Mega Code Archive
Thread demo
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For those of you who haven't been into Thread-programming, maybe this simple
demo would be of interest:
The program creates ten parallell threads, each thread is associated with a
progressbar, which is updated randomly. When the Thread is done it's reported to a memo.
You can download the pas- and dfm-file here:
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, ComCtrls;
type
TProgressThread = class(TThread)
private
fRandomNo: Integer;
fThreadNo: Integer;
fProgress: Integer;
fDone: Boolean;
protected
procedure Execute; override;
procedure ShowProgress;
end;
TForm1 = class(TForm)
Button1: TButton;
ProgressBar1: TProgressBar;
ProgressBar2: TProgressBar;
ProgressBar3: TProgressBar;
ProgressBar4: TProgressBar;
ProgressBar5: TProgressBar;
ProgressBar6: TProgressBar;
ProgressBar7: TProgressBar;
ProgressBar8: TProgressBar;
ProgressBar9: TProgressBar;
ProgressBar10: TProgressBar;
Memo1: TMemo;
procedure Button1Click(Sender: TObject);
private
ProgressThread: TProgressThread;
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
procedure TForm1.Button1Click(Sender: TObject);
var n: Integer;
begin
Randomize;
Memo1.Clear;
// Create 10 Threads, give them a random no. and start them
for n:= 1 to 10 do
begin
ProgressThread:= TProgressThread.Create(true);
ProgressThread.FreeOnTerminate:= true;
ProgressThread.fThreadNo:= n;
ProgressThread.fRandomNo:= Random(100);
ProgressThread.FProgress:= 0;
ProgressThread.fDone:= false;
// Start the Thread
ProgressThread.Resume;
end;
end;
{ TProgressThread }
procedure TProgressThread.Execute;
begin
repeat
// Compare Threads RandomNo with a RandomNo generated each time looped
// One chance of 100 000 that fProgress will be increased
if fRandomNo = Random(100000) then
begin
if fProgress < 100 then
begin
Inc(fProgress);
if fProgress = 100 then fDone:= true;
// Update ProgressBar
Synchronize(ShowProgress);
end;
end;
until fDone;
end;
procedure TProgressThread.ShowProgress;
begin
// Update the ProgressBar associated with the Thread
case fThreadNo of
1: Form1.ProgressBar1.Position:= fProgress;
2: Form1.ProgressBar2.Position:= fProgress;
3: Form1.ProgressBar3.Position:= fProgress;
4: Form1.ProgressBar4.Position:= fProgress;
5: Form1.ProgressBar5.Position:= fProgress;
6: Form1.ProgressBar6.Position:= fProgress;
7: Form1.ProgressBar7.Position:= fProgress;
8: Form1.ProgressBar8.Position:= fProgress;
9: Form1.ProgressBar9.Position:= fProgress;
10: Form1.ProgressBar10.Position:= fProgress;
end;
// Write to Memo if Done
if fDone then
Form1.Memo1.Lines.Add('Thread No: ' + IntToStr(fThreadNo) +
' terminated.');
end;
end.
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