delphi实现DBGrid全选和反选功能

delphi实现DBGrid全选和反选功能，可使用TPopupMenu在DBGrid里实现右键功能
Delphi实现Dbgrid全选和反选、清除全选的功能，代码内容如下：

//全选
procedure TForm1.ToolButton1Click(Sender: TObject);
var
  OldCurrent: TBookmark;
begin
  OldCurrent := DBGrid1.DataSource.DataSet.Bookmark;
  DBGrid1.DataSource.DataSet.DisableControls;
  DBGrid1.DataSource.DataSet.First ;
  while not DBGrid1.DataSource.DataSet.Eof do begin
    DBGrid1.SelectedRows.CurrentRowSelected := true;
    DBGrid1.DataSource.DataSet.Next;
  end;
  DBGrid1.DataSource.DataSet.GotoBookmark(OldCurrent);
  DBGrid1.DataSource.DataSet.EnableControls;
end;
//清除全选
procedure TForm1.ToolButton2Click(Sender: TObject);
var
  OldCurrent: TBookmark;
begin
  OldCurrent := DBGrid1.DataSource.DataSet.Bookmark;
  DBGrid1.DataSource.DataSet.DisableControls;
  DBGrid1.DataSource.DataSet.First ;
  while not DB