gimp/build/flatpak

GIMP Flatpak HowTo

Stable and Development releases

The Flathub repository hosts our stable and development point releases: https://github.com/flathub/org.gimp.GIMP

We recommend to look at the README.md file in respectively the master or beta branches of this repository to know more about release procedures.

Nightly builds

Flathub does not host nightly builds, therefore we publish them on GNOME's Nightly repository. Our "nightlies" are actually "weeklies" through a Gitlab job schedule named "Flatpak nightly".

This job will build whatever is on GIMP's repository master branch (this branch should be kept buildable and usable at all time, not only for scheduled jobs, but also for all contributors to be able to improve GIMP at all time).

The nightly manifest file is: build/flatpak/org.gimp.GIMP-nightly.json

This file should remain as close as possible to the development manifest (org.gimp.GIMP.json file on the beta branch of the Flathub repository) which itself should remain as close as possible to the stable manifest (org.gimp.GIMP.json file on the master branch of the Flathub repository), since the nightly manifest is meant to become beta eventually, which itself is meant to become stable eventually.

Base rule to update the nightly build manifest:

• Regularly org.gimp.GIMP-nightly.json should be diffed and synced with development and stable org.gimp.GIMP.json, in particular for all the dependencies (which are mostly the same across all 3 builds).
• A merge request with the label 5. Flatpak package will contain the flatpak job, hence allowing theoretically to build a standalone flatpak (without being published to the nightly repository) for MR code. In practice, jobs have an 1-hour timeout and our flatpak takes longer than 1 hour to build (there is an exception in our repository, but only for the master branch), so we often need to publish to master after mostly a visual review.

Custom Flatpak builds (for development)

Most contributors simply build GIMP the "old-school" way, nevertheless some projects are starting to use flatpak as a development environment. Here is how this can be done, as far as our knowledge goes.

Note 1

The below process is about using flatpak as a development environment, not for proper releases to a repository, neither for creating standalone bundles

Note 2

since we usually only use flatpak for releases, not for development, there may be better ways to make a flatpak development environment. We welcome any proposed improvement to this file.

• Dependencies:

  • flatpak (at least 0.9.5)
  • flatpak-builder (at least 0.9.5, when the option --export-only has been added to flatpak-builder so that the build and the export can be made in 2 separate steps while using the high level procedure.)
  • appstream-compose

  Note 1

  there are packages of flatpak and flatpak-builder for most distributions.

  Note 2

  appstream-compose is used to parse the appdata file and generate the appstream (metadata like comments, etc.). On Fedora, this is provided by the package libappstream-glib, on Ubuntu by appstream-util…

• Install the runtimes and the corresponding SDKs if you haven't already:

  flatpak remote-add --user --from gnome https://nightly.gnome.org/gnome-nightly.flatpakrepo
  flatpak install --user gnome org.gnome.Platform/x86_64/master org.gnome.Sdk/x86_64/master
  flatpak install --user gnome org.gnome.Platform/aarch64/master org.gnome.Sdk/aarch64/master
  

  Or simply update them if you have already installed them:

  flatpak update
  

• Setup some recommended build options:

  export BUILD_OPTIONS="--ccache --keep-build-dirs --force-clean"
  

  We recommend using ccache to improve build speed, and to keep build dirs (these will be found in .flatpak-builder/build/ relatively to the work directory; you may manually delete these once you are done to save space) for later debugging if ever any configuration or build issue arises.

• Choose what architecture to build and where you will "install" your flatpak:

  # Architectures supported with GIMP flatpak are one of 'x86_64' or 'aarch64':
  export ARCH="x86_64"
  # Path where build files are stored
  export INSTALLDIR="`pwd`/${ARCH}"
  

• Build the flatpak up to GIMP itself (not included):

  flatpak-builder $BUILD_OPTIONS --arch="$ARCH" --stop-at=gimp \
                  "${INSTALLDIR}" org.gimp.GIMP-nightly.json 2>&1 \
                  | tee gimp-nightly-flatpak.log
  

  The build log will be outputted on stdout as well as being stored in a file gimp-nightly-flatpak.log.

• Now we'll want to build GIMP itself, yet not from a clean repository clone (which is what the manifest provides) but from your local checkout, so that you can include any custom code:

  flatpak build "${INSTALLDIR}" meson setup --prefix=/app/ --libdir=/app/lib/ _gimp ../../ 2>&1 | tee -a gimp-nightly-flatpak.log
  flatpak build "${INSTALLDIR}" ninja -C _gimp 2>&1 | tee -a gimp-nightly-flatpak.log
  flatpak build "${INSTALLDIR}" ninja -C _gimp install 2>&1 | tee -a gimp-nightly-flatpak.log
  

  This assumes you are currently within build/flatpak/, therefore the repository source is 2 parent-folders away (../../). The build artifacts will be inside the _gimp/ subfolders, and finally it will be installed with the rest of the flatpak inside $INSTALLDIR.

• For development purpose, you don't need to export the flatpak to a repository or even install it. Just run it directly from your build directory:

  flatpak-builder --run "${INSTALLDIR}" org.gimp.GIMP-nightly.json gimp-2.99
  

Maintaining the manifests

• GIMP uses Flatpak's GNOME runtime, which contains a base of libraries, some of which are dependencies of GIMP. While both the stable and development versions should use the latest stable runtime version, the nightly manifest uses the master version, which is more of a rolling release.

• Other GIMP dependencies which are not available in the GNOME runtime should be built along as modules within GIMP's flatpak. Check format in org.gimp.GIMP-nightly.json and add modules if necessary. For more options, check flatpak builder's manifest format.

• On the other hand, if we increased the runtime version in particular (or when the master runtime evolves), some modules may no longer be necessary and can be removed from our manifest.

  A flatpak is a layered set of modules. Our GIMP build in particular is built over the GNOME runtime, itself built over the Freedesktop runtime, itself based on a yocto-built image. Other than by trial and error, you can find the installed dependencies by running:

flatpak run --devel --command=bash org.gnome.Sdk//master

Or if you already have a build:

flatpak run --devel --command=bash org.gimp.GIMP//master

Inside the flatpak sandbox, GIMP's manifest can be read with:

 less /app/manifest.json

GNOME and Freedesktop's module lists (generated manifest as the SDK is built from BuildStream):

less /usr/manifest.json

• Some sources have set a x-checker-data property which makes it possible to check for updates using flatpak-external-data-checker. To run the tool either install it locally, via flatpak or via OCI image.

  The OCI image is not straightforward at first but is the least intrusive if you already have docker or podman installed:

cd <path-to-gimp-repo>/flatpak/build
podman run --rm --privileged -v "$(pwd):/run/host:rw" ghcr.io/flathub/flatpak-external-data-checker:latest /run/host/org.gimp.GIMP-nightly.json

Our prefered backend for the checker is Anitya, a database maintained by the Fedora project. To set up a new dependency check by Anitya:

1. verify it is available in the database: https://release-monitoring.org/
2. then copy the project ID which is the number in the project URI within the database.
3. Finally add a "x-checker-data" field within the "source" dictionary in the manifest with type "anitya", the "project-id" and a "url-template".
4. We usually want to depend on stable releases only, i.e. set "stable-only to true. On exceptional cases, for very valid reasons only, we might bypass this limitation, adding a comment explaining why we use an unstable release.

• For the development releases and nightly builds, we added the desktop-file-name-prefix property. For a stable release, the property line can be removed from the manifest.

• For a stable release, set top "branch":"stable", and inside the "gimp", "babl" and "gegl" modules, set "tag" to the git tag (ex: GIMP_2_10_34) and "commit" to the git commit hash for this tag.

• For a development release, set top "branch":"beta", and inside the "gimp", "babl" and "gegl" modules, set "tag" to the git tag (ex: GIMP_2_99_14) and "commit" to the git commit hash for this tag.

• For a nightly build, set top "branch":"master", and inside the "gimp", "babl" and "gegl" modules, set "branch" to "master", and remove any "commit" line.