Using WinInet to identify total file size before downloading it

Question

I got the source below from a third-party site explaining how to download a file from the internet using WinInet. I\'m not too familiar with API, and I took at

Answer 1

Answering the question of how to get a download size with WinInet. This is out of one of my file downloaders that is based on WinInet.

This is the method I use to get the download size:

function TWebDownloader.GetContentLength(URLHandle: HINTERNET): Int64;
// returns the expected download size.  Returns -1 if one not provided
   var
     SBuffer: Array[1..20] of char;
     SBufferSize: Integer;
     srv: integer;
   begin
     srv := 0;
    SBufferSize := 20;
    if HttpQueryInfo(URLHandle, HTTP_QUERY_CONTENT_LENGTH, @SBuffer, SBufferSize, srv) then
       Result := StrToFloat(String(SBuffer))
    else
       Result := -1;
   end;

Use of this method requires an open request handle, and does NOT require reading any of the data:

 URLHandle := HttpOpenRequest(ConnectHandle, 'GET', Pchar(sitepath), nil,
                  nil, nil, INTERNET_FLAG_NO_CACHE_WRITE, 0);
 ...
 DownloadSize := GetContentLength(URLHandle);

HTH