Oh, so I have missed the point of it entirely. The usage of processEvents() in the example threw me off, as I somehow thought that it was necessary to control the whole incubation process.
Thanks! :) ________________________________________ From: Gianluca <gmax...@gmail.com> Sent: Wednesday, 25 November 2015 23:08 To: Curtis Mitch Cc: interest@qt-project.org Subject: Re: [Interest] Asynchronously loading Qt Quick Items (without Loader) Hello Curtis, looking at the documentation, I would suggest to create a subclass of QQmlIncubator and implent the statusChanged method with you code to execute when the object is ready. http://doc.qt.io/qt-5/qqmlincubator.html#statusChanged >From the documentation, it will be called whenever the status change and the >default implementation do nothing. So, it’s really seems that has been put >exactly for your purpose. Ciao, Gianluca. Il giorno 25/nov/2015, alle ore 21:59, Curtis Mitch <mitch.cur...@theqtcompany.com> ha scritto: > > Hi. > > I'm playing around with a project that requires asynchronous loading of > QQuickItems. Specifically, each item has some basic visuals, and some Box2D > types to construct. The items should be loaded asynchronously as there will > be a large amount of them, and they should only be loaded when the view is > close by (the items are within a Flickable). > > I thought I'd use QQmlIncubator for this. Having never used it before, I went > to the detailed description [1] to find an example: > > QQmlIncubator incubator; > component->create(incubator); > > while (incubator.isReady()) { > QCoreApplication::processEvents(QEventLoop::AllEvents, 50); > } > > QObject *object = incubator.object(); > > My first thought is that the "Performance Considerations And Suggestions" > documentation [2] explicitly suggests against such code, saying things like: > > "never manually spin the event loop" > > and: > > "Note: A pattern which is tempting, but should never be used, is creating > your own QEventLoop or calling QCoreApplication::processEvents() in order to > avoid blocking within a C++ code block invoked from QML. This is dangerous, > because when an event loop is entered in a signal handler or binding, the QML > engine continues to run other bindings, animations, transitions, etc. Those > bindings can then cause side effects which, for example, destroy the > hierarchy containing your event loop." > > I'd rather not have to handle all this stuff myself, if possible. > > So, is there a way to asynchronously create Qt Quick Items from a > QQmlComponent (without using Loader), without having to write my own > incubator? Or have I misunderstood the point of QQmlIncubator? > > The reason why I want to avoid Loader is that, from my experience with Qt > Quick Controls, it doesn't perform so well with a large number of items. > > Cheers. > > [1] http://doc.qt.io/qt-5/qqmlincubator.html#details > [2] http://doc.qt.io/qt-5/qtquick-performance.html#timing-considerations > _______________________________________________ > Interest mailing list > Interest@qt-project.org > http://lists.qt-project.org/mailman/listinfo/interest _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
