OpenCV compilation as static library [Linux].

[mrcyberfighter]

I've compiled OpenCV as static library by downloading the source from github.

 $ cmake WITH_GTK=ON WITH_GTK3=ON CMAKE_BUILD_TYPE=RELEASE BUILD_SHARED_LIBS=OFF .

so I get all the libraries as static and try to compile my program according following Makefile:

CXX = g++
CXXFLAGS = -std=c++11 

# Better sort the file order in relationship to `pkg-config --libs opencv` linking chain order.
OPENCV_A = libopencv_calib3d.a \  
    libopencv_contrib.a                    \
    libopencv_core.a                        \
    libopencv_features2d.a              \
    libopencv_flann.a                       \
    libopencv_gpu.a                         \
    libopencv_highgui.a                   \
    libopencv_imgproc.a                  \
    libopencv_legacy.a                    \
    libopencv_ml.a                          \
    libopencv_objdetect.a               \
    libopencv_ocl.a                         \
    libopencv_photo.a                    \
    libopencv_stitching.a                \
    libopencv_superres.a               \
    libopencv_ts.a                          \
    libopencv_video.a                    \
    libopencv_videostab.a             

default:
[TAB] $(CXX) $(CXXFLAGS) main.cpp $(OPENCV_A)

But it result in an error traceback: a linking problem (dlsym linking (ld) problem) related to the OpenCV dependencies (libjpeg, libpng, ...).

I find the following solution to but it doesn't take the way of a static linking:

$ cmake WITH_GTK=ON WITH_GTK3=ON CMAKE_BUILD_TYPE=RELEASE BUILD_SHARED_LIBS=OFF
$ make opencv_python2    
$ cd ./lib
$ sudo cp cv2.so /usr/local/lib
$ sudo ldconfig
$ sudo ln -s  /usr/local/lib/cv2.so /usr/local/lib/libcv2.so # It's the python2 shared libary.
$ cd /path/to/my/prg 
$ g++ -std=c++11 main.cpp -lcv2

So I compile a C++ program with the python2 shared library...

Is it correct or it risk to fail if I distribute my program on others system as mine ?

I do it like this because I don't want to pollute the LIBPATH either the INCLUDEPATH from the target host.

[StevenPuttemans]

Once you start compiling OpenCV as static library, then you will need every single dependency also as a static library provided with it. That can be a pain in the ass believe me, but in some cases, there is indeed no other way. In this case this means you will need to provide a static build of libjpeg and libpng I guess.

[mrcyberfighter]

Yes i realize it after that i have to link all the dependencies.

So i try to look up the *.pc file to simply add all links: This doesn't work.

I project to compile the OpenCV library from source, do i should have all dependencies installed in this case, or are they contains | downloaded once you launch the make command ?

[alalek]

There is simplified Makefile sample via pkgconfig:
samples/cpp/example_cmake/Makefile

Does it work for you?

[mrcyberfighter]

Thanks for the link.

I must retry because i have a solid solution with the goal to not pollute the target-host system (the -lcv solution) and the linked Makefile is only adding --libs to the linking because the --static option from pkg-config does nothing with my configuration.

Simply try the command $(pkg-config --static opencv) and sea what it return.

On my system where i don't have the shared libraries installed and the $(pkg-config --static opencv) command return nothing.

[alalek]

BTW, pkg-config --static <name> is wrong command (there is another meaning of this flag). Use pkg-config --libs --static <name> and/or pkg-config -cflags --static <name> instead.

Sample makefile works fine for me in this scenario:

cmake -DBUILD_SHARED_LIBS=OFF -DCMAKE_INSTALL_PREFIX=install ...
make install
cd <opencv>/samples/cpp/example_cmake
PKG_CONFIG_PATH=<build path>/install/lib/pkgconfig make

[mrcyberfighter]

OK thanks, I will try again to compile OpenCV as static library as soon as possible (holydays)...

The goal is to get a GTK+3 compatible version of OpenCV because my packages-manager install it with GTK+2 support.

And so you cannot compile a program with GTK+3 as GUI.

And to distribute the program without pollute the target host with a library which will take prior because the the default order from $PATH is /usr/local/lib before /usr/lib...

In the case the target host wants to use the package-manager version.