在它的workbegin work事件中写代码

procedure TfrmDownLoad.IdHTTP1WorkBegin(Sender: TObject;
AWorkMode: TWorkMode; const AWorkCountMax: Integer);
begin
ProgressBar1.Max := AWorkCountMax ;
end;


procedure TfrmDownLoad.IdHTTP1Work(Sender: TObject; AWorkMode: TWorkMode;
const AWorkCount: Integer);
begin
ProgressBar1.Position := AWorkCount ;
end;