qTox/windows/cross-compile/README.md

Cross-compile from Linux to Windows

Intro

Following these instructions you will be able to cross-compile qTox for Windows.

This script can be used by qTox users and devs to compile qTox for Windows themselves.

Please note that the compilation script doesn't build the updater.

Usage

Install Docker.

Create 3 directories:

• workspace -- a directory that will contain a cache of qTox dependencies and the final qTox cross-compilation build. You should create this directory.

• qtox -- the root directory of a qTox repository. This directory must contain the qTox source code that will be cross-compiled.

• script -- a directory that contains the build.sh script. You could create this directory and copy the build.sh script in it, or you could just use the qtox/windows/cross-compile directory for this.

These directories will be mounted inside a Docker container at /workspace, /qtox and /script.

The contents of qtox and script directories are not modified during compilation. The build.sh script makes a temporary copy of the qtox directory for compilation.

Once you sort out the directories, you are ready to run the build.sh script in a Docker container.

Note: Thebuild.sh script takes 2 arguments: architecture and build type. Valid values for the architecture are i686 for 32-bit and x86_64 for 64-bit. Valid values for the build type are release and debug. All case sensitive.

To start cross-compiling for 32-bit release version of qTox run:

sudo docker run --rm \
                -v /absolute/path/to/your/workspace:/workspace \
                -v /absolute/path/to/your/script:/script \
                -v /absolute/path/to/your/qtox:/qtox \
                debian:stretch-slim \
                /bin/bash /script/build.sh i686 release

If you want to debug some compilation issue, you might want to instead run:

# Get shell inside Debian Stretch container so that you can poke around if needed
sudo docker run -it \
                --rm \
                -v /absolute/path/to/your/workspace:/workspace \
                -v /absolute/path/to/your/script:/script \
                -v /absolute/path/to/your/qtox:/qtox \
                debian:stretch-slim \
                /bin/bash
# Run the script
bash /script/build.sh i686 release

These will cross-compile all of the qTox dependencies and qTox itself, storing them in the workspace directory. The first time you run it for each architecture, it will take a long time for the cross-compilation to finish, as qTox has a lot of dependencies that need to be cross-compiled. But once you do it once for each architecture, the dependencies will get cached inside the workspace directory, and the next time you build qTox, the build.sh script will skip recompiling them, going straight to compiling qTox, which is a lot faster.

Note: On a certain Intel Core i7 processor, a fresh build takes about 125 minutes on a single core, and about 30 minutes using all 8 hyperthreads. Once built, however, it takes about 8 minutes on a single core and 2 minutes using 8 hyperthreads to rebuild using the cached dependencies.

After cross-compiling has finished, you should find the comiled qTox in a workspace\i686\qtox or workspace\x86_64\qtox\ directory, depending on the architecture.

You will also find workspace\dep-cache directory, where all the cross-compiled qTox dependencies will be cached for the future builds. You can remove any directory inside the dep-cache, which will result in the build.sh re-compiling the removed dependency only.

The workspace direcory structure for reference

workspace/
├── i686
│   ├── dep-cache
│   │   ├── libexif
│   │   ├── libffmpeg
│   │   ├── libfilteraudio
│   │   ├── libopenal
│   │   ├── libopenssl
│   │   ├── libopus
│   │   ├── libqrencode
│   │   ├── libqt5
│   │   ├── libsodium
│   │   ├── libsqlcipher
│   │   ├── libtoxcore
│   │   ├── libvpx
│   │   ├── mingw-w64-debug-scripts
│   │   ├── nsis
│   │   └── nsis_shellexecuteasuser
│   └── qtox
│       ├── debug
│       └── release
└── x86_64
    ├── dep-cache
    │   ├── libexif
    │   ├── libffmpeg
    │   ├── libfilteraudio
    │   ├── libopenal
    │   ├── libopenssl
    │   ├── libopus
    │   ├── libqrencode
    │   ├── libqt5
    │   ├── libsodium
    │   ├── libsqlcipher
    │   ├── libtoxcore
    │   ├── libvpx
    │   ├── mingw-w64-debug-scripts
    │   ├── nsis
    │   └── nsis_shellexecuteasuser
    └── qtox
        ├── debug
        └── release