How to make copy of a treeview nodes to another treeview

Question

How do I take the data from one populated treeview and put it into another existing treeview. All the nodes and children need to be copied.

Answer 1

TTreeNode implements the TPersistent.Assign() method, so one option would be to write a recursive function that iterates the source TreeView adding-and-assigning nodes to the target TreeView. For example:

procedure CopyNodes(SrcTree, DstTree: TTreeView);
var
  DstNodes: TTreeNodes;
  SrcRootNode: TTreeNode;

  procedure DoCopyNodes(SrcNode, Relative: TTreeNode; AddMode: TNodeAttachMode);
  var
    DstNode: TTreeNode;
  begin
    while SrcNode <> nil do
    begin
      DstNode := DstNodes.AddNode(nil, Relative, '', nil, AddMode);
      try
        DstNode.Assign(SrcNode);
        DoCopyNodes(SrcNode.GetFirstChild, DstNode, naAddChild);
      except
        DstNode.Delete;
        raise;
      end;
      SrcNode := SrcNode.GetNextSibling;    
    end;
  end;

begin
  SrcRootNode := SrcTree.Items.GetFirstNode;
  if SrcRootNode <> nil then
  begin
    DstNodes := DstTree.Items;
    DstNodes.BeginUpdate;
    try
      DoCopyNodes(SrcRootNode, nil, naAdd);
    finally
      DstNodes.EndUpdate;
    end;
  end;
end;

CopyNodes(TreeView1, TreeView2);