第二天：OpenCV基本的繪圖函數

OpenCV常用繪圖函數:

line()函數------用於繪製直線

circle()函數------用於繪製圓
rectangle()函數------用於繪製矩形

ellipse()函數------用於繪製橢圓

fillPoly()/polylines()函數------用 於繪製多邊形

putText()函數------用於添加文字

1)、繪製直線-----line()

CV_EXPORTS_W void line(CV_IN_OUT Mat& img, Point pt1, Point pt2,const Scalar& color,int thickness=1,int line Type=8,int shift=0);

2)、繪製圓-----circle()

CV_EXPORTS_W void circle(CV_IN_OUT Mat& img, Point center, int radius,const Scalar& color,int thickness=1,int line Type=8,int shift=0);

3)、繪製矩形-----rectangle()

CV_EXPORTS_W void rectangle(CV_IN_OUT Mat& img, Point pt1, Point pt2,const Scalar& color,int thickness=1,int lne Type=8,int shift=0);
CV_EXPORTS_W void rectangle(CV_IN_OUT Mat& img, Rect rec,const Scalar& color,int thickness=1,int line Type=8,int shift=0);

4)、繪製橢圓-----ellipse()

CV_EXPORTS_W void ellipse(CV_IN_OUT Mat& img, Point center,Size axes,double angle,double startAngle,double endAngle,const Scalar& color,int thickness=1,int line Type=8,int shift=0);
CV_EXPORTS_W void ellipse(CV_IN_OUT Mat& img, const RotatedRect& box,const Scalar& color,int thickness=1,int line Type=8,int shift=0);

5)、繪製多邊形-----fillPoly() ||polylines()

CV_EXPORTS_W void fillPoly(CV_IN_OUT Mat& img, Point** pts,const int* npts,int ncontours,const Scalar& color,int line Type=8,int shift=0,Poinr offset=Point());//填充多邊形
CV_EXPORTS_W void polylines(CV_IN_OUT Mat& img, Point** pts,const int* npts,int ncontours,bool isClosed,const Scalar& color,int thickness=1,int line Type=8,int shift=0);//非填充多邊形

6)、添加文字-----putText()

CV_EXPORTS_W void putText(CV_IN_OUT Mat& img,const string& text,int fontFace,double fontScale,Scalar color,int thickness=1,int line Type=8,bool bottomLeftOrigin=false);

ex:
#include "opencv2/opencv.hpp"
#include <iostream>
using namespace std;
using namespace cv;

void main()
{
	
	Mat img(300, 300, CV_8UC3, Scalar(0, 0, 0));
	line(img, Point(10, 10), Point(200, 200), Scalar(0, 255, 255), 10, 8);  //畫線
	circle(img, Point(150, 150), 100, Scalar(255, 255, 0), -1, 8);  //畫圓
	rectangle(img, Point(10, 10), Point(240, 200), Scalar(0, 0, 255), 2, 8);  //畫矩形
	rectangle(img, Rect(10, 10, 230, 190), Scalar(0, 0, 255), -1, 8); //填充矩形

	ellipse(img, Point(150, 150), Size(100, 50), 45, 0, 360, Scalar(0, 255, 255), -1, 8);  //畫橢圓
	ellipse(img, RotatedRect(Point(150, 150), Size(100, 50), 0), Scalar(0,255,0), 2, 8);
	Point ppt[] = {Point(120, 50), Point(180, 50), Point(210, 100), Point(180, 150), Point(120, 150), Point(90, 100)};
	const Point* pts[] = {ppt};
	int npt[] ={6};
	fillPoly(img, pts, npt, 1, Scalar(0, 255, 255), 8); //畫填充多邊形
	polylines(img, pts, npt, 1, true, Scalar(0, 154, 209), 2, 8);  //畫非填充多邊形
	putText(img,  "China", Point(100, 100), CV_FONT_HERSHEY_COMPLEX, 2, Scalar(0, 255, 255), 2, 8);

	waitKey(0);
}

小結：這些畫圖函數常用作識別結果的標記。