Cross compile for Windows under Linux — mingw

General

This is much more convenient than building under windows, and the build is usually faster. The resulting binary can be tested in wine. If you have any questions Cruisers Forum Thread is here.

The info here is based on the CI scripts which lives in the ci/ directory. These scripts, which are continously tested is the ultimate source for how to make the mingw build.

The Fedora environment

The build is best done on Fedora, where the mingw stack seems to be well maintained. For non-Fedora users, the easiest way is to use a Fedora docker container. An example how to use a such a container, assuming a build script which lives in $PWD/build-mingw.sh:

$ echo "DOCKER_OPTS=\"-H tcp://127.0.0.1:2375 -H $DOCKER_SOCK -s devicemapper\"" \
    | sudo tee /etc/default/docker > /dev/null
$ sudo systemctl restart docker.service
$ sudo docker pull fedora:33
$ docker run --privileged  \
    -v /sys/fs/cgroup:/sys/fs/cgroup \
    -v $(pwd):/opencpn-ci:rw \
    fedora:33  /opencpn-ci/build-mingw.sh

Install build dependencies

The first line is usually not required on a regular Fedora host where these are installed anyway. Note the dependency on Leamas’s COPR opencpn-mingw repository.

$ su -c "dnf install -y sudo dnf-plugins-core"
$ sudo dnf copr enable -y --nogpgcheck leamas/opencpn-mingw
$ sudo dnf builddep -y mingw/fedora/opencpn-deps.spec

Clone the sources

The sources are quite large, a 330 MB download at the time of writing. Adding --depth 10 to the clone command brings this down to around 60 MB. However such a clone is not really usable if there is a need to submit patches. FIXME: Not mingw

$ git clone https://github.com/OpenCPN/OpenCPN.git
$ cd OpenCPN

Build

The build within Fedora is basically simple, as of commands below. Add other cmake options as required.

$ rm -rf build; mkdir build; cd build
$ cmake \
    -DCMAKE_TOOLCHAIN_FILE=../mingw/fedora/toolchain.cmake \
    -DOCPN_CI_BUILD:BOOL=ON \
    ..
$ make
$ make package

The build produces a NSIS .exe installation package. This can be used to install opencpn without problems using wine on Linux. Of course, the installer also works on Windows. Note that plugins built on windows using the MSVC compiler are not compatible with the mingw build.