Question

I want to copy the selected node and all its descendants from one TTreeView to another.

What is the best, most efficient way to achieve this?

Answer 1

It’s easiest to do this recursively, something like this:

procedure WalkChildren(Node: TTreeNode; List: TList<TTreeNode>);
var
  i: Integer;
begin
  List.Add(Node);
  for i := 0 to Node.Count-1 do begin
    WalkChildren(Node[i], List);
  end;
end;

Call it like this:

List := TList<TTreeNode>.Create;
WalkChildren(Root, List);

This example adds to a list but you can replace that action with one of your choosing.

Now that we can walk one tree, it’s time to walk two trees in tandem.

procedure CopySubTree(Src, DestParent: TTreeNode; DestNodes: TTreeNodes);
var
  i: Integer;
  Dest: TTreeNode;
begin
  Dest := DestNodes.AddChild(DestParent, Src.Text);
  //copy other parameters from Src to Dest as you please
  for i := 0 to Src.Count-1 do begin
    CopySubTree(Src[i], Dest, DestNodes);
  end;
end;

You can call it like so:

CopySubTree(SrcTree.Selected, nil, DestTree.Items);