OpenCV3学习笔记（8）：基本绘图

绝地灬酷狼 2022-12-05 00:47 200阅读 0赞

参考文档：[https://docs.opencv.org/3.4.11/d6/d6e/group\_\_imgproc\_\_draw.html][https_docs.opencv.org_3.4.11_d6_d6e_group_imgproc_draw.html]

参考教程：[https://www.w3cschool.cn/opencv/opencv-fpo82ccc.html][https_www.w3cschool.cn_opencv_opencv-fpo82ccc.html]

# 0.准备工作 #

Point 表示一个2D坐标点

Point pt;
    pt.x = 10;
    pt.y = 8;
    
    Point pt=Point(10,8);

Rect 表示一个矩形区域

Rect rect=Rect(0,0,100,100); //左上角xy+长宽

Size 表示大小

Size size=Size(100,100);

Scalar 可用来表示颜色，分别为BGRA分量

Scalar(1,2,3);  //blue=1,green=2,red=3

# 1.画圆 circle #

void cv::circle	(	
        InputOutputArray img, //图像
        Point center,         //原心位置
        int radius,           //半径大小
        const Scalar & color, //颜色
        int thickness = 1,    //画笔粗细，负值则为实心填充
        int lineType = LINE_8,//线类型枚举LineTypes，LINE_AA抗锯齿
        int shift = 0         //中心坐标和半径值中的小数位数
    )

测试代码：

circle(canvas, Point(100, 100), 50,Scalar(255,255,255) , -1);
    	circle(canvas, Point(100, 100), 60, Scalar(255, 255, 255), 2);

![20200908151210424.png][]

# 2.画直线 #

void cv::line(	
        InputOutputArray img,  //图像
        Point pt1,             //起点
        Point pt2,             //终点
        const Scalar & color,  //颜色
        int thickness = 1,     //线宽，粗细
        int lineType = LINE_8, //线类型枚举LineTypes，LINE_AA抗锯齿
        int shift = 0          //点坐标中的小数位数
    )

测试代码：

line(canvas, Point(100, 100), Point(500, 100), Scalar(255, 255, 0), 2);

![20200908152429849.png][]

# 3.画椭圆ellipse #

void cv::ellipse(	
        InputOutputArray img,    //图像
        const RotatedRect & box, //外接矩形
        const Scalar & color,    //颜色
        int thickness = 1,       //画笔粗细，负值则为实心填充
        int lineType = LINE_8    //线类型枚举LineTypes，LINE_AA抗锯齿
    )	
    
    
    void cv::ellipse(	
        InputOutputArray img, //图像
        Point center,         //圆心
        Size axes,            //主轴尺寸的一半
        double angle,         //旋转角度，单位为角度
        double startAngle,    //其实角
        double endAngle,      //终止角
        const Scalar & color, //颜色
        int thickness = 1,    //画笔粗细，负值则为实心填充
        int lineType = LINE_8,//线类型枚举LineTypes，LINE_AA抗锯齿
        int shift = 0         //中心坐标和轴值的小数位数
    )

测试代码：

ellipse(canvas, Point(100, 300), Size(100, 50),0,0,360,Scalar(0, 0, 255), -1);
    	ellipse(canvas, Point(100, 300), Size(80, 40), 0, 0, 120, Scalar(0, 255, 0), -1);
    	ellipse(canvas, Point(100, 300), Size(50, 100), 0, 0, 360, Scalar(255, 0, 0), 2);

![20200908153651950.png][]

# 4.画矩形rectangle #

void cv::rectangle(	
        InputOutputArray img, //图像
        Point pt1,            //矩形顶点1
        Point pt2,            //顶点1对角线上的顶点2
        const Scalar & color, //颜色
        int thickness = 1,    //画笔粗细，负值则为实心填充
        int lineType = LINE_8,//线类型枚举LineTypes，LINE_AA抗锯齿
        int shift = 0         //点坐标中的小数位数
    )	
    
    void cv::rectangle(	
        Mat & img,             //图像
        Rect rec,              //矩形（左上角顶点+size）
        const Scalar & color,  //颜色
        int thickness = 1,     //画笔粗细，负值则为实心填充
        int lineType = LINE_8, //线类型枚举LineTypes，LINE_AA抗锯齿
        int shift = 0          //点坐标中的小数位数
    )

测试代码：

rectangle(canvas, Point(50,475),Point(150,525),Scalar(0,0,255),-1);
    	//rectangle(canvas, Point(75, 450), Point(125, 550), Scalar(0, 255, 0), 2);
    	rectangle(canvas, Rect(75,450,50,100), Scalar(0, 255, 0), 2);

![20200908154523171.png][]

# 5.画多边形fillPoly #

void cv::fillPoly(	
        Mat & img,             //图像
        const Point ** pts,    //多边形顶点数组
        const int * npts,      //每个数组中顶点个数
        int ncontours,         //多少个顶点数组
        const Scalar & color,  //颜色
        int lineType = LINE_8, //线类型枚举LineTypes，LINE_AA抗锯齿
        int shift = 0,         //顶点坐标中的小数位数
        Point offset = Point() //轮廓所有点的可选偏移量
    )	
    
    void cv::fillPoly(	
        InputOutputArray img,   //图像
        InputArrayOfArrays pts, //多边形点数组
        const Scalar & color,   //颜色
        int lineType = LINE_8,  //线类型枚举LineTypes，LINE_AA抗锯齿
        int shift = 0,          //顶点坐标中的小数位数
        Point offset = Point()  //轮廓所有点的可选偏移量
    )

测试代码：

Point pts_1[3] = {Point(300,300),Point(300,350),Point(350,350)};
    	Point pts_2[4] = { Point(300,400),Point(300,450),Point(400,500),Point(500,420) };
    	const Point* pts_list[] = { pts_1,pts_2 };
    	const int pts_size[] = { 3,4 };
    	fillPoly(canvas, pts_list, pts_size, 2, Scalar(0, 255, 255));

![20200908154627174.png][]

# 6.绘制文字putText（英文） #

void cv::putText(	
        InputOutputArray img,  //图像
        const String & text,   //字符串
        Point org,             //文本左下角坐标
        int fontFace,          //字体类型枚举HersheyFonts
        double fontScale,      //字体比例因子乘以特定于字体的基本大小
        Scalar color,          //颜色
        int thickness = 1,     //粗细
        int lineType = LINE_8, //线类型枚举LineTypes，LINE_AA抗锯齿
        bool bottomLeftOrigin = false  //如果为true，则图像数据原点位于左下角。否则，它位于左上角
    )

测试代码：

putText(canvas, "OpenCV", Point(250, 80), FONT_HERSHEY_SIMPLEX, 1, Scalar(255, 255, 0), 2);

![20200908155752909.png][]

# 7.完整代码 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2dvbmdqaWFuYm8xOTky_size_16_color_FFFFFF_t_70][]

#include <opencv2/opencv.hpp>
    #include <iostream>
    
    using namespace cv;
    
    int main()
    {
    	//创建一个全0的黑色图作为画布
    	Mat canvas= Mat::ones(Size(600, 600), CV_8UC3);
    
    	//绘制圆形
    	circle(canvas, Point(100, 100), 50,Scalar(255,255,255) , -1);
    	circle(canvas, Point(100, 100), 60, Scalar(255, 255, 255), 2);
    
    	//绘制直线
    	line(canvas, Point(100, 100), Point(500, 100), Scalar(255, 255, 0), 2);
    
    	//画椭圆
    	ellipse(canvas, Point(100, 300), Size(100, 50),0,0,360,Scalar(0, 0, 255), -1);
    	ellipse(canvas, Point(100, 300), Size(80, 40), 0, 0, 120, Scalar(0, 255, 0), -1);
    	ellipse(canvas, Point(100, 300), Size(50, 100), 0, 0, 360, Scalar(255, 0, 0), 2);
    
    	//画矩形
    	rectangle(canvas, Point(50,475),Point(150,525),Scalar(0,0,255),-1);
    	//rectangle(canvas, Point(75, 450), Point(125, 550), Scalar(0, 255, 0), 2);
    	rectangle(canvas, Rect(75,450,50,100), Scalar(0, 255, 0), 2);
    
    	//画多边形
    	Point pts_1[3] = {Point(300,300),Point(300,350),Point(350,350)};
    	Point pts_2[4] = { Point(300,400),Point(300,450),Point(400,500),Point(500,420) };
    	const Point* pts_list[] = { pts_1,pts_2 };
    	const int pts_size[] = { 3,4 };
    	fillPoly(canvas, pts_list, pts_size, 2, Scalar(0, 255, 255));
    
    	//画文字（英文）
    	putText(canvas, "OpenCV", Point(250, 80), FONT_HERSHEY_SIMPLEX, 1, Scalar(255, 255, 0), 2);
    
    	imshow("canvas", canvas);
    	waitKey(0);
    	return 0;
    }

[https_docs.opencv.org_3.4.11_d6_d6e_group_imgproc_draw.html]: https://docs.opencv.org/3.4.11/d6/d6e/group__imgproc__draw.html
[https_www.w3cschool.cn_opencv_opencv-fpo82ccc.html]: https://www.w3cschool.cn/opencv/opencv-fpo82ccc.html
[20200908151210424.png]: /images/20221123/29ed579a8b5b4292b39e5ed1d0005ca8.png
[20200908152429849.png]: /images/20221123/7786a9b9e2a04502a7bd21ecc8ec0e26.png
[20200908153651950.png]: /images/20221123/88db1bce435f4c0e97f5df6a37df6a0a.png
[20200908154523171.png]: /images/20221123/99386bf41b8a4e969086b3ced01b9f2b.png
[20200908154627174.png]: /images/20221123/fe504d3cd40944db9d80dd796ed4bdfb.png
[20200908155752909.png]: /images/20221123/fe1d00a3358046169093123cdbbcad3c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2dvbmdqaWFuYm8xOTky_size_16_color_FFFFFF_t_70]: /images/20221123/0d0026f6665d4a8aa1bc796f9099aaf7.png