[build] Allow building wpilibc in cmake without cscore and opencv (#3605)

The hard dependency on cscore was removed a while ago in gradle, so make it not a hard requirement in cmake.

CMakeLists.txt

@@ -270,19 +270,20 @@ if (WITH_CSCORE)
     set(CAMERASERVER_DEP_REPLACE ${CAMERASERVER_DEP_REPLACE_IMPL})
     add_subdirectory(cscore)
     add_subdirectory(cameraserver)
-    if (WITH_WPILIB)
-        set(WPILIBC_DEP_REPLACE ${WPILIBC_DEP_REPLACE_IMPL})
-        add_subdirectory(wpilibj)
-        add_subdirectory(wpilibc)
-        add_subdirectory(wpilibNewCommands)
-        if (WITH_OLD_COMMANDS)
-            add_subdirectory(wpilibOldCommands)
-        endif()
-        if (WITH_EXAMPLES)
-            add_subdirectory(wpilibcExamples)
-        endif()
-        add_subdirectory(myRobot)
+endif()
+
+if (WITH_WPILIB)
+    set(WPILIBC_DEP_REPLACE ${WPILIBC_DEP_REPLACE_IMPL})
+    add_subdirectory(wpilibj)
+    add_subdirectory(wpilibc)
+    add_subdirectory(wpilibNewCommands)
+    if (WITH_OLD_COMMANDS)
+        add_subdirectory(wpilibOldCommands)
     endif()
+    if (WITH_EXAMPLES)
+        add_subdirectory(wpilibcExamples)
+    endif()
+    add_subdirectory(myRobot)
 endif()
 
 if (WITH_SIMULATION_MODULES AND NOT WITH_EXTERNAL_HAL)

wpilibc/CMakeLists.txt

@@ -3,8 +3,6 @@ project(wpilibc)
 include(CompileWarnings)
 include(AddTest)
 
-find_package( OpenCV REQUIRED )
-
 configure_file(src/generate/WPILibVersion.cpp.in WPILibVersion.cpp)
 
 file(GLOB_RECURSE
@@ -17,7 +15,18 @@ target_include_directories(wpilibc PUBLIC
                 $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src/main/native/include>
                             $<INSTALL_INTERFACE:${include_dest}/wpilibc>)
 wpilib_target_warnings(wpilibc)
-target_link_libraries(wpilibc PUBLIC cameraserver hal ntcore cscore wpimath wpiutil ${OpenCV_LIBS})
+
+if (WITH_CSCORE)
+    find_package( OpenCV )
+    target_link_libraries(wpilibc PUBLIC cameraserver cscore ${OpenCV_LIBS})
+else()
+    target_compile_definitions(wpilibc PRIVATE DYNAMIC_CAMERA_SERVER)
+    # Add just the camera server include directory
+    target_include_directories(wpilibc PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../cameraserver/src/main/native/include)
+endif()
+
+target_link_libraries(wpilibc PUBLIC hal ntcore wpimath wpiutil)
+
 
 set_property(TARGET wpilibc PROPERTY FOLDER "libraries")
 
@@ -43,4 +52,9 @@ if (WITH_TESTS)
     else()
         target_compile_options(wpilibc_test PRIVATE /WX-)
     endif()
+    if (NOT WITH_CSCORE)
+        target_compile_definitions(wpilibc_test PRIVATE DYNAMIC_CAMERA_SERVER)
+        # Add just the camera server include directory
+        target_include_directories(wpilibc_test PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../cameraserver/src/main/native/include)
+    endif()
 endif()

wpilibj/CMakeLists.txt

@@ -1,9 +1,8 @@
 project (wpilibj)
 
-find_package( OpenCV REQUIRED )
-
 # Java bindings
 if (WITH_JAVA)
+    find_package( OpenCV REQUIRED )
     find_package(Java REQUIRED)
     include(UseJava)
     set(CMAKE_JAVA_COMPILE_FLAGS "-encoding" "UTF8" "-Xlint:unchecked")