QT編譯時出現警告 Warning: Class Node implements the interface QGraphicsItem but does not list it in Q_INTERFACES. qobject_cast to QGraphicsItem will not work!

1.一定要將public QObject放在public QGraphicsItem的前面,並且在該類的定義中添加Q_OBJECT宏.

class XXGraphicsItem : public QObject, public QGraphicsItem 

編譯時出現警告 Warning: Class Node implements the interface QGraphicsItem but does not list it in Q_INTERFACES. qobject_cast to QGraphicsItem will not work!

在類的聲明（Q_OBJECT下面）中添加:Q_INTERFACES(QGraphicsItem)可解決該問題.

class XXGraphicsItem : public QObject, public QGraphicsItem 
{
	Q_OBJECT
	Q_INTERFACES(QGraphicsItem)