Fix segFault when no lines found in BinaryDescriptor

modules/line_descriptor/src/binary_descriptor.cpp

@@ -2196,6 +2196,11 @@ int BinaryDescriptor::EDLineDetector::EdgeDrawing( cv::Mat &image, EdgeChains &e
         "numofedgePixel1 = " << offsetPFirst << ",  numofedgePixel2 = " << offsetPSecond << ", MaxNumOfEdgePixel=" << edgePixelArraySize << std::endl;
     return -1;
   }
+  if( !(offsetPFirst && offsetPSecond) )
+  {
+      std::cout << "Edge drawing Error: lines not found" << std::endl;
+      return -1;
+  }
 
   /*now all the edge information are stored in pFirstPartEdgeX_, pFirstPartEdgeY_,
    *pFirstPartEdgeS_,  pSecondPartEdgeX_, pSecondPartEdgeY_, pSecondPartEdgeS_;

modules/line_descriptor/test/test_descriptors_regression.cpp

@@ -372,3 +372,18 @@ TEST( BinaryDescriptor_Descriptors, regression )
   CV_BD_DescriptorsTest<Hamming> test( std::string( "lbd_descriptors_cameraman" ), 1 );
   test.safe_run();
 }
+
+/****************************************************************************************\
+*                                Other tests                                             *
+ \****************************************************************************************/
+
+TEST( BinaryDescriptor, no_lines_found )
+{
+  Mat Image = Mat::zeros(100, 100, CV_8U);
+  Ptr<line_descriptor::BinaryDescriptor> binDescriptor =
+    line_descriptor::BinaryDescriptor::createBinaryDescriptor();
+
+  std::vector<cv::line_descriptor::KeyLine> keyLines;
+  binDescriptor->detect(Image, keyLines);
+  ASSERT_EQ(keyLines.size(), 0u);
+}