Can't compile MagickWand using CMake - c++

Question

I couldn't compile my program which uses MagickWand with CMake. I'm getting this error:
[ 33%] Linking CXX executable bin/ScreenRecorder
/usr/bin/ld: CMakeFiles/ScreenRecorder.dir/source/main.cpp.o: in function `std::thread::thread<void (&)(), , void>(void (&)())':
main.cpp:(.text._ZNSt6threadC2IRFvvEJEvEEOT_DpOT0_[_ZNSt6threadC5IRFvvEJEvEEOT_DpOT0_]+0x20): undefined reference to `pthread_create'
/usr/bin/ld: CMakeFiles/ScreenRecorder.dir/source/screenshot.cpp.o: in function `printScrn(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)':
screenshot.cpp:(.text+0xd): undefined reference to `MagickWandGenesis'
/usr/bin/ld: screenshot.cpp:(.text+0x1a): undefined reference to `NewMagickWand'
/usr/bin/ld: screenshot.cpp:(.text+0x31): undefined reference to `MagickReadImage'
/usr/bin/ld: screenshot.cpp:(.text+0x4f): undefined reference to `MagickWriteImage'
/usr/bin/ld: screenshot.cpp:(.text+0x62): undefined reference to `DestroyMagickWand'
/usr/bin/ld: screenshot.cpp:(.text+0x6b): undefined reference to `MagickWandTerminus'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/ScreenRecorder.dir/build.make:99: bin/ScreenRecorder] Error 1
make[1]: *** [CMakeFiles/Makefile2:73: CMakeFiles/ScreenRecorder.dir/all] Error 2
make: *** [Makefile:84: all] Error 2
This is my CMakeLists.txt:
cmake_minimum_required(VERSION 3.0)
project(ScreenRecorder)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14 -Wall")
set(source_dir "${PROJECT_SOURCE_DIR}/source/")
set(EXECUTABLE_OUTPUT_PATH "${PROJECT_SOURCE_DIR}/bin/")
find_package(ImageMagick REQUIRED)
include_directories(
"/usr/include/ImageMagick-6/"
)
link_libraries(
"/usr/lib/x86_64-linux-gnu/"
)
file (GLOB src_files "${source_dir}*.cpp")
add_executable(ScreenRecorder ${src_files})
I tried using variables such as ${ImageMagick_MagickWand_INCLUDE_DIR} and ${ImageMagick_MagickWand_LIBS_DIR} but it says that "wand/MagickWand.h" not found.
Thanks for your answers.

Answer 1

I was able to resolve a similar issue by enclosing the auto-generated variables in quotes:
INCLUDE_DIRECTORIES(
"${ImageMagick_INCLUDE_DIRS}"
)
TARGET_LINK_LIBRARIES(MyProject
"${ImageMagick_LIBRARIES}"
)
The reason that this resolved the issue is that the variables are CMake lists.
Without quotes, they are concatenated to a long string:
MESSAGE(${ImageMagick_INCLUDE_DIRS})
MESSAGE(${ImageMagick_LIBRARIES})
->
1> [CMake] /usr/include/ImageMagick-6/usr/include/x86_64-linux-gnu/ImageMagick-6
1> [CMake] /usr/lib/x86_64-linux-gnu/libMagickWand-6.Q16.so
However, with quotes, the different elements of the list are separated using a semicolon:
MESSAGE("${ImageMagick_INCLUDE_DIRS}")
MESSAGE("${ImageMagick_LIBRARIES}")
->
1> [CMake] /usr/include/ImageMagick-6;/usr/include/x86_64-linux-gnu/ImageMagick-6
1> [CMake] /usr/lib/x86_64-linux-gnu/libMagickWand-6.Q16.so