opencv 绘图 cvLine cvRectangle cvCircle cvEllipse cvEllipseBox cvFillPoly cvConvexPoly cvPolyLine[通俗易懂]

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常用宏定义：

#define CV_RGB( r, g, b )  cvScalar( (b), (g), (r), 0 )
#define CV_FILLED -1

#define CV_AA 16

#define cvDrawRect cvRectangle
#define cvDrawLine cvLine
#define cvDrawCircle cvCircle
#define cvDrawEllipse cvEllipse
#define cvDrawPolyLine cvPolyLine

########################################################3

直线 cvLine()

/* Draws 4-connected, 8-connected or antialiased line segment connecting two points */
CVAPI(void)  cvLine( CvArr* img, CvPoint pt1, CvPoint pt2,
                     CvScalar color, int thickness CV_DEFAULT(1),
                     int line_type CV_DEFAULT(8), int shift CV_DEFAULT(0) );

array：输入图像

pt1、pt2：直线的两点 CvPoint()结构

typedef struct CvPoint
{
    int x;
    int y;
}
CvPoint;

color：边的颜色 CvScalar结构

typedef struct CvScalar
{
    double val[4];
}
CvScalar;

这种结构是四个双精度浮点型变量的集合，前三个分别代表红、绿、蓝通道

常用的便捷宏指令CV_RGB(r, g, b)

###############################################################

矩形 cvRectagle()

/* Draws a rectangle given two opposite corners of the rectangle (pt1 & pt2),
   if thickness<0 (e.g. thickness == CV_FILLED), the filled box is drawn */
CVAPI(void)  cvRectangle( CvArr* img, CvPoint pt1, CvPoint pt2,
                          CvScalar color, int thickness CV_DEFAULT(1),
                          int line_type CV_DEFAULT(8),
                          int shift CV_DEFAULT(0));

pt1和pt2为对顶角

thickness参数可设置为CV_FILL，其值是-1，表示使用color填充内部在圆形和矩阵等很多封闭图形函数都可用

################################################################

圆形 cvCircle()

/* Draws a circle with specified center and radius.
   Thickness works in the same way as with cvRectangle */
CVAPI(void)  cvCircle( CvArr* img, CvPoint center, int radius,
                       CvScalar color, int thickness CV_DEFAULT(1),
                       int line_type CV_DEFAULT(8), int shift CV_DEFAULT(0));

center：圆中心 CvPoint()结构

radius：圆半径

##############################################################

椭圆 cvEllipse() cvEllipseBox

/* Draws ellipse outline, filled ellipse, elliptic arc or filled elliptic sector,
   depending on <thickness>, <start_angle> and <end_angle> parameters. The resultant figure
   is rotated by <angle>. All the angles are in degrees */
CVAPI(void)  cvEllipse( CvArr* img, CvPoint center, CvSize axes,
                        double angle, double start_angle, double end_angle,
                        CvScalar color, int thickness CV_DEFAULT(1),
                        int line_type CV_DEFAULT(8), int shift CV_DEFAULT(0));

axes：CvSize()结构，height和width参数分别表示椭圆的长短半轴长

typedef struct CvSize
{
    int width;
    int height;
}
CvSize;

angle：指偏离主轴的角度，从X轴算起，逆时针为正

start_angle和end_angle表示弧线可是和结束位置的角度。因此，一个完整的椭圆必须分别将这两个值分别设为0度和360度

CV_INLINE  void  cvEllipseBox( CvArr* img, CvBox2D box, CvScalar color,
                               int thickness CV_DEFAULT(1),
                               int line_type CV_DEFAULT(8), int shift CV_DEFAULT(0) )
{
    CvSize axes;
    axes.width = cvRound(box.size.width*0.5);
    axes.height = cvRound(box.size.height*0.5);

    cvEllipse( img, cvPointFrom32f( box.center ), axes, box.angle,
               0, 360, color, thickness, line_type, shift );
}

box：CvBox2D结构

typedef struct CvBox2D
{
    CvPoint2D32f center;  /* Center of the box.                          */
    CvSize2D32f  size;    /* Box width and length.                       */
    float angle;          /* Angle between the horizontal axis           */
                          /* and the first side (i.e. length) in degrees */
}
CvBox2D;

####################################################################

void paint(void)
{
	IplImage *src=cvLoadImage("lena.jpg");
	if (src == NULL)
	{
		exit(0);
	}

	cvLine(src, cvPoint(3, 3), cvPoint(3, 300), CV_RGB(255, 255, 255), 1, 8);
	cvRectangle(src, cvPoint(10, 10), cvPoint(100, 100), CV_RGB(255, 255, 255), 1);
	cvCircle(src, cvPoint(350, 350), 50, CV_RGB(255, 255, 255), 1);
	cvEllipse(src, cvPoint(200, 200), cvSize(100, 50), 90, 0, 360, CV_RGB(255, 255, 255), 1, 8);
	
	CvSize2D32f size=cvSize2D32f(100, 50);
	CvBox2D box;
	box.center.x = 100;
	box.center.y = 300;
	box.size = size;
	box.angle = 90;
	cvEllipseBox(src, box, CV_RGB(255, 255, 255), 1, 8, 0);

	cvNamedWindow("src");
	cvShowImage("src", src);
	cvWaitKey(0);
	cvReleaseImage(&src);
	cvDestroyWindow("src");
}

opencv 绘图 cvLine cvRectangle cvCircle cvEllipse cvEllipseBox cvFillPoly cvConvexPoly cvPolyLine[通俗易懂]

######################################################################################

/* Fills convex or monotonous polygon. */
CVAPI(void)  cvFillConvexPoly( CvArr* img, const CvPoint* pts, int npts, CvScalar color,
                               int line_type CV_DEFAULT(8), int shift CV_DEFAULT(0));

cvFillConvexPoly()一次只能画一个多边形，而且只能画凸多边形

pts：存储点的数组

npts：存储点的数目

void convexPoly(void)
{
	IplImage *Image1;

	CvPoint PointArray1[6];
	int PolyVertexNumber;
	int Shift;

	 CvSize ImageSize1 = cvSize(1000,700);
     Image1 = cvCreateImage(ImageSize1, IPL_DEPTH_8U, 3);

     PointArray1[0]=cvPoint(200,200);
     PointArray1[1]=cvPoint(400,100);
     PointArray1[2]=cvPoint(650,230);
     PointArray1[3]=cvPoint(800,300);
     PointArray1[4]=cvPoint(900,550);
     PointArray1[5]=cvPoint(100,400);

     CvScalar Color=CV_RGB(255,255,255);
     PolyVertexNumber=6;
     Shift=0;

     cvFillConvexPoly(Image1,PointArray1,PolyVertexNumber,Color,CV_AA,Shift);

     cvNamedWindow("FillConvexPoly",0);
     cvShowImage("FillConvexPoly",Image1);
     cvWaitKey(0);
     cvSaveImage("poly.jpg",Image1);
     cvReleaseImage(&Image1);
}

#######################################################

/* Fills an area bounded by one or more arbitrary polygons */
CVAPI(void)  cvFillPoly( CvArr* img, CvPoint** pts, const int* npts,
                         int contours, CvScalar color,
                         int line_type CV_DEFAULT(8), int shift CV_DEFAULT(0) );

/* Draws one or more polygonal curves */
CVAPI(void)  cvPolyLine( CvArr* img, CvPoint** pts, const int* npts, int contours,
                         int is_closed, CvScalar color, int thickness CV_DEFAULT(1),
                         int line_type CV_DEFAULT(8), int shift CV_DEFAULT(0) );

npts：由记数点构成的数组，与多边形对应

is_closed为true：则起点和终点连线；否则，不连线

void fillPoly(void)
{
	IplImage *src=cvLoadImage("lena.jpg");
	if (src == NULL)
		exit(0);

	CvPoint** pt=new CvPoint*[1];
	pt[0]=new CvPoint[6];

	pt[0][0]=cvPoint(100, 100);
	pt[0][1]=cvPoint(400, 50);
	pt[0][2]=cvPoint(500, 400);
	pt[0][3]=cvPoint(300, 500);
	pt[0][4]=cvPoint(200, 300);
	pt[0][5]=cvPoint(50, 400);

	int *npt=new int[1];
	npt[0]=6;

	int contours=1;

	cvFillPoly(src, pt, npt, contours, CV_RGB(255, 255, 255), 8);
	//cvPolyLine(src, pt, npt, contours, 1, CV_RGB(255, 255, 255));//is_closed为true则将起点和终点连线
	//cvPolyLine(src, pt, npt, contours, 0, CV_RGB(255, 255, 255));//is_closed为false则不将起点和终点连线

	cvNamedWindow("src");
	cvShowImage("src", src);
	cvWaitKey(0);
	cvReleaseImage(&src);
	cvDestroyWindow("src");
}