Fix missing format when writing Algorithm-based objects

Added a writeFormat() method to Algorithm which must be called by the
write() method of derived classes.

modules/ml/src/ann_mlp.cpp

@@ -1151,6 +1151,7 @@ public:
             return;
         int i, l_count = layer_count();
 
+        writeFormat(fs);
         fs << "layer_sizes" << layer_sizes;
 
         write_params( fs );

modules/ml/src/boost.cpp

@@ -387,6 +387,7 @@ public:
         if( roots.empty() )
             CV_Error( CV_StsBadArg, "RTrees have not been trained" );
 
+        writeFormat(fs);
         writeParams(fs);
 
         int k, ntrees = (int)roots.size();

modules/ml/src/em.cpp

@@ -770,6 +770,7 @@ public:
 
     void write(FileStorage& fs) const
     {
+        writeFormat(fs);
         fs << "training_params" << "{";
         write_params(fs);
         fs << "}";

modules/ml/src/knearest.cpp

@@ -466,6 +466,7 @@ public:
 
     void write( FileStorage& fs ) const
     {
+        writeFormat(fs);
         impl->write(fs);
     }
 

modules/ml/src/lr.cpp

@@ -547,6 +547,7 @@ void LogisticRegressionImpl::write(FileStorage& fs) const
     {
         CV_Error(CV_StsBadArg,"file can't open. Check file path");
     }
+    writeFormat(fs);
     string desc = "Logisitic Regression Classifier";
     fs<<"classifier"<<desc.c_str();
     fs<<"alpha"<<this->params.alpha;

modules/ml/src/nbayes.cpp

@@ -342,6 +342,7 @@ public:
     {
         int nclasses = (int)cls_labels.total(), i;
 
+        writeFormat(fs);
         fs << "var_count" << (var_idx.empty() ? nallvars : (int)var_idx.total());
         fs << "var_all" << nallvars;
 

modules/ml/src/rtrees.cpp

@@ -296,6 +296,7 @@ public:
         if( roots.empty() )
             CV_Error( CV_StsBadArg, "RTrees have not been trained" );
 
+        writeFormat(fs);
         writeParams(fs);
 
         fs << "oob_error" << oobError;

modules/ml/src/svm.cpp

@@ -2037,6 +2037,7 @@ public:
         if( !isTrained() )
             CV_Error( CV_StsParseError, "SVM model data is invalid, check sv_count, var_* and class_count tags" );
 
+        writeFormat(fs);
         write_params( fs );
 
         fs << "var_count" << var_count;

modules/ml/src/svmsgd.cpp

@@ -364,6 +364,7 @@ void SVMSGDImpl::write(FileStorage& fs) const
     if( !isTrained() )
         CV_Error( CV_StsParseError, "SVMSGD model data is invalid, it hasn't been trained" );
 
+    writeFormat(fs);
     writeParams( fs );
 
     fs << "weights" << weights_;

modules/ml/src/tree.cpp

@@ -1681,6 +1681,7 @@ void DTreesImpl::writeTree( FileStorage& fs, int root ) const
 
 void DTreesImpl::write( FileStorage& fs ) const
 {
+    writeFormat(fs);
     writeParams(fs);
     writeTree(fs, roots[0]);
 }