1 /*
2 * filestorage_sample demonstrate the usage of the opencv serialization functionality
3 */
4
5 #include "opencv2/core/core.hpp"
6 #include <iostream>
7 #include <string>
8
9 using std::string;
10 using std::cout;
11 using std::endl;
12 using std::cerr;
13 using std::ostream;
14 using namespace cv;
15
help(char ** av)16 static void help(char** av)
17 {
18 cout << "\nfilestorage_sample demonstrate the usage of the opencv serialization functionality.\n"
19 << "usage:\n"
20 << av[0] << " outputfile.yml.gz\n"
21 << "\n outputfile above can have many different extenstions, see below."
22 << "\nThis program demonstrates the use of FileStorage for serialization, that is use << and >> in OpenCV\n"
23 << "For example, how to create a class and have it serialize, but also how to use it to read and write matrices.\n"
24 << "FileStorage allows you to serialize to various formats specified by the file end type."
25 << "\nYou should try using different file extensions.(e.g. yaml yml xml xml.gz yaml.gz etc...)\n" << endl;
26 }
27
28 struct MyData
29 {
MyDataMyData30 MyData() :
31 A(0), X(0), id()
32 {
33 }
MyDataMyData34 explicit MyData(int) :
35 A(97), X(CV_PI), id("mydata1234")
36 {
37 }
38 int A;
39 double X;
40 string id;
writeMyData41 void write(FileStorage& fs) const //Write serialization for this class
42 {
43 fs << "{" << "A" << A << "X" << X << "id" << id << "}";
44 }
readMyData45 void read(const FileNode& node) //Read serialization for this class
46 {
47
48 A = (int)node["A"];
49 X = (double)node["X"];
50 id = (string)node["id"];
51 }
52 };
53
54 //These write and read functions must exist as per the inline functions in operations.hpp
write(FileStorage & fs,const std::string &,const MyData & x)55 static void write(FileStorage& fs, const std::string&, const MyData& x){
56 x.write(fs);
57 }
read(const FileNode & node,MyData & x,const MyData & default_value=MyData ())58 static void read(const FileNode& node, MyData& x, const MyData& default_value = MyData()){
59 if(node.empty())
60 x = default_value;
61 else
62 x.read(node);
63 }
64
operator <<(ostream & out,const MyData & m)65 static ostream& operator<<(ostream& out, const MyData& m){
66 out << "{ id = " << m.id << ", ";
67 out << "X = " << m.X << ", ";
68 out << "A = " << m.A << "}";
69 return out;
70 }
main(int ac,char ** av)71 int main(int ac, char** av)
72 {
73 if (ac != 2)
74 {
75 help(av);
76 return 1;
77 }
78
79 string filename = av[1];
80
81 //write
82 {
83 FileStorage fs(filename, FileStorage::WRITE);
84
85 cout << "writing images\n";
86 fs << "images" << "[";
87
88 fs << "image1.jpg" << "myfi.png" << "../data/baboon.jpg";
89 cout << "image1.jpg" << " myfi.png" << " ../data/baboon.jpg" << endl;
90
91 fs << "]";
92
93 cout << "writing mats\n";
94 Mat R =Mat_<double>::eye(3, 3),T = Mat_<double>::zeros(3, 1);
95 cout << "R = " << R << "\n";
96 cout << "T = " << T << "\n";
97 fs << "R" << R;
98 fs << "T" << T;
99
100 cout << "writing MyData struct\n";
101 MyData m(1);
102 fs << "mdata" << m;
103 cout << m << endl;
104 }
105
106 //read
107 {
108 FileStorage fs(filename, FileStorage::READ);
109
110 if (!fs.isOpened())
111 {
112 cerr << "failed to open " << filename << endl;
113 help(av);
114 return 1;
115 }
116
117 FileNode n = fs["images"];
118 if (n.type() != FileNode::SEQ)
119 {
120 cerr << "images is not a sequence! FAIL" << endl;
121 return 1;
122 }
123
124 cout << "reading images\n";
125 FileNodeIterator it = n.begin(), it_end = n.end();
126 for (; it != it_end; ++it)
127 {
128 cout << (string)*it << "\n";
129 }
130
131 Mat R, T;
132 cout << "reading R and T" << endl;
133
134 fs["R"] >> R;
135 fs["T"] >> T;
136
137 cout << "R = " << R << "\n";
138 cout << "T = " << T << endl;
139
140 MyData m;
141 fs["mdata"] >> m;
142
143 cout << "read mdata\n";
144 cout << m << endl;
145
146 cout << "attempting to read mdata_b\n"; //Show default behavior for empty matrix
147 fs["mdata_b"] >> m;
148 cout << "read mdata_b\n";
149 cout << m << endl;
150
151 }
152
153 cout << "Try opening " << filename << " to see the serialized data." << endl << endl;
154
155 //read from string
156 {
157 cout << "Read data from string\n";
158 string dataString =
159 "%YAML:1.0\n"
160 "mdata:\n"
161 " A: 97\n"
162 " X: 3.1415926535897931e+00\n"
163 " id: mydata1234\n";
164 MyData m;
165 FileStorage fs(dataString, FileStorage::READ | FileStorage::MEMORY);
166 cout << "attempting to read mdata_b from string\n"; //Show default behavior for empty matrix
167 fs["mdata"] >> m;
168 cout << "read mdata\n";
169 cout << m << endl;
170 }
171
172 //write to string
173 {
174 cout << "Write data to string\n";
175 FileStorage fs(filename, FileStorage::WRITE | FileStorage::MEMORY | FileStorage::FORMAT_YAML);
176
177 cout << "writing MyData struct\n";
178 MyData m(1);
179 fs << "mdata" << m;
180 cout << m << endl;
181 string createdString = fs.releaseAndGetString();
182 cout << "Created string:\n" << createdString << "\n";
183 }
184
185 return 0;
186 }
187
