CODEWITHSUNDEEP
delphiclassdelphi-7virtualtreeview
migajek
migajek

Reputation: 8614

Delphi, VirtualStringTree - classes (objects) instead of records

I need to use a class instead of record for VirtualStringTree node.

Should I declare it standard (but in this case - tricky) way like that:

PNode = ^TNode;
TNode = record
 obj: TMyObject;
end;
//..
var
 fNd: PNode;
begin
fNd:= vstTree.getNodeData(vstTree.AddChild(nil));
fNd.obj:= TMyObject.Create; 
//..

or should I use directly TMyObject? If so - how?! How about assigning (constructing) the object and freeing it?

Thanks in advance m.

Upvotes: 4

Views: 2497

Answers (4)

APZ28
APZ28

Reputation: 1007

  1. Setup datasize for holding object

    vstTree.NodeDataSize := SizeOf(TMyObject);

  2. Get the datasize holder and bind to your object

    vstTree.getNodeData(passed in interested node)^ := your object

    or

    vstTree.getNodeData(vstTree.AddChild(nil))^ := TMyObject.Create;

    or
    use vstTree.InsertNode method

  3. To free the binding object hookup the OnFreeNode event

    vstTree.OnFreeNode := FreeNodeMethod;

    with

    procedure TFoo.FreeNodeMethod(Sender: TBaseVirtualTree; Node: PVirtualNode);
var
  P: ^TMyObject;
begin
  P := Sender.getNodeData(Node);
  if P <> nil then
  begin
      P^.Free;
      P^ := nil; //for your safety or you can omit this line
  end;
end;

Upvotes: 8

jpfollenius
jpfollenius

Reputation: 16620

Just add an object reference to your record. Use the OnInitNode and OnFreeNode events to create and destroy your object.

Upvotes: 1

Linas
Linas

Reputation: 5545

And you can free your object in OnFreeNode event.

Upvotes: 1

zz1433
zz1433

Reputation: 3586

you could create the object instance after receiving the node data, as in :

fNd:= vstTree.getNodeData(vstTree.AddChild(nil)); 
fnd.obj := TMbyObject.Create;

or you could try and assign it directly

Pointer(Obj) := vstTree.getNodeData(...);

Upvotes: 1

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