@TOC

1.直线

1.1 API

CV_EXPORTS_W void line(InputOutputArray img, Point pt1, Point pt2, const Scalar& color,int thickness = 1, int lineType = LINE_8, int shift = 0);

• 参数如下

1.2 连通类型

enum LineTypes {
    FILLED  = -1,
    LINE_4  = 4, //!< 4-connected line
    LINE_8  = 8, //!< 8-connected line
    LINE_AA = 16 //!< antialiased line
};

• LINE_4与LINE_8差别不大，而LINE_AA的抗锯齿效果显著

2.正矩形

2.1API

CV_EXPORTS_W void rectangle(InputOutputArray img, Point pt1, Point pt2,
                          const Scalar& color, int thickness = 1,
                          int lineType = LINE_8, int shift = 0);

• 参数如下

CV_EXPORTS_W void rectangle(InputOutputArray img, Rect rec,
                          const Scalar& color, int thickness = 1,
                          int lineType = LINE_8, int shift = 0);

• 参数如下

3.圆形

3.1 API

CV_EXPORTS_W void circle(InputOutputArray img, Point center, int radius,
                       const Scalar& color, int thickness = 1,
                       int lineType = LINE_8, int shift = 0);

• 参数如下

4.椭圆

4.1 API

CV_EXPORTS_W void ellipse(InputOutputArray img, Point center, Size axes,
                        double angle, double startAngle, double endAngle,
                        const Scalar& color, int thickness = 1,
                        int lineType = LINE_8, int shift = 0);

• 参数如下

4.2 效果

Mat canvas(Size(1000,1000),CV_8U,Scalar(255));
ellipse(canvas,Point2f(500,500),Size(50,100),0,0,90,Scalar(0,0,0),5);
imshow("canvas",canvas);
waitKey();

Mat canvas(Size(1000,1000),CV_8U,Scalar(255));
ellipse(canvas,Point2f(500,500),Size(50,100),20,0,360,Scalar(0,0,0),5);
imshow("canvas",canvas);
waitKey();

Mat canvas(Size(1000,1000),CV_8U,Scalar(255));
ellipse(canvas,Point2f(500,500),Size(50,100),20,0,180,Scalar(0,0,0),5);
imshow("canvas",canvas);
waitKey();

5 斜矩形

5.1 API(通过RotatedRect类和line函数实现)

class CV_EXPORTS RotatedRect
{
public:
    //! default constructor
    RotatedRect();
   
    /*center：质心坐标
      size：（x方向上全边长，y方向上全边长）
      angle：顺时针偏角
    */
    RotatedRect(const Point2f& center, const Size2f& size, float angle);

    /**
    三点确定一矩形，记得要互相垂直
     */
    RotatedRect(const Point2f& point1, const Point2f& point2, const Point2f& point3);

    /** 返回四个角点坐标，要用Point2f类型的数组对象作为参数传入，不能是仅仅是Point类型的数组对象*/
    void points(Point2f pts[]) const;

    //! returns the minimal up-right integer rectangle containing the rotated rectangle
    Rect boundingRect() const;

    //! returns the minimal (exact) floating point rectangle containing the rotated rectangle, not intended for use with images
    Rect_<float> boundingRect2f() const;

    //! returns the rectangle mass center
    Point2f center;

    //! returns width and height of the rectangle
    Size2f size;

    //! returns the rotation angle. When the angle is 0, 90, 180, 270 etc., the rectangle becomes an up-right rectangle.
    float angle;
};

下面是自定义的一个快捷画斜矩形的函数

void drawRotatedRect(InputOutputArray img, RotatedRect rRect,const Scalar& color, int thickness = 1,int lineType = LINE_8, int shift = 0){
    Point2f vertices[4];
    rRect.points(vertices);
    for(int i=0;i<4;i++){
        line(img,vertices[i],vertices[(i+1)%4],color,lineType,shift);
    }
}

6.多边形

6.1 API

绘制方式一

CV_EXPORTS_W void polylines(InputOutputArray img, InputArrayOfArrays pts,
                            bool isClosed, const Scalar& color,
                            int thickness = 1, int lineType = LINE_8, int shift = 0 );

• 参数如下

绘制方式二

CV_EXPORTS void polylines(InputOutputArray img, const Point* const* pts, const int* npts,
                          int ncontours, bool isClosed, const Scalar& color,
                          int thickness = 1, int lineType = LINE_8, int shift = 0 );

• 参数如下

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