大虾请进，怎么能在用UrlDownloadToFile下载东东时得到下载的进度？

Question

我知道要用到IBindStatusCallback接口，但是到底怎么用，哪位大虾有Delphi例子的，马上给分！

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;

Answer 2

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtActns, ComCtrls;type
  TForm1 = class(TForm)
    ProgressBar1: TProgressBar;
    Label1: TLabel;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    DownLoadURL : TDownLoadURL;
    procedure DownloadProgress(Sender: TDownLoadURL; Progress,
      ProgressMax: Cardinal; StatusCode: TURLDownloadStatus; StatusText: String;
      var Cancel: Boolean);
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.DownloadProgress(Sender: TDownLoadURL; Progress,
  ProgressMax: Cardinal; StatusCode: TURLDownloadStatus;
  StatusText: String; var Cancel: Boolean);
begin
  Label1.Caption := StatusText;
  ProgressBar1.Max := ProgressMax;
  ProgressBar1.Position := Progress;
end;procedure TForm1.FormCreate(Sender: TObject);
begin
  DownLoadURL := TDownLoadURL.Create(self);
  with DownLoadURL do
  begin
    FileName := 'c:\p.exe';
    URL := 'http://www.teechart.net/files/vcl/public/TeeChartPro6/TeeChart601Delphi6_RTL3.EXE';
    OnDownloadProgress := DownloadProgress;
  end;
end;procedure TForm1.Button1Click(Sender: TObject);
begin
  DownLoadURL.ExecuteTarget(DownLoadURL);
end;end.  

Answer 3

HRESULT URLDownloadToFile(
    LPUNKNOWN pCaller,
    LPCTSTR szURL,
    LPCTSTR szFileName,
    DWORD dwReserved,
    LPBINDSTATUSCALLBACK lpfnCB
);
最后一个参数就是回调函数，你可以写一个让它回调，在里面处理你的进度条即可。