(14)Air Band OpenCV2.4.13_基础作图

本文是对OpenCV2.4.13文档的部分翻译，作个人学习之用，并不完整。

首先介绍两个结构：

Point

一个二维点，可以如下定义：

Point pt;

pt.x=10;

pt.y=8;

或：

Point pt=Point(10,8);

Scalar

一个四元素向量，常用于传递像素值，这里我们用于表示BGR颜色值（3参数），最后一个元素用不到可以不定义。

Scalar(a,b,c);//定义了Blue=a,Green=b,Red=c

#include <opencv2/core/core.hpp>#include <opencv2/highgui/highgui.hpp>#define w 400using namespace cv;/// 作图函数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 main( void ){  /// 窗口名称  char atom_window[] = "Drawing 1: Atom";  char rook_window[] = "Drawing 2: Rook";  /// 创建空图像  Mat atom_image = Mat::zeros( w, w, CV_8UC3 );  Mat rook_image = Mat::zeros( w, w, CV_8UC3 );  /// 1. 画一个简单的圆  /// -----------------------  /// 1.a. 创建椭圆  MyEllipse( atom_image, 90 );//第二个参数为角度  MyEllipse( atom_image, 0 );  MyEllipse( atom_image, 45 );  MyEllipse( atom_image, -45 );  /// 1.b. 创建圆  MyFilledCircle( atom_image, Point( w/2, w/2) );//第二个参数为圆心  /// 2. 画一个车（国际象棋）  /// ------------------  /// 2.a. 创建一个凸多边形  MyPolygon( rook_image );  /// 2.b. 创建矩形  rectangle( rook_image,         Point( 0, 7*w/8 ),         Point( w, w),         Scalar( 0, 255, 255 ),         -1,         8 );  /// 2.c. 创建线  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 ) );  /// 3. 显示图像  imshow( atom_window, atom_image );  moveWindow( atom_window, 0, 200 );  imshow( rook_window, rook_image );  moveWindow( rook_window, w, 200 );  waitKey( 0 );  return(0);}/// 函数定义/** * @function MyEllipse * @brief Draw a fixed-size ellipse with different angles */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 );}/** * @function MyFilledCircle * @brief Draw a fixed-size filled circle */void MyFilledCircle( Mat img, Point center ){  int thickness = -1;  int lineType = 8;  circle( img,      center,      w/32,      Scalar( 0, 0, 255 ),      thickness,      lineType );}/** * @function MyPolygon * @function Draw a simple concave polygon (rook) */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 );}/** * @function MyLine * @brief Draw a simple line */void MyLine( Mat img, Point start, Point end ){  int thickness = 2;  int lineType = 8;  line( img,    start,    end,    Scalar( 0, 0, 0 ),    thickness,    lineType );}

结果：