[Solved] [lNet] How can I download an image to a stream?
lazarus / 38-Networking and Web Programming

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Jishaxe · 2012-03-15 19:27

Hello, I am using lNet and I was wondering how I could download an
image with HTTP (that I know the URL to) to a stream so I can edit it
and save it to disk?

Is there an easier way to do what I want to achieve?

Would an image be classed as a binary file, just so I get my
definitions right?
Here is what I have so far:
 Code: [Select]unit mainunit;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs,
ExtCtrls,
  ComCtrls, StdCtrls, lNetComponents, lhttp, lhttputil;

type

  { TMainForm }

  TMainForm = class(TForm)
    StartButton: TButton;
    CloseButton: TButton;
    HTTPClient: TLHTTPClientComponent;
    StatusBar: TStatusBar;
    procedure HTTPClientDoneInput(ASocket: TLHTTPClientSocket);
    function HTTPClientInput(ASocket: TLHTTPClientSocket; ABuffer:
pchar;
      ASize: integer): integer;
    procedure StartButtonClick(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end;

var
  MainForm: TMainForm;
  JPGStream: TStream;
  JPGImage: TJpegImage;

const
  ImageLoc: String =
'http://www.enigmagroup.org/missions/programming/3/image.php';
  SaveTo: String = 'tempimage.jpg';

implementation

{$R *.lfm}

{ TMainForm }

function TMainForm.HTTPClientInput(ASocket: TLHTTPClientSocket;
ABuffer: pchar;
  ASize: integer): integer;
begin
  JPGStream.WriteBuffer(ABuffer^, ASize);
end;

procedure TMainForm.HTTPClientDoneInput(ASocket: TLHTTPClientSocket);
var
  SaveStream: TFileStream;
begin
  ASocket.Disconnect;
  JPGImage := TJpegImage.Create;
  JPGStream.Position := 0;
  JPGImage.LoadFromStream(JPGStream);
  SaveStream := TFileStream.Create(SaveTo,fmOpenWrite or fmCreate);
  JPGImage.SaveToStream(SaveStream);
  ShowMessage('Done!');
  JPGStream.Free;
  SaveStream.Free;
end;

procedure TMainForm.StartButtonClick(Sender: TObject);
var
  aHost, aURI: string;
  aPort: Word;
begin
  JPGStream := TStream.Create;
  DecomposeURL(ImageLoc, aHost, aURI, aPort);
  HTTPClient.Host := aHost;
  HTTPClient.URI  := aURI;
  HTTPClient.Port := aPort;
  HTTPClient.SendRequest;
end;


end.

It's basically bad code stuck together. It looks like I can't just use
a TStream as illustrated here:
http://www.lazarus.freepascal.org/index.php?topic=8339.0
Because it won't let me call Write on it.
Please talk with simple language, I don't know much about this.

What stream would I use for this?
Oh, and I would like for now to stick with lNet as long as what I am
trying to do is possible with it.
Thanks

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Jishaxe · 2012-03-15 19:49

Solved. Well, programmatically.
Using a TMemoryStream works fine but it needs to be the image directly
instead of inside a PHP script... I don't know how I'm going to get
that.