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Hi Group, (delphi 7 refers)
I haven't used delphi for some time. I have now a very basic app.
Three buttons on form, Start/Stop/Exit

objective>
When Start is pressed, the app enters a while(tick=true) do begin..someCode;...end; What I now require is that, when Stop is pressed, the appl abort thisstart loop and returns to the 'idle' state. I was thinking that, after Start is pressed, now the loop is being excuted, by pressing Stop, the stop proc will make tick=false, thus the Start loop will abort since the while(tick=true) is false.

(exit of course to end appl, this of course i know how to do.... :)

This stop proc does not result in the behaviour which I expected, it continues to stay in the loop. The only way, in delpi ide is to go to Run/Reset.

Else, Do away with Stop-btn, just use Startbtn to Start/End the loop. (The no stopbtn on from)
To omit using the Stop-btn, if it is possible, the StartBtn caption on idle to be eg 'Press to Start' Once the start-btn is pressed, i can change the caption of the start-btn to 'Press to Stop' Now the loop is entered. So, once you press the start btn, the caption changes to 'Press to stop', the app executes the start while(tick=true) do begin.... end; loop. Pressing the start-btn whilst in the loop, the loop to be aborted, start-btn caption reverting to 'Press to Start', system idle?

Is there someone here who can give the correct instruction/method/knowhow in order to exit the
startbutton loop, when Stop is pressed. (How do i know what the 'eventhandler name is?)

I am sure this in rather trivial basic, please help with some code samples or pointers?

Thank you very much.

Regards,
Gert

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Last Post by pritaeas
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Hi Pritaeas,
Thank for for your feedback.
Find my code for review.
Thanks,
Gert

unit RVComms_main;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, CPort, StdCtrls, Menus;

type
  TRVCommsMain_form = class(TForm)
    btnStart: TButton;
    btnExit: TButton;
    CommPort: TComPort;
    MainMenu1: TMainMenu;
    Config1: TMenuItem;
    About1: TMenuItem;
    btnStop: TButton;
    procedure btnStartClick(Sender: TObject);
    procedure btnStopClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure btnExitClick(Sender: TObject);
    procedure Config1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  RVCommsMain_form: TRVCommsMain_form;

  tick : boolean;
  comms : boolean;
  done : boolean;
  tx_cntr : integer;

  const chCRLF = #13+#10;
  const chFF   = #12;

implementation

{$R *.dfm}

procedure TRVCommsMain_form.btnStartClick(Sender: TObject);
begin
 tick := true;
   // while (tick=true) do
 //  if (tick=true) then
   while (tick=true) do
     begin
      commPort.WriteStr('01234567890'+chCRLF);
      commPort.WriteStr('0123456789abcdefghijklmnopqrstuvwxyz9876543210ABCDEFGHIJKLMNOPQRSTUVWXYZ'); //72
     end;
end;


procedure TRVCommsMain_form.btnStopClick(Sender: TObject);
begin
 tick := false;
end;

//---------------main---------------------------------------//
//----------------------------------------------------------//
//----------------------------------------------------------//

procedure TRVCommsMain_form.FormCreate(Sender: TObject);

begin
commPort.Open;
comms:=true;
 {
 tick := false;

  if (tick=true) then
 begin
     btnStart.Caption := 'Running';
     comms:=true;
     commPort.Open;

    while (tick=true) do
     begin
      commPort.WriteStr('01234567890'+chCRLF);
      commPort.WriteStr('0123456789abcdefghijklmnopqrstuvwxyz9876543210ABCDEFGHIJKLMNOPQRSTUVWXYZ'); //72
     end;

      commPort.Close;
      comms := false;

     btnStart.Caption := 'Start';

 end;
 }
end;

//------------main end-------------------------------------------//
//---------------------------------------------------------------//

procedure TRVCommsMain_form.btnExitClick(Sender: TObject);
begin
 tick := false;
 if (comms=true) then commPort.Close;
close; 
end;

procedure TRVCommsMain_form.Config1Click(Sender: TObject);
begin
 if (comms=true) then commPort.Close;
 commPort.ShowSetupDialog;
end;

end.
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That won't work that way, because the main is single threaded. once the start function runs, none of the others will get called.

Either, use Application.ProcessMessages (ugly fix), or use a TTimer or a TThread.

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Thanks, can you give me a example snippet of how to do it?
Gert

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