wthread

Component for work with a thread, Delphi&Lazarus (win&wince&*nix) (c) wadman 2016-2021, from 10.08.2021

This is my component to work with additional threads for Delphi & Lazarus. Using them is very easy. Drop a TWCThread on the form and add a few tasks. In the task you need to write a method OnExecute which will be executed in a different thread. Each task is a message flow. All tasks will run in the start order.

It is not recommended to use the call to LCL/VCL from the OnExecute method. Instead, use the Sender.PostMessage and the OnMessage task handler. Check the Terminated flag as often as possible in the OnExecute method. This means that the thread handler is waiting for the work to stop. Perhaps the application is already at the closing stage and the user expects it.

Enjoy.

Components tested on Ubuntu 14 and 16 LTS, Windows 7, 8, 10, WinCE, Lazarus 1.6/1.7/1.8/1.9/2.0/2.1/2.2, Delphi 7/XE2/10.

Example project:

unit Unit1;

interface

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

const
  WM_MY_MESSAGE = 1; 
	
type
  TForm1 = class(TForm)
    WCThread1: TWCThread;
    TaskCheckLicense: TTask;
    Label1: TLabel;
    procedure FormCreate(Sender: TObject);
    procedure TaskCheckLicenseExecute(const Sender: TTask; const Msg: Word; var Param: Variant);
    procedure TaskCheckLicenseMessage(const Sender: TTask; const Msg: Word; const Param: Variant);
    procedure TaskCheckLicenseFinish(const Sender: TTask; const Msg: Word; const Param: Variant);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  // Running a task in another thread
  TaskCheckLicense.Start(5000); // see TaskCheckLicenseExecute(... Param)
end;

procedure TForm1.TaskCheckLicenseExecute(const Sender: TTask; const Msg: Word; var Param: Variant);
begin
  // Check license, its another thread. Here it is forbidden to refer to the VCL/LCL
  Sender.PostMessage(WM_MY_MESSAGE, 'Checking license...'); // post message for logging to the main thread
  Sender.WaitMs(Param); // wait some secs for the hard work
  Param := 'License is valid.';  // Input and output parameter.  It is transferred from Start and returns to Finish.
end;

procedure TForm1.TaskCheckLicenseMessage(const Sender: TTask; const Msg: Word; const Param: Variant);
begin
  // The main thread. Here we are processing messages from the additional thread
  case Msg of
    WM_MY_MESSAGE: begin
      Label1.Caption := Param;
    end;
  end;
end;

procedure TForm1.TaskCheckLicenseFinish(const Sender: TTask; const Msg: Word; const Param: Variant);
begin
  // Main thread. Task done.
  Label1.Caption := Param;
end;

end.