On woensdag 15 juni 2016 19:00:34 CEST Igor Mironchik wrote: > Hello. > > On 15.06.2016 16:59, Konstantin Shegunov wrote: > > Hello, > > > > > > On Wed, Jun 15, 2016 at 4:15 PM, Igor Mironchik > > > > <igor.mironc...@gmail.com <mailto:igor.mironc...@gmail.com>> wrote: > > Parent of the handles is the same as Line's. But Line own objects > > of handles with QScopedPointer. > > > > This doesn't sound right. If the handles are not children to the line, > > then the line doesn't own them. Leaving semantics aside, it sounds > > you're trying to "hijack" the ownership from the parent by using these > > scoped pointers. > > Exactly. I need to Line be as parent of handles but they should be > parented to the scene (read form in my app) because I need > boundingRect() to return exactly bounding rectangle of the line without > handles. An I need handles to be removed with the Line if Line deleted. > > I know that I can implement my own method in Line like > boundingRectOfLine() and make handles children of Line. May be it would > be a better solution, but at this time I have such code and it work... > > > So my question is it possible that handle will be deleted before > > Line, so QScopedPointer will try to free already deleted pointer? > > > > From your description I'd guess this is exactly what's happening. > > Here you aren't right. In d_tor() of QGraphicsScene I see: > > while (!d->topLevelItems.isEmpty()) > delete d->topLevelItems.first(); > > where topLevelItems are in creating order... > > and in QGraphicsItem d_tor() > > while (!d_ptr->children.isEmpty()) > delete d_ptr->children.first(); > > So when Line deleted it places before handles in children list, and > before Line deleted handles already deleted and removed from children list. > Fine. So in the current implementation, it may actually work. But be aware that there is no guarantee whatsoever that it will always work or will keep working in the future. I would not depend on an implementation detail like that.
André _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
