本文是看了網上一個部落格的例項，覺得很好玩，複製程式碼，做了一些修改，調通了之後，做的一些分享。參考原文為：http://blog.csdn.net/xingchenbingbuyu/article/details/50762351

主要修改的地方：1、獲取系統時間  2、秒針更形象的顯示

如果想要看原理的話，詳見本文參考的部落格，這裡不做敘述。

下面貼出程式碼，供有興趣的人蔘考。

#include <iostream>  
#include "opencv2/highgui/highgui.hpp"  
#include "opencv2/imgproc/imgproc_c.h"  
#include "opencv2/imgproc/imgproc.hpp"  
#include <stdio.h>  
#include <time.h>  
#include <windows.h> 
#include <sys/timeb.h>  
#include<sys\utime.h>  


using namespace std;
using namespace cv;


int main()
{
	Mat clk(640, 640, CV_8UC3, Scalar(180, 120, 50)); //Mat to store clock image  
	Mat back_up(640, 640, CV_8UC3, Scalar(180, 120, 50)); //Mat to store backup image  


	Point cent(clk.rows / 2, clk.cols / 2);
	Point perim(clk.cols / 2, 0);
	int rad = clk.cols / 2;
	float sec_angle = 270;
	float min_angle = 330;
	float hour_angle = 210;


	//畫秒針刻度  
	vector<Point> pt1, pt2;
	for (int i = 0; i < 60; i++)
	{
		int x1 = cent.x + rad * cos(i * 6 * CV_PI / 180.0);
		int y1 = cent.y + rad * sin(i * 6 * CV_PI / 180.0);
		pt1.push_back(Point(x1, y1));


		int x2 = cent.x + (rad - 20)*cos(i * 6 * CV_PI / 180.0);
		int y2 = cent.y + (rad - 20)*sin(i * 6 * CV_PI / 180.0);
		pt2.push_back(Point(x2, y2));


		line(clk, pt1[i], pt2[i], Scalar(0, 255, 0, 0), 1.5, CV_AA, 0);
	}



	//畫整點刻度  
	vector<Point> pt3, pt4;
	for (int i = 0; i < 12; i++)
	{
		int x3 = cent.x + (rad - 40)*cos(i * 30 * CV_PI / 180.0);
		int y3 = cent.y + (rad - 40)*sin(i * 30 * CV_PI / 180.0);
		pt3.push_back(Point(x3, y3));


		line(clk, pt1[(i * 5)], pt3[i], Scalar(0, 255, 0, 0), 5, CV_AA, 0);
	}
	//畫最外圍的圓和圓心的三針連線點  
	circle(clk, cent, rad, Scalar(50, 50, 255, 0), 6, CV_AA, 0); //Dreaw outercircle of clock  
	circle(clk, cent, 2, Scalar(0, 255, 0, 0), 5, CV_AA, 0); //Draw inner circle  


	back_up = clk.clone(); // Clone to backup image  



	float second;
	float minute;
	float hour;
	float millisec;
	SYSTEMTIME sys;


	while (1)
	{
		GetLocalTime(&sys);//獲取本機系統時間
		second = sys.wSecond;
		minute = sys.wMinute;
		hour = sys.wHour;
		millisec = sys.wMilliseconds;


		second = second + millisec / 1000;
		sec_angle = (second * 6) + 270; //Convert second to angle  


		minute = minute + second / 60;
		min_angle = minute * 6 + 270; //Conver minute to angle  


		if (hour > 12)hour = hour - 12;
		hour_angle = (hour * 30) + (minute*.5) + 270; //Conver hour to angle  




		if (sec_angle > 360)sec_angle = sec_angle - 360;
		if (min_angle > 360)min_angle = min_angle - 360;
		if (hour_angle > 360)hour_angle = hour_angle - 360;


		//畫秒針  
		sec_angle = (cvRound(sec_angle) / 6) * 6;//將秒針的角度四捨五入到6的倍數
		perim.x = (int)round(cent.x + (rad - 5) * cos(sec_angle * CV_PI / 180.0));
		perim.y = (int)round(cent.y + (rad - 5) * sin(sec_angle * CV_PI / 180.0));
		line(clk, cent, perim, Scalar(0, 255, 255, 0), 1.5, CV_AA, 0);




		//畫分針  
		perim.x = (int)round(cent.x + (rad - 30) * cos(min_angle * CV_PI / 180.0));
		perim.y = (int)round(cent.y + (rad - 30) * sin(min_angle * CV_PI / 180.0));
		line(clk, cent, perim, Scalar(0, 255, 255, 0), 4, CV_AA, 0);




		//畫時針  
		perim.x = (int)round(cent.x + (rad - 100) * cos(hour_angle * CV_PI / 180.0));
		perim.y = (int)round(cent.y + (rad - 100) * sin(hour_angle * CV_PI / 180.0));
		line(clk, cent, perim, Scalar(0, 255, 255, 0), 12, CV_AA, 0);




		imshow("Clock", clk); //Show result in a window  
		clk.setTo(0); // set clk image to zero for next drawing  
		clk = back_up.clone(); // Clone the previously drawned markings from back-up image  


		//char c = waitKey(999); // 這裡如果引數為10，則看到的是秒針連續地轉動；如果是1000，則效果是秒針一秒一秒地跳動  
		char c = waitKey(10);
		if (c == 27)break;
	}


	return 0;
}