opencv提供了一些自带的函数供我们绘制几何图形，涵盖了一些常见的几何图形。有规则的圆形、矩形、直线椭圆等。不规则的多边形也可以绘制，只不过相比规则的稍麻烦，需要传入一系列的坐标点进行绘制。话不多说，上代码先
/**
* @file Drawing_1.cpp
* @brief Simple geometric drawing
* @author OpenCV team
*///所需头文件#include <opencv2/core.hpp>#include <opencv2/imgproc.hpp>#include <opencv2/highgui.hpp>#define w 400 //图像长宽using namespace cv;/// 函数声明void MyEllipse( Mat img, double angle );//椭圆，所需参数为图像和和角度void MyFilledCircle( Mat img, Point center );//圆面，所需参数图像和圆心坐标void MyPolygon( Mat img );//多边形，所需参数为图像void MyLine( Mat img, Point start, Point end );//直线，所需参数为图像和直线的起止坐标//主函数int main( void ){ //窗口名
char atom_window[] = "Drawing 1: Atom"; char rook_window[] = "Drawing 2: Rook"; /// Create black empty images
/// 创建两张空白的图像
Mat atom_image = Mat::zeros( w, w, CV_8UC3 );
Mat rook_image = Mat::zeros( w, w, CV_8UC3 ); //![create_images]
/// 1. Draw a simple atom:
/// 画一个简单的原子
/// -----------------------
//![draw_atom]
/// 1.a. Creating ellipses
///绘制不同角度的椭圆
MyEllipse( atom_image, 90 );
MyEllipse( atom_image, 0 );
MyEllipse( atom_image, 45 );
MyEllipse( atom_image, -45 ); /// 1.b. Creating circles
///绘制一个圆面
MyFilledCircle( atom_image, Point( w/2, w/2) ); //![draw_atom]
/// 2. Draw a rook
/// ------------------
//![draw_rook]
/// 2.a. Create a convex polygon
///绘制多边形
MyPolygon( rook_image ); //![rectangle]
/// 2.b. Creating rectangles
///绘制矩形
rectangle( rook_image,
Point( 0, 7*w/8 ),
Point( w, w),
Scalar( 0, 255, 255 ),
FILLED,
LINE_8 ); //![rectangle]
/// 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 ) ); //![draw_rook]
/// 3. Display your stuff!
///显示绘制的结果
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
*///![my_ellipse]void MyEllipse( Mat img, double angle ){ int thickness = 2;//线条的粗细程度
int lineType = 8;//线条的类型
//调用ellipse函数绘制椭圆
ellipse( img,
Point( w/2, w/2 ),
Size( w/4, w/16 ),
angle, 0, 360,
Scalar( 255, 0, 0 ),
thickness,
lineType );
}//![my_ellipse]/**
* @function MyFilledCircle
* @brief Draw a fixed-size filled circle
*///![my_filled_circle]void MyFilledCircle( Mat img, Point center ){ //绘制圆面
circle( img,
center,
w/32,
Scalar( 0, 0, 255 ),
FILLED,
LINE_8 );
}//![my_filled_circle]/**
* @function MyPolygon
* @brief Draw a simple concave polygon (rook)
*///![my_polygon]//绘制多边形void MyPolygon( Mat img ){ int lineType = LINE_8; /** Create some points */
//创建一系列的二维坐标
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 }; //调用fillPoly函数绘制多边形
fillPoly( img,
ppt,
npt, 1,
Scalar( 255, 255, 255 ),
lineType );
}//![my_polygon]/**
* @function MyLine
* @brief Draw a simple line
*///![my_line]void MyLine( Mat img, Point start, Point end ){ int thickness = 2; int lineType = LINE_8; //绘制直线
line( img,
start,
end,
Scalar( 0, 0, 0 ),
thickness,
lineType );
}//![my_line]下面来分别看看几个绘制函数
ellipse椭圆
先看看ellipse原型
void cv::ellipse ( InputOutputArray img, //图像 Point center, //圆心坐标 Size axes, //短轴长 double angle, //倾斜角 double startAngle, //起始角，长轴到起始边沿的夹角 double endAngle, //结束角，长轴到结束点的夹角 const Scalar & color, //颜色 int thickness = 1, //粗细 int lineType = LINE_8, //类型 int shift = 0 ) void cv::ellipse ( InputOutputArray img, //图像 const RotatedRect & box, //倾斜矩形 const Scalar & color, //颜色 int thickness = 1, //粗细 int lineType = LINE_8 //类型 )
函数原型有两个，看程序的调用可以知道本例程匹配个是第一个函数原型。
椭圆的绘制函数稍有点复杂，可以参考下面图示进行理解
image.png
circle圆
void cv::circle ( InputOutputArray img, //图像 Point center, //圆心坐标 int radius, //半径 const Scalar & color, //颜色 int thickness = 1, //粗细 int lineType = LINE_8, //类型 int shift = 0 )
绘制圆型的函数比较简单，圆心坐标和半径可以确定一个圆
fillPoly多边形
void cv::fillPoly ( Mat & img, //图像 const Point ** pts, //Point **类型的坐标点，与历程中相对应 const int * npts, //点的数量 int ncontours, //轮廓数 const Scalar & color, //颜色 int lineType = LINE_8, //类型 int shift = 0, Point offset = Point() ) void cv::fillPoly ( InputOutputArray img, InputArrayOfArrays pts, //点坐标集合 const Scalar & color, int lineType = LINE_8, int shift = 0, Point offset = Point() //偏移 )
line直线
void cv::line ( InputOutputArray img, //图像 Point pt1, //坐标点1 Point pt2, //坐标点2 const Scalar & color, //颜色 int thickness = 1, //粗细 int lineType = LINE_8, //类型 int shift = 0 )
rectangle矩形
void cv::rectangle ( InputOutputArray img, //图像//对角两个点可以确定一个矩形 Point pt1, Point pt2, const Scalar & color, //颜色 int thickness = 1, //粗细 int lineType = LINE_8, //线条类型 int shift = 0 ) void cv::rectangle ( Mat & img, //图像//一个Rect的矩形变量 Rect rec, const Scalar & color, //绘制的颜色 int thickness = 1, //粗细 int lineType = LINE_8, //线条类型 int shift = 0 )
可以通过上面几个函数原型得出，几何绘制图形函数的参数都是分为两部分，一部分是构成几何图形的数学参数，如直线需要两个坐标点，圆形需要圆心和半径等，这是独有的。另一部分是对绘制线条的一个限定包括如下几个参数，颜色、粗细、类型、坐标点中的小数点位数。这是共有的。
颜色
typedef Scalar_<double> cv::Scalar //原型//使用举例Scalar( 255, 255, 255 )//白色Scalar( 255, 0, 0)//蓝色Scalar( 0, 255, )//绿色Scalar( 0, 0, 255 )//红色
粗细
thickness，厚度。表示线条的粗细，单位应该是像素点
类型
lineType
image.png
作者：芒果浩明
链接：https://www.jianshu.com/p/95ea88f7c945
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