多線程編程(18)

前面的例子都是讓若干線程做同樣的事情, 下面這個例子中的三個線程將分別在三個畫板上隨機畫不同顏色的橢圓.

接下來的很多事情我想要基於這個例子來做.

本例效果圖:

代碼檔案:

unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ExtCtrls;
type
TForm1 = class(TForm)
PaintBox1: TPaintBox;
PaintBox2: TPaintBox;
PaintBox3: TPaintBox;
Button1: TButton;
procedure Button1Click(Sender: TObject);
procedure FormDestroy(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
var
h1,h2,h3: THandle;
{第一個線程的入口函數: 畫紅色橢圓}
function ThreadFun1(p: Pointer): Integer; stdcall;
var
i, x1,y1,x2,y2: Integer;
begin
Form1.PaintBox1.Canvas.Brush.Color := clRed;
for i := 0 to 50000 do with Form1.PaintBox1 do
begin
x1 := Random(Width); y1 := Random(Height);
x2 := Random(Width); y2 := Random(Height);
Canvas.Lock;
Canvas.Ellipse(x1,y1,x2,y2);
Canvas.Unlock;
Sleep(0);
end;
Result := 0;
end;
{第二個線程的入口函數: 畫綠色橢圓}
function ThreadFun2(p: Pointer): Integer; stdcall;
var
i, x1,y1,x2,y2: Integer;
begin
Form1.PaintBox2.Canvas.Brush.Color := clGreen;
for i := 0 to 50000 do with Form1.PaintBox2 do
begin
x1 := Random(Width); y1 := Random(Height);
x2 := Random(Width); y2 := Random(Height);
Canvas.Lock;
Canvas.Ellipse(x1,y1,x2,y2);
Canvas.Unlock;
Sleep(0);
end;
Result := 0;
end;
{第三個線程的入口函數: 畫藍色橢圓}
function ThreadFun3(p: Pointer): Integer; stdcall;
var
i, x1,y1,x2,y2: Integer;
begin
Form1.PaintBox3.Canvas.Brush.Color := clBlue;
for i := 0 to 50000 do with Form1.PaintBox3 do
begin
x1 := Random(Width); y1 := Random(Height);
x2 := Random(Width); y2 := Random(Height);
Canvas.Lock;
Canvas.Ellipse(x1,y1,x2,y2);
Canvas.Unlock;
Sleep(0);
end;
Result := 0;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
ID: DWORD;
begin
h1 := CreateThread(nil, 0, @ThreadFun1, nil, 0, ID);
h2 := CreateThread(nil, 0, @ThreadFun2, nil, 0, ID);
h3 := CreateThread(nil, 0, @ThreadFun3, nil, 0, ID);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
CloseHandle(h1);
CloseHandle(h2);
CloseHandle(h3);
end;
end.