I'm attempting to store interface pointers in a tree view under TTreeNode.Data
properties. While I am able to store an interface pointer (Node.Data := Pointer(MyInterface);
) it does not seem to work the other way around (MyInterface := ISomeInterface(Node.Data);
). It always comes out nil
.
I've also attempted to use manual reference counting, as I've seen required in another question. However, it is still coming out nil
and now giving memory leaks.
//Clears tree view and adds drive letters
procedure TfrmMain.cmdRefreshBrowseClick(Sender: TObject);
var
Arr, O: ISuperObject;
X: Integer;
N, C: TTreeNode;
begin
//First clear all items and release their interface refs
for N in tvBrowse.Items do begin
O:= ISuperObject(N.Data);
O._Release;
end;
tvBrowse.Items.Clear;
Arr:= ListDirectory(''); //Returns ISuperObject array listing drives
for X := 0 to Arr.AsArray.Length-1 do begin
O:= Arr.AsArray.O[X];
N:= tvBrowse.Items.Add(nil, O.S['drive']+': ['+O.S['type']+']'); //Add root node
N.Data:= Pointer(O); // Assign interface pointer to node data
O._AddRef; //Manually increment interface reference count
C:= tvBrowse.Items.AddChild(N, ''); //Add a fake child node
end;
end;
procedure TfrmMain.tvBrowseExpanding(Sender: TObject; Node: TTreeNode;
var AllowExpansion: Boolean);
var
N, C: TTreeNode;
P, A, O: ISuperObject;
X: Integer;
begin
//Check first node if it's a fake node
N:= Node.getFirstChild;
if N.Text = '' then begin //if first node is a fake node...
P:= ISuperObject(Node.Data); // <-- P always comes out nil here???
N.Delete; //Delete first "fake" node
//Get child files/folders
if Node.Parent = nil then //If root (drive) node...
A:= ListDirectory(P.S['drive']+':') //Returns ISuperObject array listing files/folders
else
A:= ListDirectory(P.S['name']); //Returns ISuperObject array listing files/folders
for X := 0 to A.AsArray.Length-1 do begin
O:= A.AsArray.O[X];
C:= tvBrowse.Items.AddChild(N, O.S['name']); //Add child node
C.Data:= Pointer(O); //Assign interface pointer to node data
O._AddRef; //Manually increment reference count
end;
end;
end;
What's the appropriate way to do this?
See Question&Answers more detail:os