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/*!

    \class QMdiArea

    \brief The QMdiArea widget provides an area in which MDI windows are displayed.

    \since 4.3

    \ingroup mainwindow-classes

    QMdiArea functions, essentially, like a window manager for MDI

    windows. For instance, it draws the windows it manages on itself

    and arranges them in a cascading or tile pattern. QMdiArea is

    commonly used as the center widget in a QMainWindow to create MDI

    applications, but can also be placed in any layout. The following

    code adds an area to a main window:

    \snippet doc/src/snippets/mdiareasnippets.cpp 0

    Unlike the window managers for top-level windows, all window flags

    (Qt::WindowFlags) are supported by QMdiArea as long as the flags

    are supported by the current widget style. If a specific flag is

    not supported by the style (e.g., the

    \l{Qt::}{WindowShadeButtonHint}), you can still shade the window

    with showShaded().

    Subwindows in QMdiArea are instances of QMdiSubWindow. They

    are added to an MDI area with addSubWindow(). It is common to pass

    a QWidget, which is set as the internal widget, to this function,

    but it is also possible to pass a QMdiSubWindow directly.The class

    inherits QWidget, and you can use the same API as with a normal

    top-level window when programming. QMdiSubWindow also has behavior

    that is specific to MDI windows. See the QMdiSubWindow class

    description for more details.

    A subwindow becomes active when it gets the keyboard focus, or

    when setFocus() is called. The user activates a window by moving

    focus in the usual ways. The MDI area emits the

    subWindowActivated() signal when the active window changes, and

    the activeSubWindow() function returns the active subwindow.

    The convenience function subWindowList() returns a list of all

    subwindows. This information could be used in a popup menu

    containing a list of windows, for example.

    The subwindows are sorted by the current

    \l{QMdiArea::}{WindowOrder}. This is used for the subWindowList()

    and for activateNextSubWindow() and acivatePreviousSubWindow().

    Also, it is used when cascading or tiling the windows with

    cascadeSubWindows() and tileSubWindows().

    QMdiArea provides two built-in layout strategies for

    subwindows: cascadeSubWindows() and tileSubWindows(). Both are

    slots and are easily connected to menu entries.

    \table

    \row \o \inlineimage mdi-cascade.png

         \o \inlineimage mdi-tile.png

    \endtable

    \note The default scroll bar property for QMdiArea is Qt::ScrollBarAlwaysOff.

    \sa QMdiSubWindow

*/

/*!

    \fn QMdiArea::subWindowActivated(QMdiSubWindow *window)

    QMdiArea emits this signal after \a window has been activated. When \a

    window is 0, QMdiArea has just deactivated its last active window, and

    there are no active windows on the workspace.

    \sa QMdiArea::activeSubWindow()

*/

/*!

    \enum QMdiArea::AreaOption

    This enum describes options that customize the behavior of the

    QMdiArea.

    \value DontMaximizeSubWindowOnActivation When the active subwindow

    is maximized, the default behavior is to maximize the next

    subwindow that is activated. Set this option if you do not want

    this behavior.

*/

/*!

    \enum QMdiArea::WindowOrder

    Specifies the criteria to use for ordering the list of child windows

    returned by subWindowList(). The functions cascadeSubWindows() and

    tileSubWindows() follow this order when arranging the windows.

    \value CreationOrder The windows are returned in the order of

    their creation.

    \value StackingOrder The windows are returned in the order in

    which they are stacked, with the top-most window being last in

    the list.

    \value ActivationHistoryOrder The windows are returned in the order in

    which they were activated.

    \sa subWindowList()

*/

/*!

    \enum QMdiArea::ViewMode

    \since 4.4

    This enum describes the view mode of the area; i.e. how sub-windows

    will be displayed.

    \value SubWindowView Display sub-windows with window frames (default).

    \value TabbedView Display sub-windows with tabs in a tab bar.

    \sa setViewMode()

*/

#include "qmdiarea_p.h"

#ifndef QT_NO_MDIAREA

#include <QApplication>

#include <QStyle>

#if defined(Q_WS_MAC) && !defined(QT_NO_STYLE_MAC)

#include <QMacStyle>

#endif

#include <QChildEvent>

#include <QResizeEvent>

#include <QScrollBar>

#include <QtAlgorithms>

#include <QMutableListIterator>

#include <QPainter>

#include <QFontMetrics>

#include <QStyleOption>

#include <QDesktopWidget>

#include <QDebug>

#include <qmath.h>

#include <private/qlayoutengine_p.h>

QT_BEGIN_NAMESPACE

using namespace QMdi;

// Asserts in debug mode, gives warning otherwise.

static bool sanityCheck(const QMdiSubWindow * const child, const char *where)

{

    if (!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 (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 (!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 0;

    QWidget *parent = widget->parentWidget();

    while (parent) {

        if (QMdiArea *area = qobject_cast<QMdiArea *>(parent))

            return area;

        parent = parent->parentWidget();

    }

    return 0;

}

#ifndef QT_NO_TABWIDGET

static inline QTabBar::Shape tabBarShapeFrom(QTabWidget::TabShape shape, QTabWidget::TabPosition position)

{

    const bool rounded = (shape == QTabWidget::Rounded);

    if (position == QTabWidget::North)

        return rounded ? QTabBar::RoundedNorth : QTabBar::TriangularNorth;

    if (position == QTabWidget::South)

        return rounded ? QTabBar::RoundedSouth : QTabBar::TriangularSouth;

    if (position == QTabWidget::East)

        return rounded ? QTabBar::RoundedEast : QTabBar::TriangularEast;

    if (position == QTabWidget::West)

        return rounded ? QTabBar::RoundedWest : QTabBar::TriangularWest;

    return QTabBar::RoundedNorth;

}

#endif // QT_NO_TABWIDGET

static inline QString tabTextFor(QMdiSubWindow *subWindow)

{

    if (!subWindow)

        return QString();

    QString title = subWindow->windowTitle();

    if (subWindow->isWindowModified()) {

        title.replace(QLatin1String("[*]"), QLatin1String("*"));

    } else {

        extern QString qt_setWindowTitle_helperHelper(const QString&, const QWidget*);

        title = qt_setWindowTitle_helperHelper(title, subWindow);

    }

    return title.isEmpty() ? QMdiArea::tr("(Untitled)") : title;

}

/*!

    \internal

*/

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));

        }

    }

}

/*!

    \internal

*/

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));

#if defined(Q_WS_MAC) && !defined(QT_NO_STYLE_MAC)

    // ### Remove this after the mac style has been fixed

    if (qobject_cast<QMacStyle *>(widgets.at(0)->style()))

        titleBarHeight -= 4;

#endif

    const QFontMetrics fontMetrics = QFontMetrics(QApplication::font("QWorkspaceTitleBar"));

    const int dy = qMax(titleBarHeight - (titleBarHeight - fontMetrics.height()) / 2, 1);

    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;

        }

    }

}

/*!

    \internal

*/

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 = widgets.at(0)->width();

    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;

        }

    }

}

/*!

    \internal

    Calculates the accumulated overlap (intersection area) between 'source' and 'rects'.