On Tue, Sep 25, 2018 at 3:35 PM Korbinian Bachl < korbinian.ba...@whiskyworld.de> wrote:
> Hi, > > take a look at > https://ci.apache.org/projects/wicket/guide/8.x/single.html#_components_lifecycle > > You might want to move the code from constructor to > onInitialize() > The benefit of using onInitialize() over the constructor is that you have access to the parent component (getParent() != null) and to the associated markup. In case of a Page there is no parent. > and you can use > onRemove() > to free it up as this is called when the component gets removed from the > page / the page itself gets removed; > "the page itself gets removed" I think this is not correct. > Keep in mind that wicket stores old pages by default. In your case you > might also want to have a look at LoadableDetachableModel, so that the > model can react with "activation"/"passivation" of its data; > > The goal should usually be to not store any data at all that can be > retrieved, so to not waste memory - said, it might be necessary in your > case to store it with the page as it might be very expensive to (re)create > the data, then the above onInitialize/ onRemove on the page level would be > good to use; > > Best, > > KB > > > > ----- Ursprüngliche Mail ----- > > Von: "yvus" <yves.courvois...@enata.com> > > An: users@wicket.apache.org > > Gesendet: Dienstag, 25. September 2018 11:22:15 > > Betreff: Demo Page with User Related Data > > > Dear All, > > > > I have the complex task to develop a webpage GUI for a java/c++ app, i.e. > > the java app contains objects that wrap c++ classes of a .so library. For > > example the Frame.java class wraps a corresponding c++ class frame.h > (which > > does the math). Therefore we call in the constructor of the Frame.java > class > > a c++ constructor through JNA and store the Pointer in a field. > > > > public class Frame { > > private Pointer cppPointer; > > public Frame() { > > cppPointer = Wrapper.INSTANCE.frameConstructor(...) // JNA call > to > > c++ constructor retrieving the c++ pointer. > > } > > } > > > > On the webpage, I have the following scenario in which we display a demo > > page which renders a 3d view. The user is able to displace an object > which > > position is determined by the fields of Frame.java and hence the c++ > > classes. Moving the object is done by changing 'values' in a form. Each > of > > these 'values' directly modify the Frames and hence the Frame c++-class's > > attributes. > > > > In order to have the pointers created only once per page, we construct > all > > the pointers in the constructor of the page and store them in a model > which > > serializes the addresses. This allows to have the c++ side created only > once > > on the page. This seems fine until we have to destroy the pointers > memory. > > > > How to determine when we leave the page in order to destroy the Pointers? > > How would you manage this scenario? is it a good thing to construct the > > pointers in the constructors of the page? When would you allow to destroy > > the c++ allocated memory? > > > > Thanks > > > > -- > > Sent from: > http://apache-wicket.1842946.n4.nabble.com/Users-forum-f1842947.html > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org > > For additional commands, e-mail: users-h...@wicket.apache.org > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org > For additional commands, e-mail: users-h...@wicket.apache.org > >
