《学习OpenCV》第八章轮廓课后题8.3

用CvSeq的函数创建圆和矩形，这两个图像用点序列来表示。

有关序列的读写方法可以自行学习，这里只给出一个示例

#include <iostream>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

using namespace std;
using namespace cv;

#define CVX_RED   CV_RGB(0xff, 0x00, 0x00)
#define CVX_GREEN CV_RGB(0x00, 0xff, 0x00)
#define CVX_BLUE  CV_RGB(0x00, 0x00, 0xff)


void DrawBox(IplImage* img)
{
    /*1、初始化相关变量*/
    CvBox2D box ;
    CvPoint2D32f center;
    CvSize2D32f  size;
    center.x = 50;
    center.y = 50;
    size.width = 30;
    size.height = 30;
    box.center = center;
    box.size = size;
    CvPoint2D32f point[4];
    int i;
    for ( i=0; i<4; i++)
    {
        point[i].x = 0;
        point[i].y = 0;
    }
    
    /*2、计算CvBox2D结构表示矩形的4顶点*/
    cvBoxPoints(box, point); //计算二维盒子顶点，把box的点赋值给point
    
    /*3、把float类型的点转化成int类型*/
    CvPoint pt[4];
    for ( i=0; i<4; i++)
    {
        pt[i].x = (int)point[i].x;
        pt[i].y = (int)point[i].y;
    }
    
    /*4、开辟一个内存管理器并创建一个序列*/
    CvMemStorage* store = cvCreateMemStorage(0);
    CvSeq* seq = cvCreateSeq(CV_SEQ_ELTYPE_POINT | CV_SEQ_KIND_CURVE | CV_SEQ_FLAG_CLOSED,sizeof(CvContour),sizeof(CvPoint),store);
    
    /*5、数据的存储和提取*/
    for (int j = 0; j < 4; j++)
    {
        cvSeqPush(seq,&pt[j]);
    }
    for (int j = 0; j < seq->total; j++)
    {
        CvPoint* p=(CvPoint*)cvGetSeqElem(seq,j);
        printf("p->x=%d,p->y=%d\n",p->x,p->y);
    }
    
    /*6、绘制图形*/
    cvDrawContours(img,seq,CV_RGB(255,255,255),CV_RGB(255,255,255),1,3,8);
    cvShowImage("Box", img);
    cvReleaseMemStorage(&store);
}

void DrawCircle(IplImage* img)
{
    /*1、开辟一个内存管理器并创建一个序列*/
    CvMemStorage* store = cvCreateMemStorage(0);
    CvSeq* seq = cvCreateSeq(CV_SEQ_ELTYPE_POINT | CV_SEQ_KIND_CURVE |CV_SEQ_FLAG_CLOSED,sizeof(CvContour),sizeof(CvPoint),store);
    
    /*2、绘制圆*/
     CvPoint pt;
    for(int x=25; x<25+50; x++)
    {
        float y = 50 + sqrt(25*25.0-(x-50)*(x-50));
       
        pt.x = x;
        pt.y = y;
        cvSeqPush(seq,&pt);
    }
    for(int x=25+50; x>25; x--)
    {
        float y = 50 - sqrt(25*25.0-(x-50)*(x-50));
        pt.x = x;
        pt.y = y;
        cvSeqPush(seq,&pt);
    }
    
    for (int j = 0; j < seq->total; j++)
    {
        CvPoint* p=(CvPoint*)cvGetSeqElem(seq,j);
        printf("p->x=%d,p->y=%d\n",p->x,p->y);
    }
    cvDrawContours(img,seq,CV_RGB(255,255,255),CV_RGB(255,255,255),1,3,8);
    cvShowImage("Circle", img);
    cvReleaseMemStorage(&store);
}

int main()
{
    /*1、申请内存、创建一个图片、*/
    CvMemStorage* storage = cvCreateMemStorage();
    IplImage* img = cvCreateImage(cvSize(200,200),8,3);
    cvZero(img);
    cvShowImage("img", img);
    
    /*2、绘制矩形*/
    DrawBox(img);
    cvSetZero(img);
    
    /*3、绘制圆*/
    DrawCircle(img);
    cvWaitKey(100000);
    
    cvReleaseImage(&img);
    cvReleaseMemStorage(&storage);
    return 1;
}