OpenCV------- 对XML和YAML文件实现I/O操作

OpenCV——对XML和YAML文件实现I/O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：

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stringfilename="I.xml";
FileStoragefs(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

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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：

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fs<<"iterationNr"<<100;

读取文件，使用 >> 运算符，例如

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intitNr;
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

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MatR=Mat_<uchar>::eye(3,3),
T=Mat_<double>::zeros(3,1);
fs<<"R"<<R;//Writecv::Mat
fs<<"T"<<T;
fs["R"]>>R;//Readcv::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：

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fs<<"strings"<<"[";//text-stringsequence
fs<<"image1.jpg"<<"Awesomeness"<<"baboon.jpg";
fs<<"]";//closesequence

对于map结构的操作使用的符号是"{"和"}"，例如：

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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：

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FileNoden=fs["strings"];//Readstringsequence-Getnode
if(n.type()!=FileNode::SEQ)
{
cerr<<"stringsisnotasequence!FAIL"<<endl;
return1;
}
FileNodeIteratorit=n.begin(),it_end=n.end();//Gothroughthenode
for(;it!=it_end;++it)
cout<<(string)*it<<endl;

5. 读写自己的数据结构

这部分比较复杂，参考最后的实例中的MyData结构自己领悟吧

最后，我这里上一个实例，供大家参考。

源文件里填入如下代码：

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#include<opencv2/core/core.hpp>
#include<iostream>
#include<string>
usingnamespacecv;
usingnamespacestd;
voidhelp(char**av)
{
cout<<endl
<<av[0]<<"showstheusageoftheOpenCVserializationfunctionality."<<endl
<<"usage:"<<endl
<<av[0]<<"outputfile.yml.gz"<<endl
<<"TheoutputfilemaybeeitherXML(xml)orYAML(yml/yaml).Youcanevencompressitby"
<<"specifyingthisinitsextensionlikexml.gzyaml.gzetc..."<<endl
<<"WithFileStorageyoucanserializeobjectsinOpenCVbyusingthe<<and>>operators"<<endl
<<"Forexample:-createaclassandhaveitserialized"<<endl
<<"-useittoreadandwritematrices."<<endl;
}
classMyData
{
public:
MyData():A(0),X(0),id()
{}
explicitMyData(int):A(97),X(CV_PI),id("mydata1234")//explicittoavoidimplicitconversion
{}
voidwrite(FileStorage&fs)const//Writeserializationforthisclass
{
fs<<"{"<<"A"<<A<<"X"<<X<<"id"<<id<<"}";
}
voidread(constFileNode&node)//Readserializationforthisclass
{
A=(int)node["A"];
X=(double)node["X"];
id=(string)node["id"];
}
public://DataMembers
intA;
doubleX;
stringid;
};
//ThesewriteandreadfunctionsmustbedefinedfortheserializationinFileStoragetowork
voidwrite(FileStorage&fs,conststd::string&,constMyData&x)
{
x.write(fs);
}
voidread(constFileNode&node,MyData&x,constMyData&default_value=MyData()){
if(node.empty())
x=default_value;
else
x.read(node);
}
//Thisfunctionwillprintourcustomclasstotheconsole
ostream&operator<<(ostream&out,constMyData&m)
{
out<<"{id="<<m.id<<",";
out<<"X="<<m.X<<",";
out<<"A="<<m.A<<"}";
returnout;
intmain(intac,char**av)
{
if(ac!=2)
{
help(av);
return1;
stringfilename=av[1];
{//write
MyDatam(1);
FileStoragefs(filename,FileStorage::WRITE);
fs<<"iterationNr"<<100;
fs<<"strings"<<"[";//text-stringsequence
fs<<"image1.jpg"<<"Awesomeness"<<"baboon.jpg";
fs<<"]";//closesequence
fs<<"Mapping";//text-mapping
fs<<"{"<<"One"<<1;
fs<<"Two"<<2<<"}";
fs<<"R"<<R;//cv::Mat
fs<<"T"<<T;
fs<<"MyData"<<m;//yourowndatastructures
fs.release();//explicitclose
cout<<"WriteDone."<<endl;
{//read
cout<<endl<<"Reading:"<<endl;
FileStoragefs;
fs.open(filename,FileStorage::READ);
intitNr;
//fs["iterationNr"]>>itNr;
itNr=(int)fs["iterationNr"];
cout<<itNr;
if(!fs.isOpened())
{
cerr<<"Failedtoopen"<<filename<<endl;
FileNoden=fs["strings"];//Readstringsequence-Getnode
if(n.type()!=FileNode::SEQ)
return1;
}
FileNodeIteratorit=n.begin(),it_end=n.end();//Gothroughthenode
for(;it!=it_end;++it)
cout<<(string)*it<<endl;
n=fs["Mapping"];//Readmappingsfromasequence
cout<<"Two"<<(int)(n["Two"])<<";";
cout<<"One"<<(int)(n["One"])<<endl<<endl;
MyDatam;
MatR,T;
fs["R"]>>R;//Readcv::Mat
fs["T"]>>T;
fs["MyData"]>>m;//Readyourownstructure_
cout<<endl
<<"R="<<R<<endl;
cout<<"T="<<T<<endl<<endl;
cout<<"MyData="<<endl<<m<<endl<<endl;
//Showdefaultbehaviorfornonexistingnodes
cout<<"AttempttoreadNonExisting(shouldinitializethedatastructurewithitsdefault).";
fs["NonExisting"]>>m;
cout<<endl<<"NonExisting="<<endl<<m<<endl;
}
cout<<endl
<<"Tip:Openup"<<filename<<"withatexteditortoseetheserializeddata."<<endl;
return0;
}

编译后，在命令行进入到文件目录，执行test test.xml，运行结果如下，生成一个test . xml文件，内容如下：

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<?xmlversion="1.0"?>
-<opencv_storage>
<iterationNr>100</iterationNr>
<strings>image1.jpgAwesomenessbaboon.jpg</strings>
-<Mapping>
<One>1</One>
<Two>2</Two>
</Mapping>
-<Rtype_id="opencv-matrix">
<rows>3</rows>
<cols>3</cols>
<dt>u</dt>
<data>100010001</data>
</R>
-<Ttype_id="opencv-matrix">
<rows>3</rows>
<cols>1</cols>
<dt>d</dt>
<data>0.0.0.</data>
</T>
-<MyData>
<A>97</A>
<X>3.1415926535897931e+000</X>
<id>mydata1234</id>
</MyData>
</opencv_storage>

原文链接：https://www.f2er.com/xml/296267.html

OpenCV------- 对XML和YAML文件实现I/O操作

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