unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, Buttons;

type
TForm1 = class(TForm)
UsedThread: TBitBtn;
NoUsedThread: TBitBtn;
procedure UsedThreadClick(Sender: TObject);
procedure NoUsedThreadClick(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

function MyThreadFunc(P:pointer):Longint;stdcall;
var
i:longint;
DC:HDC;
S:string;
begin
DC:=GetDC(Form1.Handle);
for i:=0 to 500000 do begin
S:=Inttostr(i);
Textout(DC,10,10,Pchar(S),length(S));
end;
ReleaseDC(Form1.Handle,DC);
end;


procedure TForm1.UsedThreadClick(Sender: TObject);
var
hThread:Thandle;//定义一个句柄
ThreadID:DWord;
begin
//创建线程，同时线程函数被调用
hthread:=CreateThread(nil,0,@MyThreadfunc,nil,0,ThreadID);
if hThread=0 then
messagebox(Handle,'Didn’tCreateaThread',nil,MB_OK);
end;

procedure TForm1.NoUsedThreadClick(Sender: TObject);
begin
MyThreadfunc(nil);
//没有创建线程时，直接调用线程函数
end;
end.