Merge remote-tracking branch 'upstream/3.4' into merge-3.4

modules/dnn/include/opencv2/dnn/dnn.hpp

@@ -67,12 +67,17 @@ CV__DNN_INLINE_NS_BEGIN
         //! DNN_BACKEND_DEFAULT equals to DNN_BACKEND_INFERENCE_ENGINE if
         //! OpenCV is built with Intel's Inference Engine library or
         //! DNN_BACKEND_OPENCV otherwise.
-        DNN_BACKEND_DEFAULT,
+        DNN_BACKEND_DEFAULT = 0,
         DNN_BACKEND_HALIDE,
-        DNN_BACKEND_INFERENCE_ENGINE,  //!< Intel's Inference Engine computational backend.
+        DNN_BACKEND_INFERENCE_ENGINE,            //!< Intel's Inference Engine computational backend
+                                                 //!< @sa setInferenceEngineBackendType
         DNN_BACKEND_OPENCV,
         DNN_BACKEND_VKCOM,
-        DNN_BACKEND_CUDA
+        DNN_BACKEND_CUDA,
+#ifdef __OPENCV_BUILD
+        DNN_BACKEND_INFERENCE_ENGINE_NGRAPH = 1000000,     // internal - use DNN_BACKEND_INFERENCE_ENGINE + setInferenceEngineBackendType()
+        DNN_BACKEND_INFERENCE_ENGINE_NN_BUILDER_2019,      // internal - use DNN_BACKEND_INFERENCE_ENGINE + setInferenceEngineBackendType()
+#endif
     };
 
     /**
@@ -276,6 +281,8 @@ CV__DNN_INLINE_NS_BEGIN
 
         virtual Ptr<BackendNode> initInfEngine(const std::vector<Ptr<BackendWrapper> > &inputs);
 
+        virtual Ptr<BackendNode> initNgraph(const std::vector<Ptr<BackendWrapper> > &inputs, const std::vector<Ptr<BackendNode> >& nodes);
+
         virtual Ptr<BackendNode> initVkCom(const std::vector<Ptr<BackendWrapper> > &inputs);
 
         /**

modules/dnn/include/opencv2/dnn/utils/inference_engine.hpp

@@ -14,6 +14,27 @@ namespace cv { namespace dnn {
 CV__DNN_INLINE_NS_BEGIN
 
 
+/* Values for 'OPENCV_DNN_BACKEND_INFERENCE_ENGINE_TYPE' parameter */
+#define CV_DNN_BACKEND_INFERENCE_ENGINE_NN_BUILDER_API     "NN_BUILDER"
+#define CV_DNN_BACKEND_INFERENCE_ENGINE_NGRAPH             "NGRAPH"
+
+/** @brief Returns Inference Engine internal backend API.
+ *
+ * See values of `CV_DNN_BACKEND_INFERENCE_ENGINE_*` macros.
+ *
+ * Default value is controlled through `OPENCV_DNN_BACKEND_INFERENCE_ENGINE_TYPE` runtime parameter (environment variable).
+ */
+CV_EXPORTS_W cv::String getInferenceEngineBackendType();
+
+/** @brief Specify Inference Engine internal backend API.
+ *
+ * See values of `CV_DNN_BACKEND_INFERENCE_ENGINE_*` macros.
+ *
+ * @returns previous value of internal backend API
+ */
+CV_EXPORTS_W cv::String setInferenceEngineBackendType(const cv::String& newBackendType);
+
+
 /** @brief Release a Myriad device (binded by OpenCV).
  *
  * Single Myriad device cannot be shared across multiple processes which uses

modules/dnn/include/opencv2/dnn/version.hpp

@@ -6,7 +6,7 @@
 #define OPENCV_DNN_VERSION_HPP
 
 /// Use with major OpenCV version only.
-#define OPENCV_DNN_API_VERSION 20191111
+#define OPENCV_DNN_API_VERSION 20191202
 
 #if !defined CV_DOXYGEN && !defined CV_STATIC_ANALYSIS && !defined CV_DNN_DONT_ADD_INLINE_NS
 #define CV__DNN_INLINE_NS __CV_CAT(dnn4_v, OPENCV_DNN_API_VERSION)