Unable to include a header-only library in ROS - cmake

Question

I have the following project structure:
utils
include
utils
image_utils.h
CMakelists.txt
package.xml
graph
src
graph.cpp
CMakelists.txt
package.xml
I am trying to use image_utils.h in graph.cpp.
The CMakelists inside utils looks like this:
cmake_minimum_required(VERSION 3.0.2)
project(utils)
find_package(catkin REQUIRED COMPONENTS roscpp)
catkin_package(
INCLUDE_DIRS include
LIBRARIES ${PROJECT_NAME}
CATKIN_DEPENDS roscpp
)
include_directories(
include
${catkin_INCLUDE_DIRS}
)
add_library(${PROJECT_NAME} INTERFACE)
target_link_libraries(${PROJECT_NAME} INTERFACE ${catkin_LIBRARIES} )
install(
DIRECTORY include/
DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
FILES_MATCHING PATTERN "*.h"
)
And in the CMakelists inside graph i call find_package(catkin REQUIRED COMPONENTS roscpp) as seen below:
cmake_minimum_required(VERSION 3.0.2)
project(pose_graph)
set(CMAKE_BUILD_TYPE "Release")
set(CMAKE_CXX_FLAGS "-std=c++11")
find_package(catkin REQUIRED COMPONENTS roscpp std_msgs cv_bridge utils)
find_package(OpenCV 3.4 REQUIRED)
include_directories(${catkin_INCLUDE_DIRS} )
catkin_package(CATKIN_DEPENDS utils)
add_executable(graph src/graph.cpp)
target_link_libraries(graph ${catkin_LIBRARIES} ${OpenCV_LIBS} utils)
The package.xml of graph has the following relevant tag:
<depend>utils</depend>
My error message is:
graph.cpp:12:10: fatal error: utils/image_utils.h: No such file or directory
#include "utils/image_utils.h"
^~~~~~~~~~~~~~~~~~~~~
Any idea what I am doing wrong here?

Answer 1

You need to rearrange your folder structure to utils/include/utils/image_utils.h and then also add an add_library(...) call in your CMakeLists.txt file.

Answer 2

Finally figured it out. Here are my CMakelists files:
utils:
cmake_minimum_required(VERSION 3.0.2)
project(utils)
find_package(catkin REQUIRED COMPONENTS roscpp)
catkin_package(
INCLUDE_DIRS include
CATKIN_DEPENDS roscpp
)
include_directories(
include
${catkin_INCLUDE_DIRS}
)
install(
DIRECTORY include/${PROJECT_NAME}/
DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
FILES_MATCHING PATTERN "*.h"
)
graph:
cmake_minimum_required(VERSION 3.0.2)
project(pose_graph)
set(CMAKE_BUILD_TYPE "Release")
set(CMAKE_CXX_FLAGS "-std=c++11")
find_package(catkin REQUIRED COMPONENTS roscpp std_msgs cv_bridge utils)
find_package(OpenCV 3.4 REQUIRED)
catkin_package(CATKIN_DEPENDS utils)
include_directories(${catkin_INCLUDE_DIRS} )
add_executable(graph src/graph.cpp)
target_link_libraries(graph ${catkin_LIBRARIES} ${OpenCV_LIBS})