问题
I need an example how to use "virtual treeview" IterateSubtree in C++ Embarcadero Xe1-7.
I have the problem with this code:
void __fastcall TMyForm::BuSearchClick(TObject *)
{
MyTreeView->IterateSubtree(NULL, SearchDataSomeId, (void*)&PNodeData, TVirtualNodeStates(), false, false);
}
void __fastcall TMyForm::SearchDataSomeId(TBaseVirtualTree*, PVirtualNode Node, void *Data, bool &Abort)
{
}
The compiler gives the following error:
[bcc32 Error] MyFile.cpp(363): E2034 Cannot convert 'void (_fastcall * (_closure )(TBaseVirtualTree *,TVirtualNode *,void *,bool &))(TBaseVirtualTree *,TVirtualNode *,void *,bool &)' to '_di_TVTGetNodeProc'
回答1:
You're trying to use what Delphi/C++Builder calls a method pointer or __closure
. Virtual Treeview expects an anonymous method. See here for more details.
I think that creating an anonymous method in C++Builder involves subclassing from TProc and implementing the Invoke method, but it seems to be very poorly documented.
If subclassing TProc doesn't work or is too hard to figure out, I can think of a couple of options:
- Hack the Virtual Treeview source to create an IterateSubtree overload taking a method pointer.
- Ask a new question on Stack Overflow in hopes that someone else knows how to create a Delphi anonymous method in C++Builder.
回答2:
thanks very much`
i have found the solution
typedef void (*TIterateSubtreeCallBack)(TBaseVirtualTree*, PVirtualNode Node, void *_Data, bool &Abort);
class TMyVTGetNodeProcRef : public TCppInterfacedObject<TVTGetNodeProc>
{
private:
TIterateSubtreeCallBack callback;
public:
TMyVTGetNodeProcRef(TIterateSubtreeCallBack _callback) : callback(_callback) {}
INTFOBJECT_IMPL_IUNKNOWN(TInterfacedObject);
void __fastcall Invoke(TBaseVirtualTree* Sender, TVirtualNode *Node, void *Data, bool &Abort)
{
return callback(Sender, Node, Data, Abort);
}
};
void __fastcall TMyForm::BuSearchClick(TObject *)
{
Node= MyTreeView->IterateSubtree(NULL, new TMyVTGetNodeProcRef(SearchDataId), (void*)&PNodeData, TVirtualNodeStates(), false, false);
}
void TMyForm::SearchDataId(TBaseVirtualTree*Tr, PVirtualNode Node, void *_Data, bool &Abort)
{
put my code ...
}
//---------------------------------------------------------------------------
来源:https://stackoverflow.com/questions/29901427/example-virtual-treeview-iteratesubtree-in-cbuilder-xe-xe7