libprotobuf is optional dependency now

modules/dnn/CMakeLists.txt

@@ -1,34 +1,38 @@
 cmake_minimum_required(VERSION 2.8)
 
-macro(_dnn_do_protobuf_actions)
-option(WITH_PROTOBUF "Build with libprotobuf" ON)
+macro(_dnn_find_protobuf)
 
-if(NOT WITH_PROTOBUF)
-  message(FATAL_ERROR "libprotobuf is required for dnn module")
-endif()
-
-find_package( Protobuf REQUIRED )
+find_package( Protobuf )
 
-if(EXISTS ${PROTOBUF_PROTOC_EXECUTABLE})
+if(${PROTOBUF_FOUND} AND EXISTS ${PROTOBUF_PROTOC_EXECUTABLE})
   message(STATUS "Found PROTOBUF Compiler: ${PROTOBUF_PROTOC_EXECUTABLE}")
+  file(GLOB PROTO_FILES src/*.proto)
+  PROTOBUF_GENERATE_CPP(PROTO_HDRS PROTO_SRCS ${PROTO_FILES})
+  set(HAVE_PROTOBUF ON)
 else()
-  message(FATAL_ERROR "Could not find PROTOBUF Compiler")
+  message(WARNING "PROTOBUF not found. Caffe import function will be disabled.")
+  set(HAVE_PROTOBUF OFF)
 endif()
 
-file(GLOB PROTO_FILES src/*.proto)
-PROTOBUF_GENERATE_CPP(PROTO_HDRS PROTO_SRCS ${PROTO_FILES})
-endmacro(_dnn_do_protobuf_actions)
+endmacro(_dnn_find_protobuf)
 
-if(BUILD_opencv_core)#it's build for OpenCV module
-_dnn_do_protobuf_actions()
-set(the_description "Deep neural network module. Allow load models and make forward pass")
+if(BUILD_opencv_core)#build as OpenCV module
+_dnn_find_protobuf()
+set(the_description "Deep neural network module. It allows to load models and to make forward pass")
 set(OPENCV_MODULE_IS_PART_OF_WORLD OFF)
 
 ocv_add_module(dnn opencv_imgproc opencv_core opencv_highgui WRAP python matlab)
 ocv_warnings_disable(CMAKE_CXX_FLAGS -Wno-shadow -Wno-parentheses)
+if(HAVE_PROTOBUF)
+add_definitions(-DHAVE_PROTOBUF 1)
 ocv_glob_module_sources(${PROTO_SRCS} ${PROTO_HDRS})
 ocv_source_group("Src\\protobuf" FILES ${PROTO_SRCS} ${PROTO_HDRS})
-ocv_module_include_directories(${PROTOBUF_INCLUDE_DIR} include src/caffe)
+else()
+file(GLOB NON_CAFFE_SOURCES "src/*.cpp" "src/layers/*.cpp")
+file(GLOB NON_CAFFE_HEADERS "src/*.hpp" "src/layers/*.hpp")
+ocv_set_module_sources(HEADERS ${NON_CAFFE_HEADERS} SOURCES ${NON_CAFFE_SOURCES})
+endif()
+ocv_module_include_directories(include src/caffe ${PROTOBUF_INCLUDE_DIR})
 
 ocv_create_module(${PROTOBUF_LIBRARIES})
 
@@ -36,10 +40,10 @@ ocv_add_accuracy_tests()
 ocv_add_perf_tests()
 ocv_add_samples()
 
-else()#it's standalone module (development purposes)
+else()#build as standalone module (for development purposes)
 project(dnn_standalone)
 
-_dnn_do_protobuf_actions()
+_dnn_find_protobuf()
 find_package( OpenCV 3.0 REQUIRED )
 
 file(GLOB_RECURSE MODULE_SOURCES "src/*.cpp")

modules/dnn/src/caffe_importer.cpp

@@ -1,4 +1,8 @@
-#include "opencv2/dnn.hpp"
+#include "precomp.hpp"
+using namespace cv;
+using namespace cv::dnn;
+
+#if HAVE_PROTOBUF
 #include "caffe.pb.h"
 
 #include <iostream>
@@ -9,9 +13,6 @@
 #include <google/protobuf/io/zero_copy_stream_impl.h>
 #include "caffe/util/upgrade_proto.hpp"
 
-using namespace cv;
-using namespace cv::dnn;
-
 using ::google::protobuf::RepeatedField;
 using ::google::protobuf::RepeatedPtrField;
 using ::google::protobuf::Message;
@@ -242,4 +243,14 @@ namespace
 Ptr<Importer> cv::dnn::createCaffeImporter(const String &prototxt, const String &caffeModel)
 {
     return Ptr<Importer>(new CaffeImporter(prototxt.c_str(), caffeModel.c_str()));
-}
+}
+
+#else //HAVE_PROTOBUF
+
+Ptr<Importer> cv::dnn::createCaffeImporter(const String &prototxt, const String &caffeModel)
+{
+    CV_Error(cv::Error::StsNotImplemented, "libprotobuf required to import data from Caffe models");
+    return Ptr<Importer>();
+}
+
+#endif //HAVE_PROTOBUF