18轮廓-绘制方形，原型

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

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#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;  
}  

结果如下：