关于线程的有关问题

关于线程的问题?
大家好,我在FORM上放两个PROGRESSBAR ,目的想让程序执行时,两个进度条同时前进,同时显示,用了线程的SYNCHRONIZE,可是依然是一个一个显示,不知哪位能帮一下.谢谢,源代码如下.

FORM上只有三个BUTTON,两个PROGRESSBAR.


unit Unit1;

interface

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

type
  TForm1 = class(TForm)
  pb1: TProgressBar;
  pb2: TProgressBar;
  Button1: TButton;
  Button2: TButton;
  start: TButton;
  procedure Button1Click(Sender: TObject);
  procedure Button2Click(Sender: TObject);
  procedure startClick(Sender: TObject);
  private
  { Private declarations }
  public
  { Public declarations }
  end;
type
  tpbthread = class(tthread)
  private
  {}
  protected
  procedure execute; override;
  procedure startpb1;
  procedure startpb2;
  end;
var
  Form1: TForm1;
  pbthread: tpbthread;
implementation

{$R *.dfm}

{ tpbthread }

procedure tpbthread.execute;
begin
  inherited;
  //这个地方想让两个进度条同时显示,可是结果是先显示第一个进度条,
  //再显示第二个进度条.
  //有什么办法能让两个进度条让用户看上去是同时显示的吗?
  synchronize(startpb1);
  synchronize(startpb2);
end;
 //BUTTON1执行第一个进度条
procedure TForm1.Button1Click(Sender: TObject);
var
  I: Integer;
begin
  pb1.Position := 0;
  pb1.Smooth := true;
  pb1.Min := 0;
  pb1.Max := 10;

  for I := pb1.Min to pb1.max do // Iterate
  begin
  pb1.Position := i;
  end; // for

end;
//BUTTON2 执行第二个进度条
procedure TForm1.Button2Click(Sender: TObject);
var
  i: integer;
begin
  pb2.Position := 0;
  pb2.Smooth := true;
  pb2.Min := 0;
  pb2.Max := 10;

  for I := pb2.Min to pb2.max do // Iterate
  begin
  pb2.Position := i;
  end; // for
end;
 //此按钮执行线程
procedure TForm1.startClick(Sender: TObject);
begin
  pbthread := tpbthread.Create(true);
  pbthread.Resume;
end;
//线程的其中一个方法,执行第一个进度条
procedure tpbthread.startpb1;
begin
  form1.Button1Click(self);
end;
//线程的第二个方法,执行第二个进度条.
procedure tpbthread.startpb2;
begin
  form1.button2Click(self);
end;

end.


[解决办法]
synchronize()所说的同步不是同步执行的意思,而是先执行一个在此期间另一个不能执行,线程同步主要是为了防止线程同时进行使共同访问的数据混乱
[解决办法]
所有的界面元素都是在主线程中执行显示的.

在线程中执行循环,然后分别向主窗体发送消息,用POSTMESSAGE,线程循环中用Sleep(0)来让系统进行线程切换.
然后在主窗体收到消息后改变进度条的值.
[解决办法]
刚的代码有点问题，死循環

Delphi(Pascal) code

//线程执行 procedure tpbthread.execute; beginwith Form1 dobeginpb1.Position := 0;pb2.Position := 0;while (pb1.Position < pb1.Max) and (pb2.Position < pb2.Max) dobeginif pb1.Position < pb1.Max thenpb1.Position := pb1.Position + 1;if pb2.Position < pb2.Max thenpb2.Position := pb2.Position + 1;end;end;end;
[解决办法]
unit Unit1;

interface

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

Const
 WM_PROGRESS_POSTION=WM_USER+1000;
type
 TForm1 = class(TForm)
   btn_OK: TButton;
   pb_One: TProgressBar;
   pb_Two: TProgressBar; 
 
   procedure btn_OKClick(Sender: TObject);
 private
   { Private declarations }
 public
   { Public declarations }
   procedure OnWM_PROGRESS_POSTION(var msg:TMessage);Message WM_PROGRESS_POSTION;
 end;

 TMyThread=class(TThread)
 private
   FWinHandle:THandle;
   FMax:Integer;
   FID:Integer;
 public
   constructor Create(CreateSuspended: Boolean;AWinHandle:THandle;AID,AMax:Integer);
   procedure Execute; override;
 published

 end;

var
 Form1: TForm1;

implementation

{$R *.dfm}

{ TMyThread }

constructor TMyThread.Create(CreateSuspended: Boolean;
 AWinHandle: THandle;AID,AMax:Integer);
begin
 inherited Create(CreateSuspended);
 FWinHandle:=AWinHandle;
 FMax:=AMax;
 FID:=AID;
end;

procedure TMyThread.Execute;
var
 i,L:Integer;
begin
 inherited;
 L:=FMax-1;
 for i:=0 to L do
 begin
   PostMessage(FWinHandle,WM_PROGRESS_POSTION,FID,i);
   Sleep(100);
 end;
end;

procedure TForm1.btn_OKClick(Sender: TObject);
begin
 TMyThread.Create(False,Self.Handle,1,1000);
 TMyThread.Create(False,Self.Handle,2,2000);
end;

procedure TForm1.OnWM_PROGRESS_POSTION(var msg: TMessage);
begin
 case msg.WParam of
   1:pb_One.Position:=msg.LParam;
   2:pb_Two.Position:=msg.LParam;
 end;
end;

end.