Qt及Qt Quick开发实战精解项目二俄罗斯方块 items方法报错

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在练习《Qt及Qt Quick开发实战精解》第二章的项目时，在MyView::clearFullRows中有这样一行代码

QList<QGraphicsItem*> list = scene()->items(199, y, 202, 22, Qt::ContainsItemShape);

编辑器就直接报错了，报错信息如下

myview.cpp:75:47: error: no matching member function for call to 'items'
qgraphicsscene.h:158:28: note: candidate function not viable: requires at most 4 arguments, but 5 were provided
qgraphicsscene.h:159:28: note: candidate function not viable: requires at most 4 arguments, but 5 were provided
qgraphicsscene.h:160:28: note: candidate function not viable: requires at most 4 arguments, but 5 were provided
qgraphicsscene.h:161:28: note: candidate function not viable: requires at most 4 arguments, but 5 were provided
qgraphicsscene.h:175:35: note: candidate function not viable: requires at least 6 arguments, but 5 were provided
qgraphicsscene.h:156:28: note: candidate function not viable: allows at most single argument 'order', but 5 arguments were provided

大概意思是参数不匹配

F1进入文档，找到如下方法：

QList<QGraphicsItem *> QGraphicsScene::items(Qt::SortOrder order = Qt::DescendingOrder) const

QList<QGraphicsItem *> QGraphicsScene::items(const QPointF &pos, Qt::ItemSelectionMode mode = Qt::IntersectsItemShape, Qt::SortOrder order = Qt::DescendingOrder, const QTransform &deviceTransform = QTransform()) const

QList<QGraphicsItem *> QGraphicsScene::items(const QRectF &rect, Qt::ItemSelectionMode mode = Qt::IntersectsItemShape, Qt::SortOrder order = Qt::DescendingOrder, const QTransform &deviceTransform = QTransform()) const

QList<QGraphicsItem *> QGraphicsScene::items(const QPolygonF &polygon, Qt::ItemSelectionMode mode = Qt::IntersectsItemShape, Qt::SortOrder order = Qt::DescendingOrder, const QTransform &deviceTransform = QTransform()) const

QList<QGraphicsItem *> QGraphicsScene::items(const QPainterPath &path, Qt::ItemSelectionMode mode = Qt::IntersectsItemShape, Qt::SortOrder order = Qt::DescendingOrder, const QTransform &deviceTransform = QTransform()) const

QList<QGraphicsItem *> QGraphicsScene::items(qreal x, qreal y, qreal w, qreal h, Qt::ItemSelectionMode mode, Qt::SortOrder order, const QTransform &deviceTransform = QTransform()) const

很明显最后一个方法比较匹配，但最后一个方法有7个参数，最少需要提供6个参数，现在代码指提供了5个参数

Qt::ContainsItemShape是ItemSelectionMode的一个枚举值

enum ItemSelectionMode { ContainsItemShape, IntersectsItemShape, ContainsItemBoundingRect, IntersectsItemBoundingRect }

所以我们需要最后一个参数Qt::SortOrder

看了下文档

Qt::SortOrder 此枚举描述如何对小部件中的项进行排序

值有

enum SortOrder { AscendingOrder, DescendingOrder }

所以我们选一个，就选正序吧

QList<QGraphicsItem*> list = scene()->items(199, y, 202, 22, Qt::ContainsItemShape, Qt::AscendingOrder);

这样就不报错了。

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