OpenCV笔记（一）-XML文件读写

雨点打透心脏的1/2处 2022-03-20 08:46 417阅读 0赞

平台： ubuntu10.04 + OpenCV2.3 + cmake

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 = "test.xml";    
FileStorage fs(filename, FileStorage::WRITE);    
\\\\或者  
fs.open(filename, FileStorage::WRITE);    
  
// 文件读写模式  
// file storage mode  
 enum  
    \{  
        READ=0, //! read mode  
        WRITE=1, //! write mode  
        APPEND=2 //! append mode  
    \};  
  
  
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;    
  
  
//！FileNode的类型  
//! type of the file storage node  
    enum  
    \{  
        NONE=0, //!< empty node  
        INT=1, //!< an integer  
        REAL=2, //!< floating-point number  
        FLOAT=REAL, //!< synonym or REAL  
        STR=3, //!< text string in UTF-8 encoding  
        STRING=STR, //!< synonym for STR  
        REF=4, //!< integer of size size\_t. Typically used for storing complex dynamic structures where some elements reference the others   
        SEQ=5, //!< sequence  
        MAP=6, //!< mapping  
        TYPE\_MASK=7,  
        FLOW=8, //!< compact representation of a sequence or mapping. Used only by YAML writer  
        USER=16, //!< a registered object (e.g. a matrix)  
        EMPTY=32, //!< empty structure (sequence or mapping)  
        NAMED=64 //!< the node has a name (i.e. it is element of a mapping)  
    \};  
  
  
5. 文件读写源码  
\#\#\# xml2.cpp  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
// XML/YAML File Storage Class.  
//   
// The class describes an object associated with XML or YAML file.  
// It can be used to store data to such a file or read and decode the data.  
//   
// The storage is organized as a tree of nested sequences (or lists) and mappings.  
// Sequence is a heterogenious array, which elements are accessed by indices or sequentially using an iterator.  
// Mapping is analogue of std::map or C structure, which elements are accessed by names.  
// The most top level structure is a mapping.  
// Leaves of the file storage tree are integers, floating-point numbers and text strings.   
//   
// For example, the following code:  
\#include"opencv2/core/core.hpp"  
\#include<iostream>  
\#include<string>  
using namespace std;  
using namespace cv;  
   
int main(int agc, char\*\* agv)  
\{  
// open file storage for writing. Type of the file is determined from the extension  
\{  
FileStorage fs("test.xml", FileStorage::WRITE);  
fs << "test\_int" << 5 << "test\_real" << 3.1 << "test\_string" << "ABCDEFGH";  
fs << "test\_mat" << Mat::eye(3,3,CV\_32F);  
   
fs << "test\_list" << "\[" << 0.0000000000001 << 2 << CV\_PI << -3435345 << "2-502 2-029 3egegeg" <<  
"\{:" << "month" << 12 << "day" << 31 << "year" << 1969 << "\}" << "\]";  
fs << "test\_map" << "\{" << "x" << 1 << "y" << 2 << "width" << 100 << "height" << 200 << "lbp" << "\[:";  
  
  
const uchar arr\[\] = \{0, 1, 1, 0, 1, 1, 0, 1\};  
fs.writeRaw("u", arr, (int)(sizeof(arr)/sizeof(arr\[0\])));  
   
fs << "\]" << "\}";  
\}  
   
// open file storage for reading.  
// Type of the file is determined from the content, not the extension  
\{  
FileStorage fs("test.xml", FileStorage::READ);  
int test\_int = (int)fs\["test\_int"\];  
double test\_real = (double)fs\["test\_real"\];  
string test\_string = (string)fs\["test\_string"\];  
cout << "test\_int " << test\_int << " test\_real " << test\_real << " test\_string " << test\_string << endl;  
   
Mat M;  
fs\["test\_mat"\] >> M;  
cout << "test\_mat " << M << endl;  
   
FileNode tl = fs\["test\_list"\];  
CV\_Assert(tl.type() == FileNode::SEQ && tl.size() == 6);  
double tl0 = (double)tl\[0\];  
int tl1 = (int)tl\[1\];  
double tl2 = (double)tl\[2\];  
int tl3 = (int)tl\[3\];  
string tl4 = (string)tl\[4\];  
CV\_Assert(tl\[5\].type() == FileNode::MAP && tl\[5\].size() == 3);  
   
int month = (int)tl\[5\]\["month"\];  
int day = (int)tl\[5\]\["day"\];  
int year = (int)tl\[5\]\["year"\];  
   
cout << "test\_list" << endl;  
cout << "tl0 " << tl0 << " tl1 " << tl1 << " tl2 " << tl2 << " tl3 " << tl3 << " tl4 " << tl4 << endl;  
cout << "tl5 " << " month " << month << " day " << day << " year " << year << endl;  
   
FileNode tm = fs\["test\_map"\];  
   
int x = (int)tm\["x"\];  
int y = (int)tm\["y"\];  
int width = (int)tm\["width"\];  
int height = (int)tm\["height"\];  
   
cout << "test\_map " << " x " << x << " y " << y << " width " << width << " height " << height << endl;  
   
int lbp\_val = 0;  
FileNodeIterator it = tm\["lbp"\].begin();  
for(int k = 0; k < 8; k++, ++it)  
\{  
lbp\_val |= ((int)\*it) << k;  
\}  
cout << "blp " << lbp\_val << endl;  
  
  
   
\}  
return 0;  
\}  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
  
  
6、XML文件 test.xml  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
<?xml version="1.0"?>  
<opencv\_storage>  
<test\_int>5</test\_int>  
<test\_real>3.1000000000000001e+00</test\_real>  
<test\_string>ABCDEFGH</test\_string>  
<test\_mat type\_id="opencv-matrix">  
  <rows>3</rows>  
  <cols>3</cols>  
  <dt>f</dt>  
  <data>  
    1. 0. 0. 0. 1. 0. 0. 0. 1.</data></test\_mat>  
<test\_list>  
  1.0000000000000000e-13 2 3.1415926535897931e+00 -3435345  
  "2-502 2-029 3egegeg"  
  <\_><month>12</month>  
    <day>31</day>  
    <year>1969</year></\_></test\_list>  
<test\_map>  
  <x>1</x>  
  <y>2</y>  
  <width>100</width>  
  <height>200</height>  
  <lbp>  
    0 1 1 0 1 1 0 1</lbp></test\_map>  
</opencv\_storage>  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
7、YML文件 tet.yml 运行时需将Filename改为test.yml  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
%YAML:1.0  
test\_int: 5  
test\_real: 3.1000000000000001e+00  
test\_string: ABCDEFGH  
test\_mat: !!opencv-matrix  
   rows: 3  
   cols: 3  
   dt: f  
   data: \[ 1., 0., 0., 0., 1., 0., 0., 0., 1. \]  
test\_list:  
   - 1.0000000000000000e-13  
   - 2  
   - 3.1415926535897931e+00  
   - -3435345  
   - "2-502 2-029 3egegeg"  
   - \{ month:12, day:31, year:1969 \}  
test\_map:  
   x: 1  
   y: 2  
   width: 100  
   height: 200  
   lbp: \[ 0, 1, 1, 0, 1, 1, 0, 1 \]  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
  
  
8、CMakeList.txt文件   
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
PROJECT(xml)  
  
  
CMAKE\_MINIMUM\_REQUIRED(VERSION 2.6)  
if(COMMAND cmake\_policy)  
      cmake\_policy(SET CMP0003 NEW)  
endif(COMMAND cmake\_policy)  
  
  
FIND\_PACKAGE( OpenCV REQUIRED )  
  
  
\# Declare the target (an executable)  
ADD\_EXECUTABLE(xml  xml.cpp)  
  
  
TARGET\_LINK\_LIBRARIES(xml $\{OpenCV\_LIBS\})  
  
  
\#MESSAGE(STATUS "OpenCV\_LIBS: $\{OpenCV\_LIBS\}")  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
  
  
编译执行：  
cd currentPath  
cmake -Unix   
make   
./xml2