domain, newGeometry));
        }
    }
}
 
void SimpleCascader::rearrange(QList<QWidget *> &widgets, const QRect &domain) const
{
    if (widgets.isEmpty())
        return;
 
    // Tunables:
    const int topOffset = 0;
    const int bottomOffset = 50;
    const int leftOffset = 0;
    const int rightOffset = 100;
    const int dx = 10;
 
    QStyleOptionTitleBar options;
    options.initFrom(widgets.at(0));
    int titleBarHeight = widgets.at(0)->style()->pixelMetric(QStyle::PM_TitleBarHeight, &options, widgets.at(0));
    const QFontMetrics fontMetrics = QFontMetrics(QApplication::font("QMdiSubWindowTitleBar"));
    const int dy = qMax(titleBarHeight - (titleBarHeight - fontMetrics.height()) / 2, 1)
        + widgets.at(0)->style()->pixelMetric(QStyle::PM_FocusFrameVMargin, nullptr, widgets.at(0));
 
    const int n = widgets.size();
    const int nrows = qMax((domain.height() - (topOffset + bottomOffset)) / dy, 1);
    const int ncols = qMax(n / nrows + ((n % nrows) ? 1 : 0), 1);
    const int dcol = (domain.width() - (leftOffset + rightOffset)) / ncols;
 
    int i = 0;
    for (int row = 0; row < nrows; ++row) {
        for (int col = 0; col < ncols; ++col) {
            const int x = leftOffset + row * dx + col * dcol;
            const int y = topOffset + row * dy;
            if (!sanityCheck(widgets, i, "SimpleCascader"))
                continue;
            QWidget *widget = widgets.at(i++);
            QRect newGeometry = QRect(QPoint(x, y), widget->sizeHint());
            widget->setGeometry(QStyle::visualRect(widget->layoutDirection(), domain, newGeometry));
            if (i == n)
                return;
        }
    }
}
 
void IconTiler::rearrange(QList<QWidget *> &widgets, const QRect &domain) const
{
    if (widgets.isEmpty() || !sanityCheck(widgets, 0, "IconTiler"))
        return;
 
    const int n = widgets.size();
    const int width = qMax(widgets.at(0)->width(), 1);
    const int height = widgets.at(0)->height();
    const int ncols = qMax(domain.width() / width, 1);
    const int nrows = n / ncols + ((n % ncols) ? 1 : 0);
 
    int i = 0;
    for (int row = 0; row < nrows; ++row) {
        for (int col = 0; col < ncols; ++col) {
            const int x = col * width;
            const int y = domain.height() - height - row * height;
            if (!sanityCheck(widgets, i, "IconTiler"))
                continue;
            QWidget *widget = widgets.at(i++);
            QPoint newPos(x, y);
            QRect newGeometry = QRect(newPos.x(), newPos.y(), widget->width(), widget->height());
            widget->setGeometry(QStyle::visualRect(widget->layoutDirection(), domain, newGeometry));
            if (i == n)
                return;
        }
    }
}
 
int MinOverlapPlacer::accumulatedOverlap(const QRect &source, const QList<QRect> &rects)
{
    int accOverlap = 0;
    for (const QRect &rect : rects) {
        QRect intersection = source.intersected(rect);
        accOverlap += intersection.width() * intersection.height();
    }
    return accOverlap;
}
 
 
QRect MinOverlapPlacer::findMinOverlapRect(const QList<QRect> &source, const QList<QRect> &rects)
{
    int minAccOverlap = -1;
    QRect minAccOverlapRect;
    for (const QRect &srcRect : source) {
        const int accOverlap = accumulatedOverlap(srcRect, rects);
        if (accOverlap < minAccOverlap || minAccOverlap == -1) {
            minAccOverlap = accOverlap;
            minAccOverlapRect = srcRect;
        }
    }
    return minAccOverlapRect;
}
 
QList<QRect> MinOverlapPlacer::getCandidatePlacements(const QSize &size, const QList<QRect> &rects,
                                                      const QRect &domain)
{
    QList<QRect> result;
 
    QList<int> xlist;
    xlist.reserve(2 + rects.size());
    xlist << domain.left() << domain.right() - size.width() + 1;
 
    QList<int> ylist;
    ylist.reserve(2 + rects.size());
    ylist << domain.top();
    if (domain.bottom() - size.height() + 1 >= 0)
        ylist << domain.bottom() - size.height() + 1;
 
    for (const QRect &rect : rects) {
        xlist << rect.right() + 1;
        ylist << rect.bottom() + 1;
    }
 
    std::sort(xlist.begin(), xlist.end());
    xlist.erase(std::unique(xlist.begin(), xlist.end()), xlist.end());
 
    std::sort(ylist.begin(), ylist.end());
    ylist.erase(std::unique(ylist.begin(), ylist.end()), ylist.end());
 
    result.reserve(ylist.size() * xlist.size());
    for (int y : std::as_const(ylist))
        for (int x : std::as_const(xlist))
            result << QRect(QPoint(x, y), size);
    return result;
}
 
QList<QRect> MinOverlapPlacer::findNonInsiders(const QRect &domain, QList<QRect> &source)
{
    const auto containedInDomain =
            [domain](const QRect &srcRect) { return domain.contains(srcRect); };
 
    const auto firstOut = std::stable_partition(source.begin(), source.end(), containedInDomain);
 
    QList<QRect> result;
    result.reserve(source.end() - firstOut);
    std::copy(firstOut, source.end(), std::back_inserter(result));
 
    source.erase(firstOut, source.end());
 
    return result;
}
 
QList<QRect> MinOverlapPlacer::findMaxOverlappers(const QRect &domain, const QList<QRect> &source)
{
    QList<QRect> result;
    result.reserve(source.size());
 
    int maxOverlap = -1;
    for (const QRect &srcRect : source) {
        QRect intersection = domain.intersected(srcRect);
        const int overlap = intersection.width() * intersection.height();
        if (overlap >= maxOverlap || maxOverlap == -1) {
            if (overlap > maxOverlap) {
                maxOverlap = overlap;
                result.clear();
            }
            result << srcRect;
        }
    }
 
    return result;
}
 
QPoint MinOverlapPlacer::findBestPlacement(const QRect &domain, const QList<QRect> &rects,
                                           QList<QRect> &source)
{
    const QList<QRect> nonInsiders = findNonInsiders(domain, source);
 
    if (!source.empty())
        return findMinOverlapRect(source, rects).topLeft();
 
    QList<QRect> maxOverlappers = findMaxOverlappers(domain, nonInsiders);
    return findMinOverlapRect(maxOverlappers, rects).topLeft();
}
 
 
QPoint MinOverlapPlacer::place(const QSize &size, const QList<QRect> &rects,
                               const QRect &domain) const
{
    if (size.isEmpty() || !domain.isValid())
        return QPoint();
    for (const QRect &rect : rects) {
        if (!rect.isValid())
            return QPoint();
    }
 
    QList<QRect> candidates = getCandidatePlacements(size, rects, domain);
    return findBestPlacement(domain, rects, candidates);
}
 
#if QT_CONFIG(tabbar)
class QMdiAreaTabBar : public QTabBar
{
public:
    QMdiAreaTabBar(QWidget *parent) : QTabBar(parent) {}
 
protected:
    void mousePressEvent(QMouseEvent *event) override;
#ifndef QT_NO_CONTEXTMENU
    void contextMenuEvent(QContextMenuEvent *event) override;
#endif
 
private:
    QMdiSubWindow *subWindowFromIndex(int index) const;
};
 
void QMdiAreaTabBar::mousePressEvent(QMouseEvent *event)
{
    if (event->button() != Qt::MiddleButton) {
        QTabBar::mousePressEvent(event);
        return;
    }
 
    QMdiSubWindow *subWindow = subWindowFromIndex(tabAt(event->position().toPoint()));
    if (!subWindow) {
        event->ignore();
        return;
    }
 
    subWindow->close();
}
 
#ifndef QT_NO_CONTEXTMENU
void QMdiAreaTabBar::contextMenuEvent(QContextMenuEvent *event)
{
    QPointer<QMdiSubWindow> subWindow = subWindowFromIndex(tabAt(event->pos()));
    if (!subWindow || subWindow->isHidden()) {
        event->ignore();
        return;
    }
 
#if QT_CONFIG(menu)
    QMdiSubWindowPrivate *subWindowPrivate = subWindow->d_func();
    if (!subWindowPrivate->systemMenu) {
        event->ignore();
        return;
    }
 
    QMdiSubWindow *currentSubWindow = subWindowFromIndex(currentIndex());
    Q_ASSERT(currentSubWindow);
 
    // We don't want these actions to show up in the system menu when the
    // current sub-window is maximized, i.e. covers the entire viewport.
    if (currentSubWindow->isMaximized()) {
        subWindowPrivate->setVisible(QMdiSubWindowPrivate::MoveAction, false);
        subWindowPrivate->setVisible(QMdiSubWindowPrivate::ResizeAction, false);
        subWindowPrivate->setVisible(QMdiSubWindowPrivate::MinimizeAction, false);
        subWindowPrivate->setVisible(QMdiSubWindowPrivate::MaximizeAction, false);
        subWindowPrivate->setVisible(QMdiSubWindowPrivate::RestoreAction, false);
        subWindowPrivate->setVisible(QMdiSubWindowPrivate::StayOnTopAction, false);
    }
 
    // Show system menu.
    subWindowPrivate->systemMenu->exec(event->globalPos());
    if (!subWindow)
        return;
 
    // Restore action visibility.
    subWindowPrivate->updateActions();
#endif // QT_CONFIG(menu)
}
#endif // QT_NO_CONTEXTMENU
 
QMdiSubWindow *QMdiAreaTabBar::subWindowFromIndex(int index) const
{
    if (index < 0 || index >= count())
        return nullptr;
 
    QMdiArea *mdiArea = qobject_cast<QMdiArea *>(parentWidget());
    Q_ASSERT(mdiArea);
 
    const QList<QMdiSubWindow *> subWindows = mdiArea->subWindowList();
    Q_ASSERT(index < subWindows.size());
 
    QMdiSubWindow *subWindow = mdiArea->subWindowList().at(index);
    Q_ASSERT(subWindow);
 
    return subWindow;
}
#endif // QT_CONFIG(tabbar)
 
QMdiAreaPrivate::QMdiAreaPrivate()
    : cascader(nullptr),
      regularTiler(nullptr),
      iconTiler(nullptr),
      placer(nullptr),
#if QT_CONFIG(rubberband)
      rubberBand(nullptr),
#endif
#if QT_CONFIG(tabbar)
      tabBar(nullptr),
#endif
      activationOrder(QMdiArea::CreationOrder),
      viewMode(QMdiArea::SubWindowView),
#if QT_CONFIG(tabbar)
      documentMode(false),
      tabsClosable(false),
      tabsMovable(false),
#endif
#if QT_CONFIG(tabwidget)
      tabShape(QTabWidget::Rounded),
      tabPosition(QTabWidget::North),
#endif
      ignoreGeometryChange(false),
      ignoreWindowStateChange(false),
      isActivated(false),
      isSubWindowsTiled(false),
      showActiveWindowMaximized(false),
      tileCalledFromResizeEvent(false),
      updatesDisabledByUs(false),
      inViewModeChange(false),
      indexToNextWindow(-1),
      indexToPreviousWindow(-1),
      indexToHighlighted(-1),
      indexToLastActiveTab(-1),
      resizeTimerId(-1),
      tabToPreviousTimerId(-1)
{
}
 
void QMdiAreaPrivate::_q_deactivateAllWindows(QMdiSubWindow *aboutToActivate)
{
    if (ignoreWindowStateChange)
        return;
 
    Q_Q(QMdiArea);
    if (!aboutToActivate)
        aboutToBecomeActive = qobject_cast<QMdiSubWindow *>(q->sender());
    else
        aboutToBecomeActive = aboutToActivate;
    Q_ASSERT(aboutToBecomeActive);
 
    // Take a copy because child->showNormal() could indirectly call
    // QCoreApplication::sendEvent(), which could call unknown code that e.g.
    // recurses into the class modifying childWindows.
    const auto subWindows = childWindows;
    for (QMdiSubWindow *child : subWindows) {
        if (!sanityCheck(child, "QMdiArea::deactivateAllWindows") || aboutToBecomeActive == child)
            continue;
        // We don't want to handle signals caused by child->showNormal().
        ignoreWindowStateChange = true;
        if (!(options & QMdiArea::DontMaximizeSubWindowOnActivation) && !showActiveWindowMaximized)
            showActiveWindowMaximized = child->isMaximized() && child->isVisible();
        if (showActiveWindowMaximized && child->isMaximized()) {
            if (q->updatesEnabled()) {
                updatesDisabledByUs = true;
                q->setUpdatesEnabled(false);
            }
            child->showNormal();
        }
        if (child->isMinimized() && !child->isShaded() && !windowStaysOnTop(child))
            child->lower();
        ignoreWindowStateChange = false;
        child->d_func()->setActive(false);
    }
}
 
void QMdiAreaPrivate::_q_processWindowStateChanged(Qt::WindowStates oldState,
                                                   Qt::WindowStates newState)
{
    if (ignoreWindowStateChange)
        return;
 
    Q_Q(QMdiArea);
    QMdiSubWindow *child = qobject_cast<QMdiSubWindow *>(q->sender());
    if (!child)
        return;
 
    // windowActivated
    if (!(oldState & Qt::WindowActive) && (newState & Qt::WindowActive))
        emitWindowActivated(child);
    // windowDeactivated
    else if ((oldState & Qt::WindowActive) && !(newState & Qt::WindowActive))
        resetActiveWindow(child);
 
    // windowMinimized
    if (!(oldState & Qt::WindowMinimized) && (newState & Qt::WindowMinimized)) {
        isSubWindowsTiled = false;
        arrangeMinimizedSubWindows();
    // windowMaximized
    } else if (!(oldState & Qt::WindowMaximized) && (newState & Qt::WindowMaximized)) {
        internalRaise(child);
    // windowRestored
    } else if (!(newState & (Qt::WindowMaximized | Qt::WindowMinimized))) {
        internalRaise(child);
        if (oldState & Qt::WindowMinimized)
            arrangeMinimizedSubWindows();
    }
}
 
void QMdiAreaPrivate::_q_currentTabChanged(int index)
{
#if !QT_CONFIG(tabbar)
    Q_UNUSED(index);
#else
    if (!tabBar || index < 0)
        return;
 
    // If the previous active sub-window was hidden, disable the tab.
    if (indexToLastActiveTab >= 0 && indexToLastActiveTab < tabBar->count()
        && indexToLastActiveTab < childWindows.size()) {
        QMdiSubWindow *lastActive = childWindows.at(indexToLastActiveTab);
        if (lastActive && lastActive->isHidden())
            tabBar->setTabEnabled(indexToLastActiveTab, false);
    }
 
    indexToLastActiveTab = index;
    Q_ASSERT(childWindows.size() > index);
    QMdiSubWindow *subWindow = childWindows.at(index);
    Q_ASSERT(subWindow);
    activateWindow(subWindow);
#endif // QT_CONFIG(tabbar)
}
 
void QMdiAreaPrivate::_q_closeTab(int index)
{
#if !QT_CONFIG(tabbar)
    Q_UNUSED(index);
#else
    QMdiSubWindow *subWindow = childWindows.at(index);
    Q_ASSERT(subWindow);
    subWindow->close();
#endif // QT_CONFIG(tabbar)
}
 
void QMdiAreaPrivate::_q_moveTab(int from, int to)
{
#if !QT_CONFIG(tabbar)
    Q_UNUSED(from);
    Q_UNUSED(to);
#else
    childWindows.move(from, to);
#endif // QT_CONFIG(tabbar)
}
 
void QMdiAreaPrivate::appendChild(QMdiSubWindow *child)
{
    Q_Q(QMdiArea);
    Q_ASSERT(child && childWindows.indexOf(child) == -1);
 
    if (child->parent() != viewport)
        child->setParent(viewport, child->windowFlags());
    childWindows.append(QPointer<QMdiSubWindow>(child));
 
    if (!child->testAttribute(Qt::WA_Resized) && q->isVisible()) {
        QSize newSize(child->sizeHint().boundedTo(viewport->size()));
        child->resize(newSize.expandedTo(qSmartMinSize(child)));
    }
 
    if (!placer)
        placer = new MinOverlapPlacer;
    place(placer, child);
 
    if (hbarpolicy != Qt::ScrollBarAlwaysOff)
        child->setOption(QMdiSubWindow::AllowOutsideAreaHorizontally, true);
    else
        child->setOption(QMdiSubWindow::AllowOutsideAreaHorizontally, false);
 
    if (vbarpolicy != Qt::ScrollBarAlwaysOff)
        child->setOption(QMdiSubWindow::AllowOutsideAreaVertically, true);
    else
        child->setOption(QMdiSubWindow::AllowOutsideAreaVertically, false);
 
    internalRaise(child);
    indicesToActivatedChildren.prepend(childWindows.size() - 1);
    Q_ASSERT(indicesToActivatedChildren.size() == childWindows.size());
 
#if QT_CONFIG(tabbar)
    if (tabBar) {
        tabBar->addTab(child->windowIcon(), tabTextFor(child));
        updateTabBarGeometry();
        if (childWindows.size() == 1 && !(options & QMdiArea::DontMaximizeSubWindowOnActivation))
            showActiveWindowMaximized = true;
    }
#endif
 
    if (!(child->windowFlags() & Qt::SubWindow))
        child->setWindowFlags(Qt::SubWindow);
    child->installEventFilter(q);
 
    QObject::connect(child, SIGNAL(aboutToActivate()), q, SLOT(_q_deactivateAllWindows()));
    QObject::connect(child, SIGNAL(windowStateChanged(Qt::WindowStates,Qt::WindowStates)),
                     q, SLOT(_q_processWindowStateChanged(Qt::WindowStates,Qt::WindowStates)));
}
 
void QMdiAreaPrivate::place(Placer *placer, QMdiSubWindow *child)
{
    if (!placer || !child)
        return;
 
    Q_Q(QMdiArea);
    if (!q->isVisible()) {
        // The window is only laid out when it's added to QMdiArea,
        // so there's no need to check that we don't have it in the
        // list already. appendChild() ensures that.
        pendingPlacements.append(child);
        return;
    }
 
    QList<QRect> rects;
    rects.reserve(childWindows.size());
    QRect parentRect = q->rect();
    for (QMdiSubWindow *window : std::as_const(childWindows)) {
        if (!sanityCheck(window, "QMdiArea::place") || window == child || !window->isVisibleTo(q)
                || !window->testAttribute(Qt::WA_Moved)) {
            continue;
        }
        QRect occupiedGeometry;
        if (window->isMaximized()) {
            occupiedGeometry = QRect(window->d_func()->oldGeometry.topLeft(),
                                     window->d_func()->restoreSize);
        } else {
            occupiedGeometry = window->geometry();
        }
        rects.append(QStyle::visualRect(child->layoutDirection(), parentRect, occupiedGeometry));
    }
    QPoint newPos = placer->place(child->size(), rects, parentRect);
    QRect newGeometry = QRect(newPos.x(), newPos.y(), child->width(), child->height());
    child->setGeometry(QStyle::visualRect(child->layoutDirection(), parentRect, newGeometry));
}
 
void QMdiAreaPrivate::rearrange(Rearranger *rearranger)
{
    if (!rearranger)
        return;
 
    Q_Q(QMdiArea);
    if (!q->isVisible()) {
        // Compress if we already have the rearranger in the list.
        int index = pendingRearrangements.indexOf(rearranger);
        if (index != -1)
            pendingRearrangements.move(index, pendingRearrangements.size() - 1);
        else
            pendingRearrangements.append(rearranger);
        return;
    }
 
    QList<QWidget *> widgets;
    const bool reverseList = rearranger->type() == Rearranger::RegularTiler;
    const QList<QMdiSubWindow *> subWindows = subWindowList(activationOrder, reverseList);
    QSize minSubWindowSize;
    for (QMdiSubWindow *child : subWindows) {
        if (!sanityCheck(child, "QMdiArea::rearrange") || !child->isVisible())
            continue;
        if (rearranger->type() == Rearranger::IconTiler) {
            if (child->isMinimized() && !child->isShaded())
                widgets.append(child);
        } else {
            if (child->isMinimized() && !child->isShaded())
                continue;
            if (child->isMaximized() || child->isShaded())
                child->showNormal();
            minSubWindowSize = minSubWindowSize.expandedTo(child->minimumSize())
                               .expandedTo(child->d_func()->internalMinimumSize);
            widgets.append(child);
        }
    }
 
    QRect domain = viewport->rect();
    if (rearranger->type() == Rearranger::RegularTiler && !widgets.isEmpty())
        domain = resizeToMinimumTileSize(minSubWindowSize, widgets.size());
 
    rearranger->rearrange(widgets, domain);
 
    if (rearranger->type() == Rearranger::RegularTiler && !widgets.isEmpty()) {
        isSubWindowsTiled = true;
        updateScrollBars();
    } else if (rearranger->type() == Rearranger::SimpleCascader) {
        isSubWindowsTiled = false;
    }
}
 
void QMdiAreaPrivate::arrangeMinimizedSubWindows()
{
    if (!iconTiler)
        iconTiler = new IconTiler;
    rearrange(iconTiler);
}
 
void QMdiAreaPrivate::activateWindow(QMdiSubWindow *child)
{
    if (childWindows.isEmpty()) {
        Q_ASSERT(!child);
        Q_ASSERT(!active);
        return;
    }
 
    if (!child) {
        if (active) {
            Q_ASSERT(active->d_func()->isActive);
            active->d_func()->setActive(false);
            resetActiveWindow();
        }
        return;
    }
 
    if (child->isHidden() || child == active)
        return;
 
    if (child->d_func()->isActive && active == nullptr)
        child->d_func()->isActive = false;
 
    child->d_func()->setActive(true);
}
 
void QMdiAreaPrivate::activateCurrentWindow()
{
    QMdiSubWindow *current = q_func()->currentSubWindow();
    if (current && !isExplicitlyDeactivated(current)) {
        current->d_func()->activationEnabled = true;
        current->d_func()->setActive(true, /*changeFocus=*/false);
    }
}
 
void QMdiAreaPrivate::activateHighlightedWindow()
{
    if (indexToHighlighted < 0)
        return;
 
    Q_ASSERT(indexToHighlighted < childWindows.size());
    if (tabToPreviousTimerId != -1)
        activateWindow(nextVisibleSubWindow(-1, QMdiArea::ActivationHistoryOrder));
    else
        activateWindow(childWindows.at(indexToHighlighted));
#if QT_CONFIG(rubberband)
    hideRubberBand();
#endif
}
 
void QMdiAreaPrivate::emitWindowActivated(QMdiSubWindow *activeWindow)
{
    Q_Q(QMdiArea);
    Q_ASSERT(activeWindow);
    if (activeWindow == active)
        return;
    Q_ASSERT(activeWindow->d_func()->isActive);
 
    if (!aboutToBecomeActive)
        _q_deactivateAllWindows(activeWindow);
    Q_ASSERT(aboutToBecomeActive);
 
    // This is true only if 'DontMaximizeSubWindowOnActivation' is disabled
    // and the previous active window was maximized.
    if (showActiveWindowMaximized) {
        if (!activeWindow->isMaximized())
            activeWindow->showMaximized();
        showActiveWindowMaximized = false;
    }
 
    // Put in front to update activation order.
    const int indexToActiveWindow = childWindows.indexOf(activeWindow);
    Q_ASSERT(indexToActiveWindow != -1);
    const int index = indicesToActivatedChildren.indexOf(indexToActiveWindow);
    Q_ASSERT(index != -1);
    indicesToActivatedChildren.move(index, 0);
    internalRaise(activeWindow);
 
    if (updatesDisabledByUs) {
        q->setUpdatesEnabled(true);
        updatesDisabledByUs = false;
    }
 
    Q_ASSERT(aboutToBecomeActive == activeWindow);
    active = activeWindow;
    aboutToBecomeActive = nullptr;
    Q_ASSERT(active->d_func()->isActive);
 
#if QT_CONFIG(tabbar)
    if (tabBar && tabBar->currentIndex() != indexToActiveWindow)
        tabBar->setCurrentIndex(indexToActiveWindow);
#endif
 
    if (active->isMaximized() && scrollBarsEnabled())
        updateScrollBars();
 
    emit q->subWindowActivated(active);
}
 
void QMdiAreaPrivate::resetActiveWindow(QMdiSubWindow *deactivatedWindow)
{
    Q_Q(QMdiArea);
    if (deactivatedWindow) {
        if (deactivatedWindow != active)
            return;
        active = nullptr;
        if ((aboutToBecomeActive || isActivated || lastWindowAboutToBeDestroyed())
            && !isExplicitlyDeactivated(deactivatedWindow) && !q->window()->isMinimized()) {
            return;
        }
        emit q->subWindowActivated(nullptr);
        return;
    }
 
    if (aboutToBecomeActive)
        return;
 
    active = nullptr;
    emit q->subWindowActivated(nullptr);
}
 
void QMdiAreaPrivate::updateActiveWindow(int removedIndex, bool activeRemoved)
{
    Q_ASSERT(indicesToActivatedChildren.size() == childWindows.size());
 
#if QT_CONFIG(tabbar)
    if (tabBar && removedIndex >= 0) {
        const QSignalBlocker blocker(tabBar);
        tabBar->removeTab(removedIndex);
        updateTabBarGeometry();
    }
#endif
 
    if (childWindows.isEmpty()) {
        showActiveWindowMaximized = false;
        resetActiveWindow();
        return;
    }
 
    if (indexToHighlighted >= 0) {
#if QT_CONFIG(rubberband)
        // Hide rubber band if highlighted window is removed.
        if (indexToHighlighted == removedIndex)
            hideRubberBand();
        else
#endif
        // or update index if necessary.
        if (indexToHighlighted > removedIndex)
            --indexToHighlighted;
    }
 
    // Update indices list
    for (int i = 0; i < indicesToActivatedChildren.size(); ++i) {
        int *index = &indicesToActivatedChildren[i];
        if (*index > removedIndex)
            --*index;
    }
 
    if (!activeRemoved)
        return;
 
    // Activate next window.
    QMdiSubWindow *next = nextVisibleSubWindow(0, activationOrder, removedIndex);
    if (next)
        activateWindow(next);
}
 
void QMdiAreaPrivate::updateScrollBars()
{
    if (ignoreGeometryChange || !scrollBarsEnabled())
        return;
 
    Q_Q(QMdiArea);
    QSize maxSize = q->maximumViewportSize();
    QSize hbarExtent = hbar->sizeHint();
    QSize vbarExtent = vbar->sizeHint();
 
    if (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, nullptr, q)) {
        const int doubleFrameWidth = frameWidth * 2;
        if (hbarpolicy == Qt::ScrollBarAlwaysOn)
            maxSize.rheight() -= doubleFrameWidth;
        if (vbarpolicy == Qt::ScrollBarAlwaysOn)
            maxSize.rwidth() -= doubleFrameWidth;
        hbarExtent.rheight() += doubleFrameWidth;
        vbarExtent.rwidth() += doubleFrameWidth;
    }
 
    const QRect childrenRect = active && active->isMaximized()
                               ? active->geometry() : viewport->childrenRect();
    bool useHorizontalScrollBar = useScrollBar(childrenRect, maxSize, Qt::Horizontal);
    bool useVerticalScrollBar = useScrollBar(childrenRect, maxSize, Qt::Vertical);
 
    if (useHorizontalScrollBar && !useVerticalScrollBar) {
        const QSize max = maxSize - QSize(0, hbarExtent.height());
        useVerticalScrollBar = useScrollBar(childrenRect, max, Qt::Vertical);
    }
 
    if (useVerticalScrollBar && !useHorizontalScrollBar) {
        const QSize max = maxSize - QSize(vbarExtent.width(), 0);
        useHorizontalScrollBar = useScrollBar(childrenRect, max, Qt::Horizontal);
    }
 
    if (useHorizontalScrollBar && hbarpolicy != Qt::ScrollBarAlwaysOn)
        maxSize.rheight() -= hbarExtent.height();
    if (useVerticalScrollBar && vbarpolicy != Qt::ScrollBarAlwaysOn)
        maxSize.rwidth() -= vbarExtent.width();
 
    QRect viewportRect(QPoint(0, 0), maxSize);
    const int startX = q->isLeftToRight() ? childrenRect.left() : viewportRect.right()
                                                                  - childrenRect.right();
 
    // Horizontal scroll bar.
    if (isSubWindowsTiled && hbar->value() != 0)
        hbar->setValue(0);
    const int xOffset = startX + hbar->value();
    hbar->setRange(qMin(0, xOffset),
                   qMax(0, xOffset + childrenRect.width() - viewportRect.width()));
    hbar->setPageStep(childrenRect.width());
    hbar->setSingleStep(childrenRect.width() / 20);
 
    // Vertical scroll bar.
    if (isSubWindowsTiled && vbar->value() != 0)
        vbar->setValue(0);
    const int yOffset = childrenRect.top() + vbar->value();
    vbar->setRange(qMin(0, yOffset),
                   qMax(0, yOffset + childrenRect.height() - viewportRect.height()));
    vbar->setPageStep(childrenRect.height());
    vbar->setSingleStep(childrenRect.height() / 20);
}
 
void QMdiAreaPrivate::internalRaise(QMdiSubWindow *mdiChild) const
{
    if (!sanityCheck(mdiChild, "QMdiArea::internalRaise") || childWindows.size() < 2)
        return;
 
    QMdiSubWindow *stackUnderChild = nullptr;
    if (!windowStaysOnTop(mdiChild)) {
        const auto children = viewport->children(); // take a copy, as raising/stacking under changes the order
        for (QObject *object : children) {
            QMdiSubWindow *child = qobject_cast<QMdiSubWindow *>(object);
            if (!child || !childWindows.contains(child))
                continue;
            if (!child->isHidden() && windowStaysOnTop(child)) {
                if (stackUnderChild)
                    child->stackUnder(stackUnderChild);
                else
                    child->raise();
                stackUnderChild = child;
            }
        }
    }
 
    if (stackUnderChild)
        mdiChild->stackUnder(stackUnderChild);
    else
        mdiChild->raise();
}
 
QRect QMdiAreaPrivate::resizeToMinimumTileSize(const QSize &minSubWindowSize, int subWindowCount)
{
    Q_Q(QMdiArea);
    if (!minSubWindowSize.isValid() || subWindowCount <= 0)
        return viewport->rect();
 
    // Calculate minimum size.
    const int columns = qMax(qCeil(qSqrt(qreal(subWindowCount))), 1);
    const int rows = qMax((subWindowCount % columns) ? (subWindowCount / columns + 1)
                                                     : (subWindowCount / columns), 1);
    const int minWidth = minSubWindowSize.width() * columns;
    const int minHeight = minSubWindowSize.height() * rows;
 
    // Increase area size if necessary. Scroll bars are provided if we're not able
    // to resize to the minimum size.
    if (!tileCalledFromResizeEvent) {
        QWidget *topLevel = q;
        // Find the topLevel for this area, either a real top-level or a sub-window.
        while (topLevel && !topLevel->isWindow() && topLevel->windowType() != Qt::SubWindow)
            topLevel = topLevel->parentWidget();
        // We don't want sub-subwindows to be placed at the edge, thus add 2 pixels.
        int minAreaWidth = minWidth + left + right + 2;
        int minAreaHeight = minHeight + top + bottom + 2;
        if (hbar->isVisible())
            minAreaHeight += hbar->height();
        if (vbar->isVisible())
            minAreaWidth += vbar->width();
        if (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, nullptr, q)) {
            const int frame = q->style()->pixelMetric(QStyle::PM_DefaultFrameWidth, nullptr, q);
            minAreaWidth += 2 * frame;
            minAreaHeight += 2 * frame;
        }
        const QSize diff = QSize(minAreaWidth, minAreaHeight).expandedTo(q->size()) - q->size();
        // Only resize topLevel widget if scroll bars are disabled.
        if (hbarpolicy == Qt::ScrollBarAlwaysOff)
            topLevel->resize(topLevel->size().width() + diff.width(), topLevel->size().height());
        if (vbarpolicy == Qt::ScrollBarAlwaysOff)
            topLevel->resize(topLevel->size().width(), topLevel->size().height() + diff.height());
    }
 
    QRect domain = viewport->rect();
 
    // Adjust domain width and provide horizontal scroll bar.
    if (domain.width() < minWidth) {
        domain.setWidth(minWidth);
        if (hbarpolicy == Qt::ScrollBarAlwaysOff)
            q->setHorizontalScrollBarPolicy(Qt::ScrollBarAsNeeded);
        else
            hbar->setValue(0);
    }
    // Adjust domain height and provide vertical scroll bar.
    if (domain.height() < minHeight) {
        domain.setHeight(minHeight);
        if (vbarpolicy  == Qt::ScrollBarAlwaysOff)
            q->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded);
        else
            vbar->setValue(0);
    }
    return domain;
}
 
bool QMdiAreaPrivate::scrollBarsEnabled() const
{
    return hbarpolicy != Qt::ScrollBarAlwaysOff || vbarpolicy != Qt::ScrollBarAlwaysOff;
}
 
bool QMdiAreaPrivate::lastWindowAboutToBeDestroyed() const
{
    if (childWindows.size() != 1)
        return false;
 
    QMdiSubWindow *last = childWindows.at(0);
    if (!last)
        return true;
 
    if (!last->testAttribute(Qt::WA_DeleteOnClose))
        return false;
 
    return last->d_func()->data.is_closing;
}
 
void QMdiAreaPrivate::setChildActivationEnabled(bool enable, bool onlyNextActivationEvent) const
{
    for (QMdiSubWindow *subWindow : childWindows) {
        if (!subWindow || !subWindow->isVisible())
            continue;
        if (onlyNextActivationEvent)
            subWindow->d_func()->ignoreNextActivationEvent = !enable;
        else
            subWindow->d_func()->activationEnabled = enable;
    }
}
 
void QMdiAreaPrivate::scrollBarPolicyChanged(Qt::Orientation orientation, Qt::ScrollBarPolicy policy)
{
    if (childWindows.isEmpty())
        return;
 
    const QMdiSubWindow::SubWindowOption option = orientation == Qt::Horizontal ?
        QMdiSubWindow::AllowOutsideAreaHorizontally : QMdiSubWindow::AllowOutsideAreaVertically;
    const bool enable = policy != Qt::ScrollBarAlwaysOff;
    // Take a copy because child->setOption() may indirectly call QCoreApplication::sendEvent(),
    // the latter could call unknown code that could e.g. recurse into the class
    // modifying childWindows.
    const auto subWindows = childWindows;
    for (QMdiSubWindow *child : subWindows) {
        if (!sanityCheck(child, "QMdiArea::scrollBarPolicyChanged"))
            continue;
        child->setOption(option, enable);
    }
    updateScrollBars();
}
 
QList<QMdiSubWindow*>
QMdiAreaPrivate::subWindowList(QMdiArea::WindowOrder order, bool reversed) const
{
    QList<QMdiSubWindow *> list;
    if (childWindows.isEmpty())
        return list;
 
    if (order == QMdiArea::CreationOrder) {
        for (QMdiSubWindow *child : childWindows) {
            if (!child)
                continue;
            if (!reversed)
                list.append(child);
            else
                list.prepend(child);
        }
    } else if (order == QMdiArea::StackingOrder) {
        for (QObject *object : viewport->children()) {
            QMdiSubWindow *child = qobject_cast<QMdiSubWindow *>(object);
            if (!child || !childWindows.contains(child))
                continue;
            if (!reversed)
                list.append(child);
            else
                list.prepend(child);
        }
    } else { // ActivationHistoryOrder
        Q_ASSERT(indicesToActivatedChildren.size() == childWindows.size());
        for (int i = indicesToActivatedChildren.size() - 1; i >= 0; --i) {
            QMdiSubWindow *child = childWindows.at(indicesToActivatedChildren.at(i));
            if (!child)
                continue;
            if (!reversed)
                list.append(child);
            else
                list.prepend(child);
        }
    }
    return list;
}
 
void QMdiAreaPrivate::disconnectSubWindow(QObject *subWindow)
{
    if (!subWindow)
        return;
 
    Q_Q(QMdiArea);
    QObject::disconnect(subWindow, nullptr, q, nullptr);
    subWindow->removeEventFilter(q);
}
 
QMdiSubWindow *QMdiAreaPrivate::nextVisibleSubWindow(int increaseFactor, QMdiArea::WindowOrder order,
                                                     int removedIndex, int fromIndex) const
{
    if (childWindows.isEmpty())
        return nullptr;
 
    Q_Q(const QMdiArea);
    const QList<QMdiSubWindow *> subWindows = q->subWindowList(order);
    QMdiSubWindow *current = nullptr;
 
    if (removedIndex < 0) {
        if (fromIndex >= 0 && fromIndex < subWindows.size())
            current = childWindows.at(fromIndex);
        else
            current = q->currentSubWindow();
    }
 
    // There's no current sub-window (removed or deactivated),
    // so we have to pick the last active or the next in creation order.
    if (!current) {
        if (removedIndex >= 0 && order == QMdiArea::CreationOrder) {
            int candidateIndex = -1;
            setIndex(&candidateIndex, removedIndex, 0, subWindows.size() - 1, true);
            current = childWindows.at(candidateIndex);
        } else {
            current = subWindows.back();
        }
    }
    Q_ASSERT(current);
 
    // Find the index for the current sub-window in the given activation order
    const int indexToCurrent = subWindows.indexOf(current);
    const bool increasing = increaseFactor > 0;
 
    // and use that index + increseFactor as a candidate.
    int index = -1;
    setIndex(&index, indexToCurrent + increaseFactor, 0, subWindows.size() - 1, increasing);
    Q_ASSERT(index != -1);
 
    // Try to find another window if the candidate is hidden.
    while (subWindows.at(index)->isHidden()) {
        setIndex(&index, index + increaseFactor, 0, subWindows.size() - 1, increasing);
        if (index == indexToCurrent)
            break;
    }
 
    if (!subWindows.at(index)->isHidden())
        return subWindows.at(index);
    return nullptr;
}
 
void QMdiAreaPrivate::highlightNextSubWindow(int increaseFactor)
{
    if (childWindows.size() == 1)
        return;
 
    Q_Q(QMdiArea);
    // There's no highlighted sub-window atm, use current.
    if (indexToHighlighted < 0) {
        QMdiSubWindow *current = q->currentSubWindow();
        if (!current)
            return;
        indexToHighlighted = childWindows.indexOf(current);
    }
 
    Q_ASSERT(indexToHighlighted >= 0);
    Q_ASSERT(indexToHighlighted < childWindows.size());
 
    QMdiSubWindow *highlight = nextVisibleSubWindow(increaseFactor, activationOrder, -1, indexToHighlighted);
    if (!highlight)
        return;
 
#if QT_CONFIG(rubberband)
    if (!rubberBand) {
        rubberBand = new QRubberBand(QRubberBand::Rectangle, q);
        // For accessibility to identify this special widget.
        rubberBand->setObjectName("qt_rubberband"_L1);
        rubberBand->setWindowFlags(rubberBand->windowFlags() | Qt::WindowStaysOnTopHint);
    }
#endif
 
    // Only highlight if we're not switching back to the previously active window (Ctrl-Tab once).
#if QT_CONFIG(rubberband)
    if (tabToPreviousTimerId == -1)
        showRubberBandFor(highlight);
#endif
 
    indexToHighlighted = childWindows.indexOf(highlight);
    Q_ASSERT(indexToHighlighted >= 0);
}
 
#if QT_CONFIG(rubberband)
void QMdiAreaPrivate::showRubberBandFor(QMdiSubWindow *subWindow)
{
    if (!subWindow || !rubberBand)
        return;
 
#if QT_CONFIG(tabbar)
    if (viewMode == QMdiArea::TabbedView)
        rubberBand->setGeometry(tabBar->tabRect(childWindows.indexOf(subWindow)));
    else
#endif
        rubberBand->setGeometry(subWindow->geometry());
 
    rubberBand->raise();
    rubberBand->show();
}
#endif // QT_CONFIG(rubberBand)
void QMdiAreaPrivate::setViewMode(QMdiArea::ViewMode mode)
{
    Q_Q(QMdiArea);
    if (viewMode == mode || inViewModeChange)
        return;
 
    // Just a guard since we cannot set viewMode = mode here.
    inViewModeChange = true;
 
#if QT_CONFIG(tabbar)
    if (mode == QMdiArea::TabbedView) {
        Q_ASSERT(!tabBar);
        tabBar = new QMdiAreaTabBar(q);
        tabBar->setDocumentMode(documentMode);
        tabBar->setTabsClosable(tabsClosable);
        tabBar->setMovable(tabsMovable);
#if QT_CONFIG(tabwidget)
        tabBar->setShape(_q_tb_tabBarShapeFrom(tabShape, tabPosition));
#endif
 
        isSubWindowsTiled = false;
 
        // Take a copy as tabBar->addTab() will (indirectly) create a connection between
        // the tab close button clicked() signal and the _q_closeTab() slot, which may
        // indirectly call QCoreApplication::sendEvent(), the latter could result in
        // invoking unknown code that could e.g. recurse into the class modifying childWindows.
        const auto subWindows = childWindows;
        for (QMdiSubWindow *subWindow : subWindows)
            tabBar->addTab(subWindow->windowIcon(), tabTextFor(subWindow));
 
        QMdiSubWindow *current = q->currentSubWindow();
        if (current) {
            tabBar->setCurrentIndex(childWindows.indexOf(current));
            // Restore sub-window (i.e. cleanup buttons in menu bar and window title).
            if (current->isMaximized())
                current->showNormal();
 
            viewMode = mode;
 
            // Now, maximize it.
            if (!q->testOption(QMdiArea::DontMaximizeSubWindowOnActivation)) {
                current->showMaximized();
            }
        } else {
            viewMode = mode;
        }
 
        if (q->isVisible())
            tabBar->show();
        updateTabBarGeometry();
 
        QObject::connect(tabBar, SIGNAL(currentChanged(int)), q, SLOT(_q_currentTabChanged(int)));
        QObject::connect(tabBar, SIGNAL(tabCloseRequested(int)), q, SLOT(_q_closeTab(int)));
        QObject::connect(tabBar, SIGNAL(tabMoved(int,int)), q, SLOT(_q_moveTab(int,int)));
    } else
#endif // QT_CONFIG(tabbar)
    { // SubWindowView
#if QT_CONFIG(tabbar)
        delete tabBar;
        tabBar = nullptr;
#endif // QT_CONFIG(tabbar)
 
        viewMode = mode;
        q->setViewportMargins(0, 0, 0, 0);
        indexToLastActiveTab = -1;
 
        QMdiSubWindow *current = q->currentSubWindow();
        if (current && current->isMaximized())
            current->showNormal();
    }
 
    Q_ASSERT(viewMode == mode);
    inViewModeChange = false;
}
 
#if QT_CONFIG(tabbar)
void QMdiAreaPrivate::updateTabBarGeometry()
{
    if (!tabBar)
        return;
 
    Q_Q(QMdiArea);
#if QT_CONFIG(tabwidget)
    Q_ASSERT(_q_tb_tabBarShapeFrom(tabShape, tabPosition) == tabBar->shape());
#endif
    const QSize tabBarSizeHint = tabBar->sizeHint();
 
    int areaHeight = q->height();
    if (hbar && hbar->isVisible())
        areaHeight -= hbar->height();
 
    int areaWidth = q->width();
    if (vbar && vbar->isVisible())
        areaWidth -= vbar->width();
 
    QRect tabBarRect;
#if QT_CONFIG(tabwidget)
    switch (tabPosition) {
    case QTabWidget::North:
        q->setViewportMargins(0, tabBarSizeHint.height(), 0, 0);
        tabBarRect = QRect(0, 0, areaWidth, tabBarSizeHint.height());
        break;
    case QTabWidget::South:
        q->setViewportMargins(0, 0, 0, tabBarSizeHint.height());
        tabBarRect = QRect(0, areaHeight - tabBarSizeHint.height(), areaWidth, tabBarSizeHint.height());
        break;
    case QTabWidget::East:
        if (q->layoutDirection() == Qt::LeftToRight)
            q->setViewportMargins(0, 0, tabBarSizeHint.width(), 0);
        else
            q->setViewportMargins(tabBarSizeHint.width(), 0, 0, 0);
        tabBarRect = QRect(areaWidth - tabBarSizeHint.width(), 0, tabBarSizeHint.width(), areaHeight);
        break;
    case QTabWidget::West:
        if (q->layoutDirection() == Qt::LeftToRight)
            q->setViewportMargins(tabBarSizeHint.width(), 0, 0, 0);
        else
            q->setViewportMargins(0, 0, tabBarSizeHint.width(), 0);
        tabBarRect = QRect(0, 0, tabBarSizeHint.width(), areaHeight);
        break;
    default:
        break;
    }
#endif // QT_CONFIG(tabwidget)
 
    tabBar->setGeometry(QStyle::visualRect(q->layoutDirection(), q->contentsRect(), tabBarRect));
}
 
void QMdiAreaPrivate::refreshTabBar()
{
    if (!tabBar)
        return;
 
    tabBar->setDocumentMode(documentMode);
    tabBar->setTabsClosable(tabsClosable);
    tabBar->setMovable(tabsMovable);
#if QT_CONFIG(tabwidget)
    tabBar->setShape(_q_tb_tabBarShapeFrom(tabShape, tabPosition));
#endif
    updateTabBarGeometry();
}
#endif // QT_CONFIG(tabbar)
 
QMdiArea::QMdiArea(QWidget *parent)
    : QAbstractScrollArea(*new QMdiAreaPrivate, parent)
{
    setBackground(palette().brush(QPalette::Dark));
    setFrameStyle(QFrame::NoFrame);
    setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setViewport(nullptr);
    setFocusPolicy(Qt::NoFocus);
    QApplication::instance()->installEventFilter(this);
}
 
QMdiArea::~QMdiArea()
{
    Q_D(QMdiArea);
    delete d->cascader;
    d->cascader = nullptr;
 
    delete d->regularTiler;
    d->regularTiler = nullptr;
 
    delete d->iconTiler;
    d->iconTiler = nullptr;
 
    delete d->placer;
    d->placer = nullptr;
}
 
QSize QMdiArea::sizeHint() const
{
    // Calculate a proper scale factor for the desktop's size.
    // This also takes into account that we can have nested workspaces.
    int nestedCount = 0;
    QWidget *widget = this->parentWidget();
    while (widget) {
        if (qobject_cast<QMdiArea *>(widget))
            ++nestedCount;
        widget = widget->parentWidget();
    }
    const int scaleFactor = 3 * (nestedCount + 1);
 
    QSize desktopSize = QGuiApplication::primaryScreen()->virtualSize();
    QSize size(desktopSize.width() * 2 / scaleFactor, desktopSize.height() * 2 / scaleFactor);
    for (QMdiSubWindow *child : d_func()->childWindows) {
        if (!sanityCheck(child, "QMdiArea::sizeHint"))
            continue;
        size = size.expandedTo(child->sizeHint());
    }
    return size;
}
 
QSize QMdiArea::minimumSizeHint() const
{
    Q_D(const QMdiArea);
    QSize size(style()->pixelMetric(QStyle::PM_MdiSubWindowMinimizedWidth, nullptr, this),
               style()->pixelMetric(QStyle::PM_TitleBarHeight, nullptr, this));
    size = size.expandedTo(QAbstractScrollArea::minimumSizeHint());
    if (!d->scrollBarsEnabled()) {
        for (QMdiSubWindow *child : d->childWindows) {
            if (!sanityCheck(child, "QMdiArea::sizeHint"))
                continue;
            size = size.expandedTo(child->minimumSizeHint());
        }
    }
    return size;
}
 
QMdiSubWindow *QMdiArea::currentSubWindow() const
{
    Q_D(const QMdiArea);
    if (d->childWindows.isEmpty())
        return nullptr;
 
    if (d->active)
        return d->active;
 
    if (d->isActivated && !window()->isMinimized())
        return nullptr;
 
    Q_ASSERT(d->indicesToActivatedChildren.size() > 0);
    int index = d->indicesToActivatedChildren.at(0);
    Q_ASSERT(index >= 0 && index < d->childWindows.size());
    QMdiSubWindow *current = d->childWindows.at(index);
    Q_ASSERT(current);
    return current;
}
 
QMdiSubWindow *QMdiArea::activeSubWindow() const
{
    Q_D(const QMdiArea);
    return d->active;
}
 
void QMdiArea::setActiveSubWindow(QMdiSubWindow *window)
{
    Q_D(QMdiArea);
    if (!window) {
        d->activateWindow(nullptr);
        return;
    }
 
    if (Q_UNLIKELY(d->childWindows.isEmpty())) {
        qWarning("QMdiArea::setActiveSubWindow: workspace is empty");
        return;
    }
 
    if (Q_UNLIKELY(d->childWindows.indexOf(window) == -1)) {
        qWarning("QMdiArea::setActiveSubWindow: window is not inside workspace");
        return;
    }
 
    d->activateWindow(window);
}
 
void QMdiArea::closeActiveSubWindow()
{
    Q_D(QMdiArea);
    if (d->active)
        d->active->close();
}
 
QList<QMdiSubWindow *> QMdiArea::subWindowList(WindowOrder order) const
{
    Q_D(const QMdiArea);
    return d->subWindowList(order, false);
}
 
void QMdiArea::closeAllSubWindows()
{
    Q_D(QMdiArea);
    if (d->childWindows.isEmpty())
        return;
 
    d->isSubWindowsTiled = false;
    // Take a copy because the child->close() call below may end up indirectly calling
    // QCoreApplication::send{Spontaneous}Event(), which may call unknown code that
    // could e.g. recurse into the class modifying d->childWindows.
    const auto subWindows = d->childWindows;
    for (QMdiSubWindow *child : subWindows) {
        if (!sanityCheck(child, "QMdiArea::closeAllSubWindows"))
            continue;
        child->close();
    }
 
    d->updateScrollBars();
}
 
void QMdiArea::activateNextSubWindow()
{
    Q_D(QMdiArea);
    if (d->childWindows.isEmpty())
        return;
 
    QMdiSubWindow *next = d->nextVisibleSubWindow(1, d->activationOrder);
    if (next)
        d->activateWindow(next);
}
 
void QMdiArea::activatePreviousSubWindow()
{
    Q_D(QMdiArea);
    if (d->childWindows.isEmpty())
        return;
 
    QMdiSubWindow *previous = d->nextVisibleSubWindow(-1, d->activationOrder);
    if (previous)
        d->activateWindow(previous);
}
 
QMdiSubWindow *QMdiArea::addSubWindow(QWidget *widget, Qt::WindowFlags windowFlags)
{
    if (Q_UNLIKELY(!widget)) {
        qWarning("QMdiArea::addSubWindow: null pointer to widget");
        return nullptr;
    }
 
    Q_D(QMdiArea);
    // QWidget::setParent clears focusWidget so store it
    QWidget *childFocus = widget->focusWidget();
    QMdiSubWindow *child = qobject_cast<QMdiSubWindow *>(widget);
 
    // Widget is already a QMdiSubWindow
    if (child) {
        if (Q_UNLIKELY(d->childWindows.indexOf(child) != -1)) {
            qWarning("QMdiArea::addSubWindow: window is already added");
            return child;
        }
        child->setParent(viewport(), windowFlags ? windowFlags : child->windowFlags());
    // Create a QMdiSubWindow
    } else {
        child = new QMdiSubWindow(viewport(), windowFlags);
        child->setAttribute(Qt::WA_DeleteOnClose);
        child->setWidget(widget);
        Q_ASSERT(child->testAttribute(Qt::WA_DeleteOnClose));
    }
 
    d->appendChild(child);
 
    if (childFocus)
        childFocus->setFocus();
 
    return child;
}
 
void QMdiArea::removeSubWindow(QWidget *widget)
{
    if (Q_UNLIKELY(!widget)) {
        qWarning("QMdiArea::removeSubWindow: null pointer to widget");
        return;
    }
 
    Q_D(QMdiArea);
    if (d->childWindows.isEmpty())
        return;
 
    if (QMdiSubWindow *child = qobject_cast<QMdiSubWindow *>(widget)) {
        int index = d->childWindows.indexOf(child);
        if (Q_UNLIKELY(index == -1)) {
            qWarning("QMdiArea::removeSubWindow: window is not inside workspace");
            return;
        }
        d->disconnectSubWindow(child);
        d->childWindows.removeAll(child);
        d->indicesToActivatedChildren.removeAll(index);
        d->updateActiveWindow(index, d->active == child);
        child->setParent(nullptr);
        return;
    }
 
    bool found = false;
    // Take a copy because child->setWidget(nullptr) will indirectly
    // QCoreApplication::sendEvent(); the latter could call unknown code that could
    // e.g. recurse into the class modifying d->childWindows.
    const auto subWindows = d->childWindows;
    for (QMdiSubWindow *child : subWindows) {
        if (!sanityCheck(child, "QMdiArea::removeSubWindow"))
            continue;
        if (child->widget() == widget) {
            child->setWidget(nullptr);
            Q_ASSERT(!child->widget());
            found = true;
            break;
        }
    }
 
    if (Q_UNLIKELY(!found))
        qWarning("QMdiArea::removeSubWindow: widget is not child of any window inside QMdiArea");
}
 
QBrush QMdiArea::background() const
{
    return d_func()->background;
}
 
void QMdiArea::setBackground(const QBrush &brush)
{
    Q_D(QMdiArea);
    if (d->background != brush) {
        d->background = brush;
        d->viewport->setAttribute(Qt::WA_OpaquePaintEvent, brush.isOpaque());
        d->viewport->update();
    }
}
 
 
QMdiArea::WindowOrder QMdiArea::activationOrder() const
{
    Q_D(const QMdiArea);
    return d->activationOrder;
}
 
void QMdiArea::setActivationOrder(WindowOrder order)
{
    Q_D(QMdiArea);
    if (order != d->activationOrder)
        d->activationOrder = order;
}
 
void QMdiArea::setOption(AreaOption option, bool on)
{
    Q_D(QMdiArea);
    d->options.setFlag(option, on);
}
 
bool QMdiArea::testOption(AreaOption option) const
{
    return d_func()->options & option;
}
 
QMdiArea::ViewMode QMdiArea::viewMode() const
{
    Q_D(const QMdiArea);
    return d->viewMode;
}
 
void QMdiArea::setViewMode(ViewMode mode)
{
    Q_D(QMdiArea);
    d->setViewMode(mode);
}
 
#if QT_CONFIG(tabbar)
bool QMdiArea::documentMode() const
{
    Q_D(const QMdiArea);
    return d->documentMode;
}
 
void QMdiArea::setDocumentMode(bool enabled)
{
    Q_D(QMdiArea);
    if (d->documentMode == enabled)
        return;
 
    d->documentMode = enabled;
    d->refreshTabBar();
}
 
bool QMdiArea::tabsClosable() const
{
    Q_D(const QMdiArea);
    return d->tabsClosable;
}
 
void QMdiArea::setTabsClosable(bool closable)
{
    Q_D(QMdiArea);
    if (d->tabsClosable == closable)
        return;
 
    d->tabsClosable = closable;
    d->refreshTabBar();
}
 
bool QMdiArea::tabsMovable() const
{
    Q_D(const QMdiArea);
    return d->tabsMovable;
}
 
void QMdiArea::setTabsMovable(bool movable)
{
    Q_D(QMdiArea);
    if (d->tabsMovable == movable)
        return;
 
    d->tabsMovable = movable;
    d->refreshTabBar();
}
#endif // QT_CONFIG(tabbar)
 
#if QT_CONFIG(tabwidget)
QTabWidget::TabShape QMdiArea::tabShape() const
{
    Q_D(const QMdiArea);
    return d->tabShape;
}
 
void QMdiArea::setTabShape(QTabWidget::TabShape shape)
{
    Q_D(QMdiArea);
    if (d->tabShape == shape)
        return;
 
    d->tabShape = shape;
    d->refreshTabBar();
}
 
QTabWidget::TabPosition QMdiArea::tabPosition() const
{
    Q_D(const QMdiArea);
    return d->tabPosition;
}
 
void QMdiArea::setTabPosition(QTabWidget::TabPosition position)
{
    Q_D(QMdiArea);
    if (d->tabPosition == position)
        return;
 
    d->tabPosition = position;
    d->refreshTabBar();
}
#endif // QT_CONFIG(tabwidget)
 
void QMdiArea::childEvent(QChildEvent *childEvent)
{
    Q_D(QMdiArea);
    if (childEvent->type() == QEvent::ChildPolished) {
        if (QMdiSubWindow *mdiChild = qobject_cast<QMdiSubWindow *>(childEvent->child())) {
            if (d->childWindows.indexOf(mdiChild) == -1)
                d->appendChild(mdiChild);
        }
    }
}
 
void QMdiArea::resizeEvent(QResizeEvent *resizeEvent)
{
    Q_D(QMdiArea);
    if (d->childWindows.isEmpty()) {
        resizeEvent->ignore();
        return;
    }
 
#if QT_CONFIG(tabbar)
    d->updateTabBarGeometry();
#endif
 
    // Re-tile the views if we're in tiled mode. Re-tile means we will change
    // the geometry of the children, which in turn means 'isSubWindowsTiled'
    // is set to false, so we have to update the state at the end.
    if (d->isSubWindowsTiled) {
        d->tileCalledFromResizeEvent = true;
        tileSubWindows();
        d->tileCalledFromResizeEvent = false;
        d->isSubWindowsTiled = true;
        d->startResizeTimer();
        // We don't have scroll bars or any maximized views.
        return;
    }
 
    // Resize maximized views.
    bool hasMaximizedSubWindow = false;
    // Take a copy because child->resize() may call QCoreApplication::sendEvent()
    // which may invoke unknown code, that could e.g. recurse into the class
    // modifying d->childWindows.
    const auto subWindows = d->childWindows;
    for (QMdiSubWindow *child : subWindows) {
        if (sanityCheck(child, "QMdiArea::resizeEvent") && child->isMaximized()
                && child->size() != resizeEvent->size()) {
            auto realSize = resizeEvent->size();
            const auto minSizeHint = child->minimumSizeHint();
            // QMdiSubWindow is no tlw so minimumSize() is not set by the layout manager
            // and therefore we have to take care by ourself that we're not getting smaller
            // than allowed
            if (minSizeHint.isValid())
                realSize = realSize.expandedTo(minSizeHint);
            child->resize(realSize);
            if (!hasMaximizedSubWindow)
                hasMaximizedSubWindow = true;
        }
    }
 
    d->updateScrollBars();
 
    // Minimized views are stacked under maximized views so there's
    // no need to re-arrange minimized views on-demand. Start a timer
    // just to make things faster with subsequent resize events.
    if (hasMaximizedSubWindow)
        d->startResizeTimer();
    else
        d->arrangeMinimizedSubWindows();
}
 
void QMdiArea::timerEvent(QTimerEvent *timerEvent)
{
    Q_D(QMdiArea);
    if (timerEvent->timerId() == d->resizeTimerId) {
        killTimer(d->resizeTimerId);
        d->resizeTimerId = -1;
        d->arrangeMinimizedSubWindows();
    } else if (timerEvent->timerId() == d->tabToPreviousTimerId) {
        killTimer(d->tabToPreviousTimerId);
        d->tabToPreviousTimerId = -1;
        if (d->indexToHighlighted < 0)
            return;
#if QT_CONFIG(rubberband)
        // We're not doing a "quick switch" ... show rubber band.
        Q_ASSERT(d->indexToHighlighted < d->childWindows.size());
        Q_ASSERT(d->rubberBand);
        d->showRubberBandFor(d->childWindows.at(d->indexToHighlighted));
#endif
    }
}
 
void QMdiArea::showEvent(QShowEvent *showEvent)
{
    Q_D(QMdiArea);
    if (!d->pendingRearrangements.isEmpty()) {
        bool skipPlacement = false;
        // Take a copy because d->rearrange() may modify d->pendingRearrangements
        const auto pendingRearrange = d->pendingRearrangements;
        for (Rearranger *rearranger : pendingRearrange) {
            // If this is the case, we don't have to lay out pending child windows
            // since the rearranger will find a placement for them.
            if (rearranger->type() != Rearranger::IconTiler && !skipPlacement)
                skipPlacement = true;
            d->rearrange(rearranger);
        }
        d->pendingRearrangements.clear();
 
        if (skipPlacement && !d->pendingPlacements.isEmpty())
            d->pendingPlacements.clear();
    }
 
    if (!d->pendingPlacements.isEmpty()) {
        // Nothing obvious in the loop body changes the container (in this code path)
        // during iteration, this is calling into a non-const method that does change
        // the container when called from other places. So take a copy anyway for good
        // measure.
        const auto copy = d->pendingPlacements;
        for (QMdiSubWindow *window : copy) {
            if (!window)
                continue;
            if (d->viewMode == TabbedView && window->d_func()->isActive && !d->active) {
                d->showActiveWindowMaximized = true;
                d->emitWindowActivated(window); // Also maximizes the window
                continue;
            }
            if (!window->testAttribute(Qt::WA_Resized)) {
                QSize newSize(window->sizeHint().boundedTo(viewport()->size()));
                window->resize(newSize.expandedTo(qSmartMinSize(window)));
            }
            if (!window->testAttribute(Qt::WA_Moved) && !window->isMinimized()
                    && !window->isMaximized()) {
                d->place(d->placer, window);
            }
        }
        d->pendingPlacements.clear();
    }
 
    d->setChildActivationEnabled(true);
    d->activateCurrentWindow();
 
    QAbstractScrollArea::showEvent(showEvent);
}
 
bool QMdiArea::viewportEvent(QEvent *event)
{
    Q_D(QMdiArea);
    switch (event->type()) {
    case QEvent::ChildRemoved: {
        d->isSubWindowsTiled = false;
        QObject *removedChild = static_cast<QChildEvent *>(event)->child();
        for (int i = 0; i < d->childWindows.size(); ++i) {
            QObject *child = d->childWindows.at(i);
            if (!child || child == removedChild || !child->parent()
                    || child->parent() != viewport()) {
                if (!testOption(DontMaximizeSubWindowOnActivation)) {
                    // In this case we can only rely on the child being a QObject
                    // (or 0), but let's try and see if we can get more information.
                    QWidget *mdiChild = qobject_cast<QWidget *>(removedChild);
                    if (mdiChild && mdiChild->isMaximized())
                        d->showActiveWindowMaximized = true;
                }
                d->disconnectSubWindow(child);
                const bool activeRemoved = i == d->indicesToActivatedChildren.at(0);
                d->childWindows.removeAt(i);
                d->indicesToActivatedChildren.removeAll(i);
                d->updateActiveWindow(i, activeRemoved);
                d->arrangeMinimizedSubWindows();
                break;
            }
        }
        d->updateScrollBars();
        break;
    }
    case QEvent::Destroy:
        d->isSubWindowsTiled = false;
        d->resetActiveWindow();
        d->childWindows.clear();
        qWarning("QMdiArea: Deleting the view port is undefined, use setViewport instead.");
        break;
    default:
        break;
    }
    return QAbstractScrollArea::viewportEvent(event);
}
 
void QMdiArea::scrollContentsBy(int dx, int dy)
{
    Q_D(QMdiArea);
    const bool wasSubWindowsTiled = d->isSubWindowsTiled;
    d->ignoreGeometryChange = true;
    viewport()->scroll(isLeftToRight() ? dx : -dx, dy);
    d->arrangeMinimizedSubWindows();
    d->ignoreGeometryChange = false;
    if (wasSubWindowsTiled)
        d->isSubWindowsTiled = true;
}
 
void QMdiArea::tileSubWindows()
{
    Q_D(QMdiArea);
    if (!d->regularTiler)
        d->regularTiler = new RegularTiler;
    d->rearrange(d->regularTiler);
}
 
void QMdiArea::cascadeSubWindows()
{
    Q_D(QMdiArea);
    if (!d->cascader)
        d->cascader = new SimpleCascader;
    d->rearrange(d->cascader);
}
 
bool QMdiArea::event(QEvent *event)
{
    Q_D(QMdiArea);
    switch (event->type()) {
    case QEvent::WindowActivate: {
        d->isActivated = true;
        if (d->childWindows.isEmpty())
            break;
        if (!d->active)
            d->activateCurrentWindow();
        d->setChildActivationEnabled(false, true);
        break;
    }
    case QEvent::WindowDeactivate:
        d->isActivated = false;
        d->setChildActivationEnabled(false, true);
        break;
    case QEvent::StyleChange:
        // Re-tile the views if we're in tiled mode. Re-tile means we will change
        // the geometry of the children, which in turn means 'isSubWindowsTiled'
        // is set to false, so we have to update the state at the end.
        if (d->isSubWindowsTiled) {
            tileSubWindows();
            d->isSubWindowsTiled = true;
        }
        break;
    case QEvent::WindowIconChange: {
        // Take a copy because QCoreApplication::sendEvent() may call unknown code,
        // that may cause recursing into the class
        const auto subWindows = d->childWindows;
        for (QMdiSubWindow *window : subWindows) {
            if (sanityCheck(window, "QMdiArea::WindowIconChange"))
                QCoreApplication::sendEvent(window, event);
        }
        break;
    }
    case QEvent::Hide:
        d->setActive(d->active, false, false);
        d->setChildActivationEnabled(false);
        break;
#if QT_CONFIG(tabbar)
    case QEvent::LayoutDirectionChange:
        d->updateTabBarGeometry();
        break;
#endif
    default:
        break;
    }
    return QAbstractScrollArea::event(event);
}
 
bool QMdiArea::eventFilter(QObject *object, QEvent *event)
{
    if (!object)
        return QAbstractScrollArea::eventFilter(object, event);
 
    Q_D(QMdiArea);
    // Global key events with Ctrl modifier.
    if (event->type() == QEvent::KeyPress || event->type() == QEvent::KeyRelease) {
 
        QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
        // Ignore key events without a Ctrl modifier (except for press/release on the modifier itself).
        if (!(keyEvent->modifiers() & Qt::ControlModifier) && keyEvent->key() != Qt::Key_Control)
            return QAbstractScrollArea::eventFilter(object, event);
 
        // Find closest mdi area (in case we have a nested workspace).
        QMdiArea *area = mdiAreaParent(static_cast<QWidget *>(object));
        if (!area)
            return QAbstractScrollArea::eventFilter(object, event);
 
        const bool keyPress = (event->type() == QEvent::KeyPress);
 
        // 1) Ctrl-Tab once -> activate the previously active window.
        // 2) Ctrl-Tab (Tab, Tab, ...) -> iterate through all windows (activateNextSubWindow()).
        // 3) Ctrl-Shift-Tab (Tab, Tab, ...) -> iterate through all windows in the opposite
        //    direction (activatePreviousSubWindow())
        switch (keyEvent->key()) {
        case Qt::Key_Control:
            if (keyPress)
                area->d_func()->startTabToPreviousTimer();
            else
                area->d_func()->activateHighlightedWindow();
            break;
        case Qt::Key_Tab:
        case Qt::Key_Backtab:
            if (keyPress)
                area->d_func()->highlightNextSubWindow(keyEvent->key() == Qt::Key_Tab ? 1 : -1);
            return true;
#if QT_CONFIG(rubberband)
        case Qt::Key_Escape:
            area->d_func()->hideRubberBand();
            break;
#endif
        default:
            break;
        }
        return QAbstractScrollArea::eventFilter(object, event);
    }
 
    QMdiSubWindow *subWindow = qobject_cast<QMdiSubWindow *>(object);
 
    if (!subWindow) {
        // QApplication events:
        if (event->type() == QEvent::ApplicationActivate && !d->active
            && isVisible() && !window()->isMinimized()) {
            d->activateCurrentWindow();
        } else if (event->type() == QEvent::ApplicationDeactivate && d->active) {
            d->setActive(d->active, false, false);
        }
        return QAbstractScrollArea::eventFilter(object, event);
    }
 
    if (subWindow->mdiArea() != this)
        return QAbstractScrollArea::eventFilter(object, event);
 
    // QMdiSubWindow events:
    switch (event->type()) {
    case QEvent::Move:
    case QEvent::Resize:
        if (d->tileCalledFromResizeEvent)
            break;
        d->updateScrollBars();
        if (!subWindow->isMinimized())
            d->isSubWindowsTiled = false;
        break;
    case QEvent::Show:
#if QT_CONFIG(tabbar)
        if (d->tabBar) {
            const int tabIndex = d->childWindows.indexOf(subWindow);
            if (!d->tabBar->isTabEnabled(tabIndex))
                d->tabBar->setTabEnabled(tabIndex, true);
        }
#endif // QT_CONFIG(tabbar)
        Q_FALLTHROUGH();
    case QEvent::Hide:
        // Do not reset the isSubWindowsTiled flag if the event is a spontaneous system window event.
        // This ensures that tiling will be performed during the resizeEvent after an application
        // window minimize (hide) and then restore (show).
        if (!event->spontaneous())
            d->isSubWindowsTiled = false;
        break;
#if QT_CONFIG(rubberband)
    case QEvent::Close:
        if (d->childWindows.indexOf(subWindow) == d->indexToHighlighted)
            d->hideRubberBand();
        break;
#endif
#if QT_CONFIG(tabbar)
    case QEvent::WindowTitleChange:
    case QEvent::ModifiedChange:
        if (d->tabBar)
            d->tabBar->setTabText(d->childWindows.indexOf(subWindow), tabTextFor(subWindow));
        break;
    case QEvent::WindowIconChange:
        if (d->tabBar)
            d->tabBar->setTabIcon(d->childWindows.indexOf(subWindow), subWindow->windowIcon());
        break;
#endif // QT_CONFIG(tabbar)
    default:
        break;
    }
    return QAbstractScrollArea::eventFilter(object, event);
}
 
void QMdiArea::paintEvent(QPaintEvent *paintEvent)
{
    Q_D(QMdiArea);
    QPainter painter(d->viewport);
    for (const QRect &exposedRect : paintEvent->region())
        painter.fillRect(exposedRect, d->background);
}
 
void QMdiArea::setupViewport(QWidget *viewport)
{
    Q_D(QMdiArea);
    if (viewport)
        viewport->setAttribute(Qt::WA_OpaquePaintEvent, d->background.isOpaque());
    // Take a copy because the child->setParent() call below may call QCoreApplication::sendEvent()
    // which may call unknown code that could e.g. recurse into the class modifying d->childWindows.
    const auto subWindows = d->childWindows;
    for (QMdiSubWindow *child : subWindows) {
        if (!sanityCheck(child, "QMdiArea::setupViewport"))
            continue;
        child->setParent(viewport, child->windowFlags());
    }
}
 
QT_END_NAMESPACE
 
#include "moc_qmdiarea.cpp"