中年人学C语言Windows程序设计，33 计时器SetTimer

#define ID_TIMER 1001

 switch (message)
    {
    	case WM_CREATE:
            SetTimer(hWnd, ID_TIMER, 1000, NULL);//设置计时器，间隔1000毫秒
            break;

        case WM_TIMER://计时器到时时调用
            //随机改变背景颜色
            SetClassLongPtr(hWnd, GCLP_HBRBACKGROUND, (long)CreateSolidBrush(RGB(rand() % 256, rand() % 256, rand() %256)));
            InvalidateRect(hWnd, NULL, TRUE);// 重绘背景
            break;

void CALLBACK TimerPro(HWND, UINT, UINT, DWORD);

 case WM_CREATE:
            SetTimer(hWnd, ID_TIMER, 1000, TimerPro);//设置计时器，间隔1000毫秒
            break;

void CALLBACK TimerPro(HWND hWnd, UINT message, UINT iTmerid, DWORD dwTime)
{
    SetClassLongPtr(hWnd, GCLP_HBRBACKGROUND, (long)CreateSolidBrush(RGB(rand() % 256, rand() % 256, rand() % 256)));
    InvalidateRect(hWnd, NULL, TRUE);// 重绘背景
}