Opencv学习——对XML和YAML文件读写操作

1. XML、YAML文件的打开和关闭

XML\YAML文件在OpenCV中的数据结构为FileStorage，打开操作例如：

string filename = "I.xml";
FileStorage fs(filename, FileStorage::WRITE);
\\...
fs.open(filename, FileStorage::READ);

文件关闭操作会在FileStorage结构销毁时自动进行，但也可调用如下函数实现

fs.release();

2.文本和数字的输入和输出

写入文件使用 << 运算符，例如：

fs << "iterationNr" << 100;

读取文件，使用 >> 运算符，例如

int itNr;
fs["iterationNr"] >> itNr;
itNr = (int) fs["iterationNr"];

3. OpenCV数据结构的输入和输出，和基本的C++形式相同

    Mat R = Mat_<uchar >::eye (3, 3),
    T = Mat_<double>::zeros(3, 1);
    fs << "R" << R; // Write cv::Mat
    fs << "T" << T;
    fs["R"] >> R; // Read cv::Mat
    fs["T"] >> T;

4. vector（arrays） 和 maps的输入和输出
vector要注意在第一个元素前加上“[”，在最后一个元素前加上"]"。例如：

 fs << "strings" << "["; // text - string sequence
 fs << "image1.jpg" << "Awesomeness" << "baboon.jpg";
 fs << "]"; // close sequence

对于map结构的操作使用的符号是"{“和”}"，例如：

fs << "Mapping"; // text - mapping
fs << "{" << "One" << 1;
fs << "Two" << 2 << "}";

读取这些结构的时候，会用到FileNode和FileNodeIterator数据结构。对FileStorage类的[]操作符会返回FileNode数据类型，对于一连串的node，可以使用FileNodeIterator结构，例如：

FileNode n = fs["strings"]; // Read string sequence - Get node
if (n.type() != FileNode::SEQ)
{
cerr << "strings is not a sequence! FAIL" << endl;
return 1;
}
FileNodeIterator it = n.begin(), it_end = n.end(); // Go through the node
for (; it != it_end; ++it)
cout << (string)*it << endl;

XML和YAML文件的写入

#include <opencv2/opencv.hpp>
#include <time.h>
using namespace cv;
int main()
{
       //初始化
       FileStorage fs("test.yaml", FileStorage::WRITE);
       //开始文件写入
       fs << "frameCount" << 5;
       time_t rawtime;
       time(&rawtime);
       fs << "calibrationDate" << asctime(localtime(&rawtime));
       Mat cameraMatrix = (Mat_<double>(3, 3) << 1000, 0, 320, 0, 1000, 240, 0, 0, 1);
       Mat disCoeffs = (Mat_<double>(5, 1) << 0.1, 0.01, -0.001, 0, 0);
       fs << "cameraMatrix" << cameraMatrix << "disCoeffs" << disCoeffs;
       fs << "features" << "[";
       for (int i = 0; i < 3; i++)
       {
              int x = rand() % 640;
              int y = rand() % 480;
              uchar lbp = rand() % 256;
              fs << "{:" << "x" << x << "y" << y << "lbp" << "[:";
              for (int j = 0; j < 8; j++)
              {
                     fs << ((lbp >> j) & 1);
              }
              fs << "]" << "}";
       }
       fs << "]";
       fs.release();
       printf("文件读写完毕，请在工程目录下查看生成的文件~");
       getchar();
       return 0;
}

%YAML:1.0
---
frameCount: 5
calibrationDate: "Wed Aug  1 11:13:44 2018\n"
cameraMatrix: !!opencv-matrix
   rows: 3
   cols: 3
   dt: d
   data: [ 1000., 0., 320., 0., 1000., 240., 0., 0., 1. ]
disCoeffs: !!opencv-matrix
   rows: 5
   cols: 1
   dt: d
   data: [ 1.0000000000000001e-01, 1.0000000000000000e-02,
       -1.0000000000000000e-03, 0., 0. ]
features:
   - { x:41, y:227, lbp:[ 0, 1, 1, 1, 1, 1, 0, 1 ] }
   - { x:260, y:449, lbp:[ 0, 0, 1, 1, 0, 1, 1, 0 ] }
   - { x:598, y:78, lbp:[ 0, 1, 0, 0, 1, 0, 1, 0 ] }

XML和YAML文件读取

#include <opencv2/opencv.hpp>
#include <time.h>
using namespace std;
using namespace cv;
int main()
{
       // 改变console字体颜色
       system("color 6F");
       //初始化
       FileStorage fs2("test.yaml", FileStorage::READ);
       // 第一种方法 对FileNote操作
       int frameCount = (int)fs2["frameCount"];
       std::string date;
       //第二种方法:使用 FileNote运算符
       fs2["calibrationDate"] >> date;
       Mat cameraMatrix2, disCoeffs2;
       fs2["cameraMatrix"] >> cameraMatrix2;
       fs2["disCoeffs"] >> disCoeffs2;
       cout << "framCount: " << frameCount << endl
              << "calibration date: " << date << endl
              << "camera matrix: " << cameraMatrix2 << endl
              << "distortion coeffs: " << disCoeffs2 << endl;
       FileNode features = fs2["features"];
       FileNodeIterator it = features.begin(), it_end = features.end();
       int idx = 0;
       std::vector<uchar> lbpval;
       //使用FileNoteIterator 遍历序列
       for (; it != it_end; ++it, ++idx)
       {
              cout << "feature #" << idx << ": ";
              cout << "x=" << (int)(*it)["x"] << ", y =" << (int)(*it)["y"] << ", lbp: (";
              (*it)["lbp"] >> lbpval;
              for (int i = 0; i < (int)lbpval.size(); i++)
              {
                     cout << " " << (int)lbpval[i];
              }
              cout << ")" << endl;
       }
       fs2.release();
       printf("\n文件读取完毕，请输入任意键结束程序~");
       getchar();
       return 0;
}