source: trunk/src/gui/graphicsview/qgraphicswidget.cpp@ 463

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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 multimedia
    \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}
*/

/*!
    \property QGraphicsWidget::enabled
    \brief whether the item is enabled or not

    This property is declared in QGraphicsItem.

    By default, this property is true.

    \sa QGraphicsItem::isEnabled(), QGraphicsItem::setEnabled()
*/

/*!
    \property QGraphicsWidget::visible
    \brief whether the item is visible or not

    This property is declared in QGraphicsItem.

    By default, this property is true.

    \sa QGraphicsItem::isVisible(), QGraphicsItem::setVisible(), show(),
    hide()
*/

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

/*!
    \property QGraphicsWidget::pos
    \brief the position of the widget
*/    

/*!
    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)
    : QGraphicsItem(*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)
    : QGraphicsItem(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) {
        delete 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);
            }
        }
    }

    // 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.