gimp/NEWS

                   ------------------------------
                   GNU Image Manipulation Program
                         Development Branch
                   ------------------------------

This is the unstable branch of GIMP.


Overview of Changes from GIMP 2.10.x to GIMP 2.99.2
===================================================

Core:

  - Improved "space invasion".
  - New extension format support (.gex a.k.a. GIMP Extension) which is
    an archive containing various supported data. So far, it can
    package: brushes, MyPaint brushes, dynamics, patterns, gradients,
    palettes, tool presets, plug-ins, splash images and themes.
  - New extension manager allowing to enable, disable or uninstall
    installed extensions, with a dialog available in `Edit > Manage
    Extensions`.
  - Multi selection of layers now possible. Various tools and features
    are now multi-selection aware.
  - XCF format bumped to version 14 with awareness of multiple layer
    selection.
  - All code is year-2038-safe with deprecated time API replaced.
  - "Alpha to Selection" various actions warn when the result selection
    is empty.
  - Color Profile Policy (import) now exposes a "Convert to Preferred
    Profile" (fourth) choice and the import dialog default "Convert"
    action will convert the image to the preferred profile (if any was
    set, otherwise it falls back to the built-in profile). Converting to
    the built-in profile will be still available as secondary action.
  - A new "Metadata Rotation Policy" is now exposed in the Preferences
    dialog, next to the "Color Profile Policy" (in page `Preferences >
    Image Import & Export`) with 3 options: "Ask what to do", "Discard
    metadata without rotating" and "Rotate the image then discard
    metadata".
    This policy used to be handled API-size, with a dialog generated by
    libgimpui gimp_image_metadata_load_finish(), and saved in a global
    parasite. The whole logics and GUI has been moved as core logics,
    similar to the "Color Profile Policy".

User Interface:

  - Whole interface ported to GTK+3:
    * Proper HiDPI support, which will follow the system's scale factor
      for all widgets. This is a core toolkit support, unlike the basic
      better-than-nothing hacks from GIMP 2.10.x.
    * GTK+3 CSS-like support. All themes for former versions are
      therefore not working anymore.
    * GTK+3 themes have the concept of "dark variant", so a same theme
      may propose both a light and a dark versions. Preference for dark
      variants can now be checked in `Preferences > Themes > Use dark
      theme variant if available` checkbox, allowing for instance to use
      your system theme in its light variant everywhere except in GIMP.
      This option is checked by default as graphics software are often
      prefered in dark modes.
    * Symbolic icon themes are now recolored automatically according to
      the theme colors (no theme and icon theme tweaking anymore to end
      up with dark on dark or light on light interfaces), except for
      color elements whose SVG style is marked as "!important".
    * Native Wayland support.
    * Various dialogs now use Client-Side decorations and modern GTK+
      widgets are being used when relevant.
  - Image display rendered faster with a render cache that keeps the
    result of scaling, color management, display filters and shell mask
    (for tools like fuzzy select).
  - Shift-click on layer GimpContainerTreeView (typically the Layers
    dockable) allows to expand/collapse all item groups but the clicked
    one.
  - Compact GimpSpinScale is now the only available version.

Devices:

  - Device hotplug supported (thanks to GTK+3). In particular:
    * you don't need to have your tablets and other devices plugged
      before you start GIMP anymore;
    * enabling your devices in the "Configure Input Devices" dialog is
      not needed anymore. Tablets will work out-of-the box;
    * you can safely unplug and replug the same or other input devices
      while GIMP is running.

Plug-ins:

  - Major rewrite of the API. So GIMP 2.10.x plug-ins and below must be
    ported to the new API.
  - Various objects are now proper GObject in the plug-in API, and not
    just ID integers.
  - The API is GObject Introspected into 2 modules: Gimp and GimpUi.
    This means plug-ins can be written in various non-C languages. So
    far the following languages have been tested and work well: Python
    3, Lua, Javascript and Vala.
    (Note: Python 2 is also still working, but considering that this
    language is end-of-life since 2020, we don't really care).
  - Every introspected binding which we test comes with a "Goat
    Exercise", which is a demo plug-in popping a dialog and showing its
    own source code. It processes a simple "gegl:invert" operation on a
    drawable. All "Goat Exercises" must do the same thing in the same
    way, simply in their respective languages, as documentation/example
    code for a language binding.
  - Plug-ins must be installed in their own subdirectory in
    `$XDG_CONFIG_HOME/GIMP/2.99/plug-ins/`, thus preventing data mess
    (with plug-ins coming with data and installing it all in the root
    plug-ins/ directory) and DLL hell. The main plug-in executable must
    be named the same as the directory (possibly with an added
    extension).
    E.g.: `plug-ins/my-cool-plug-in/my-cool-plug-in.py`
  - HEIF export allows selecting color subsampling/pixel format (YUV444,
    YUV420, RGB) and encoder speed (Slow, Balanced, Fast).
    Lossless option delivers visually lossless output.
  - New "file-heif-av1-load" procedure separate from "file-heif-load"
    for AVIF only.

API:

  - gimp_image_metadata_load_finish() is now fully GUI/GTK-code free.
    The first consequence is that it is not in libgimpui anymore, but in
    libgimp, as it should. The second consequence is that the boolean
    `interactive` argument has been removed. Now all image rotation
    logics (the part which needed a GUI) has been moved into core and
    will be automatically run when normally loading images from GIMP's
    interface, similarly as to how color profiles was already handled.
  - 2 new libgimp API: gimp_image_policy_rotate() and
    gimp_image_policy_color_profile() are now available to explicitly
    call the Preferences-set policy on an image. This may result in a
    dialog being presented to the user if `interactive` is TRUE and
    settings is "Ask what to do".
    It is unecessary to call these functions when developing a new
    GimpLoadProcedure because the core will automatically do the right
    thing and call these on normal image loading workflow.
    Instead if a plug-in calls such GimpLoadProcedure through the PDB,
    no such functions will be run automatically. It is up to the plug-in
    to decide what to do (no conversion, mandatory conversion, or using
    user settings, possibly with a dialog to decide, hence calling these
    functions explicitly).
  - All pygimp specific Python API does not exist anymore. Python will
    use the same API as C plug-ins, introspected through GObject
    Introspection.

Documentation:

  - `devel-docs/xcf.txt` updated to handle XCF 14.

Build:

  - New meson build system. Still deemed "experimental" for the time
    being. Packagers are recommended to continue using the autotools
    build system in order to avoid specific bugs.
  - Continuous integration in Gitlab with:
    - an autotools build with GCC on a Debian/testing runner
    - a meson build with GCC on a Debian/testing runner
    - a meson build with Clang on a Debian/testing runner
    - a meson cross-build with Mingw-w64 for Windows 32-bit
    - a meson cross-build with Mingw-w64 for Windows 64-bit
    - static code analysis with cppcheck

Known blocker issues:

  - GTK+3 port is functional but not complete as some deprecated APIs
    are still being used.
  - Space invasion is still a work-in-progress.
  - Plug-ins API update is still a work-in-progress.
  - GIMP extensions are still a work-in-progress.
  - Multiple layer selection is still work-in-progress. Some issues are
    expected, and possibly even some crashes in code paths which were
    not updated yet.
  - No custom theme yet, in particular we want a neutral gray theme with
    light/dark variants, and a middle-gray theme too.
  - We probably want to revive a "Small" theme as well with smaller
    icons (useful on smaller displays, or mid-high density displays or
    simply depending on tastes).
  - Various blocking bugs happen on Wayland only.