Merge pull request #13337 from sergiud:eigen-cross-compile

* added support for Eigen cross-compilation

* cmake: fix Eigen detection

CMakeLists.txt

@@ -253,8 +253,8 @@ OCV_OPTION(WITH_CUBLAS "Include NVidia Cuda Basic Linear Algebra Subprograms (BL
 OCV_OPTION(WITH_NVCUVID "Include NVidia Video Decoding library support" WITH_CUDA
   VISIBLE_IF WITH_CUDA
   VERIFY HAVE_NVCUVID)
-OCV_OPTION(WITH_EIGEN "Include Eigen2/Eigen3 support" (NOT CV_DISABLE_OPTIMIZATION)
-  VISIBLE_IF NOT WINRT AND NOT CMAKE_CROSSCOMPILING
+OCV_OPTION(WITH_EIGEN "Include Eigen2/Eigen3 support" (NOT CV_DISABLE_OPTIMIZATION AND NOT CMAKE_CROSSCOMPILING)
+  VISIBLE_IF NOT WINRT
   VERIFY HAVE_EIGEN)
 OCV_OPTION(WITH_VFW "Include Video for Windows support (deprecated, consider using MSMF)" OFF
   VISIBLE_IF WIN32

cmake/OpenCVFindLibsPerf.cmake

@@ -40,19 +40,67 @@ To eliminate this warning remove WITH_CUDA=ON CMake configuration option.
 endif(WITH_CUDA)
 
 # --- Eigen ---
-if(WITH_EIGEN)
-  find_path(EIGEN_INCLUDE_PATH "Eigen/Core"
-            PATHS /usr/local /opt /usr $ENV{EIGEN_ROOT}/include ENV ProgramFiles ENV ProgramW6432
-            PATH_SUFFIXES include/eigen3 include/eigen2 Eigen/include/eigen3 Eigen/include/eigen2
-            DOC "The path to Eigen3/Eigen2 headers"
-            CMAKE_FIND_ROOT_PATH_BOTH)
+if(WITH_EIGEN AND NOT HAVE_EIGEN)
+  find_package(Eigen3 QUIET)
 
-  if(EIGEN_INCLUDE_PATH)
-    ocv_include_directories(${EIGEN_INCLUDE_PATH})
-    ocv_parse_header("${EIGEN_INCLUDE_PATH}/Eigen/src/Core/util/Macros.h" EIGEN_VERSION_LINES EIGEN_WORLD_VERSION EIGEN_MAJOR_VERSION EIGEN_MINOR_VERSION)
-    set(HAVE_EIGEN 1)
+  if(Eigen3_FOUND)
+    if(TARGET Eigen3::Eigen)
+      # Use Eigen3 imported target if possible
+      list(APPEND OPENCV_LINKER_LIBS Eigen3::Eigen)
+      set(HAVE_EIGEN 1)
+    else()
+      if(DEFINED EIGEN3_INCLUDE_DIRS)
+        set(EIGEN_INCLUDE_PATH ${EIGEN3_INCLUDE_DIRS})
+        set(HAVE_EIGEN 1)
+      elseif(DEFINED EIGEN3_INCLUDE_DIR)
+        set(EIGEN_INCLUDE_PATH ${EIGEN3_INCLUDE_DIR})
+        set(HAVE_EIGEN 1)
+      endif()
+    endif()
+    if(HAVE_EIGEN)
+      if(DEFINED EIGEN3_WORLD_VERSION)  # CMake module
+        set(EIGEN_WORLD_VERSION ${EIGEN3_WORLD_VERSION})
+        set(EIGEN_MAJOR_VERSION ${EIGEN3_MAJOR_VERSION})
+        set(EIGEN_MINOR_VERSION ${EIGEN3_MINOR_VERSION})
+      else()  # Eigen config file
+        set(EIGEN_WORLD_VERSION ${EIGEN3_VERSION_MAJOR})
+        set(EIGEN_MAJOR_VERSION ${EIGEN3_VERSION_MINOR})
+        set(EIGEN_MINOR_VERSION ${EIGEN3_VERSION_PATCH})
+      endif()
+    endif()
+  endif()
+
+  if(NOT HAVE_EIGEN)
+    if(NOT EIGEN_INCLUDE_PATH OR NOT EXISTS "${EIGEN_INCLUDE_PATH}")
+      set(__find_paths "")
+      set(__find_path_extra_options "")
+      if(NOT CMAKE_CROSSCOMPILING)
+        list(APPEND __find_paths /opt)
+      endif()
+      if(DEFINED ENV{EIGEN_ROOT})
+        set(__find_paths "$ENV{EIGEN_ROOT}/include")
+        list(APPEND __find_path_extra_options NO_DEFAULT_PATH)
+      else()
+        set(__find_paths ENV ProgramFiles ENV ProgramW6432)
+      endif()
+      find_path(EIGEN_INCLUDE_PATH "Eigen/Core"
+                PATHS ${__find_paths}
+                PATH_SUFFIXES include/eigen3 include/eigen2 Eigen/include/eigen3 Eigen/include/eigen2
+                DOC "The path to Eigen3/Eigen2 headers"
+                ${__find_path_extra_options}
+      )
+    endif()
+    if(EIGEN_INCLUDE_PATH AND EXISTS "${EIGEN_INCLUDE_PATH}")
+      ocv_parse_header("${EIGEN_INCLUDE_PATH}/Eigen/src/Core/util/Macros.h" EIGEN_VERSION_LINES EIGEN_WORLD_VERSION EIGEN_MAJOR_VERSION EIGEN_MINOR_VERSION)
+      set(HAVE_EIGEN 1)
+    endif()
   endif()
-endif(WITH_EIGEN)
+endif()
+if(HAVE_EIGEN)
+  if(EIGEN_INCLUDE_PATH AND EXISTS "${EIGEN_INCLUDE_PATH}")
+    ocv_include_directories(SYSTEM ${EIGEN_INCLUDE_PATH})
+  endif()
+endif()
 
 # --- Clp ---
 # Ubuntu: sudo apt-get install coinor-libclp-dev coinor-libcoinutils-dev