使用計時器-方法2

第一種方法 是把WM_TIMER消息發送給正常的窗口過程。

第二種方法 是 本身讓 windows把計時器消息發送給程序中的另外一個窗口過程

 

回調函數：

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

第一種方式調用的SetTImer函數，第四個參數通常直接爲NULL

SetTimer(hwnd,iTimerID,iMsecInterval,NULL);

第二種方式調用的SetTimer函數，第四個參數要設定爲回調函數地址

SetTimer(hwnd,iTimerID,iMsecInterval,TimerProc);

函數代碼以下：

/*---------------------------------------- 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) ; }