Как вывести в TTreeView содержимое папок

implementation
 
{$R *.DFM}
{$R FileCtrl}
 
procedure NextLevel(ParentNode: TTreeNode);
  function DirectoryName(name: string): boolean;
  begin
    result := (name <> '.') and (name <> '..');
  end;
var
  sr, srChild: TSearchRec;
  node: TTreeNode;
  path: string;
begin
  node := ParentNode;
  path := '';
  repeat
    path := node.Text + '\' + path;
    node := node.Parent;
  until node = nil;
  if FindFirst(path + '*.*', faDirectory, sr) = 0 then begin
    repeat
      if (sr.Attr and faDirectory <> 0) and DirectoryName(sr.Name) then begin
        node := Form1.TreeView1.Items.AddChild(ParentNode, sr.Name);
        node.ImageIndex := 0;
        node.SelectedIndex := 1;
        node.HasChildren := false;
        if FindFirst(path + sr.Name + '\*.*', faDirectory, srChild) = 0 then begin
          repeat
            if (srChild.Attr and faDirectory <> 0) and DirectoryName(srChild.Name)
              then node.HasChildren := true;
          until (FindNext(srChild) <> 0) or node.HasChildren;
        end;
        FindClose(srChild);
      end;
    until FindNext(sr) <> 0;
  end else ParentNode.HasChildren := false;
  FindClose(sr);
end;
 
procedure TForm1.FormCreate(Sender: TObject);
const
  IconNames: array [0..6] of string = ('CLOSEDFOLDER', 'OPENFOLDER',
    'FLOPPY', 'HARD', 'NETWORK', 'CDROM', 'RAM');
var
  c: char;
  s: string;
  node: TTreeNode;
  DriveType: integer;
  bm, mask: TBitmap;
  i: integer;
begin
  TreeView1.Items.BeginUpdate;
  TreeView1.Images := TImageList.CreateSize(16, 16);
  bm := TBitmap.Create;
  mask := TBitmap.Create;
  for i := low(IconNames) to high(IconNames) do begin
    bm.Handle := LoadBitmap(HInstance, PChar(IconNames[i]));
    bm.Width := 16;
    bm.Height := 16;
    mask.Assign(bm);
    mask.Mask(clBlue);
    TreeView1.Images.Add(bm, mask);
  end;
  for c := 'A' to 'Z' do begin
    s := c + ':';
    DriveType := GetDriveType(PChar(s));
    if DriveType = 1 then continue;
    node := Form1.TreeView1.Items.AddChild(nil, s);
    case DriveType of
      DRIVE_REMOVABLE: node.ImageIndex := 2;
      DRIVE_FIXED: node.ImageIndex := 3;
      DRIVE_REMOTE: node.ImageIndex := 4;
      DRIVE_CDROM: node.ImageIndex := 5;
      else node.ImageIndex := 6;
    end;
    node.SelectedIndex := node.ImageIndex;
    node.HasChildren := true;
  end;
  TreeView1.Items.EndUpdate;
end;
 
procedure TForm1.TreeView1Expanding(Sender: TObject; Node: TTreeNode;
  var AllowExpansion: Boolean);
begin
  TreeView1.Items.BeginUpdate;
  node.DeleteChildren;
  NextLevel(node);
  TreeView1.Items.EndUpdate;
end;