Fix link library

- Address review comment opentrack#1306 (comment)
- Update ONNXRuntime module to use a specific `onnxruntime` target.
- Use OpenCV components instead.

NOTE:

ONNXRuntinme may provide their own ONNXRuntimeConfig.cmake and
ONNXRuntimeVersion.cmake in the future.
See microsoft/onnxruntime#3124 for reference

cmake/FindONNXRuntime.cmake

@@ -13,10 +13,9 @@
 # Output variable
 # ---------------
 # 
-#   ONNXRuntime_FOUND           Variable indicating that ONNXRuntime has been
-#                               found.
-#   ONNXRuntime_LIBRARIES       Library implementing ONNXRuntime
-#   ONNXRuntime_INCLUDE_DIRS    Headers for ONNXRuntime
+#   ONNXRuntime_FOUND           True if headers and requested libraries were found
+#   ONNXRuntime_LIBRARIES       Component libraries to be linked.
+#   ONNXRuntime_INCLUDE_DIRS    Include directories.
 
 find_library(ORT_LIB onnxruntime
     CMAKE_FIND_ROOT_PATH_BOTH)
@@ -25,7 +24,17 @@ find_path(ORT_INCLUDE onnxruntime/core/session/onnxruntime_cxx_api.h
 
 if(ORT_LIB AND ORT_INCLUDE)
     set(ONNXRuntime_FOUND TRUE)
-    # For CMake output only
-    set(ONNXRuntime_LIBRARIES "${ORT_LIB}" CACHE STRING "ONNX Runtime libraries")
-    set(ONNXRuntime_INCLUDE_DIRS "${ORT_INCLUDE}" CACHE STRING "ONNX Runtime include path")
+    set(ONNXRuntime_INCLUDE_DIRS "${ORT_INCLUDE}")
+
+    if(NOT TARGET onnxruntime)
+        add_library(onnxruntime UNKNOWN IMPORTED)
+        set_target_properties(onnxruntime PROPERTIES
+            IMPORTED_LOCATION "${ORT_LIB}"
+            INTERFACE_INCLUDE_DIRECTORIES "${ORT_INCLUDE}"
+            INTERFACE_LINK_LIBRARIES "onnxruntime")
+        list(APPEND ONNXRuntime_LIBRARIES onnxruntime)
+    endif()
 endif()
+
+unset(ORT_LIB CACHE)
+unset(ORT_INCLUDE CACHE)

tracker-neuralnet/CMakeLists.txt

@@ -1,19 +1,25 @@
 include(opentrack-opencv)
-find_package(OpenCV QUIET)
+find_package(OpenCV QUIET COMPONENTS imgproc core imgcodecs calib3d)
 find_package(OpenMP QUIET) # Used to control number of onnx threads.
 find_package(ONNXRuntime QUIET)
 
 if(OpenCV_FOUND AND ONNXRuntime_FOUND AND OpenMP_FOUND)
     otr_module(tracker-neuralnet)
-    target_include_directories(${self} SYSTEM PUBLIC 
-        ${OpenCV_INCLUDE_DIRS} "${ONNXRuntime_INCLUDE_DIRS}")
-    target_link_libraries(${self} "${ONNXRuntime_LIBRARIES}"
-        opentrack-cv opencv_imgproc opencv_core
-        opencv_imgcodecs opencv_calib3d
-        OpenMP::OpenMP_C)
-
+    target_include_directories(${self} 
+        SYSTEM PRIVATE 
+        ${OpenCV_INCLUDE_DIRS} 
+        ${ONNXRuntime_INCLUDE_DIRS}
+        )
+    target_link_libraries(${self} 
+        opentrack-cv 
+        ${ONNXRuntime_LIBRARIES} 
+        ${OpenCV_LIBS} 
+        OpenMP::OpenMP_C
+        )
     install(
-        FILES "models/head-localizer.onnx" "models/head-pose.onnx"
+        FILES "models/head-localizer.onnx" 
+              "models/head-pose.onnx"
         DESTINATION "${opentrack-libexec}/models"
-        PERMISSIONS ${opentrack-perms-file})
+        PERMISSIONS ${opentrack-perms-file}
+        )
 endif()