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{
***************************************************************************
* *
* This source is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This code is distributed in the hope that it will be useful, but *
* WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* General Public License for more details. *
* *
* A copy of the GNU General Public License is available on the World *
* Wide Web at <http://www.gnu.org/copyleft/gpl.html>. You can also *
* obtain it by writing to the Free Software Foundation, *
* Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1335, USA. *
* *
***************************************************************************
Abstract:
Demo to show, how to start a thread and how synchronize with the main
thread.
Important: The cthread unint must be added to the uses section of the .lpr
file. See multithreadingexample1.lpr.
}
unit MainUnit;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils, Forms, Controls, Graphics, Dialogs;
type
{ TMyThread }
TMyThread = class(TThread)
private
fStatusText: string;
procedure ShowStatus;
protected
procedure Execute; override;
public
constructor Create(CreateSuspended: boolean);
end;
{ TForm1 }
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
private
public
end;
var
Form1: TForm1;
implementation
{$R *.lfm}
{ TForm1 }
procedure TForm1.FormCreate(Sender: TObject);
var
MyThread : TMyThread;
begin
MyThread := TMyThread.Create(True); // With the True parameter it doesn't start automatically
if Assigned(MyThread.FatalException) then
raise MyThread.FatalException;
// Here the code initialises anything required before the threads starts executing
MyThread.Start;
end;
{ TMyThread }
procedure TMyThread.ShowStatus;
// this method is only called by Synchronize(@ShowStatus) and therefore
// executed by the main thread
// The main thread can access GUI elements, for example Form1.Caption.
begin
Form1.Caption := fStatusText;
end;
procedure TMyThread.Execute;
var
newStatus : string;
begin
fStatusText := 'TMyThread Starting ...';
Synchronize(@Showstatus);
fStatusText := 'TMyThread Running ...';
while (not Terminated) and (true {any condition required}) do begin
//here goes the code of the main thread loop
newStatus:='TMyThread Time: '+FormatDateTime('YYYY-MM-DD HH:NN:SS',Now);
if NewStatus <> fStatusText then begin
fStatusText := newStatus;
Synchronize(@Showstatus);
end;
end;
end;
constructor TMyThread.Create(CreateSuspended: boolean);
begin
FreeOnTerminate := True;
inherited Create(CreateSuspended);
end;
end.
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