使用计时器-方法2

第一种方法 是把WM_TIMER消息发送给正常的窗口过程。

第二种方法 是 自己让 windows把计时器消息发送给程序中的另一个窗口过程

回调函数：

VOID CALLBACK TimerProc（HWND hwnd,UINT message,UINT iTimerID,DWORD dwTimer）
{
    ....
}  

第一种方式调用的SetTImer函数，第四个参数一般直接为NULL

SetTimer(hwnd,iTimerID,iMsecInterval,NULL);

第二种方式调用的SetTimer函数，第四个参数要设定为回调函数地址

SetTimer(hwnd,iTimerID,iMsecInterval,TimerProc);

函数代码如下：

/*----------------------------------------
   BEEPER2.C -- Timer Demo Program No. 2
                (c) Charles Petzold, 1998
  ----------------------------------------*/
 
#include <windows.h>

#define ID_TIMER    1

LRESULT CALLBACK WndProc   (HWND, UINT, WPARAM, LPARAM) ;
VOID    CALLBACK TimerProc (HWND, UINT, UINT,   DWORD ) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName[] = TEXT ("Beeper2") ;
     HWND         hwnd ;
     MSG          msg ;
     WNDCLASS     wndclass ;
     
     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
     wndclass.lpfnWndProc   = WndProc ;
     wndclass.cbClsExtra    = 0 ;
     wndclass.cbWndExtra    = 0 ;
     wndclass.hInstance     = hInstance ;
     wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = NULL ;
     wndclass.lpszClassName = szAppName ;
     
     if (!RegisterClass (&wndclass))
     {
          MessageBox (NULL, TEXT ("Program requires Windows NT!"), 
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }
     
     hwnd = CreateWindow (szAppName, TEXT ("Beeper2 Timer Demo"),
                          WS_OVERLAPPEDWINDOW,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          NULL, NULL, hInstance, NULL) ;
     
     ShowWindow (hwnd, iCmdShow) ;
     UpdateWindow (hwnd) ;
          
     while (GetMessage (&msg, NULL, 0, 0))
     {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
     }
     return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     switch (message)
     {
     case WM_CREATE:
          SetTimer (hwnd, ID_TIMER, 1000, TimerProc) ;
          return 0 ;
          
     case WM_DESTROY:
          KillTimer (hwnd, ID_TIMER) ;
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}

VOID CALLBACK TimerProc (HWND hwnd, UINT message, UINT iTimerID, DWORD dwTime)
{
     static BOOL fFlipFlop = FALSE ;
     HBRUSH      hBrush ;
     HDC         hdc ;
     RECT        rc ;
     
     MessageBeep (-1) ;
     fFlipFlop = !fFlipFlop ;
     
     GetClientRect (hwnd, &rc) ;
     
     hdc = GetDC (hwnd) ;
     hBrush = CreateSolidBrush (fFlipFlop ? RGB(255,0,0) : RGB(0,0,255)) ;
     
     FillRect (hdc, &rc, hBrush) ;
     ReleaseDC (hwnd, hdc) ;
     DeleteObject (hBrush) ;
}