Simple project doesn't link and examples don't build.

[pauljurczak]

I followed the instructions at https://github.com/alandefreitas/matplotplusplus#build-from-source on Ubuntu 18.04.5 with gcc-10.1.0 for source build. The installation was successful, but when building a test project I'm getting missing linker dependencies:

[build] : && /usr/bin/g++-10 -O3 -DNDEBUG  CMakeFiles/o3d.dir/main.cpp.o -o o3d  -lmatplot && :
[build] //usr/local/lib/libmatplot.a(common.cpp.o): In function `cimg_library::CImg<unsigned char>::_save_png(_IO_FILE*, char const*, unsigned int) const [clone .isra.0]':
[build] common.cpp:(.text+0x79c4): undefined reference to `png_create_write_struct'

Here is my CMakeLists.txt:

cmake_minimum_required(VERSION 3.18)
project(o3d VERSION 0.1.0)
add_executable(o3d main.cpp)
find_package(Matplot++ REQUIRED)
target_link_libraries(o3d matplot)

I tried to build the examples and build/examples was not created:

paul@extra:~/matplotplusplus/build$ cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_FLAGS="-O2"
CMAKE_MODULE_PATH=/home/paul/matplotplusplus/cmake
CMAKE_INSTALL_PREFIX=/usr/local
CMAKE_INSTALL_LIBDIR=lib
-- Configuring done
-- Generating done
-- Build files have been written to: /home/paul/matplotplusplus/build
paul@extra:~/matplotplusplus/build$ cmake --build . --parallel 2 --config Release
[ 13%] Built target nodesoup
[100%] Built target matplot
paul@extra:~/matplotplusplus/build$ ls
CMakeCache.txt  cmake_install.cmake  CPackSourceConfig.cmake  Makefile                Matplot++ConfigVersion.cmake
CMakeFiles      CPackConfig.cmake    install_manifest.txt     matplot++-config.cmake  source

[pauljurczak]

I tried again with gcc 9.3.0 and gnuplot built from source instead of Ubuntu 18.04 binary package. This time, I can build sample programs. The only problem I found so far is zoom not working.