[SOLVED] TidHttp and thread
lazarus / 38-Networking and Web Programming

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superc · 2022-02-10 13:16

Hello,

I'm must to download a file and i used TidHttp with this simple code:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var  tm :
TMemoryStream;  pk: string;begin  try    tm := TMemoryStream.Create;  
  http.Get(FDOWN, tm);    tm.SaveToFile('c:\td\test.fl');   finally  
tm.Free;  end;end; 
and works fine, but i noticed that that the application remains
freezed: is the nature of this component to be used inside a thread?

Thanks in advance.

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Remy Lebeau · 2022-02-10 17:50

Quote from: superc on February 10, 2022, 02:16:29 pmi noticed that
that the application remains freezed: is the nature of this component
to be used inside a thread?

All of Indy's components are blocking.  So, if you use them in the
context of the main UI thread, then the UI will indeed freeze up until
the operations are finished.  To avoid that, you can use a separate
worker thread, yes (and that is preferred, even required in some cases
[ahem, Android]).  Or, you can simply put down a TIdAntiFreeze
component instead (may not work on all platforms).

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superc · 2022-02-11 08:24

Quote from: Remy Lebeau on February 10, 2022, 06:50:51 pmQuote from:
superc on February 10, 2022, 02:16:29 pmi noticed that that the
application remains freezed: is the nature of this component to be
used inside a thread?

All of Indy's components are blocking.  So, if you use them in the
context of the main UI thread, then the UI will indeed freeze up until
the operations are finished.  To avoid that, you can use a separate
worker thread, yes (and that is preferred, even required in some cases
[ahem, Android]).  Or, you can simply put down a TIdAntiFreeze
component instead (may not work on all platforms).

Thanks Remy, I've tried a code like this:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
httpThreadDownloader; {$mode ObjFPC}{$H+} interface uses  Classes,
IdHTTP, IdSSLOpenSSL,IdComponent, SysUtils; type   TCallBack =
procedure(Sender: TObject; oPercentage: Integer) of object;   {
TDownloaderThread }   TDownloaderThread = class (TThread)    callBck:
TCallBack;  private    ctrlVar         : Boolean;    fDownloFname    :
string;    fhttpEPD        : string;    _http           : TIdHTTP;   
_socketOpenssl  : TIdSSLIOHandlerSocketOpenSSL;    _byteToTransfer :
Int64;  public    Constructor Create(CreateSuspended : boolean);
overload;    constructor Create(CreateSuspended : Boolean; aCallBack:
TCallBack);     procedure IdHTTP1Work(ASender: TObject; AWorkMode:
TWorkMode; AWorkCount: Int64);    procedure IdHTTP1WorkBegin(ASender:
TObject; AWorkMode: TWorkMode;AWorkCountMax: Int64);    procedure
IdHTTP1Status(ASender: TObject; const AStatus: TIdStatus; const
AStatusText: string);    procedure IdHTTP1WorkEnd(ASender: TObject;
AWorkMode: TWorkMode);     property httpEndPointDownload: string read
fhttpEPD write fhttpEPD;    property downloadFilename: string read
fDownloFname write fDownloFname;  protected    procedure Execute;
override;  end; implementation { TDownloaderThread }  constructor
TDownloaderThread.Create(CreateSuspended: boolean);begin  inherited
Create(CreateSuspended);   FreeOnTerminate := True;   _http :=
TIdHTTP.Create;   _http.OnWork      := @IdHTTP1Work; 
_http.OnWorkBegin := @IdHTTP1WorkBegin;  _http.OnStatus    :=
@IdHTTP1Status;  _http.OnWorkEnd   := @IdHTTP1WorkEnd;   
_socketOpenssl := TIdSSLIOHandlerSocketOpenSSL.Create; 
_socketOpenssl.SSLOptions.Method := sslvTLSv1_2;  _http.IOHandler   :=
_socketOpenssl; end; constructor
TDownloaderThread.Create(CreateSuspended: Boolean;                   
                aCallBack: TCallBack);begin  inherited
Create(CreateSuspended);   FreeOnTerminate := True;   _http :=
TIdHTTP.Create;  _socketOpenssl :=
TIdSSLIOHandlerSocketOpenSSL.Create;  _socketOpenssl.SSLOptions.Method
:= sslvTLSv1_2;  _http.IOHandler := _socketOpenssl;   if aCallBack <>
nil then    callBck:=aCallBack;end; procedure
TDownloaderThread.IdHTTP1Work(ASender: TObject; AWorkMode: TWorkMode; 
AWorkCount: Int64);var  x: Integer;begin  x := Round((AWorkCount /
_byteToTransfer) * 100);  callBck(self, x);end; procedure
TDownloaderThread.IdHTTP1WorkBegin(ASender: TObject;  AWorkMode:
TWorkMode; AWorkCountMax: Int64);begin 
_byteToTransfer:=AWorkCountMax;end; procedure
TDownloaderThread.IdHTTP1Status(ASender: TObject;  const AStatus:
TIdStatus; const AStatusText: string);begin end; procedure
TDownloaderThread.IdHTTP1WorkEnd(ASender: TObject;  AWorkMode:
TWorkMode);begin end; procedure TDownloaderThread.Execute;var  tm
:TMemoryStream;begin  try    tm := TMemoryStream.Create;   
_http.Get(httpEndPointDownload, tm);   
tm.SaveToFile(downloadFilename);   finally    tm.Free; 
end;end; end.  
But the IdHTTP1Work, IdHTTP1WorkBegin,IdHTTP1Status,IdHTTP1WorkEnd
procedure seems not correctly hooked to component.... On the example
there are two methods with thread and not... What's I wrong?

Thanks in advance.

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superc · 2022-02-11 12:18

I found error: on overloaded constructor I don't set procedures.