程序最终效果

源代码：

/*-------------------------------------------	
	WinMain.cpp --七段数字时钟演示程序
			GreenLeaf1976 791869691@qq.com
----------------------------------------------*/

#include <windows.h>

#define ID_TIMER	1

HINSTANCE g_hInstance = 0;

//主窗口回调函数
LRESULT CALLBACK AfxWndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

//主函数WinMain
int WINAPI WinMain(_In_ HINSTANCE hInstance,
	_In_opt_ HINSTANCE hPrevInstance,
	_In_ LPSTR lpCmdLine, _In_ int nShowCmd)
{
	g_hInstance = hInstance;
	//定义窗口类名
	TCHAR szClassName[] = TEXT("AfxWndClassName");

	//设计窗口类
	WNDCLASSEX wcEx = { 0 };
	wcEx.cbSize = sizeof(WNDCLASSEX);				//窗口类结构大小
	wcEx.cbClsExtra = 0;							//窗口类额外数据
	wcEx.cbWndExtra = 0;							//窗口额外数据	
	wcEx.style = CS_VREDRAW | CS_HREDRAW;			//窗口类样式
	wcEx.lpfnWndProc = AfxWndProc;					//窗口类过程函数
	wcEx.lpszClassName = szClassName;				//窗口类名
	wcEx.lpszMenuName = nullptr;					//菜单句柄
	wcEx.hbrBackground = (HBRUSH)(COLOR_3DFACE + 1);//窗口类背景色
	wcEx.hInstance = hInstance;						//应用程序实例
	wcEx.hCursor = LoadCursor(NULL, IDC_ARROW);		//设置默认光标
	wcEx.hIconSm = LoadIcon(NULL, IDI_APPLICATION);	//窗口类小图标
	wcEx.hIcon = wcEx.hIconSm;						//窗口类大图标

	//注册窗口类
	if (!RegisterClassEx(&wcEx))
	{
		MessageBox(nullptr, TEXT("窗口类注册失败!"), TEXT("窗口类注册消息"), MB_ICONERROR);
		return -1;
	}

	//创建窗口
	HWND hWnd = CreateWindowEx(0,	//窗口扩展样式
		szClassName,				//窗口类名称
		TEXT("我的窗口"),			//窗口标题文本
		WS_OVERLAPPEDWINDOW,		//窗口样式
		100, 100, 800, 500,			//窗口显示的矩形位置(x,y,widht,height)
		nullptr,					//父窗口句柄
		nullptr,					//窗口菜单句柄(如果是子窗口就是窗口的ID号)
		hInstance,					//应用程序实例
		0);							//附加数据

	if (!hWnd)
	{
		MessageBox(hWnd, TEXT("窗口创建失败!"), TEXT("窗口创建消息"), MB_ICONERROR);
		return -2;
	}

	//显示与更新窗口
	ShowWindow(hWnd, nShowCmd);
	UpdateWindow(hWnd);
	SetForegroundWindow(hWnd); //设置为前台显示窗口

	//消息循环
	MSG msg;
	while (GetMessage(&msg, nullptr, 0, 0))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}


	return msg.wParam;
}

//绘制要显示的数字的形状
void DisplayDigit(HDC hdc, int iNumber)
{
	//数字的显示字段顺序为:
	//1,是上面一横,
	//2,第二排左面一竖
	//3,第二排右面一竖
	//4,中间一横
	//5,第四排左边一竖
	//6,第四排右边一竖
	//7,最后一排的一横
	static BOOL fSevenSegment[10][7] = {
		1,1,1,0,1,1,1,	//0
		0,0,1,0,0,1,0,	//1
		1,0,1,1,1,0,1,	//2
		1,0,1,1,0,1,1,	//3
		0,1,1,1,0,1,0,	//4
		1,1,0,1,0,1,1,	//5
		1,1,0,1,1,1,1,	//6
		1,0,1,0,0,1,0,	//7
		1,1,1,1,1,1,1,	//8
		1,1,1,1,0,1,1	//9
	};

	//七段数字的各个棱形的坐标
	//可在绘图上画好图形后,用工具测量实际坐标值
	static POINT ptSegment[7][6] = {
		7,6,11,2,31,2,35,6,31,10,11,10,		//最上面一横的坐标
		6,7,10,11,10,31,6,35,2,31,2,11,		//上面左边一竖的坐标
		36,7,40,11,40,31,36,35,32,31,32,11,	//上面右边一竖的坐标
		7,36,11,32,31,32,35,36,31,40,11,40,	//中间一横的坐标
		6,37,10,41,10,61,6,65,2,61,2,41,	//下面左边一竖的坐标
		36,37,40,41,40,61,36,65,32,61,32,41,//下面右边一竖的坐标
		7,66,11,62,31,62,35,66,31,70,11,70	//最下面一横的坐标
	};

	int iSeg;
	for (iSeg = 0; iSeg < 7; iSeg++)
	{
		if (fSevenSegment[iNumber][iSeg])
			Polygon(hdc, ptSegment[iSeg], 6);
	}
}

//绘制数字
void DisplayTwoDigits(HDC hdc, int iNumber, BOOL fSuppress)
{
	if (fSuppress || (iNumber / 10 != 0))
		DisplayDigit(hdc, iNumber / 10);

	OffsetWindowOrgEx(hdc, -42, 0, nullptr);
	DisplayDigit(hdc, iNumber % 10);
	OffsetWindowOrgEx(hdc, -42, 0, nullptr);
}

//绘制冒号
void DisplayColon(HDC hdc)
{
	POINT ptColon[2][4] = {
		2,21,6,17,10,21,6,25,
		2,51,6,47,10,51,6,55
	};

	Polygon(hdc, ptColon[0], 4);
	Polygon(hdc, ptColon[1], 4);

	OffsetWindowOrgEx(hdc, -12, 0, nullptr);
}

//绘制时间
void DisplayTime(HDC hdc, BOOL f24Hour, BOOL fSuppress)
{
	SYSTEMTIME st;
	GetLocalTime(&st);

	if (f24Hour)
		DisplayTwoDigits(hdc, st.wHour, fSuppress);
	else
		DisplayTwoDigits(hdc, (st.wHour %= 12) ? st.wHour : 12, fSuppress);

	DisplayColon(hdc);
	DisplayTwoDigits(hdc, st.wMinute, TRUE);
	DisplayColon(hdc);
	DisplayTwoDigits(hdc, st.wSecond, TRUE);

}

LRESULT CALLBACK AfxWndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	static BOOL f24Hour, fSupperss;
	static HBRUSH hBrushRed;
	static int cxClient, cyClient;
	HDC hdc;
	PAINTSTRUCT ps;
	TCHAR szBuffer[2];

	switch (uMsg)
	{
		case WM_CREATE:
			SetWindowText(hWnd, TEXT("七段数字时钟演示程序"));
			hBrushRed = CreateSolidBrush(RGB(255, 0, 0));
			SetTimer(hWnd, ID_TIMER, 1000, nullptr);
			//break;

		case WM_SETTINGCHANGE:
			GetLocaleInfo(LOCALE_USER_DEFAULT, LOCALE_ITIME, szBuffer, 2);
			f24Hour = (szBuffer[0] == '1');

			GetLocaleInfo(LOCALE_USER_DEFAULT, LOCALE_ITLZERO, szBuffer, 2);
			fSupperss = (szBuffer[0] == '0');

			InvalidateRect(hWnd, nullptr, TRUE);
			break;

		case WM_SIZE:
			cxClient = LOWORD(lParam);
			cyClient = HIWORD(lParam);
			break;

		case WM_TIMER:
			InvalidateRect(hWnd, nullptr, TRUE);
			break;

		case WM_PAINT:
			hdc = BeginPaint(hWnd, &ps);

			SetMapMode(hdc, MM_ISOTROPIC);
			SetWindowExtEx(hdc, 276, 72, nullptr);
			SetViewportExtEx(hdc, cxClient, cyClient, nullptr);

			SetWindowOrgEx(hdc, 138, 36, nullptr);
			SetViewportOrgEx(hdc, cxClient / 2, cyClient / 2, nullptr);

			SelectObject(hdc, GetStockObject(NULL_PEN));
			SelectObject(hdc, hBrushRed);

			DisplayTime(hdc, f24Hour, fSupperss);
			EndPaint(hWnd, &ps);
			break;

		case WM_DESTROY:
			KillTimer(hWnd, ID_TIMER);
			DeleteObject(hBrushRed);
			PostQuitMessage(0);
			return 0;

		default:
			break;
	}


	return DefWindowProc(hWnd, uMsg, wParam, lParam);
}