MFC中多线程的应用

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MFC中多线程的应用

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  我试着用自已的话来表述线程的概念,还有很短时间里编的一个小示例程序(不知恰当不?,也不知能说得清不..),见笑了.

  线程其实和标准的windows主程序(WinMain)没啥两样...主程序其实是一个特殊的线程,称为主线程而已,其实你完全可以把线程想象成和winmain一起**同时运行**,但是** 可以相互访问(即在一个地址空间) **的一些小的WinMain程序.它和主线程一样,里面可以创建窗口,获取消息,等等..

   由于线程们在一个地址空间且同时运行,所以会造成一些麻烦。因为我们编程都要用别人的函数库,而他们的函数库里面往往会有很多静态或全局的状态或中间变量,有着很复杂的相互依赖关系,如果执行某个功能不串行化(所谓串行化,也就是只能等一个功能调用返回后,另一个线程才能调用,不可以同时调用),就会造成大乱.这对线程来说,有术语称同步,windows为我们提供了很多同步的方法,MFC也提供了一些同步核心对象的类封装.对于某个功能调用库来说,叫线程安全.比如MFC的类库并不是线程安全的.

   现在我举个刚刚自编的例子来简单说明这些概念。下面的一个对话框应用是多线程的.演示两个小动画:

  (1)第一个动画由主线程的Timer来驱动,第二个动画由主线所创建的工作线程来驱动.分别显示在不同的位置.之所以我要加入Timer,也是为了形成线程驱动和timer驱动的对照,这是动画的两种驱动方式(还有在idle中驱动的)。

  (2)这两个动画永远是不同的.也就是比如:一个是变哭,一个就会变笑,等那个变笑了,这个就变哭.动画图片来自于OICQ中的Face目录下,一般同样的头像会oicq会带三个图片(*-1.bmp,*-2.bmp,*-3.bmp),*-2.bmp是变灰的图片,我就取了1和3的图片来作动画.

   这个程序的几个关键要注意的:

  (1)主线程用PostThreadMessage和工作线程通信.工作线程用PeekMessage来取回消息。为了简单起见,我只用了一个WM_QUIT的消息来指示工作线程退出.

  (2)主线程和工作线程同时调用了一个DisplayFace函数来进行动画显示.为了让两个动画一哭一笑做到不同,采用了CCriticalSection来进行同步.


  示例如下:

  (1)先用appwizards生成一个MFC的Dialog应用模板,假定对话框类为CTest01Dlg。

  (2)再添入两个oicq的bmp文件到资源中去

  (3)添加一个按钮(button)到对话框上.用作启动、停止动画的button

  (4)用ClassWizard为button/onclick及dlg/ontimer生成事件响应函数,

  (5)用Resource Symbol加入一个标识定义IDC_TIMER1

  (6)在ClassView中为CTest01Dlg加入以下成员变量和成员函数

    CriticalSection ccs;

    CBitmap bm[2];

    CWinThread* pMyThread;

    static UINT MyThreadProc( LPVOID pParam);

    void DisplayFace(CPoint r);

    实现文件中加入相应代码(见下面)

  (7)stdafx.h中加入#include

  源代码如下,凡是我新加的代码周围都有注释包围,其它是ClassWizards自动写的:

  // stdafx.h : include file for standard system include files,

  // or project specific include files that are used frequently, but

  // are changed infrequently

  file://

   #if !defined(AFX_STDAFX_H__5B92DAA8_FE27_4702_8037_A2538343E69D__INCLUDED_)

   #define AFX_STDAFX_H__5B92DAA8_FE27_4702_8037_A2538343E69D__INCLUDED_

  #if _MSC_VER > 1000

  #pragma once

  #endif // _MSC_VER > 1000

  #define VC_EXTRALEAN // Exclude rarely-used stuff from Windows headers

  #include // MFC core and standard components

  #include // MFC extensions

  #include // MFC support for Internet Explorer 4 Common Controls

  file://加入头引用主要是CCriticalSection对象的定义.

  #include

  file://加入结束

  #ifndef _AFX_NO_AFXCMN_SUPPORT

  #include // MFC support for Windows Common Controls

  #endif // _AFX_NO_AFXCMN_SUPPORT

  file://{{AFX_INSERT_LOCATION}}

  // Microsoft Visual C++ will insert additional declarations immediately before the previous line.

  #endif // !defined(AFX_STDAFX_H__5B92DAA8_FE27_4702_8037_A2538343E69D__INCLUDED_)

  // test01Dlg.h : header file

  file://

  #if !defined(AFX_TEST01DLG_H__F3780E23_CCFC_468C_A262_50FFF1D991BC__INCLUDED_)

  #define AFX_TEST01DLG_H__F3780E23_CCFC_468C_A262_50FFF1D991BC__INCLUDED_

  #if _MSC_VER > 1000

  #pragma once

  #endif // _MSC_VER > 1000

  /////////////////////////////////////////////////////////////////////////////

  // CTest01Dlg dialog

  class CTest01Dlg : public CDialog

  {

   // Construction

   public:

   file://加入

   CBitmap bm[2];

   CCriticalSection ccs;

   CWinThread* pMyThread;

   static UINT MyThreadProc( LPVOID pParam);

   void DisplayFace(CPoint r);

   CTest01Dlg(CWnd* pParent = NULL); // standard constructor

   file://加入结束

   // Dialog Data

   file://{{AFX_DATA(CTest01Dlg)

   enum { IDD = IDD_TEST01_DIALOG };

   // NOTE: the ClassWizard will add data members here

   file://}}AFX_DATA

   // ClassWizard generated virtual function overrides

   file://{{AFX_VIRTUAL(CTest01Dlg)

   protected:

   virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support

   file://}}AFX_VIRTUAL

   // Implementation

   protected:

    HICON m_hIcon;

    // Generated message map functions

    file://{{AFX_MSG(CTest01Dlg)

    virtual BOOL OnInitDialog();

    afx_msg void OnSysCommand(UINT nID, LPARAM lParam);

    afx_msg void OnPaint();

    afx_msg HCURSOR OnQueryDragIcon();

    afx_msg void OnButton1();

    afx_msg void OnTimer(UINT nIDEvent);

   file://}}AFX_MSG

   DECLARE_MESSAGE_MAP()

   };

   file://{{AFX_INSERT_LOCATION}}

   // Microsoft Visual C++ will insert additional declarations immediately before the previous line.

   #endif // !defined(AFX_TEST01DLG_H__F3780E23_CCFC_468C_A262_50FFF1D991BC__INCLUDED_)

   // test01Dlg.cpp : implementation file

   file://

   #include "stdafx.h"

   #include "test01.h"

   #include "test01Dlg.h"

   #ifdef _DEBUG

   #define new DEBUG_NEW

   #undef THIS_FILE

   static char THIS_FILE[] = __FILE__;

   #endif

   /////////////////////////////////////////////////////////////////////////////

   // CAboutDlg dialog used for App About

   class CAboutDlg : public CDialog

    {

     public:

     CAboutDlg();

     // Dialog Data

     file://{{AFX_DATA(CAboutDlg)

     enum { IDD = IDD_ABOUTBOX };

     file://}}AFX_DATA

   // ClassWizard generated virtual function overrides

   file://{{AFX_VIRTUAL(CAboutDlg)

   protected:

   virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support

   file://}}AFX_VIRTUAL

   // Implementation

   protected:

   file://{{AFX_MSG(CAboutDlg)

   file://}}AFX_MSG

   DECLARE_MESSAGE_MAP()

   };

   CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)

   {

    file://{{AFX_DATA_INIT(CAboutDlg)

    file://}}AFX_DATA_INIT

   }

   void CAboutDlg::DoDataExchange(CDataExchange* pDX)

    {

     CDialog::DoDataExchange(pDX);

     file://{{AFX_DATA_MAP(CAboutDlg)

     file://}}AFX_DATA_MAP

    }

  BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)

  file://{{AFX_MSG_MAP(CAboutDlg)

  // No message handlers

  file://}}AFX_MSG_MAP

  END_MESSAGE_MAP()

  /////////////////////////////////////////////////////////////////////////////

  // CTest01Dlg dialog

  CTest01Dlg::CTest01Dlg(CWnd* pParent /*=NULL*/)

  : CDialog(CTest01Dlg::IDD, pParent)

   {

    file://{{AFX_DATA_INIT(CTest01Dlg)

    // NOTE: the ClassWizard will add member initialization here

    file://}}AFX_DATA_INIT

    // Note that LoadIcon does not require a subsequent DestroyIcon in Win32

    m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);

    file://加入

    pMyThread =NULL;

    file://加入结束

   }

  void CTest01Dlg::DoDataExchange(CDataExchange* pDX)

  {

   CDialog::DoDataExchange(pDX);

   file://{{AFX_DATA_MAP(CTest01Dlg)

   // NOTE: the ClassWizard will add DDX and DDV calls here

   file://}}AFX_DATA_MAP

  }

  BEGIN_MESSAGE_MAP(CTest01Dlg, CDialog)

   file://{{AFX_MSG_MAP(CTest01Dlg)

    ON_WM_SYSCOMMAND()

    ON_WM_PAINT()

    ON_WM_QUERYDRAGICON()

    ON_BN_CLICKED(IDC_BUTTON1, OnButton1)

    ON_WM_TIMER()

   file://}}AFX_MSG_MAP

   END_MESSAGE_MAP()

   /////////////////////////////////////////////////////////////////////////////

   // CTest01Dlg message handlers

   BOOL CTest01Dlg::OnInitDialog()

   {

    CDialog::OnInitDialog();

    // Add "About..." menu item to system menu.

    // IDM_ABOUTBOX must be in the system command range.

    ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);

    ASSERT(IDM_ABOUTBOX < 0xF000);

    CMenu* pSysMenu = GetSystemMenu(FALSE);

    if (pSysMenu != NULL)

     {

      CString strAboutMenu;

      strAboutMenu.LoadString(IDS_ABOUTBOX);

      if (!strAboutMenu.IsEmpty())

      {

       pSysMenu->AppendMenu(MF_SEPARATOR);

       pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);

      }

     }

    // Set the icon for this dialog. The framework does this automatically

    // when the application''s main window is not a dialog

    SetIcon(m_hIcon, TRUE); // Set big icon

    SetIcon(m_hIcon, FALSE); // Set small icon

    // TODO: Add extra initialization here

    file://加入

    bm[0].LoadBitmap (IDB_BITMAP1);

    bm[1].LoadBitmap (IDB_BITMAP3);

    file://加入结束

    return TRUE; // return TRUE unless you set the focus to a control

   }

   void CTest01Dlg::OnSysCommand(UINT nID, LPARAM lParam)

   {

    if ((nID & 0xFFF0) == IDM_ABOUTBOX)

     {

      CAboutDlg dlgAbout;

      dlgAbout.DoModal();

     }

    else

     {

      CDialog::OnSysCommand(nID, lParam);

      }

    }

   void CTest01Dlg::OnPaint()

    {

     if (IsIconic())

      {

       CPaintDC dc(this); // device context for painting

       SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);

       // Center icon in client rectangle

       int cxIcon = GetSystemMetrics(SM_CXICON);

       int cyIcon = GetSystemMetrics(SM_CYICON);

       CRect rect;

       GetClientRect(&rect);

       int x = (rect.Width() - cxIcon + 1) / 2;

       int y = (rect.Height() - cyIcon + 1) / 2;

       // Draw the icon

       dc.DrawIcon(x, y, m_hIcon);

    }

    else

    {

     CDialog::OnPaint();

    }

   }

   HCURSOR CTest01Dlg::OnQueryDragIcon()

    {

     return (HCURSOR) m_hIcon;

     }

    file://加入

    void CTest01Dlg::OnButton1()

     {

      static BOOL bStarted=FALSE;

      if (!bStarted){

       SetTimer(IDC_TIMER1,500,NULL);

       pMyThread=AfxBeginThread(MyThreadProc,this);

      }else{

      if (pMyThread){

       pMyThread->PostThreadMessage (WM_QUIT,0,0);

       ::WaitForSingleObject(pMyThread->m_hThread ,INFINITE);

       pMyThread=NULL;

       }

       KillTimer(IDC_TIMER1);

      }

     bStarted=!bStarted;

     ((CButton*)GetDlgItem(IDC_BUTTON1))->SetWindowText((bStarted?_T("停止"):_T("启动")));

    }

    void CTest01Dlg::OnTimer(UINT nIDEvent)

    {

     if (nIDEvent==IDC_TIMER1)

      DisplayFace(CPoint(10,10));

      CDialog::OnTimer(nIDEvent);

     }

    void CTest01Dlg::DisplayFace(CPoint p)

     {

      static int i=0;

      ccs.Lock ();

      BITMAP bmo;

      bm[i].GetObject (sizeof(bmo),&bmo);

      CClientDC dc(this);

      CDC bmpDC;

      bmpDC.CreateCompatibleDC (&dc);

      bmpDC.SelectObject (&bm[i]);

      dc.BitBlt (p.x ,p.y ,bmo.bmWidth,bmo.bmHeight,&bmpDC,0,0,SRCCOPY);

      i++;

      if (i==sizeof(bm)/sizeof(bm[0])) i=0;

       ccs.Unlock ();

      }

     UINT CTest01Dlg::MyThreadProc(LPVOID pParam)

     {

      CTest01Dlg *me=(CTest01Dlg *)pParam;

      MSG msg;

      while(!PeekMessage(&msg,NULL,0,0,PM_NOREMOVE)){

       me->DisplayFace (CPoint(100,10));

       ::Sleep (200);

       }

      return 0;

    }

    file://加入结束

 


 

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