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https://gitlab.com/freepascal.org/lazarus/lazarus.git
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118 lines
3.4 KiB
ObjectPascal
118 lines
3.4 KiB
ObjectPascal
{
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***************************************************************************
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* *
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* This source is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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* This code is distributed in the hope that it will be useful, but *
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* WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
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* General Public License for more details. *
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* *
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* A copy of the GNU General Public License is available on the World *
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* Wide Web at <http://www.gnu.org/copyleft/gpl.html>. You can also *
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* obtain it by writing to the Free Software Foundation, *
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* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
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* *
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***************************************************************************
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Abstract:
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Demo to show, how to start a thread and how synchronize with the main
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thread.
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Important: The cthread unint must be added to the uses section of the .lpr
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file. See multithreadingexample1.lpr.
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}
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unit MainUnit;
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{$mode objfpc}{$H+}
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interface
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uses
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Classes, SysUtils, LResources, Forms, Controls, Graphics, Dialogs;
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type
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{ TMyThread }
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TMyThread = class(TThread)
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private
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fStatusText: string;
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procedure ShowStatus;
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protected
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procedure Execute; override;
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public
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constructor Create(CreateSuspended: boolean);
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end;
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{ TForm1 }
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TForm1 = class(TForm)
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procedure FormCreate(Sender: TObject);
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private
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public
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end;
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var
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Form1: TForm1;
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implementation
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{ TForm1 }
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procedure TForm1.FormCreate(Sender: TObject);
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var
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MyThread : TMyThread;
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begin
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MyThread := TMyThread.Create(True); // With the True parameter it doesn't start automatically
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if Assigned(MyThread.FatalException) then
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raise MyThread.FatalException;
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// Here the code initialises anything required before the threads starts executing
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MyThread.Resume;
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end;
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{ TMyThread }
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procedure TMyThread.ShowStatus;
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// this method is only called by Synchronize(@ShowStatus) and therefore
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// executed by the main thread
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// The main thread can access GUI elements, for example Form1.Caption.
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begin
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Form1.Caption := fStatusText;
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end;
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procedure TMyThread.Execute;
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var
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newStatus : string;
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begin
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fStatusText := 'TMyThread Starting...';
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Synchronize(@Showstatus);
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fStatusText := 'TMyThread Running...';
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while (not Terminated) and (true {any condition required}) do begin
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//here goes the code of the main thread loop
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newStatus:='TMyThread Time: '+FormatDateTime('YYYY-MM-DD HH:NN:SS',Now);
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if NewStatus <> fStatusText then begin
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fStatusText := newStatus;
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Synchronize(@Showstatus);
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end;
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end;
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end;
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constructor TMyThread.Create(CreateSuspended: boolean);
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begin
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FreeOnTerminate := True;
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inherited Create(CreateSuspended);
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end;
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initialization
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{$I mainunit.lrs}
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end.
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