Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Ask a Question
Welcome To Ask or Share your Answers For Others

Categories

delphi - Why UrlDownloadToFile::OnProgress always return ulProgress and ulProgressMax with the same value

0 votes
1.6k views
in Technique[技术] by (71.8m points)

delphi - Why UrlDownloadToFile::OnProgress always return ulProgress and ulProgressMax with the same value

This is my delphi code:

TDownloadCallback = class(TInterfacedObject, IBindStatusCallback)
private
    fOwner: TDownload;
    fUrl: string;
public
    constructor Create(owner: TDownload; url: string);

    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;
end;

TDownloadStatus =
(
dsNULL                , dsFindingresource         , dsConnecting              , dsRedirecting,
dsBegindownloaddata   , dsDownloadingdata         , dsEnddownloaddata         , dsBegindownloadcomponents,
dsInstallingcomponents, dsEnddownloadcomponents   , dsUsingcachedcopy         , dsSendingrequest,
dsClassidavailable    , dsMimetypeavailable       , dsCachefilenameavailable  , dsBeginsyncoperation,
dsEndsyncoperation    , dsBeginuploaddata         , dsUploadingdata           , dsEnduploadingdata,
dsProtocolclassid     , dsEncoding                , dsVerfiedmimetypeavailable, dsClassinstalllocation,
dsDecoding            , dsLoadingmimehandler      , dsContentdispositionattach, dsFilterreportmimetype,
dsClsidcaninstantiate , dsIunknownavailable       , dsDirectbind              , dsRawmimetype,
dsProxydetecting      , dsAcceptranges
);

const
  WinNetLib = 'Wininet.DLL';

function DeleteUrlCacheEntry(pszUrl: PChar): BOOL; stdcall; external WinNetLib name 'DeleteUrlCacheEntry';

{ TDownloadCallback }

constructor TDownloadCallback.Create(owner: TDownload; url: string);
begin
  fOwner := owner;
  fUrl := url;
end;

function TDownloadCallback.GetBindInfo(out grfBINDF: DWORD;
  var bindinfo: TBindInfo): HResult;
begin
  DeleteUrlCacheEntry(PChar(fUrl));
  Result := S_OK;
end;

function TDownloadCallback.GetPriority(out nPriority): HResult;
begin
  Result := S_OK;
end;

function TDownloadCallback.OnDataAvailable(grfBSCF, dwSize: DWORD;
  formatetc: PFormatEtc; stgmed: PStgMedium): HResult;
begin
  Result := S_OK;
end;

function TDownloadCallback.OnLowResource(reserved: DWORD): HResult;
begin
  Result := S_OK;
end;

function TDownloadCallback.OnObjectAvailable(const iid: TGUID;
  punk: IInterface): HResult;
begin
  Result := S_OK;
end;

function TDownloadCallback.OnProgress(ulProgress, ulProgressMax,
  ulStatusCode: ULONG; szStatusText: LPCWSTR): HResult;
var
  status: TDownloadStatus;
begin
  if fOwner.fProgress <> nil then
  begin
    status := TDownloadStatus(ulStatusCode);
    case (status) of
    dsBegindownloaddata:
      begin
        fOwner.fProgress.Max := ulProgressMax;
        DeleteUrlCacheEntry(PChar(szStatusText));
      end;
    dsDownloadingdata:
      begin
        // progressbar here!
      end;
    end;
  end;

  Form1.Memo1.Lines.Add(Format('ulProgress: %d, ulProgressMax: %d, ulStatusCode: %d (%s), szStatusText: %s', [
    ulProgress, ulProgressMax, ulStatusCode, GetEnumName(TypeInfo(TDownloadStatus), Integer(status)), szStatusText
  ]));

  Result := S_OK;
  Application.ProcessMessages;
end;

function TDownloadCallback.OnStartBinding(dwReserved: DWORD;
  pib: IBinding): HResult;
begin
  Result := S_OK;
end;

function TDownloadCallback.OnStopBinding(hresult: HResult;
  szError: LPCWSTR): HResult;
begin
  Result := S_OK;
end;

procedure download(url, filename: string);
var
  intf: IBindStatusCallback;
begin
  CoInitialize(nil);
  try
    intf := TDownloadCallback.Create(self, url);
    try
      URLDownloadToFile(nil, PChar(url), Pchar(filename), 0, intf);
    finally
      intf := nil;
    end;
  finally
    CoUninitialize;
  end;
end;

When I call download('htp://....', 'filename.exe') my memo prints:

ulProgress: 0, ulProgressMax: 0, ulStatusCode: 32 (dsProxydetecting), szStatusText: 
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 1 (dsFindingresource), szStatusText: www.jjw.com.br
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 2 (dsConnecting), szStatusText: 177.200.200.199
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 11 (dsSendingrequest), szStatusText: 
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 64 (@
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 3 (dsRedirecting), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 32 (dsProxydetecting), szStatusText: 
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 1 (dsFindingresource), szStatusText: get.anydesk.com
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 2 (dsConnecting), szStatusText: 188.40.104.135
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 11 (dsSendingrequest), szStatusText: 
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 26 (dsContentdispositionattach), szStatusText: C:UsersJJWAppDataLocalMicrosoftWindowsTemporary Internet FilesContent.IE5YQIDXOIQjjwsuporteremotoFAYWSU4M.exe
ulProgress: 0, ulProgressMax: 0, ulStatusCode: 13 (dsMimetypeavailable), szStatusText: application/x-msdownload
ulProgress: 32398, ulProgressMax: 32398, ulStatusCode: 4 (dsBegindownloaddata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 32398, ulProgressMax: 32398, ulStatusCode: 14 (dsCachefilenameavailable), szStatusText: C:UsersJJWAppDataLocalMicrosoftWindowsTemporary Internet FilesContent.IE5YQIDXOIQjjwsuporteremotoFAYWSU4M.exe
ulProgress: 48774, ulProgressMax: 48774, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 65158, ulProgressMax: 65158, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 81534, ulProgressMax: 81534, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 97918, ulProgressMax: 97918, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 114294, ulProgressMax: 114294, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 130678, ulProgressMax: 130678, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 147054, ulProgressMax: 147054, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 163438, ulProgressMax: 163438, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 179814, ulProgressMax: 179814, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 196198, ulProgressMax: 196198, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 212574, ulProgressMax: 212574, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 278094, ulProgressMax: 278094, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 294478, ulProgressMax: 294478, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 327238, ulProgressMax: 327238, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 343614, ulProgressMax: 343614, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 392758, ulProgressMax: 392758, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 474654, ulProgressMax: 474654, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 540174, ulProgressMax: 540174, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 572934, ulProgressMax: 572934, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 589318, ulProgressMax: 589318, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 1326414, ulProgressMax: 1326414, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 1342798, ulProgressMax: 1342798, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 1424694, ulProgressMax: 1424694, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 1441078, ulProgressMax: 1441078, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 1473838, ulProgressMax: 1473838, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 1490214, ulProgressMax: 1490214, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 1703158, ulProgressMax: 1703158, ulStatusCode: 5 (dsDownloadingdata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe
ulProgress: 2127952, ulProgressMax: 2127952, ulStatusCode: 6 (dsEnddownloaddata), szStatusText: https://get.anydesk.com/psTS1FIS/jjwsuporteremoto.exe

Note that the ulProgress and ulPorgressMax always return the same value and it changes.

How can I create a real progressbar based on the file size (Content-Length header) using the UrlDownloadToFile ?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

Some web servers do not provide the content length header so the best guess of file size is how much has been received so far.


与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

Just Browsing Browsing

2.1m questions

2.1m answers

60 comments

56.5k users

Most popular tags

Powered by Question2Answer
Donate
Theme by Q2A Market&&OStack.cn
...