serialization - IDataObject store managed object reference -

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i trying implement drag-and-drop functionality within c++/cli application, using standard winforms , wpf (managed) apis. these apis accept object wrapped in implementation of idataobject, serialize it, , deserialize once drag-and-drop target has been specified. not want data transferred serialized , deserialized.

a bit more concretely (albeit dramatically simplified):

[serializableattribute] ref class mytype : public system::iobserver<object^> { public:     system::iobservable<object^> ^myobj;     static void watch(mytype ^wrapper)     {         myobj->subscribe(watcher);     } private:     static mytype ^watcher = gcnew mytype();     void oncompleted(void) = system::iobserver<object^>::oncompleted {}     void onerror(system::exception^) = system::iobserver<object^>::onerror {}     void onnext(object^) = system::iobserver::onnext     {         system::windows::forms::messagebox::show("hi!");     } } ref class mycontrol : public system::windows::controls::usercontrol { public:     mycontrol(void)     {         this->drop += gcnew drageventhandler(this, &mycontrol::this_drop);     } private:     void this_drop(object^, system::windows::drageventargs ^e)     {         mytype::watch(dynamic_cast<mytype^>(e->data->getdata("myformat")));     } } ref class myform : public system::windows::forms::form { public:     myform(void)     {         initializecomponent();         mytreeview->itemdrag += gcnew system::windows::forms::itemdrageventhandler(this, &myform::mytreeview_itemdrag);     } private:     mytype ^data = gcnew mytype();     system::windows::forms::treeview ^mytreeview;     mycontrol ^mycontrol;     void modifymyobjfield(mytype^);     void myeventhandler(object^, eventargs^)     {         modifymyobjfield(data);     }     void mytreeview_itemdrag(object^, system::windows::forms::itemdrageventargs^)     {         mytreeview->dodragdrop(gcnew dataobject("myformat", mytype), dragdropeffects::copy);     } }

when myeventhandler called, no messagebox appears, because different mytype object receives iobservable subscription 1 modified.

because drag-and-drop occurs cis-application, can work around issue pinning myform::data , passing intptr back-and-forth. myform::mytreeview_itemdrag becomes

{     mytreeview->dodragdrop(gcnew dataobject("myformat", system::runtime::interopservices::gchandle::alloc(data, system::runtime::interopservices::gchandletype::pinned).tointptr()), dragdropeffects::copy); }

and mycontrol::this_drop becomes

{     system::runtime::interopservices::gchandle handle = system::runtime::interopservices::gchandle::fromintptr(*dynamic_cast<intptr^>(e->data->getdata("myformat")));     mytype::watch(dynamic_cast<mytype^>(handle.target));     handle.free(); }

this seems extraordinarily complicated way accomplish simple task, , (obviously) bog down garbage collector. there better way missing?


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