Compile static OpenCV (Windows) executables using Docker

• reproducible build environment thanks to Docker
• includes opencv-contrib packages
• no need for weird Windows Docker images thanks to crosscompile with mingw
• CMakeLists example with:
  • OpenCV demo
  • UDP socket demo
• based on dockcross
• multistage Docker build to reduce final image size (still 2.6GB though)
• tested on:
  • Docker for Windows
  • Docker for Mac
  • docker-tools, for Win7/Win8, see notes!

Usage

# Pull image and extract the dockcross utility script
docker pull rknt/opencv-static-windows-buildenv-docker
docker tag rknt/opencv-static-windows-buildenv-docker buildenv
docker run --rm buildenv > ./dockcross
chmod +x ./dockcross

# Build executables in a separate build directory
./dockcross cmake -Bbuild -Hsrc -GNinja
./dockcross ninja -Cbuild

The latter two steps constitute compile.sh.

• configure what gets built in /src/CMakeLists.txt
• use rm -r build to build from a clean start
• compiled .exe land in /build

If you need further libraries you can be lucky and they are part of the mingw install in the Docker image, or you'll have to cross-compile them in the docker image yourself. The latter is what we did for OpenCV (see the buildenv-docker/Dockerfile).

OpenCV

Change ENV OPENCV_VERSION 3.3.1 in the Dockerfile to obtain your desired version.

Remove the OPENCV_EXTRA_MODULES_PATH line in the cmake section of the Dockerfile if you do not need opencv-contrib. If this is the case you can also remove the ADD line with opencv-contrib to skip downloading it.

Docker on Windows 7 and 8

Docker for Windows only runs on Windows 10. For older versions you have to use docker-tools to install docker.

This version of docker handles filepast for volume mounts differently and this is not supported by the dockcross script so you have to insert the following under line 192 in the script.

HOST_PWD=${HOST_PWD/c:/\/c}

Otherwise Docker will complain about mounting /work due to the : behind the c in the path.

If you want to run this script on a drive other than C: you will probably have to mess around with the VirtualBox settings for docker.

Acknowledgments

dockcross for crosscompiles using Docker.

Tobias Gerschner's example for static compiling of OpenCV in dockcross for ARM architectures.