学习OpenCV2——绘制基本图形及文字

    OpenCV中可以绘制的图形有直线、矩形、多边形、圆、椭圆。以及一个写文本的函数puttext

1. 基本函数

Line

C++: void line(Mat& img, Point pt1,Point pt2, const Scalar& color, int thickness=1, int lineType=8,int shift=0)
Parameters:

img – 图像.

pt1 – 线条起点.

pt2 – 线条终点.

color – 线条颜色.

thickness – 线条宽度.

lineType – 线型

Type of the line:  8 (or omitted) - 8-连接线.

                           4 - 4-连接线.

                           CV_AA - 反走样线条.

shift – 坐标点小数点位数.

Rectangle

C++: void rectangle(Mat& img,Point pt1, Pointpt2, const Scalar&color, intthickness=1,intlineType=8, intshift=0)
C++: void rectangle(Mat& img,Rect rec, const Scalar&color, intthickness=1, intlineType=8,intshift=0 )
Parameters:

img – 画矩形的对象

pt1 – 矩形的一个顶点，左上角的.

pt2 – 另一个顶点，右下角的.

rec – 确定矩形的另一种方式，给左上角坐标和长宽

color – 指定矩形的颜色或亮度(灰度图像)，scalar(255,0,255)既可指定.

thickness – 矩形边框的粗细. 负值（like CV_FILLED）表示要画一个填充的矩形

lineType – 边框线型. （ 8 (or 0) - 8-connected line（8邻接)连接线。

                                      4 - 4-connected line(4邻接)连接线。

                                      CV_AA - antialiased 线条。）

shift –坐标点的小数点位数

PolyLine

C++: void polylines(Mat& img, const Point** pts, const int* npts, int ncontours, bool isClosed, const Scalar& color, int thickness=1, int lineType=8, int shift=0 )
C++: void polylines(InputOutputArray img, InputArrayOfArrays pts, bool isClosed, const Scalar& color, int thickness=1, int lineType=8, int shift=0 )
Parameters:

img – 折线所在图像.

pts – 折线中拐点坐标指针.

npts – 折线拐点个数指针.

ncontours – 折线线段数量.

isClosed – 折线是否闭合.

color – 折线颜色.

thickness – 折线宽度.

lineType – 线型.

shift – 顶点坐标小数点位数.

Circle

C++: void circle(Mat&img, Point center, intradius, const Scalar&color,intthickness=1, intlineType=8, intshift=0)
Parameters:

img – 要画圆的那个矩形.

center – 圆心坐标.

radius – 半径.

color – 圆边框颜色，scalar类型的

thickness – 正值表示圆边框宽度. 负值表示画一个填充圆形

lineType – 圆边框线型

shift – 圆心坐标和半径的小数点位数

Ellipse

C++: void ellipse(Mat& img, Point center,Size axes, double angle, double startAngle, double endAngle, const Scalar& color,int thickness=1, int lineType=8, int shift=0)
C++: void ellipse(Mat& img, constRotatedRect& box, const Scalar& color, int thickness=1, int lineType=8)
Parameters:

img – 椭圆所在图像.

center – 椭圆中心.

axes – 椭圆主轴一半的长度

angle – 椭圆旋转角度

startAngle – 椭圆弧起始角度

endAngle –椭圆弧终止角度

box – 指定椭圆中心和旋转角度的信息，通过 RotatedRect 或 CvBox2D. 这表示椭圆画在旋转矩形上（矩形是不可见的，只是指定了一个框而已）

color – 椭圆边框颜色.

thickness – 正值代表椭圆边框宽度，负值代表填充的椭圆

lineType – 线型

shift – 椭圆中心坐标和坐标轴的小数点位数

PutText

C++: void putText(Mat& img, const string& text, Point org, int fontFace, double fontScale, Scalar color, int thickness=1, int lineType=8, bool bottomLeftOrigin=false )
Parameters:

img – 显示文字所在图像.

text – 待显示的文字.

org – 文字在图像中的左下角 坐标.

font – 字体结构体.

fontFace – 字体类型， 可选择字体：

FONT_HERSHEY_SIMPLEX,                    FONT_HERSHEY_PLAIN,                             

          FONT_HERSHEY_DUPLEX,                     FONT_HERSHEY_COMPLEX, 
          FONT_HERSHEY_TRIPLEX,                     FONT_HERSHEY_COMPLEX_SMALL, 
          FONT_HERSHEY_SCRIPT_SIMPLEX, or FONT_HERSHEY_SCRIPT_COMPLEX,

以上所有类型都可以配合 FONT_HERSHEY_ITALIC使用，产生斜体效果。

fontScale – 字体大小，该值和字体内置大小相乘得到字体大小

color – 文本颜色

thickness –  写字的线的粗细

lineType – 线型.

bottomLeftOrigin – true, 图像数据原点在左下角. Otherwise, 图像数据原点在左上角.

2. 一些参数取值情况

lineType：    8或0  8-连接线

                    4   4-连接线

                    CV_AA 反走样线条

thickness： ＞0，线条粗细   <0，填充

fontFace ： 

        CV_FONT_HERSHEY_SIMPLEX                       正常尺寸sanserif字体

        CV_FONT_HERSHEY_PLAIN                            小尺寸sanserif字体

        CV_FONT_HERSHEY_DUPLEX                         正常尺寸sanserif, 比CV_FONT_HERSHEY_SIMPLEX更复杂

        CV_FONT_HERSHEY_COMPLEX                      正常尺寸serif, 比CV_FONT_HERSHEY_DUPLEX更复杂

        CV_FONT_HERSHEY_TRIPLEX                         正常尺寸serif, 比CV_FONT_HERSHEY_COMPLEX更复杂

        CV_FONT_HERSHEY_COMPLEX_SMALL        小尺寸的CV_FONT_HERSHEY_COMPLEX

        CV_FONT_HERSHEY_SCRIPT_SIMPLEX        手写风格
        CV_FONT_HERSHEY_SCRIPT_COMPLEX       比CV_FONT_HERSHEY_SCRIPT_SIMPLEX更复杂的风格

常见颜色RGB值对照表

	R	G	B	值		R	G	B	值		R	G	B	值
黑色	0	0	0	#000000	黄色	255	255	0	#FFFF00	浅灰蓝色	176	224	230	#B0E0E6
象牙黑	41	36	33	#292421	香蕉色	227	207	87	#E3CF57	品蓝	65	105	225	#4169E1
灰色	192	192	192	#C0C0C0	镉黄	255	153	18	#FF9912	石板蓝	106	90	205	#6A5ACD
冷灰	128	138	135	#808A87	dougello	235	142	85	#EB8E55	天蓝	135	206	235	#87CEEB
石板灰	112	128	105	#708069	forum gold	255	227	132	#FFE384
暖灰色	128	128	105	#808069	金黄色	255	215	0	#FFD700	青色	0	255	255	#00FFFF
					黄花色	218	165	105	#DAA569	绿土	56	94	15	#385E0F
白色	225	225	225	#FFFFFF	瓜色	227	168	105	#E3A869	靛青	8	46	84	#082E54
古董白	250	235	215	#FAEBD7	橙色	255	97	0	#FF6100	碧绿色	127	255	212	#7FFFD4
天蓝色	240	255	255	#F0FFFF	镉橙	255	97	3	#FF6103	青绿色	64	224	208	#40E0D0
白烟	245	245	245	#F5F5F5	胡萝卜色	237	145	33	#ED9121	绿色	0	255	0	#00FF00
白杏仁	255	235	205	#FFFFCD	桔黄	255	128	0	#FF8000	黄绿色	127	255	0	#7FFF00
cornsilk	255	248	220	#FFF8DC	淡黄色	245	222	179	#F5DEB3	钴绿色	61	145	64	#3D9140
蛋壳色	252	230	201	#FCE6C9						翠绿色	0	201	87	#00C957
花白	255	250	240	#FFFAF0	棕色	128	42	42	#802A2A	森林绿	34	139	34	#228B22
gainsboro	220	220	220	#DCDCDC	米色	163	148	128	#A39480	草地绿	124	252	0	#7CFC00
ghostWhite	248	248	255	#F8F8FF	锻浓黄土色	138	54	15	#8A360F	酸橙绿	50	205	50	#32CD32
蜜露橙	240	255	240	#F0FFF0	锻棕土色	135	51	36	#873324	薄荷色	189	252	201	#BDFCC9
象牙白	250	255	240	#FAFFF0	巧克力色	210	105	30	#D2691E	草绿色	107	142	35	#6B8E23
亚麻色	250	240	230	#FAF0E6	肉色	255	125	64	#FF7D40	暗绿色	48	128	20	#308014
navajoWhite	255	222	173	#FFDEAD	黄褐色	240	230	140	#F0E68C	海绿色	46	139	87	#2E8B57
old lace	253	245	230	#FDF5E6	玫瑰红	188	143	143	#BC8F8F	嫩绿色	0	255	127	#00FF7F
海贝壳色	255	245	238	#FFF5EE	肖贡土色	199	97	20	#C76114
雪白	255	250	250	#FFFAFA	标土棕	115	74	18	#734A12	紫色	160	32	240	#A020F0
					乌贼墨棕	94	38	18	#5E2612	紫罗蓝色	138	43	226	#8A2BE2
红色	255	0	0	#FF0000	赫色	160	82	45	#A0522D	jasoa	160	102	211	#A066D3
砖红	156	102	31	#9C661F	马棕色	139	69	19	#8B4513	湖紫色	153	51	250	#9933FA
镉红	227	23	13	#E3170D	沙棕色	244	164	96	#F4A460	淡紫色	218	112	214	#DA70D6
珊瑚色	255	127	80	#FF7F50	棕褐色	210	180	140	#D2B48C	梅红色	221	160	221	#DDA0DD
耐火砖红	178	34	34	#B22222
印度红	176	23	31	#B0171F	蓝色	0	0	255	#0000FF
栗色	176	48	96	#B03060	钴色	61	89	171	#3D59AB
粉红	255	192	203	#FFC0CB	dodger blue	30	144	255	#1E90FF
草莓色	135	38	87	#872657	jackie blue	11	23	70	#0B1746
橙红色	250	128	114	#FA8072	锰蓝	3	168	158	#03A89E
蕃茄红	255	99	71	#FF6347	深蓝色	25	25	112	#191970
桔红	255	69	0	#FF4500	孔雀蓝	51	161	201	#33A1C9
深红色	255	0	255	#FF00FF	土耳其玉色	0	199	140	#00C78C

更全的RGB颜色对照表参见 ：http://tool.oschina.net/commons?type=3

3. 示例代码

例1.

#include <iostream>
#include "cv.h"
#include "highgui.h"

using namespace std;
using namespace cv;

static void help()
{
	cout << "This program demonstrates OpenCV drawing and text output functions" << endl 
		<< "Usage:" << endl
		<<"./drawing" << endl;
}

static Scalar randomColor(RNG& rng)
{
	int iColor = unsigned(rng);
	//255 = 0xFF
	return Scalar(iColor & 255,(iColor >> 8) & 255,(iColor >> 16) & 255);    //产生一种颜色
}

int main(int argc,char** argv)
{
	help();
	char wndName[] = "Drawing Demo";
	const int randomNumber = 100;
	const int DELAY = 10;
	int lineType = CV_AA;
	int height = 700;
	int width = 1000;
	int x1 = - width/2;      //-500
	int x2 = 3 * width/2;    //1500
	int y1 = - height/2;     //-350
	int y2 = 3 * height/2;   //1050
	RNG rng(0xFFFFFFFF);

	
	Mat image = Mat::zeros(height,width,CV_8UC3);
	imshow(wndName,image);
	waitKey(DELAY);

	//draw line
	for(int i = 0;i < randomNumber;i++)
	{
		Point pt1,pt2;
		pt1.x = rng.uniform(x1,x2);
		pt1.y = rng.uniform(y1,y2);
		pt2.x = rng.uniform(x1,x2);
		pt2.y = rng.uniform(y1,y2);
		line(image,pt1,pt2,randomColor(rng),rng.uniform(1,10),lineType);
		imshow(wndName,image);
		if(waitKey(DELAY) >= 0)
			return 0;
	}

	//draw rectangle
	for(int i = 0;i < randomNumber;i++)
	{
		Point pt1,pt2;
		pt1.x = rng.uniform(x1,x2);
		pt1.y = rng.uniform(y1,y2);
		pt2.x = rng.uniform(x1,x2);
		pt2.y = rng.uniform(y1,y2);
		int thickness = rng.uniform(-3,10);

		/*----------------------draws a simple, thick, or filled up-right rectangle-----------
		*	C++: void rectangle(Mat& img, Point pt1, Point pt2, const Scalar& color, 
								int thickness=1, int lineType=8,int shift=0)
		*	C++: void rectangle(Mat& img, Rect rec, const Scalar& color, int thickness=1, 
								int lineType=8, int shift=0)
		*	img – image
		*	pt1 – Vertex of the rectangle                    矩形的一个顶点p1
		*	pt2 – Vertex of the rectangle opposite to pt1    矩形的另一个顶点，与p1相对
		*	rec – Alternative specification of the drawn rectangle
		*	color – Rectangle color or brightness (grayscale image)      线条颜色，对于灰度图是亮度
		*	thickness – Thickness of lines that make up the rectangle. Negative values,   线条粗细
			like CV_FILLED, mean that the function has to draw a filled rectangle
		*	lineType – Type of the line. See the line() description       线条类型
		*	shift – Number of fractional bits in the point coordinates    
		-----------------------------------------------------------------------------*/
		rectangle(image,pt1,pt2,randomColor(rng),MAX(thickness,-1),lineType);
		imshow(wndName,image);
		if(waitKey(DELAY) >= 0)
			return 0;
	}




	//draw ellipse
	for(int i = 0; i < randomNumber;i++)
	{
		Point center;
		center.x = rng.uniform(x1,x2);
		center.y = rng.uniform(y1,y2);
		Size axes;
		axes.width = rng.uniform(0,200);
		axes.height = rng.uniform(0,200);
		double angle = rng.uniform(0,180);

		/*---------draws a simple or thick elliptic arc or fills an ellipse sector---------
		*	C++: void ellipse(Mat& img, Point center, Size axes, double angle, 
								double startAngle,double endAngle,const Scalar& color, 
								int thickness=1, int lineType=8, int shift=0)
		*	C++: void ellipse(Mat& img, const RotatedRect& box, const Scalar& color, 
								int thickness=1, int lineType=8)
		*	img – image 
		*	center – Center of the ellipse 椭圆中心
		*	axes – Half of the size of the ellipse main axes 椭圆长轴的一半
		*	angle – Ellipse rotation angle in degrees 椭圆旋转的角度
		*	startAngle – Starting angle of the elliptic arc in degrees 弧度开始的角度
		*	endAngle – Ending angle of the elliptic arc in degrees 弧度结束的角度
		*	box – Alternative ellipse representation via RotatedRect or CvBox2D
			This means that the function draws an ellipse inscribed in the rotated rectangle
		*	color – Ellipse color
		*	thickness – Thickness of the ellipse arc outline, if positive. Otherwise, this indicates that a
			filled ellipse sector is to be drawn
		*	lineType – Type of the ellipse boundary. See the line() description
		*	shift – Number of fractional bits in the coordinates of the center and values of axes
		-----------------------------------------------------------------------------*/
		ellipse(image,center,axes,angle,angle - 100,angle + 200,randomColor(rng),rng.uniform(1,8),lineType);
		imshow(wndName,image);
		if(waitKey(DELAY) >= 0)
			return 0;
	}

	//draw polylines
	for(int i = 0;i < randomNumber;i++)
	{
		Point pt[2][3];
		pt[0][0].x = rng.uniform(x1,x2);
		pt[0][0].y = rng.uniform(y1,y2);
		pt[0][1].x = rng.uniform(x1,x2);
		pt[0][1].y = rng.uniform(y1,y2);
		pt[0][2].x = rng.uniform(x1,x2);
		pt[0][2].y = rng.uniform(y1,y2);
		pt[1][0].x = rng.uniform(x1,x2);
		pt[1][0].y = rng.uniform(y1,y2);
		pt[1][1].x = rng.uniform(x1,x2);
		pt[1][1].y = rng.uniform(y1,y2);
		pt[1][2].x = rng.uniform(x1,x2);
		pt[1][2].y = rng.uniform(y1,y2);
		const Point* ppt[2] = {pt[0],pt[1]};
		int npt[] = {3,3};

		/*-------------------draws several polygonal curves----------------------------
		*	C++: void polylines(Mat& img, const Point** pts, const int* npts, int ncontours, 
									bool isClosed, const Scalar& color, int thickness=1,
										int lineType=8, int shift=0 )
		*	C++: void polylines(InputOutputArray img, InputArrayOfArrays pts, bool isClosed, 
							const Scalar& color,int thickness=1, int lineType=8, int shift=0 )
		*	img – image
		*	pts – Array of polygonal curves 多边形曲线数组
		*	npts – Array of polygon vertex counters 顶点数组
		*	ncontours – Number of curves 曲线数量
		*	isClosed – Flag indicating whether the drawn polylines are closed or not
						If they are closed,the function draws a line from the last vertex 
						of each curve to its first vertex 标志曲线是否闭合
		*	color – Polyline color
		*	thickness – Thickness of the polyline edges
		*	lineType – Type of the line segments. See the line() description
		*	shift – Number of fractional bits in the vertex coordinates 
		-----------------------------------------------------------------------------*/
		polylines(image,ppt,npt,2,TRUE,randomColor(rng),rng.uniform(1,10),lineType);
		imshow(wndName,image);
		if(waitKey(DELAY) >= 0)
			return 0;
	}

	//draw polygons with filled area
	for(int i = 0;i < randomNumber;i++)
	{
		Point pt[2][3];
		pt[0][0].x = rng.uniform(x1, x2);
		pt[0][0].y = rng.uniform(y1, y2);
		pt[0][1].x = rng.uniform(x1, x2);
		pt[0][1].y = rng.uniform(y1, y2);
		pt[0][2].x = rng.uniform(x1, x2);
		pt[0][2].y = rng.uniform(y1, y2);
		pt[1][0].x = rng.uniform(x1, x2);
		pt[1][0].y = rng.uniform(y1, y2);
		pt[1][1].x = rng.uniform(x1, x2);
		pt[1][1].y = rng.uniform(y1, y2);
		pt[1][2].x = rng.uniform(x1, x2);
		pt[1][2].y = rng.uniform(y1, y2);
		const Point* ppt[2] = {pt[0], pt[1]};
		int npt[] = {3, 3};

		/*--------------fills the area bounded by one or more polygons---------------
		*	C++: void fillPoly( Mat& img, const Point** pts, const int* npts, int ncontours,
						const Scalar& color, int lineType=8, int shift=0, Point offset=Point() )
		*	img – image
		*	pts – Array of polygons where each polygon is represented as an array of points
		*	npts – Array of polygon vertex counters
		*	ncontours – Number of contours that bind the filled region
		*	color – Polygon color
		*	lineType – Type of the polygon boundaries. See the line() description
		*	shift – Number of fractional bits in the vertex coordinates
		*	offset – Optional offset of all points of the contours
		-----------------------------------------------------------------------------*/
		fillPoly(image, ppt, npt, 2, randomColor(rng), lineType);
		imshow(wndName, image);
		if(waitKey(DELAY) >= 0)
			return 0;
	}

	//draw circle
	for(int i = 0;i < randomNumber;i++)
	{
		Point center;
		center.x = rng.uniform(x1,x2);
		center.y = rng.uniform(y1,y2);

		/*-----------------------------draw a circle----------------------------------
		*	C++: void circle(Mat& img, Point center, int radius, const Scalar& color,
								int thickness=1, int lineType=8,int shift=0)
		*	img – Image where the circle is drawn
		*	center – Center of the circle
		*	radius – Radius of the circle
		*	color – Circle color
		*	thickness – Thickness of the circle outline, if positive.
						Negative thickness means that a
		*	filled circle is to be drawn
		*	lineType – Type of the circle boundary. See the line() description
		*	shift – Number of fractional bits in the coordinates of the center and 
			in the radius value
		-----------------------------------------------------------------------------*/
		circle(image,center,rng.uniform(0,300),randomColor(rng),rng.uniform(-1,9),lineType);
		imshow(wndName,image);
		if(waitKey(DELAY) >= 0)
			return 0;
	}

	//put text on the image
	for(int i = 0;i < randomNumber;i++)
	{
		Point org;
		org.x = rng.uniform(x1,x2);
		org.y = rng.uniform(y1,y2);
		putText(image,"Testing text rendering",org,rng.uniform(0,8)/*font type*/,
				rng.uniform(0,100)*0.05 + 0.1/*font scale*/,
					randomColor(rng),rng.uniform(1,10)/*thickness*/,lineType);
		imshow(wndName,image);
		if(waitKey(DELAY) >= 0)
			return 0;
	}
	
	/*------------------calculates the width and height of a text string--------------
	*	C++: Size getTextSize( const string& text, int fontFace, double fontScale,
								int thickness, int* baseLine)
	*	text – Input text string
	*	fontFace – Font to use. See the putText() for details
	*	fontScale – Font scale. See the putText() for details
	*	thickness – Thickness of lines used to render the text
	*	baseLine – Output parameter - y-coordinate of the baseline relative 
					to the bottom-most text	point.
	--------------------------------------------------------------------------------------*/
	//string text = " OpenCV Forever!" ;
	//int fontFace = FONT_HERSHEY_COMPLEX;
	//double fontScale = 2;
	//int thickness = 3;
	//int baseline=0;
	//baseline += thickness;
	//Size textSize = getTextSize(text, fontFace,
	//						fontScale, thickness, &baseline);

	Size textSize = getTextSize("OpenCV Forever!",FONT_HERSHEY_COMPLEX,3,5,0);
	Point org((width - textSize.width)/2,(height - textSize.height)/2);

	Mat image2;
	for(int i = 0;i < 255;i += 2)
	{
		image2 = image - Scalar::all(i);
		putText(image2,"OpenCV Forever!",org,FONT_HERSHEY_COMPLEX,
			3,Scalar(i,i,255),5,lineType);

		imshow(wndName,image2);
		if(waitKey(DELAY) >= 0)
			return 0;
	}

	waitKey();
	return 0;
}

结果

例2.

/**
* @file Drawing_1.cpp
* @brief Simple sample code
*/

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>

#define w 400

using namespace cv;

/// Function headers
void MyEllipse( Mat img, double angle );
void MyFilledCircle( Mat img, Point center );
void MyPolygon( Mat img );
void MyLine( Mat img, Point start, Point end );

/**
* @function main
* @brief Main function
*/
int main( void ){

	/// Windows names
	char atom_window[] = "Drawing 1: Atom";
	char rook_window[] = "Drawing 2: Rook";

	/// Create black empty images
	Mat atom_image = Mat::zeros( w, w, CV_8UC3 );
	Mat rook_image = Mat::zeros( w, w, CV_8UC3 );

	/// 1. Draw a simple atom:
	/// -----------------------

	/// 1.a. Creating ellipses
	MyEllipse( atom_image, 90 );
	MyEllipse( atom_image, 0 );
	MyEllipse( atom_image, 45 );
	MyEllipse( atom_image, -45 );

	/// 1.b. Creating circles
	MyFilledCircle( atom_image, Point( w/2, w/2) );

	/// 2. Draw a rook
	/// ------------------

	/// 2.a. Create a convex polygon
	MyPolygon( rook_image );

	/// 2.b. Creating rectangles
	rectangle( rook_image,
		Point( 0, 7*w/8 ),
		Point( w, w),
		Scalar( 0, 255, 255 ),
		-1,
		8 );

	RotatedRect rRect = RotatedRect(Point2f(100,100), Size2f(100,50), 30);
	ellipse(rook_image, rRect, Scalar(255,255,0));

	/// 2.c. Create a few lines
	MyLine( rook_image, Point( 0, 15*w/16 ), Point( w, 15*w/16 ) );
	MyLine( rook_image, Point( w/4, 7*w/8 ), Point( w/4, w ) );
	MyLine( rook_image, Point( w/2, 7*w/8 ), Point( w/2, w ) );
	MyLine( rook_image, Point( 3*w/4, 7*w/8 ), Point( 3*w/4, w ) );

	/// 3. Display your stuff!
	imshow( atom_window, atom_image );
	moveWindow( atom_window, 0, 200 );
	imshow( rook_window, rook_image );
	moveWindow( rook_window, w, 200 );

	waitKey( 0 );
	return(0);
}

/// Function Declaration

/**
* @function MyEllipse
* @brief Draw a fixed-size ellipse with different angles
*/
void MyEllipse( Mat img, double angle )
{
	int thickness = 2;
	int lineType = 8;

	ellipse( img,
		Point( w/2, w/2 ),
		Size( w/4, w/16 ),
		angle,
		0,
		360,
		Scalar( 255, 0, 0 ),
		thickness,
		lineType );
}

/**
* @function MyFilledCircle
* @brief Draw a fixed-size filled circle
*/
void MyFilledCircle( Mat img, Point center )
{
	int thickness = -1;
	int lineType = 8;

	circle( img,
		center,
		w/32,
		Scalar( 0, 0, 255 ),
		thickness,
		lineType );
}

/**
* @function MyPolygon
* @function Draw a simple concave polygon (rook)
*/
void MyPolygon( Mat img )
{
	int lineType = 8;

	/** Create some points */
	Point rook_points[1][20];
	rook_points[0][0]  = Point(    w/4,   7*w/8 );
	rook_points[0][1]  = Point(  3*w/4,   7*w/8 );
	rook_points[0][2]  = Point(  3*w/4,  13*w/16 );
	rook_points[0][3]  = Point( 11*w/16, 13*w/16 );
	rook_points[0][4]  = Point( 19*w/32,  3*w/8 );
	rook_points[0][5]  = Point(  3*w/4,   3*w/8 );
	rook_points[0][6]  = Point(  3*w/4,     w/8 );
	rook_points[0][7]  = Point( 26*w/40,    w/8 );
	rook_points[0][8]  = Point( 26*w/40,    w/4 );
	rook_points[0][9]  = Point( 22*w/40,    w/4 );
	rook_points[0][10] = Point( 22*w/40,    w/8 );
	rook_points[0][11] = Point( 18*w/40,    w/8 );
	rook_points[0][12] = Point( 18*w/40,    w/4 );
	rook_points[0][13] = Point( 14*w/40,    w/4 );
	rook_points[0][14] = Point( 14*w/40,    w/8 );
	rook_points[0][15] = Point(    w/4,     w/8 );
	rook_points[0][16] = Point(    w/4,   3*w/8 );
	rook_points[0][17] = Point( 13*w/32,  3*w/8 );
	rook_points[0][18] = Point(  5*w/16, 13*w/16 );
	rook_points[0][19] = Point(    w/4,  13*w/16 );

	const Point* ppt[1] = { rook_points[0] };
	int npt[] = { 20 };

	fillPoly( img,
		ppt,
		npt,
		1,
		Scalar( 255, 255, 255 ),
		lineType );
}

/**
* @function MyLine
* @brief Draw a simple line
*/
void MyLine( Mat img, Point start, Point end )
{
	int thickness = 2;
	int lineType = 8;
	line( img,
		start,
		end,
		Scalar( 0, 0, 0 ),
		thickness,
		lineType );
}

结果