Creating Chat Application with Borland Delphi/Indy: The Client

    procedure TForm1.btConnectClick(Sender: TObject);
    begin
//the mname.text must contain a nickname(this will be the name
recorded by the server upon connection)
    if mname.Text='' then begin showmessage('Please enter a
nickname!') ;
    exit;
    end
    else if mname.Text<>'' then
//if there is a name, try to connect
    mname.Enabled:=false;
    tc.Host:=ip;
    tc.Port:=port;
    with tc do
    begin
    try
    Connect;
//after you’ve connected,send your name to the server.
    Socket.WriteLn(mname.Text);
    except on E : Exception do
    showmessage('Could not connect to remote host. Check to see
if you entered the right IP address');
    end;
    end;
    end;
//The procedure below sends a text message, it should
contain:to@from:msg
    procedure TForm1.btsendClick(Sender: TObject);
    begin
    if (edto.Text='') and (edmsg.Text='') then begin
    edto.Color:=clred;
    edto.Color:=clred;
    showmessage('You need to enter a message or a name to send
the message to.');
    exit;
    end;
    tc.Socket.WriteLn(edto.text + '@' +edmsg.Text);
    end;

    procedure TForm1.listnameClick(Sender: TObject);
    begin
//request list of connected client names
    tc.Socket.WriteLn('listnames@one');
    end;
//start the listening/reading thread
    procedure TForm1.tcConnected(Sender: TObject);
    begin
      rt := TReadingThread.Create(tc);

    end;
//close the reading/listening thread if client logs off
    procedure TForm1.tcDisconnected(Sender: TObject);
    begin
    if rt <> nil then
        begin
            rt.Terminate;
            rt.WaitFor;
            FreeAndNil(rt);
        end;
    end;
//This procedure automatically adds a client name to the  edto.text edit
    procedure TForm1.lnamesClick(Sender: TObject);
    begin
    edto.Text:=lnames.Items[lnames.Itemindex];
    end;
//send a message to all connected clients – command ‘all’
    procedure TForm1.btsendallClick(Sender: TObject);
    begin
    tc.Socket.WriteLn('all@'+edmsg.Text+':'+mname.Text);

    end;
//show setup form
    procedure TForm1.SetupConnection1Click(Sender: TObject);
    begin
    form3.show;
    end;

//Connect to server
    procedure TForm1.btConnect2chatClick(Sender: TObject);
    begin
    if mname.Text='' then begin showmessage('Please enter a
nickname!') ;
    exit;
    end
    else if mname.Text<>'' then
//set connection settings
    tc.Host:=ip;
    tc.Port:=port;

    with tc do
    begin
    try
    Connect;
    Socket.WriteLn(mname.Text);

    mname.Enabled:=false;

    btsendall.Enabled:=true;
    btsend.Enabled:=true;
    listname.Enabled:=true;

      except
 //on E : Exception do
      showmessage('Could not connect to remote host. Check to see
if you entered the right IP address');

       end;

    end;

    btConnect2chat.Enabled:=false;

end;

//When the chat application is started, it reads the connection
settings from a ini file
//the procedure fromshow shows how it’s done…
//The setup form helps you to set up the connection values you
need.

    procedure TForm1.FormShow(Sender: TObject);
     var
        jnclient : TINIFile;
    begin
    form1.Height:=444;
    form1.Width:=673;
    btsendall.Enabled:=false;
    btsend.Enabled:=false;
    listname.Enabled:=false;
        jnclient := TINIFile.Create(ExtractFilePath
(Application.EXEName) + 'jnclient.ini');
    try
    ip:=jnclient.ReadString('Settings', 'ip address', 'Empty');
    port:=jnclient.ReadInteger('Settings', 'port number', 1053);

   finally
   jnclient.Free;
    end;
    if (ip= 'Empty') or (port<1) then begin
    messagedlg('Your connection details are not set. Click ok to
continue.', mtInformation,[mbOk], 0);
    form3.Show;
        end;
    end;

    procedure TForm1.Exit1Click(Sender: TObject);
    begin
//Close connection
    tc.Disconnect;
    close;
    end;

    procedure TForm1.SetupNewConnection1Click(Sender: TObject);
    begin
//open setup form
    form3.Show;
    end;

    procedure TForm1.ExitChat1Click(Sender: TObject);
    begin
//close form
    tc.Disconnect;
    close;
    end;

    procedure TForm1.About1Click(Sender: TObject);
    begin
    form4.show;
    end;

The next three procedures deal with the progress bar when sending a file to a client. The progress bar will visually show the progress of the file being sent.

Click on the tcpclient component and then go to the object inspectors event tab. Double click on onWork and add the following code:

procedure TForm1.tcWork(ASender: TObject; AWorkMode: TWorkMode;
  AWorkCount: Integer);
begin
form5.prog.Position := AWorkCount;
end;

Do the same for WorkBegin.. and WorkEnd…

procedure TForm1.tcWorkBegin(ASender: TObject; AWorkMode: TWorkMode;
  AWorkCountMax: Integer);
begin
 form5.prog.Max := AWorkCountMax;
 form5.prog.Position := 0;

end;

procedure TForm1.tcWorkEnd(ASender: TObject; AWorkMode: TWorkMode);
begin
sleep(300);
form5.edfn.clear;
form5.cb.Clear;
form5.Close;
end;
end.

As you can see from the code, the client starts to send the file, and when the file transfer is completed, the form is closed.

That’s it for now. In the next instalment, I will deal with the actual code that sends a file and also the form that receives a screenshot image to display.

Till next time.