OpenCV入门：(六：基础画图函数)

有时程序中需要画一些基础的图形，例如直线，矩形，椭圆以及多边形。OpenCV中当然有此类函数。

1.函数介绍

直线line：

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

img – 图像

pt1 – 直线起点

pt2 – 直线终点

color – 颜色

thickness – 粗细

lineType – 直线类型，可以是如下值

8 (or omitted) - 8-connected 线

4 - 4-connected 线.

CV_AA - 抗锯齿线.

shift – 分位的点坐标

椭圆ellipse：

void ellipse(Mat& img, Point center, Size axes, double angle, double startAngle, double endAngle, const Scalar& color, int thickness=1, int lineType=8, int shift=0)

void ellipse(Mat& img, const RotatedRect& box, const Scalar& color, int thickness=1, int lineType=8)

参数说明：

img – 图像

center – 椭圆中心

axes – 椭圆主半轴长度

angle –旋转角度

startAngle – 椭圆弧起始角度

endAngle – 椭圆弧终止角度

box – Alternative ellipse representation via RotatedRect or CvBox2D. This means that the function draws an ellipse inscribed in the rotated rectangle.

color – 颜色

thickness –  粗细，如果小于0，表示填充椭圆

lineType – 和line函数一样，直线类型

shift – 部分点位坐标

矩形rectangle：

void rectangle(Mat& img, Point pt1, Point pt2, const Scalar& color, int thickness=1, int lineType=8, int shift=0)

void rectangle(Mat& img, Rect rec, const Scalar& color, int thickness=1, int lineType=8, int shift=0 )

参数说明：

img – 图像

pt1 – 顶点坐标

pt2 – 与p1相对的顶点坐标

rec – 矩形的选择规范

color – 矩形的颜色或亮度

thickness – 和椭圆函数一样

lineType – 和line函数一样

shift – 部分点位坐标

圆circle：

void circle(Mat& img, Point center, int radius, const Scalar& color, int thickness=1, int lineType=8, int shift=0)

参数说明：

img – Image where the circle is drawn.

center – Center of the circle.

radius – Radius of the circle.

color – Circle color.

thickness – Thickness of the circle outline, if positive. Negative thickness means that a filled circle is to be drawn.

lineType – Type of the circle boundary. See the line() description.

shift – Number of fractional bits in the coordinates of the center and in the radius value.

多边形fillPoly：

void fillPoly(Mat& img, const Point** pts, const int* npts, int ncontours, const Scalar& color, int lineType=8, int shift=0, Point offset=Point() )

参数说明：

img – Image.

pts – Array of polygons where each polygon is represented as an array of points.

npts – Array of polygon vertex counters.

ncontours – Number of contours that bind the filled region.

color – Polygon color.

lineType – Type of the polygon boundaries. See the line() description.

shift – Number of fractional bits in the vertex coordinates.

offset – Optional offset of all points of the contours.

2.代码

#define w 400

/// 函数定义

void MyEllipse( Mat img, double angle );

void MyFilledCircle( Mat img, Point center );

void MyPolygon( Mat img );

void MyLine( Mat img, Point start, Point end );

int BasicDraw( void ){

  char atom_window[] = "Drawing 1: Atom";

  char rook_window[] = "Drawing 2: Rook";

  Mat atom_image = Mat::zeros( w, w, CV_8UC3 );

  Mat rook_image = Mat::zeros( w, w, CV_8UC3 );

  MyEllipse( atom_image, 90 );

  MyEllipse( atom_image, 0 );

  MyEllipse( atom_image, 45 );

  MyEllipse( atom_image, -45 );

  MyFilledCircle( atom_image, Point( w/2, w/2) );

  MyPolygon( rook_image );

  rectangle( rook_image,

         Point( 0, 7*w/8 ),

         Point( w, w),

         Scalar( 0, 255, 255 ),

         -1,

         8 );

  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 ) );

  imshow( atom_window, atom_image );

  moveWindow( atom_window, 0, 200 );

  imshow( rook_window, rook_image );

  moveWindow( rook_window, w, 200 );

  waitKey( 0 );

  return(0);

}

//画椭圆的函数

void MyEllipse( Mat img, double angle )

{

  int thickness = 2;

  int lineType = 8;

  ellipse( img,

       Point( w/2, w/2 ),

       Size( w/4, w/16 ),

       angle,

       0,

       360,

       Scalar( 255, 0, 0 ),

       thickness,

       lineType );

}

//画圆

void MyFilledCircle( Mat img, Point center )

{

  int thickness = -1;

  int lineType = 8;

  circle( img,

      center,

      w/32,

      Scalar( 0, 0, 255 ),

      thickness,

      lineType );

}

//画多边形

void MyPolygon( Mat img )

{

  int lineType = 8;

  /** Create some points */

  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 };

  fillPoly( img,

        ppt,

        npt,

          1,

        Scalar( 255, 255, 255 ),

        lineType );

}

//画直线的函数

void MyLine( Mat img, Point start, Point end )

{

  int thickness = 2;

  int lineType = 8;

  line( img,

    start,

    end,

    Scalar( 0, 0, 0 ),

    thickness,

    lineType );

}

3.结果

4.其他说明

Point结构：

定义一个”点“，x参数和y参数。

Scalar结构：

Scalar是有四个元素的容器，可以只使用其部分元素，例如上面使用Scalar(a,b,c)来表示颜色的RGB。

巴特西

OpenCV入门：(六：基础画图函数)

1.函数介绍

直线line：

椭圆ellipse：

矩形rectangle：

圆circle：

多边形fillPoly：

2.代码

3.结果

4.其他说明

Point结构：

Scalar结构：

5.结束

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