问题
Good day!
With Qt 4.7.3 an example below crashes at QGraphicsScene::~QGraphicsScene() call:
#include <QCoreApplication>
#include <QGraphicsScene>
int main( int argc, char* argv[] )
{
// replace this with QObject app; and no problems
QCoreApplication app( argc, argv );
new QGraphicsScene( &app );
return 0;
}
Any ideas?
UPDATE:
Bug report created.
回答1:
When a QGraphicsScene
instance is constructed it appends itself in a list stored in a private member of the single QApplication
instance, and when it is deleted, it also remove itself from that list:
QGraphicsScene::~QGraphicsScene()
{
Q_D(QGraphicsScene);
// Remove this scene from qApp's global scene list.
qApp->d_func()->scene_list.removeAll(this);
...
}
When the application object is destroyed, the inherited base class' destructors are called recursively, so, ~QApplication()
calls ~QCoreApplication()
which itself calls ~QObject()
.
The actual deletion of child objects is done in ~QObject()
.
Which means that at the time the scene object is destroyed, all the QApplication
members are already destroyed, so ~QGraphicsScene()
crashes when it tries to access the list.
来源:https://stackoverflow.com/questions/7929981/qgraphicssceneqgraphicsscene-segmentation-fault