怎么做下载进度条？？？？？？？？？？

Question

用这个API函数：UrlDownloadToFile
然后怎么做呀？能否给源代码？？？？？？？？？？？？

Answer 1

frmUpdate = class(TForm,IBindStatusCallback)
    ImgTop: TImage;
    LblTop: TLabel;
    SpdBtnClose: TSpeedButton;
    Bevel1: TBevel;
    plStatus: TPanel;
    plInfo: TPanel;
    btnCancel: TFlatSpeedButton;
    tmrUdapte: TTimer;
    plProgress: TPanel;
    procedure tmrUdapteTimer(Sender: TObject);
    procedure btnCancelClick(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure ImgTopMouseMove(Sender: TObject; Shift: TShiftState; X,Y: Integer);
    procedure SpdBtnCloseClick(Sender: TObject);
  private
    function OnStartBinding(dwReserved: DWORD; pib: IBinding): HResult; stdcall;
    function GetPriority(out nPriority): HResult; stdcall;
    function OnLowResource(reserved: DWORD): HResult; stdcall;
    function OnProgress(ulProgress, ulProgressMax, ulStatusCode: ULONG;szStatusText: LPCWSTR): HResult; stdcall;
    function OnStopBinding(hresult: HResult; szError: LPCWSTR): HResult; stdcall;
    function GetBindInfo(out grfBINDF: DWORD; var bindinfo: TBindInfo): HResult; stdcall;
    function OnDataAvailable(grfBSCF: DWORD; dwSize: DWORD; formatetc: PFormatEtc;stgmed: PStgMedium): HResult; stdcall;
    function OnObjectAvailable(const iid: TGUID; punk: IUnknown): HResult; stdcall;
    function GetHTMLFile(URL, FileName: string): HRESULT;
  public
    { Public declarations }
  end;//------------------------------------------------------------------------------
function TfrmUpdate.GetHTMLFile( URL , FileName : string) : HRESULT;
var
  status : IBindStatusCallback ;
begin
  status := IBindStatusCallback(self);
  result := UrlDownLoadToFile(nil, pChar( URL ) ,pChar( FileName ),0 ,Status );
end;//------------------------------------------------------------------------------
function TfrmUpdate.GetBindInfo(out grfBINDF: DWORD;
  var bindinfo: TBindInfo): HResult;
begin
   result := E_NOTIMPL;
end;//------------------------------------------------------------------------------
function TfrmUpdate.GetPriority(out nPriority): HResult;
begin
   result := E_NOTIMPL;
end;//------------------------------------------------------------------------------
function TfrmUpdate.OnDataAvailable(grfBSCF, dwSize: DWORD;
  formatetc: PFormatEtc; stgmed: PStgMedium): HResult;
begin
   result := E_NOTIMPL;
end;//------------------------------------------------------------------------------
function TfrmUpdate.OnLowResource(reserved: DWORD): HResult;
begin
   result := E_NOTIMPL;
end;//------------------------------------------------------------------------------
function TfrmUpdate.OnObjectAvailable(const iid: TGUID;
  punk: IInterface): HResult;
begin
   result := E_NOTIMPL;
end;//------------------------------------------------------------------------------
function TfrmUpdate.OnStartBinding(dwReserved: DWORD;
  pib: IBinding): HResult;
begin
   result := E_NOTIMPL;
end;//------------------------------------------------------------------------------
function TfrmUpdate.OnStopBinding(hresult: HResult;
  szError: LPCWSTR): HResult;
begin
   result := E_NOTIMPL;
end;