Download form - which library to use?

[BigChimp]

Hmmm, that code looks very familiar

[BeniBela]

Everyone is always writing this so needless complicated.

With my Internet Tools, getting the absolute url of the first to an exe on that page:

Code: [Select]

uses simpleinternet;
var
  listingPage, absoluteUrlToFirstExe: String;
begin
  listingPage := 'http://get.videolan.org:81/vlc/last/win32/';
  absoluteUrlToFirstExe := process(listingPage, 'resolve-uri(//a/@href[ends-with(., "exe")], "'+listingPage+'")').toString;
  showMessage(absoluteUrlToFirstExe);
end;


[mesiarm]

Yes it is much faster and easier but it doesnt support Onstatus - for progressbar to work....

[mesiarm]

and Jurassic Pork ... I found it, but it is procedure in your case and I don´t see how your code works...because with this code I will ask server for directory index file... it will return it with Resultcode 200 and then change file to read? should´t it be sooner?

[BeniBela]

but it doesnt support Onstatus - for progressbar to work....

Why would you want to show a progressbar while downloading the directory listing?
That should be almost instantaneously.

Anyways:

Code: [Select]

uses simpleinternet;
procedure tform.progress(sender: TObject; progress, maxprogress: longint);
begin
  progressbar1.position := progress;
  progressbar1.max := maxprogress;
end;

procedure tform.download;
var
  listingPage, absoluteUrlToFirstExe: String;
begin
  needInternetAccess;
  defaultInternet.OnProgress:=@progress;
  listingPage := 'http://get.videolan.org:81/vlc/last/win32/';
  absoluteUrlToFirstExe := process(listingPage, 'resolve-uri(//a/@href[ends-with(., "exe")], "'+listingPage+'")').toString;
  showMessage(absoluteUrlToFirstExe);
end;

on Windows at least.
(on Linux it does not work. More precise, on Linux progress is the same value as synapse's THttpSend.DownloadSize, which seems to be not what I expected it to be)

[Jurassic Pork]

hello,

BeniBela : read the entire post . mesiarm wants to download a big file but for this he wants to know the last name of the file ( with the version in the name).

Mesiarm : Sorry    i show you a wrong way. Forget the ListHTTPFiles.
to do what you want :
1 - get the Filename of the last version of vlc
2 - get the Url from which the file will be downloaded.
3 - download the file

to do this a function to extract text from URL ( on 200 (OK) or 302 (redirect) result code )

Code: [Select]

function GetTextFromURL(URL,regExpress: string): String;
var
  HTTPGetResult: Boolean;
  HTTPSender: THTTPSend;
  TextHttp : TStringList;
  x: integer;
  re: TRegExpr;
  s : string;
begin
  Result := '';
  HTTPSender := THTTPSend.Create;
  try
    HTTPGetResult := HTTPSender.HTTPMethod('GET', URL);
    if (HTTPSender.ResultCode = 200) or
       (HTTPSender.ResultCode = 302) then
     begin
       Texthttp := TStringList.Create();
       Texthttp.LoadFromStream(HTTPSender.Document);
       re := TRegExpr.Create;
       // expression to extract text from URL :
       re.Expression := regexpress;
       For x := 0 to Texthttp.Count -1  do
       begin
       s := Texthttp.Strings[x];
       if re.Exec(s) then Result := re.Match[1];
       end;
       re.Free;
       Texthttp.Free;
     end;
  finally
    HTTPSender.Free;
  end;
end;
code to download the file :

Code: [Select]

procedure TForm1.Button1Click(Sender: TObject);
  var i:integer;
  URLtoDL,FileNameToDL:string;
  download: THTTPDownload;
begin
  FileNameToDL := GetTextFromURL('http://get.videolan.org:81/vlc/last/win32/',
                  '<li><a href=\"(.*\.exe)\".+');
  if FileNameToDL <> '' then
  begin
  URLtoDL := GetTextFromURL('http://get.videolan.org:81/vlc/last/win32/' +
             FileNameToDL,'<p>The document has moved <a href=\"(.*\.exe)\".+');
  if URLtoDL <> '' then
    begin
     Updater.Progressbar1.Position := 0;
     download:= THTTPDownload.Create(URLtoDL, FileNameToDL);
     download.Resume;
     Updater.ShowModal;
     download.free;
    end;
  end;
end;
if you want more simple, use the great benibela's internet tools   (GPL)
here : http://benibela.de/sources_en.html#internettools

Friendly, J.P

[mesiarm]

Jurrasic Pork thank you very much for your patience with me and for your advices  and  BeniBela also thank you  And please look at this image - it ´s preview of my project -  http://img199.imageshack.us/img199/5716/ddyb.png Acessing to form .... in main form updater is global variable ... and I have also changed Owner from nil to Application and Showmodal to Show and deleted updater.Free line  but it didnt worked. Now I have added line :

Code: [Select]

if assigned (self) then showmessage ('yes in form activate') else showmessage ('no in form activate');    to Tupdater.Formactivate and it returns yes... so in formactivate and other form methods it works because I have changed updater to self.... But in thread I have to call it as updater because thread is other class and there it returns no (if I call

Code: [Select]

if assigned (updater) then showmessage ('yes in thread') else showmessage ('no in thread'); and even

Code: [Select]

  if fupdater = nil then showmessage ('yes nil') else showmessage ('no nil');  returns yes nil in thread) Please help me ...

[Jurassic Pork]

hello mesiarm,
the best solution would be to put your whole project in attachment (if it is possible) to see what is wrong.

Friendly, J.P

[mesiarm]

Sorry I wasn´t online for long time but now I have created demo project of my problem because I wanted to know where s the problem - here it is : http://uploadir.com/uploads/l79yb6ji/downloads/new

[Jurassic Pork]

Hello Mesiarm,
i don't know why you don't work with Form2 all the time and why you use fupdater variable.

With those changes it seems that your project run :

1 - remove unit2 from the uses at the beginning of the unit1.

Code: [Select]

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;
2 - replace your code by this code after  implementation :

Code: [Select]

implementation
uses Unit2;  //  here is the trick
{$R *.lfm}

{ TForm1 }

procedure TForm1.btnClick(Sender: TObject);

begin
  Form2.showmodal;
  end;

end.
3 - in the unit2 replace all the occurences of Fupdater by Form2.

Friendly, J.P

[mesiarm]

Yes than you... now it works.... and please can you explain me what´s difference in using in interface and implementation part? Idon´t understand that....

[Jurassic Pork]

for example read this about circular unit references

[mesiarm]

ok thanks   I have read it. now I want to implement cancel button and I have downloadthread.terminate command in cancelonclick, but it won´t cancel download... I have read that terminate only send instruction to terminate and i didn´t found way to force terminate thread ...so i wanted to add while not terminated loop.... debbugging I have found that during download is still running this command: 

Code: [Select]

HTTPGetResult:=http.HTTPMethod('GET', fURL); so i have added

Code: [Select]

while not terminated do HTTPGetResult:=http.HTTPMethod('GET', fURL); It didn´t worked... I wanted to use something like Application.ProcessMessages and since I can´t use this command inside thread I tried this code which i had found

Code: [Select]

  if MsgWaitForMultipleObjects(0, nil, FALSE, 10, QS_ALLINPUT) = WAIT_OBJECT_0 then
    begin
      while PeekMessage(Msg, 0, 0, 0, PM_REMOVE) do
      begin
        TranslateMessage(Msg);
        DispatchMessage(Msg);
      end;
    end;    without success. What can I do with it?

[mesiarm]

Hm I found it, with http.Abort.... but Jurrasic Pork you have earlier gave me function GetTextFromURL and it worked till now...please look at it...  now I don´t know, why it stopped working and although it with redirect with code you have said to me, when it connect to server, it will return 302 Moved Temporarily