source: trunk/src/gui/graphicsview/qgraphicswidget.cpp@ 809

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#include "qglobal.h"

#ifndef QT_NO_GRAPHICSVIEW

#include "qgraphicswidget.h"
#include "qgraphicswidget_p.h"
#include "qgraphicslayout.h"
#include "qgraphicslayout_p.h"
#include "qgraphicsscene.h"
#include "qgraphicssceneevent.h"

#ifndef QT_NO_ACTION
#include <private/qaction_p.h>
#endif
#include <private/qapplication_p.h>
#include <private/qgraphicsscene_p.h>
#ifndef QT_NO_SHORTCUT
#include <private/qshortcutmap_p.h>
#endif
#include <QtCore/qmutex.h>
#include <QtGui/qapplication.h>
#include <QtGui/qgraphicsview.h>
#include <QtGui/qgraphicsproxywidget.h>
#include <QtGui/qpalette.h>
#include <QtGui/qstyleoption.h>

#include <qdebug.h>

QT_BEGIN_NAMESPACE

/*!
    \class QGraphicsWidget
    \brief The QGraphicsWidget class is the base class for all widget
    items in a QGraphicsScene.
    \since 4.4
    \ingroup graphicsview-api

    QGraphicsWidget is an extended base item that provides extra functionality
    over QGraphicsItem. It is similar to QWidget in many ways:

    \list
        \o Provides a \l palette, a \l font and a \l style().
        \o Has a defined geometry().
        \o Supports layouts with setLayout() and layout().
        \o Supports shortcuts and actions with grabShortcut() and insertAction()
    \endlist

    Unlike QGraphicsItem, QGraphicsWidget is not an abstract class; you can
    create instances of a QGraphicsWidget without having to subclass it.
    This approach is useful for widgets that only serve the purpose of
    organizing child widgets into a layout.

    QGraphicsWidget can be used as a base item for your own custom item if
    you require advanced input focus handling, e.g., tab focus and activation, or
    layouts.

    Since QGraphicsWidget resembles QWidget and has similar API, it is
    easier to port a widget from QWidget to QGraphicsWidget, instead of
    QGraphicsItem.

    \note QWidget-based widgets can be directly embedded into a
    QGraphicsScene using QGraphicsProxyWidget.

    Noticeable differences between QGraphicsWidget and QWidget are:

    \table
    \header \o QGraphicsWidget
                \o QWidget
    \row      \o Coordinates and geometry are defined with qreals (doubles or
                    floats, depending on the platform).
                \o QWidget uses integer geometry (QPoint, QRect).
    \row      \o The widget is already visible by default; you do not have to
                    call show() to display the widget.
                \o QWidget is hidden by default until you call show().
    \row      \o A subset of widget attributes are supported.
                \o All widget attributes are supported.
    \row      \o A top-level item's style defaults to QGraphicsScene::style
                \o A top-level widget's style defaults to QApplication::style
    \row      \o Graphics View provides a custom drag and drop framework, different
                    from QWidget.
                \o Standard drag and drop framework.
    \row      \o Widget items do not support modality.
                \o Full modality support.
    \endtable

    QGraphicsWidget supports a subset of Qt's widget attributes,
    (Qt::WidgetAttribute), as shown in the table below. Any attributes not
    listed in this table are unsupported, or otherwise unused.

    \table
    \header \o Widget Attribute                         \o Usage
    \row    \o Qt::WA_SetLayoutDirection
                    \o Set by setLayoutDirection(), cleared by
                        unsetLayoutDirection(). You can test this attribute to
                        check if the widget has been explicitly assigned a
                        \l{QGraphicsWidget::layoutDirection()}
                        {layoutDirection}. If the attribute is not set, the
                        \l{QGraphicsWidget::layoutDirection()}
                        {layoutDirection()} is inherited.
    \row    \o Qt::WA_RightToLeft
                    \o Toggled by setLayoutDirection(). Inherited from the
                        parent/scene. If set, the widget's layout will order
                        horizontally arranged widgets from right to left.
    \row    \o Qt::WA_SetStyle
                    \o Set and cleared by setStyle(). If this attribute is
                        set, the widget has been explicitly assigned a style.
                        If it is unset, the widget will use the scene's or the
                        application's style.
    \row    \o Qt::WA_Resized
                    \o Set by setGeometry() and resize().
    \row    \o Qt::WA_SetPalette
                    \o Set by setPalette().
    \row    \o Qt::WA_SetFont
                    \o Set by setPalette().
    \row    \o Qt::WA_WindowPropagation
                    \o Enables propagation to window widgets.
    \endtable

    Although QGraphicsWidget inherits from both QObject and QGraphicsItem,
    you should use the functions provided by QGraphicsItem, \e not QObject, to
    manage the relationships between parent and child items. These functions
    control the stacking order of items as well as their ownership.

    \note The QObject::parent() should always return 0 for QGraphicsWidgets,
    but this policy is not strictly defined.

    \sa QGraphicsProxyWidget, QGraphicsItem, {Widgets and Layouts}
*/

/*!
    Constructs a QGraphicsWidget instance. The optional \a parent argument is
    passed to QGraphicsItem's constructor. The optional \a wFlags argument
    specifies the widget's window flags (e.g., whether the widget should be a
    window, a tool, a popup, etc).
*/
QGraphicsWidget::QGraphicsWidget(QGraphicsItem *parent, Qt::WindowFlags wFlags)
    : QGraphicsObject(*new QGraphicsWidgetPrivate, 0, 0), QGraphicsLayoutItem(0, false)
{
    Q_D(QGraphicsWidget);
    d->init(parent, wFlags);
}

/*!
    \internal

    Constructs a new QGraphicsWidget, using \a dd as parent.
*/
QGraphicsWidget::QGraphicsWidget(QGraphicsWidgetPrivate &dd, QGraphicsItem *parent, QGraphicsScene *scene, Qt::WindowFlags wFlags)
    : QGraphicsObject(dd, 0, scene), QGraphicsLayoutItem(0, false)
{
    Q_D(QGraphicsWidget);
    d->init(parent, wFlags);
}

/*
    \internal
    \class QGraphicsWidgetStyles

    We use this thread-safe class to maintain a hash of styles for widgets
    styles. Note that QApplication::style() itself isn't thread-safe, QStyle
    isn't thread-safe, and we don't have a thread-safe factory for creating
    the default style, nor cloning a style.
*/
class QGraphicsWidgetStyles
{
public:
    QStyle *styleForWidget(const QGraphicsWidget *widget) const
    {
        QMutexLocker locker(&mutex);
        return styles.value(widget, 0);
    }

    void setStyleForWidget(QGraphicsWidget *widget, QStyle *style)
    {
        QMutexLocker locker(&mutex);
        if (style)
            styles[widget] = style;
        else
            styles.remove(widget);
    }

private:
    QMap<const QGraphicsWidget *, QStyle *> styles;
    mutable QMutex mutex;
};
Q_GLOBAL_STATIC(QGraphicsWidgetStyles, widgetStyles)

/*!
    Destroys the QGraphicsWidget instance.
*/
QGraphicsWidget::~QGraphicsWidget()
{
    Q_D(QGraphicsWidget);
#ifndef QT_NO_ACTION
    // Remove all actions from this widget
    for (int i = 0; i < d->actions.size(); ++i) {
        QActionPrivate *apriv = d->actions.at(i)->d_func();
        apriv->graphicsWidgets.removeAll(this);
    }
    d->actions.clear();
#endif

    if (QGraphicsScene *scn = scene()) {
        QGraphicsScenePrivate *sceneD = scn->d_func();
        if (sceneD->tabFocusFirst == this)
            sceneD->tabFocusFirst = (d->focusNext == this ? 0 : d->focusNext);
    }
    d->focusPrev->d_func()->focusNext = d->focusNext;
    d->focusNext->d_func()->focusPrev = d->focusPrev;

    // Play it really safe
    d->focusNext = this;
    d->focusPrev = this;

    clearFocus();

    //we check if we have a layout previously
    if (d->layout) {
        QGraphicsLayout *temp = d->layout;
        foreach (QGraphicsItem * item, childItems()) {
            // In case of a custom layout which doesn't remove and delete items, we ensure that
            // the parent layout item does not point to the deleted layout. This code is here to
            // avoid regression from 4.4 to 4.5, because according to 4.5 docs it is not really needed.
            if (item->isWidget()) {
                QGraphicsWidget *widget = static_cast<QGraphicsWidget *>(item);
                if (widget->parentLayoutItem() == d->layout)
                    widget->setParentLayoutItem(0);
            }
        }
        d->layout = 0;
        delete temp;
    }

    // Remove this graphics widget from widgetStyles
    widgetStyles()->setStyleForWidget(this, 0);
}

/*!
    \property QGraphicsWidget::size
    \brief the size of the widget

    Calling resize() resizes the widget to a \a size bounded by minimumSize()
    and maximumSize(). This property only affects the widget's width and
    height (e.g., its right and bottom edges); the widget's position and
    top-left corner remains unaffected.

    Resizing a widget triggers the widget to immediately receive a
    \l{QEvent::GraphicsSceneResize}{GraphicsSceneResize} event with the
    widget's old and new size.  If the widget has a layout assigned when this
    event arrives, the layout will be activated and it will automatically
    update any child widgets's geometry.

    This property does not affect any layout of the parent widget. If the
    widget itself is managed by a parent layout; e.g., it has a parent widget
    with a layout assigned, that layout will not activate.

    By default, this property contains a size with zero width and height.

    \sa setGeometry(), QGraphicsSceneResizeEvent, QGraphicsLayout
*/
QSizeF QGraphicsWidget::size() const
{
    return QGraphicsLayoutItem::geometry().size();
}

void QGraphicsWidget::resize(const QSizeF &size)
{
    setGeometry(QRectF(pos(), size));
}

/*!
    \fn void QGraphicsWidget::resize(qreal w, qreal h)

    This convenience function is equivalent to calling resize(QSizeF(w, h)).

    \sa setGeometry(), setTransform()
*/

/*!
    \property QGraphicsWidget::sizePolicy
    \brief the size policy for the widget
    \sa sizePolicy(), setSizePolicy(), QWidget::sizePolicy()
*/

/*!
    \property QGraphicsWidget::geometry
    \brief the geometry of the widget

    Sets the item's geometry to \a rect. The item's position and size are
    modified as a result of calling this function. The item is first moved,
    then resized.

    A side effect of calling this function is that the widget will receive
    a move event and a resize event. Also, if the widget has a layout
    assigned, the layout will activate.

    \sa geometry(), resize()
*/
void QGraphicsWidget::setGeometry(const QRectF &rect)
{
    QGraphicsWidgetPrivate *wd = QGraphicsWidget::d_func();
    QGraphicsLayoutItemPrivate *d = QGraphicsLayoutItem::d_ptr.data();
    QRectF newGeom;
    QPointF oldPos = d->geom.topLeft();
    if (!wd->inSetPos) {
        setAttribute(Qt::WA_Resized);
        newGeom = rect;
        newGeom.setSize(rect.size().expandedTo(effectiveSizeHint(Qt::MinimumSize))
                                   .boundedTo(effectiveSizeHint(Qt::MaximumSize)));
        if (newGeom == d->geom)
            return;

        // setPos triggers ItemPositionChange, which can adjust position
        wd->inSetGeometry = 1;
        setPos(newGeom.topLeft());
        wd->inSetGeometry = 0;
        newGeom.moveTopLeft(pos());

        if (newGeom == d->geom)
           return;

         // Update and prepare to change the geometry (remove from index) if the size has changed.
        if (wd->scene) {
            if (rect.topLeft() == d->geom.topLeft()) {
                prepareGeometryChange();
            }
        }
    }

    // Update the layout item geometry
    bool moved = oldPos != pos();
    if (moved) {
        // Send move event.
        QGraphicsSceneMoveEvent event;
        event.setOldPos(oldPos);
        event.setNewPos(pos());
        QApplication::sendEvent(this, &event);
        if (wd->inSetPos) {
            //set the new pos
            d->geom.moveTopLeft(pos());
            return;
        }
    }
    QSizeF oldSize = size();
    QGraphicsLayoutItem::setGeometry(newGeom);

    // Send resize event
    bool resized = newGeom.size() != oldSize;
    if (resized) {
        QGraphicsSceneResizeEvent re;
        re.setOldSize(oldSize);
        re.setNewSize(newGeom.size());
        QApplication::sendEvent(this, &re);
    }
}

/*!
    \fn QRectF QGraphicsWidget::rect() const

    Returns the item's local rect as a QRectF. This function is equivalent
    to QRectF(QPointF(), size()).

    \sa setGeometry(), resize()
*/

/*!
    \fn void QGraphicsWidget::setGeometry(qreal x, qreal y, qreal w, qreal h)

    This convenience function is equivalent to calling setGeometry(QRectF(
    \a x, \a y, \a w, \a h)).

    \sa geometry(), resize()
*/

/*!
    \property QGraphicsWidget::minimumSize
    \brief the minimum size of the widget

    \sa setMinimumSize(), minimumSize(), preferredSize, maximumSize
*/

/*!
    \property QGraphicsWidget::preferredSize
    \brief the preferred size of the widget

    \sa setPreferredSize(), preferredSize(), minimumSize, maximumSize
*/

/*!
    \property QGraphicsWidget::maximumSize
    \brief the maximum size of the widget

    \sa setMaximumSize(), maximumSize(), minimumSize, preferredSize
*/

/*!
    Sets the widget's contents margins to \a left, \a top, \a right and \a
    bottom.

    Contents margins are used by the assigned layout to define the placement
    of subwidgets and layouts. Margins are particularily useful for widgets
    that constrain subwidgets to only a section of its own geometry. For
    example, a group box with a layout will place subwidgets inside its frame,
    but below the title.

    Changing a widget's contents margins will always trigger an update(), and
    any assigned layout will be activated automatically. The widget will then
    receive a \l{QEvent::ContentsRectChange}{ContentsRectChange} event.

    \sa getContentsMargins(), setGeometry()
*/
void QGraphicsWidget::setContentsMargins(qreal left, qreal top, qreal right, qreal bottom)
{
    Q_D(QGraphicsWidget);

    if (!d->margins && left == 0 && top == 0 && right == 0 && bottom == 0)
        return;
    d->ensureMargins();
    if (left == d->margins[d->Left]
        && top == d->margins[d->Top]
        && right == d->margins[d->Right]
        && bottom == d->margins[d->Bottom])
        return;

    d->margins[d->Left] = left;
    d->margins[d->Top] = top;
    d->margins[d->Right] = right;
    d->margins[d->Bottom] = bottom;

    if (QGraphicsLayout *l = d->layout)
        l->invalidate();
    else
        updateGeometry();

    QEvent e(QEvent::ContentsRectChange);
    QApplication::sendEvent(this, &e);
}

/*!
    Gets the widget's contents margins. The margins are stored in \a left, \a
    top, \a right and \a bottom, as pointers to qreals. Each argument can
    be \e {omitted} by passing 0.

    \sa setContentsMargins()
*/
void QGraphicsWidget::getContentsMargins(qreal *left, qreal *top, qreal *right, qreal *bottom) const
{
    Q_D(const QGraphicsWidget);
    if (left || top || right || bottom)
        d->ensureMargins();
    if (left)
        *left = d->margins[d->Left];
    if (top)
        *top = d->margins[d->Top];
    if (right)
        *right = d->margins[d->Right];
    if (bottom)
        *bottom = d->margins[d->Bottom];
}

/*!
    Sets the widget's window frame margins to \a left, \a top, \a right and
    \a bottom. The default frame margins are provided by the style, and they
    depend on the current window flags.

    If you would like to draw your own window decoration, you can set your
    own frame margins to override the default margins.

    \sa unsetWindowFrameMargins(), getWindowFrameMargins(), windowFrameRect()
*/
void QGraphicsWidget::setWindowFrameMargins(qreal left, qreal top, qreal right, qreal bottom)
{
    Q_D(QGraphicsWidget);

    if (!d->windowFrameMargins && left == 0 && top == 0 && right == 0 && bottom == 0)
        return;
    d->ensureWindowFrameMargins();
    bool unchanged =
        d->windowFrameMargins[d->Left] == left
        && d->windowFrameMargins[d->Top] == top
        && d->windowFrameMargins[d->Right] == right
        && d->windowFrameMargins[d->Bottom] == bottom;
    if (d->setWindowFrameMargins && unchanged)
        return;
    if (!unchanged)
        prepareGeometryChange();
    d->windowFrameMargins[d->Left] = left;
    d->windowFrameMargins[d->Top] = top;
    d->windowFrameMargins[d->Right] = right;
    d->windowFrameMargins[d->Bottom] = bottom;
    d->setWindowFrameMargins = true;
}

/*!
    Gets the widget's window frame margins. The margins are stored in \a left,
    \a top, \a right and \a bottom as pointers to qreals. Each argument can
    be \e {omitted} by passing 0.

    \sa setWindowFrameMargins(), windowFrameRect()
*/
void QGraphicsWidget::getWindowFrameMargins(qreal *left, qreal *top, qreal *right, qreal *bottom) const
{
    Q_D(const QGraphicsWidget);
    if (left || top || right || bottom)
        d->ensureWindowFrameMargins();
    if (left)
        *left = d->windowFrameMargins[d->Left];
    if (top)
        *top = d->windowFrameMargins[d->Top];
    if (right)
        *right = d->windowFrameMargins[d->Right];
    if (bottom)
        *bottom = d->windowFrameMargins[d->Bottom];
}

/*!
    Resets the window frame margins to the default value, provided by the style.

    \sa setWindowFrameMargins(), getWindowFrameMargins(), windowFrameRect()
*/
void QGraphicsWidget::unsetWindowFrameMargins()
{
    Q_D(QGraphicsWidget);
    if ((d->windowFlags & Qt::Window) && (d->windowFlags & Qt::WindowType_Mask) != Qt::Popup &&
         (d->windowFlags & Qt::WindowType_Mask) != Qt::ToolTip && !(d->windowFlags & Qt::FramelessWindowHint)) {
        QStyleOptionTitleBar bar;
        d->initStyleOptionTitleBar(&bar);
        QStyle *style = this->style();
        qreal margin = style->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth);
        qreal titleBarHeight  = d->titleBarHeight(bar);
        setWindowFrameMargins(margin, titleBarHeight, margin, margin);
    } else {
        setWindowFrameMargins(0, 0, 0, 0);
    }
    d->setWindowFrameMargins = false;
}

/*!
    Returns the widget's geometry in parent coordinates including any window
    frame.

    \sa windowFrameRect(), getWindowFrameMargins(), setWindowFrameMargins()
*/
QRectF QGraphicsWidget::windowFrameGeometry() const
{
    Q_D(const QGraphicsWidget);
    return d->windowFrameMargins
        ? geometry().adjusted(-d->windowFrameMargins[d->Left], -d->windowFrameMargins[d->Top],
                              d->windowFrameMargins[d->Right], d->windowFrameMargins[d->Bottom])
        : geometry();
}

/*!
    Returns the widget's local rect including any window frame.

    \sa windowFrameGeometry(), getWindowFrameMargins(), setWindowFrameMargins()
*/
QRectF QGraphicsWidget::windowFrameRect() const
{
    Q_D(const QGraphicsWidget);
    return d->windowFrameMargins
        ? rect().adjusted(-d->windowFrameMargins[d->Left], -d->windowFrameMargins[d->Top],
                          d->windowFrameMargins[d->Right], d->windowFrameMargins[d->Bottom])
        : rect();
}

/*!
    Populates a style option object for this widget based on its current
    state, and stores the output in \a option. The default implementation
    populates \a option with the following properties.

    \table
      \header
        \o Style Option Property
        \o Value
      \row
        \o state & QStyle::State_Enabled
        \o Corresponds to QGraphicsItem::isEnabled().
      \row
        \o state & QStyle::State_HasFocus
        \o Corresponds to QGraphicsItem::hasFocus().
      \row
        \o state & QStyle::State_MouseOver
        \o Corresponds to QGraphicsItem::isUnderMouse().
      \row
        \o direction
        \o Corresponds to QGraphicsWidget::layoutDirection().
      \row
        \o rect
        \o Corresponds to QGraphicsWidget::rect().toRect().
      \row
        \o palette
        \o Corresponds to QGraphicsWidget::palette().
      \row
        \o fontMetrics
        \o Corresponds to QFontMetrics(QGraphicsWidget::font()).
    \endtable

    Subclasses of QGraphicsWidget should call the base implementation, and
    then test the type of \a option using qstyleoption_cast<>() or test
    QStyleOption::Type before storing widget-specific options.

    For example:

    \snippet doc/src/snippets/code/src_gui_graphicsview_qgraphicswidget.cpp 0

    \sa QStyleOption::initFrom()
*/
void QGraphicsWidget::initStyleOption(QStyleOption *option) const
{
    Q_ASSERT(option);

    option->state = QStyle::State_None;
    if (isEnabled())
        option->state |= QStyle::State_Enabled;
    if (hasFocus())
        option->state |= QStyle::State_HasFocus;
    // if (window->testAttribute(Qt::WA_KeyboardFocusChange)) // ### Window
    //     option->state |= QStyle::State_KeyboardFocusChange;
    if (isUnderMouse())
        option->state |= QStyle::State_MouseOver;
    if (QGraphicsWidget *w = window()) {
        if (w->isActiveWindow())
            option->state |= QStyle::State_Active;
    }
    if (isWindow())
        option->state |= QStyle::State_Window;
    /*
      ###
#ifdef Q_WS_MAC
    extern bool qt_mac_can_clickThrough(const QGraphicsWidget *w); //qwidget_mac.cpp
    if (!(option->state & QStyle::State_Active) && !qt_mac_can_clickThrough(widget))
        option->state &= ~QStyle::State_Enabled;

    switch (QMacStyle::widgetSizePolicy(widget)) {
    case QMacStyle::SizeSmall:
        option->state |= QStyle::State_Small;
        break;
    case QMacStyle::SizeMini:
        option->state |= QStyle::State_Mini;
        break;
    default:
        ;
    }
#endif
#ifdef QT_KEYPAD_NAVIGATION
    if (widget->hasEditFocus())
        state |= QStyle::State_HasEditFocus;
#endif
    */
    option->direction = layoutDirection();
    option->rect = rect().toRect(); // ### truncation!
    option->palette = palette();
    if (!isEnabled()) {
        option->palette.setCurrentColorGroup(QPalette::Disabled);
    } else if (isActiveWindow()) {
        option->palette.setCurrentColorGroup(QPalette::Active);
    } else {
        option->palette.setCurrentColorGroup(QPalette::Inactive);
    }
    option->fontMetrics = QFontMetrics(font());
}

/*!
    \reimp
*/
QSizeF QGraphicsWidget::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const
{
    Q_D(const QGraphicsWidget);
    QSizeF sh;
    if (d->layout) {
        QSizeF marginSize(0,0);
        if (d->margins) {
            marginSize = QSizeF(d->margins[d->Left] + d->margins[d->Right],
                         d->margins[d->Top] + d->margins[d->Bottom]);
        }
        sh = d->layout->effectiveSizeHint(which, constraint - marginSize);
        sh += marginSize;
    } else {
        switch (which) {
            case Qt::MinimumSize:
                sh = QSizeF(0, 0);
                break;
            case Qt::PreferredSize:
                sh = QSizeF(50, 50);    //rather arbitrary
                break;
            case Qt::MaximumSize:
                sh = QSizeF(QWIDGETSIZE_MAX, QWIDGETSIZE_MAX);
                break;
            default:
                qWarning("QGraphicsWidget::sizeHint(): Don't know how to handle the value of 'which'");
                break;
        }
    }
    return sh;
}

/*!
    Returns this widget's layout, or 0 if no layout is currently managing this
    widget.

    \sa setLayout()
*/
QGraphicsLayout *QGraphicsWidget::layout() const
{
    Q_D(const QGraphicsWidget);
    return d->layout;
}

/*!
    \fn void QGraphicsWidget::setLayout(QGraphicsLayout *layout)

    Sets the layout for this widget to \a layout. Any existing layout manager
    is deleted before the new layout is assigned. If \a layout is 0, the
    widget is left without a layout. Existing subwidgets' geometries will
    remain unaffected.

    All widgets that are currently managed by \a layout or all of its
    sublayouts, are automatically reparented to this item. The layout is then
    invalidated, and the child widget geometries are adjusted according to
    this item's geometry() and contentsMargins(). Children who are not
    explicitly managed by \a layout remain unaffected by the layout after
    it has been assigned to this widget.

    QGraphicsWidget takes ownership of \a layout.

    \sa layout(), QGraphicsLinearLayout::addItem(), QGraphicsLayout::invalidate()
*/
void QGraphicsWidget::setLayout(QGraphicsLayout *l)
{
    Q_D(QGraphicsWidget);
    if (d->layout == l)
        return;
    d->setLayout_helper(l);
    if (!l)
        return;

    // Prevent assigning a layout that is already assigned to another widget.
    QGraphicsLayoutItem *oldParent = l->parentLayoutItem();
    if (oldParent && oldParent != this) {
        qWarning("QGraphicsWidget::setLayout: Attempting to set a layout on %s"
                 " \"%s\", when the layout already has a parent",
                 metaObject()->className(), qPrintable(objectName()));
        return;
    }

    // Install and activate the layout.
    l->setParentLayoutItem(this);
    l->d_func()->reparentChildItems(this);
    l->invalidate();
}

/*!
    Adjusts the size of the widget to its effective preferred size hint.

    This function is called implicitly when the item is shown for the first
    time.

    \sa effectiveSizeHint(), Qt::MinimumSize
*/
void QGraphicsWidget::adjustSize()
{
    QSizeF sz = effectiveSizeHint(Qt::PreferredSize);
    // What if sz is not valid?!
    if (sz.isValid())
        resize(sz);
}

/*!
    \property QGraphicsWidget::layoutDirection
    \brief the layout direction for this widget.

    This property modifies this widget's and all of its descendants'
    Qt::WA_RightToLeft attribute. It also sets this widget's
    Qt::WA_SetLayoutDirection attribute.

    The widget's layout direction determines the order in which the layout
    manager horizontally arranges subwidgets of this widget. The default
    value depends on the language and locale of the application, and is
    typically in the same direction as words are read and written. With
    Qt::LeftToRight, the layout starts placing subwidgets from the left
    side of this widget towards the right. Qt::RightToLeft does the opposite -
    the layout will place widgets starting from the right edge moving towards
    the left.

    Subwidgets inherit their layout direction from the parent. Top-level
    widget items inherit their layout direction from
    QGraphicsScene::layoutDirection. If you change a widget's layout direction
    by calling setLayoutDirection(), the widget will send itself a
    \l{QEvent::LayoutDirectionChange}{LayoutDirectionChange} event, and then
    propagate the new layout direction to all its descendants.

    \sa QWidget::layoutDirection, QApplication::layoutDirection
*/
Qt::LayoutDirection QGraphicsWidget::layoutDirection() const
{
    return testAttribute(Qt::WA_RightToLeft) ? Qt::RightToLeft : Qt::LeftToRight;
}
void QGraphicsWidget::setLayoutDirection(Qt::LayoutDirection direction)
{
    Q_D(QGraphicsWidget);
    setAttribute(Qt::WA_SetLayoutDirection, true);
    d->setLayoutDirection_helper(direction);
}
void QGraphicsWidget::unsetLayoutDirection()
{
    Q_D(QGraphicsWidget);
    setAttribute(Qt::WA_SetLayoutDirection, false);
    d->resolveLayoutDirection();
}

/*!
    Returns a pointer to the widget's style. If this widget does not have any
    explicitly assigned style, the scene's style is returned instead. In turn,
    if the scene does not have any assigned style, this function returns
    QApplication::style().

    \sa setStyle()
*/
QStyle *QGraphicsWidget::style() const
{
    if (QStyle *style = widgetStyles()->styleForWidget(this))
        return style;
    // ### This is not thread-safe. QApplication::style() is not thread-safe.
    return scene() ? scene()->style() : QApplication::style();
}

/*!
    Sets the widget's style to \a style. QGraphicsWidget does \e not take
    ownership of \a style.

    If no style is assigned, or \a style is 0, the widget will use
    QGraphicsScene::style() (if this has been set). Otherwise the widget will
    use QApplication::style().

    This function sets the Qt::WA_SetStyle attribute if \a style is not 0;
    otherwise it clears the attribute.

    \sa style()
*/
void QGraphicsWidget::setStyle(QStyle *style)
{
    setAttribute(Qt::WA_SetStyle, style != 0);
    widgetStyles()->setStyleForWidget(this, style);

    // Deliver StyleChange to the widget itself (doesn't propagate).
    QEvent event(QEvent::StyleChange);
    QApplication::sendEvent(this, &event);
}

/*!
    \property QGraphicsWidget::font
    \brief the widgets' font

    This property provides the widget's font.

    QFont consists of font properties that have been explicitly defined and
    properties implicitly inherited from the widget's parent. Hence, font()
    can return a different font compared to the one set with setFont().
    This scheme allows you to define single entries in a font without
    affecting the font's inherited entries.

    When a widget's font changes, it resolves its entries against its
    parent widget. If the widget does not have a parent widget, it resolves
    its entries against the scene. The widget then sends itself a
    \l{QEvent::FontChange}{FontChange} event and notifies all its
    descendants so that they can resolve their fonts as well.

    By default, this property contains the application's default font.

    \sa QApplication::font(), QGraphicsScene::font, QFont::resolve()
*/
QFont QGraphicsWidget::font() const
{
    Q_D(const QGraphicsWidget);
    return d->font;
}
void QGraphicsWidget::setFont(const QFont &font)
{
    Q_D(QGraphicsWidget);
    setAttribute(Qt::WA_SetFont, font.resolve() != 0);

    QFont naturalFont = d->naturalWidgetFont();
    QFont resolvedFont = font.resolve(naturalFont);
    d->setFont_helper(resolvedFont);
}

/*!
    \property QGraphicsWidget::palette
    \brief the widget's palette

    This property provides the widget's palette. The palette provides colors
    and brushes for color groups (e.g., QPalette::Button) and states (e.g.,
    QPalette::Inactive), loosely defining the general look of the widget and
    its children.

    QPalette consists of color groups that have been explicitly defined, and
    groups that are implicitly inherited from the widget's parent. Because of
    this, palette() can return a different palette than what has been set with
    setPalette(). This scheme allows you to define single entries in a palette
    without affecting the palette's inherited entries.

    When a widget's palette changes, it resolves its entries against its
    parent widget, or if it doesn't have a parent widget, it resolves against
    the scene. It then sends itself a \l{QEvent::PaletteChange}{PaletteChange}
    event, and notifies all its descendants so they can resolve their palettes
    as well.

    By default, this property contains the application's default palette.

    \sa QApplication::palette(), QGraphicsScene::palette, QPalette::resolve()
*/
QPalette QGraphicsWidget::palette() const
{
    Q_D(const QGraphicsWidget);
    return d->palette;
}
void QGraphicsWidget::setPalette(const QPalette &palette)
{
    Q_D(QGraphicsWidget);
    setAttribute(Qt::WA_SetPalette, palette.resolve() != 0);

    QPalette naturalPalette = d->naturalWidgetPalette();
    QPalette resolvedPalette = palette.resolve(naturalPalette);
    d->setPalette_helper(resolvedPalette);
}

/*!
    If this widget is currently managed by a layout, this function notifies
    the layout that the widget's size hints have changed and the layout
    may need to resize and reposition the widget accordingly.

    Call this function if the widget's sizeHint() has changed.

    \sa QGraphicsLayout::invalidate()
*/
void QGraphicsWidget::updateGeometry()
{
    QGraphicsLayoutItem::updateGeometry();
    QGraphicsLayoutItem *parentItem = parentLayoutItem();

    if (parentItem && parentItem->isLayout()) {
        parentItem->updateGeometry();
    } else {
        if (parentItem) {
            QGraphicsWidget *parentWid = parentWidget();    //###
            if (parentWid->isVisible())
                QApplication::postEvent(parentWid, new QEvent(QEvent::LayoutRequest));
        }
        bool wasResized = testAttribute(Qt::WA_Resized);
        resize(size()); // this will restrict the size
        setAttribute(Qt::WA_Resized, wasResized);
    }
}

/*!
    \reimp

    QGraphicsWidget uses the base implementation of this function to catch and
    deliver events related to state changes in the item. Because of this, it is
    very important that subclasses call the base implementation.

    \a change specifies the type of change, and \a value is the new value.

    For example, QGraphicsWidget uses ItemVisibleChange to deliver
    \l{QEvent::Show} {Show} and \l{QEvent::Hide}{Hide} events,
    ItemPositionHasChanged to deliver \l{QEvent::Move}{Move} events,
    and ItemParentChange both to deliver \l{QEvent::ParentChange}
    {ParentChange} events, and for managing the focus chain.

    QGraphicsWidget enables the ItemSendsGeometryChanges flag by default in
    order to track position changes.

    \sa QGraphicsItem::itemChange()
*/
QVariant QGraphicsWidget::itemChange(GraphicsItemChange change, const QVariant &value)
{
    Q_D(QGraphicsWidget);
    switch (change) {
    case ItemEnabledHasChanged: {
        // Send EnabledChange after the enabled state has changed.
        QEvent event(QEvent::EnabledChange);
        QApplication::sendEvent(this, &event);
        break;
    }
    case ItemVisibleChange:
        if (value.toBool()) {
            // Send Show event before the item has been shown.
            QShowEvent event;
            QApplication::sendEvent(this, &event);
            bool resized = testAttribute(Qt::WA_Resized);
            if (!resized) {
                adjustSize();
                setAttribute(Qt::WA_Resized, false);
            }
        }
        break;
    case ItemVisibleHasChanged:
        if (!value.toBool()) {
            // Send Hide event after the item has been hidden.
            QHideEvent event;
            QApplication::sendEvent(this, &event);
        }
        break;
    case ItemPositionHasChanged:
        d->setGeometryFromSetPos();
        break;
    case ItemParentChange: {
        QGraphicsItem *parent = qVariantValue<QGraphicsItem *>(value);
        d->fixFocusChainBeforeReparenting((parent && parent->isWidget()) ? static_cast<QGraphicsWidget *>(parent) : 0, scene());

        // Deliver ParentAboutToChange.
        QEvent event(QEvent::ParentAboutToChange);
        QApplication::sendEvent(this, &event);
        break;
    }
    case ItemParentHasChanged: {
        // Deliver ParentChange.
        QEvent event(QEvent::ParentChange);
        QApplication::sendEvent(this, &event);
        break;
    }
    case ItemCursorHasChanged: {
        // Deliver CursorChange.
        QEvent event(QEvent::CursorChange);
        QApplication::sendEvent(this, &event);
        break;
    }
    case ItemToolTipHasChanged: {
        // Deliver ToolTipChange.
        QEvent event(QEvent::ToolTipChange);
        QApplication::sendEvent(this, &event);
        break;
    }
    default:
        break;
    }
    return QGraphicsItem::itemChange(change, value);
}

/*!
    \internal

    This virtual function is used to notify changes to any property (both
    dynamic properties, and registered with Q_PROPERTY) in the
    widget. Depending on the property itself, the notification can be
    delivered before or after the value has changed.

    \a propertyName is the name of the property (e.g., "size" or "font"), and
    \a value is the (proposed) new value of the property. The function returns
    the new value, which may be different from \a value if the notification
    supports adjusting the property value. The base implementation simply
    returns \a value for any \a propertyName.

    QGraphicsWidget delivers notifications for the following properties:

    \table     \o propertyName        \o Property
    \row       \o layoutDirection     \o QGraphicsWidget::layoutDirection
    \row       \o size                \o QGraphicsWidget::size
    \row       \o font                \o QGraphicsWidget::font
    \row       \o palette             \o QGraphicsWidget::palette
    \endtable

    \sa itemChange()
*/
QVariant QGraphicsWidget::propertyChange(const QString &propertyName, const QVariant &value)
{
    Q_UNUSED(propertyName);
    return value;
}

/*!
    QGraphicsWidget's implementation of sceneEvent() simply passes \a event to
    QGraphicsWidget::event(). You can handle all events for your widget in
    event() or in any of the convenience functions; you should not have to
    reimplement this function in a subclass of QGraphicsWidget.

    \sa QGraphicsItem::sceneEvent()
*/
bool QGraphicsWidget::sceneEvent(QEvent *event)
{
    return QGraphicsItem::sceneEvent(event);
}

/*!
    This event handler, for \a event, receives events for the window frame if
    this widget is a window. Its base implementation provides support for
    default window frame interaction such as moving, resizing, etc.

    You can reimplement this handler in a subclass of QGraphicsWidget to
    provide your own custom window frame interaction support.

    Returns true if \a event has been recognized and processed; otherwise,
    returns false.

    \sa event()
*/
bool QGraphicsWidget::windowFrameEvent(QEvent *event)
{
    Q_D(QGraphicsWidget);
    switch (event->type()) {
    case QEvent::GraphicsSceneMousePress:
        d->windowFrameMousePressEvent(static_cast<QGraphicsSceneMouseEvent *>(event));
        break;
    case QEvent::GraphicsSceneMouseMove:
        d->ensureWindowData();
        if (d->windowData->grabbedSection != Qt::NoSection) {
            d->windowFrameMouseMoveEvent(static_cast<QGraphicsSceneMouseEvent *>(event));
            event->accept();
        }
        break;
    case QEvent::GraphicsSceneMouseRelease:
        d->windowFrameMouseReleaseEvent(static_cast<QGraphicsSceneMouseEvent *>(event));
        break;
    case QEvent::GraphicsSceneHoverMove:
        d->windowFrameHoverMoveEvent(static_cast<QGraphicsSceneHoverEvent *>(event));
        break;
    case QEvent::GraphicsSceneHoverLeave:
        d->windowFrameHoverLeaveEvent(static_cast<QGraphicsSceneHoverEvent *>(event));
        break;
    default:
        break;
    }
    return event->isAccepted();
}

/*!
    \since 4.4

    Returns the window frame section at position \a pos, or
    Qt::NoSection if there is no window frame section at this
    position.

    This function is used in QGraphicsWidget's base implementation for window
    frame interaction.

    You can reimplement this function if you want to customize how a window
    can be interactively moved or resized.  For instance, if you only want to
    allow a window to be resized by the bottom right corner, you can
    reimplement this function to return Qt::NoSection for all sections except
    Qt::BottomRightSection.

    \sa windowFrameEvent(), paintWindowFrame(), windowFrameGeometry()
*/
Qt::WindowFrameSection QGraphicsWidget::windowFrameSectionAt(const QPointF &pos) const
{
    Q_D(const QGraphicsWidget);

    const QRectF r = windowFrameRect();
    if (!r.contains(pos))
        return Qt::NoSection;

    const qreal left = r.left();
    const qreal top = r.top();
    const qreal right = r.right();
    const qreal bottom = r.bottom();
    const qreal x = pos.x();
    const qreal y = pos.y();

    const qreal cornerMargin = 20;
    //### Not sure of this one, it should be the same value for all edges.
    const qreal windowFrameWidth = d->windowFrameMargins
        ? d->windowFrameMargins[d->Left] : 0;

    Qt::WindowFrameSection s = Qt::NoSection;
    if (x <= left + cornerMargin) {
        if (y <= top + windowFrameWidth || (x <= left + windowFrameWidth && y <= top + cornerMargin)) {
            s = Qt::TopLeftSection;
        } else if (y >= bottom - windowFrameWidth || (x <= left + windowFrameWidth && y >= bottom - windowFrameWidth)) {
            s = Qt::BottomLeftSection;
        } else if (x <= left + windowFrameWidth) {
            s = Qt::LeftSection;
        }
    } else if (x >= right - cornerMargin) {
        if (y <= top + windowFrameWidth || (x >= right - windowFrameWidth && y <= top + cornerMargin)) {
            s = Qt::TopRightSection;
        } else if (y >= bottom - windowFrameWidth || (x >= right - windowFrameWidth && y >= bottom - windowFrameWidth)) {
            s = Qt::BottomRightSection;
        } else if (x >= right - windowFrameWidth) {
            s = Qt::RightSection;
        }
    } else if (y <= top + windowFrameWidth) {
        s = Qt::TopSection;
    } else if (y >= bottom - windowFrameWidth) {
        s = Qt::BottomSection;
    }
    if (s == Qt::NoSection) {
        QRectF r1 = r;
        r1.setHeight(d->windowFrameMargins
                     ? d->windowFrameMargins[d->Top] : 0);
        if (r1.contains(pos))
            s = Qt::TitleBarArea;
    }
    return s;
}

/*!
    \reimp

    Handles the \a event.  QGraphicsWidget handles the following
    events:

    \table   \o Event                 \o Usage
    \row     \o Polish
                    \o Delivered to the widget some time after it has been
                        shown.
    \row     \o GraphicsSceneMove
                    \o Delivered to the widget after its local position has
                        changed.
    \row     \o GraphicsSceneResize
                    \o Delivered to the widget after its size has changed.
    \row     \o Show
                    \o Delivered to the widget before it has been shown.
    \row     \o Hide
                    \o Delivered to the widget after it has been hidden.
    \row     \o PaletteChange
                    \o Delivered to the widget after its palette has changed.
    \row     \o FontChange
                    \o Delivered to the widget after its font has changed.
    \row     \o EnabledChange