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39 
40 #ifndef QGRAPHICSSCENELINEARINDEX_H
41 #define QGRAPHICSSCENELINEARINDEX_H
42 
43 //
44 //  W A R N I N G
45 //  -------------
46 //
47 // This file is not part of the Qt API.  It exists for the convenience
48 // of other Qt classes.  This header file may change from version to
49 // version without notice, or even be removed.
50 //
51 // We mean it.
52 //
53 
54 #include <QtWidgets/private/qtwidgetsglobal_p.h>
55 
56 #include <QtCore/qrect.h>
57 #include <QtCore/qlist.h>
58 #include <QtWidgets/qgraphicsitem.h>
59 #include <private/qgraphicssceneindex_p.h>
60 
61 QT_REQUIRE_CONFIG(graphicsview);
62 
63 QT_BEGIN_NAMESPACE
64 
65 class Q_AUTOTEST_EXPORT QGraphicsSceneLinearIndex : public QGraphicsSceneIndex
66 {
67     Q_OBJECT
68 
69 public:
QGraphicsSceneIndex(scene)70     QGraphicsSceneLinearIndex(QGraphicsScene *scene = nullptr) : QGraphicsSceneIndex(scene), m_numSortedElements(0)
71     { }
72 
73     QList<QGraphicsItem *> items(Qt::SortOrder order = Qt::DescendingOrder) const override
74     { Q_UNUSED(order); return m_items; }
75 
estimateItems(const QRectF & rect,Qt::SortOrder order)76     virtual QList<QGraphicsItem *> estimateItems(const QRectF &rect, Qt::SortOrder order) const override
77     {
78         Q_UNUSED(rect);
79         Q_UNUSED(order);
80         return m_items;
81     }
82 
83 protected :
clear()84     virtual void clear() override
85     {
86         m_items.clear();
87         m_numSortedElements = 0;
88     }
89 
addItem(QGraphicsItem * item)90     virtual void addItem(QGraphicsItem *item) override
91     { m_items << item; }
92 
removeItem(QGraphicsItem * item)93     virtual void removeItem(QGraphicsItem *item) override
94     {
95         // Sort m_items if needed
96         if (m_numSortedElements < m_items.size())
97         {
98             std::sort(m_items.begin() + m_numSortedElements, m_items.end() );
99             std::inplace_merge(m_items.begin(), m_items.begin() + m_numSortedElements, m_items.end());
100             m_numSortedElements = m_items.size();
101         }
102 
103         QList<QGraphicsItem*>::iterator element = std::lower_bound(m_items.begin(), m_items.end(), item);
104         if (element != m_items.end() && *element == item)
105         {
106             m_items.erase(element);
107             --m_numSortedElements;
108         }
109     }
110 
111 private:
112     QList<QGraphicsItem*> m_items;
113     int m_numSortedElements;
114 };
115 
116 QT_END_NAMESPACE
117 
118 #endif // QGRAPHICSSCENELINEARINDEX_H
119