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Doc: Let SQL Drill Down example show correct use of qgraphicsitem_cast

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For qgraphicsitem_cast to work correctly with custom items, one must
reimplement the type() function for each custom QGraphicsItem subclass.
Do that in the example code.

Fixes: QTBUG-7357
Change-Id: Ibf221817908355f0347cddfc46747b6955958f5f
Reviewed-by: Andy Shaw <andy.shaw@qt.io>
This commit is contained in:
Paul Wicking 2020-03-06 07:29:12 +01:00
parent c3ae30085e
commit a2446c0eed
2 changed files with 6 additions and 0 deletions
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3
examples/sql/doc/src/drilldown.qdoc
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@ -437,6 +437,9 @@
\snippet drilldown/imageitem.h 0 \snippet drilldown/imageitem.h 0
We declare a \c Type enum value for our custom item and reimplement
\l{QGreaphicsItem::}{type()}. This is done so we can safely use
qgraphicsitem_cast().
In addition, we implement a public \c id() function to be able to In addition, we implement a public \c id() function to be able to
identify the associated location and a public \c adjust() function identify the associated location and a public \c adjust() function
that can be called to ensure that the image item is given the that can be called to ensure that the image item is given the

3
examples/sql/drilldown/imageitem.h
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@ -60,8 +60,11 @@ class ImageItem : public QObject, public QGraphicsPixmapItem
Q_OBJECT Q_OBJECT
public: public:
enum { Type = UserType + 1 };
ImageItem(int id, const QPixmap &pixmap, QGraphicsItem *parent = nullptr); ImageItem(int id, const QPixmap &pixmap, QGraphicsItem *parent = nullptr);
int type() const override { return Type; }
void adjust(); void adjust();
int id() const; int id() const;