WM_TIMER， 改写其中的两个时钟程序

我相信大家都会觉得作者提供的两个时钟程序有点复杂， 复杂在于“画图”……
所以我改写了， 看起来相当简单:

源代码：

#include <windows.h>
#define ID_TIMER 1

VOID CALLBACK TimerProc(HWND, UINT, UINT, DWORD);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance,
                 HINSTANCE hPrevInstance,
                 PSTR szCmdLine,
                 int iCmdShow) {
    static TCHAR szAppName[] = TEXT("timer1");
    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 = GetStockObject(WHITE_BRUSH);
    wndclass.lpszMenuName = NULL;
    wndclass.lpszClassName = szAppName;
    
    if(!RegisterClass(&wndclass)) {
        MessageBox(NULL, TEXT("Register failure..."),
            szAppName, MB_ICONERROR);
        return 0;
    }
    
    hwnd = CreateWindow(szAppName,
        szAppName,
        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) {
    HDC hdc;
    SYSTEMTIME tm;
    TCHAR buffer[20];
    RECT rect;
    GetClientRect(hwnd, &rect);
        GetLocalTime(&tm);

    hdc = GetDC(hwnd);
    DrawText(hdc, buffer, wsprintf(buffer, "%4d-%02d-%02d %02d:%02d:%02d",
        tm.wYear, tm.wMonth, tm.wDay, tm.wHour, tm.wMinute,
        tm.wSecond), &rect, DT_SINGLELINE | DT_CENTER | DT_VCENTER);
    ReleaseDC(hwnd, hdc);
}