build: CMake option to disable OpenCV with CImg

Author: Zacrain

CMakeLists.txt

@@ -56,6 +56,7 @@ option(MATPLOTPP_BUILD_WITH_EXCEPTIONS "Add compiler flags to use exceptions." O
 option(MATPLOTPP_BUILD_HIGH_RESOLUTION_WORLD_MAP "Compile the high resolution maps for geoplots" ON)
 option(MATPLOTPP_BUILD_FOR_DOCUMENTATION_IMAGES "Bypass show() commands and save figures as .svg at destruction" OFF)
 option(MATPLOTPP_BUILD_EXPERIMENTAL_OPENGL_BACKEND "Compile target with the experimental OpenGL backend" OFF)
+option(MATPLOTPP_WITH_OPENCV "Use OpenCV in CImg" ON)
 
 # Where to find dependencies
 option(MATPLOTPP_WITH_SYSTEM_CIMG "Use system-provided CImg.h instead of bundled" OFF)

source/3rd_party/CMakeLists.txt

@@ -117,7 +117,9 @@ endif()
 if (CMAKE_MODULE_PATH)
   find_package(OpenCV QUIET)
   if (OpenCV_FOUND)
-    target_compile_definitions(cimg INTERFACE cimg_use_opencv)
+    if (MATPLOTPP_WITH_OPENCV)
+      target_compile_definitions(cimg INTERFACE cimg_use_opencv)
+    endif()
     target_link_libraries(cimg INTERFACE ${OpenCV_LIBRARIES})
     target_include_directories(cimg INTERFACE ${OpenCV_INCLUDE_DIRS})
   endif()