qgraphicsscenelinearindex_p.h

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// 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
 
#ifndef QGRAPHICSSCENELINEARINDEX_H
#define QGRAPHICSSCENELINEARINDEX_H
 
//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists for the convenience
// of other Qt classes.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
 
#include <QtWidgets/private/qtwidgetsglobal_p.h>
 
#include <QtCore/qrect.h>
#include <QtCore/qlist.h>
#include <QtWidgets/qgraphicsitem.h>
#include <private/qgraphicssceneindex_p.h>
 
QT_REQUIRE_CONFIG(graphicsview);
 
QT_BEGIN_NAMESPACE
 
class Q_AUTOTEST_EXPORT QGraphicsSceneLinearIndex : public QGraphicsSceneIndex
{
    Q_OBJECT
 
public:
    QGraphicsSceneLinearIndex(QGraphicsScene *scene = nullptr) : QGraphicsSceneIndex(scene), m_numSortedElements(0)
    { }
 
    QList<QGraphicsItem *> items(Qt::SortOrder order = Qt::DescendingOrder) const override
    { Q_UNUSED(order); return m_items; }
 
    virtual QList<QGraphicsItem *> estimateItems(const QRectF &rect, Qt::SortOrder order) const override
    {
        Q_UNUSED(rect);
        Q_UNUSED(order);
        return m_items;
    }
 
protected :
    virtual void clear() override
    {
        m_items.clear();
        m_numSortedElements = 0;
    }
 
    virtual void addItem(QGraphicsItem *item) override
    { m_items << item; }
 
    virtual void removeItem(QGraphicsItem *item) override
    {
        // Sort m_items if needed
        if (m_numSortedElements < m_items.size())
        {
            std::sort(m_items.begin() + m_numSortedElements, m_items.end() );
            std::inplace_merge(m_items.begin(), m_items.begin() + m_numSortedElements, m_items.end());
            m_numSortedElements = m_items.size();
        }
 
        QList<QGraphicsItem*>::iterator element = std::lower_bound(m_items.begin(), m_items.end(), item);
        if (element != m_items.end() && *element == item)
        {
            m_items.erase(element);
            --m_numSortedElements;
        }
    }
 
private:
    QList<QGraphicsItem*> m_items;
    int m_numSortedElements;
};
 
QT_END_NAMESPACE
 
#endif // QGRAPHICSSCENELINEARINDEX_H