Fix link library

- Address review comment https://github.com/opentrack/opentrack/pull/1306#discussion_r680484878
- 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 https://github.com/microsoft/onnxruntime/issues/3124 for reference

1 files changed, 16 insertions, 7 deletions

diff --git a/cmake/FindONNXRuntime.cmake b/cmake/FindONNXRuntime.cmake
index 733bdb36..f485ecdd 100644
--- a/cmake/FindONNXRuntime.cmake
+++ b/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)