                   ------------------------------
                   GNU Image Manipulation Program
                         2.10 Stable Branch
                   ------------------------------

This is the stable branch of GIMP. Unlike earlier stable branches,
we do allow some new features here, if they are not too invasive.
Otherwise, this branch is only for bug-fixes.


Overview of Changes from GIMP 2.10.16 to GIMP 2.10.18
=====================================================

Core:

  - In gimp:replace, when compositing the same content over itself,
    i.e., when the input and aux buffers share the same storage and
    same tile alignment, pass the input buffer directly as output,
    instead of doing actual processing. In particular, this happens
    when processing a pass-through group outside of its actual bounds.

User interface:

  - Add new Symbolic-High-Contrast and Symbolic-Inverted-High-Contrast
    themes, which are automatically-generated high-contrast variants
    of the (original) Symbolic theme.  The contrast factor is settable
    in the makefile, and is currently at 1.5 for both themes.
    
  - Rename tools/invert-svg to tools/svg-contrast, which now takes a
    contrast-factor argument, and adjusts the input SVG contrast,
    instead of just inverting it.  Note that we can still use the tool
    to invert icons, using a contrast of -1.

  - Allow horizontal scrollbars in all the Preferences dialog tree-
    views, so that they don't limit the minimal width of the dialog
    (in particular, the UI- and icon-theme tree-views may contain
    arbitrarily-long paths).

  - Draw a border around the color FG/BG color areas as a pair of
    black and white rectangles instead of letting GTK do this. This
    imporoves the legibility of borders, especially in dark themes.

Tools:

  - In GimpPaintTool, when not snapping brush outline to stroke, make
    sure to properly snap the cursor position to 15-degree angle
    multiples in line mode, not only when painting the line, but also
    during motion.

Plug-ins:

  - Add naive support for CMYK 8-bit PSD files

Updated translations:

  - Basque, Catalan, Danish, Polish, Spanish, Swedish, Ukrainian

Bug fixes:

  - #4643, #4634

Developers:

  - Ell, Massimo Valentini

Translators:

  - Alan Mortensen, Anders Jonsson, Asier Sarasua Garmendia, Daniel
    Korostil, Jordi Mas, Piotr Drąg, Rodrigo Lledó Milanca


Overview of Changes from GIMP 2.10.14 to GIMP 2.10.16
=====================================================

Core:

  - In gimp_gegl_apply_cached_operation(), use gint64 for storing the
    total and processed pixel counts used for reporting progress, to
    avoid overflowing when applying an operation to a large image.

  - In GimpFilterTool and gimp_drawable_apply_operation(), use
    gimp_drawable_filter_set_add_alpha() to add an alpha channel when
    applying an operation that specifies "needs-alpha" to a drawable
    that can have alpha.

  - In GimpFilterTool, move all the drawable-filter option setup to a
    new gimp_filter_tool_update_filter() function, and call it
    whenever the drawable-filter's options need to be updated. This
    avoids duplicating logic in various places.

  - Improve the efficiency of decoding RLE data when loading ABR
    brushes, by reading entire scanlines into a buffer all-at-once,
    instead of reading the stream byte-by-byte.

  - GIMP now optionally phones home to find out if there's a new
    version available and then tells the user if there is one
    indeed. It also keeps track of the installer revision and then
    warns if there's a newer installer available. This can be disabled
    in Preferences. In that case, users still have the option to
    manually check for an update via the About dialog. The feature can
    be disabled entirely with the '--disable-check-update' configure
    switch.

Tools:

  - New 3D Transform tool where you can set vanishing point, camera's
    focal length, and the move and rotate layer, selection, path, or
    image in 2.5 space. With the "Unified interaction" option enabled,
    all three interaction modes of the grid (camera, move, and rotate)
    are available simultaneously. In this mode, the inner and outer
    regions of the item are used for moving and rotation, respectively,
    and the vanishing point is controlled through through a handle.

  - Transform tools now respect the Clip option and update the canvas
    preview accordingly.

  - New "Composited preview" option allows respecting layer's blending
    mode and position in the layer stack rather than rendering it as
    an overlay on top of the overall layer stack. This simplifies
    creating complex layer compositions greatly. The option requires
    mipmaps to be used and thus is disabled by default. It also comes
    with an experimental "Synchronous preview" suboption to render the
    composited preview synchronously. This reduces the lag for
    painting the preview, but can harm responsiveness for bigger
    images, where rendering the preview is slow.

  - Add a new "Preview linked items" option to the transform-grid
    tools. When this option is enabled, together with composited
    previews, the transform preview includes all linked layers and
    channels when transforming a layer/channel. Paths are currently
    unsupported.

  - New widget called GimpPivotSelector, a 3x3 grid of toggle buttons,
    is now used for selecting a natural pivot position (e.g. for a
    transform) relative to an item: its center, its corners, and the
    midpoints of its edges. Currently used in Rotate and 3D Transform
    tools.
 
  - Add "Show all" support to the Bucket Fill tool in line-art mode

  - Color picker and sample points now support displaying vlaues in
    Yu'v' (CIE 1976 UCS) color space.

  - The Symmetry Painting dock now has an "Enable reflection" option
    that allows painting patterns resembling a kaleidoscope.

  - Transform clipping is temporarily disabled for layer groups. No
    preview other than 'Adjust' works anyway. This will be fixed later
    on.

  - Construct a box-filtered mipmap hierarchy for the original brush
    on-demand, and the closest mipmap is used as the resampling source
    for downscaled brushes, significantly improving the output
    quality.

  - Now that painting is done in a separate thread, the display update
    rate has a far smaller impact on it. Increase the GimpDisplay
    update rate, which handles image updates, to 60 FPS, and the
    GimpDrawTool update rate to 120 FPS. In particular, the latter
    change makes the brush outline motion much smoother.

  - In the Airbrush tool, increase the maximal stamp FPS from 15 to
    60, and change the corresponding maximal Rate value from 150 to
    100. This technically affects tool presets, but we'll live.

  - Add a new "Snap brush outline to stroke" toggle to the "Image
    Windows" preferences page. When enabled, the brush outline in
    paint tools snaps to the individual dabs while painting, which is
    how it worked before version 2.10.16. Disable the option by
    default.  This seems to be what most other programs are doing, and
    it does give paitning a smoother feel.

  - The Warp Transform tool now respects settings for painting tools:
    showing the brush outline, snapping to dabs, and showing the paint
    tool cursor.

UI:

  - Tools are now logically grouped in the toolbox by default. Users
    can customize the groups to their liking or disable this feature
    altogether in the Preferences dialog (Interface / Toolbox page).

  - New opt-out compact style for sliders with revamped interaction.
    The widget uses a narrower layout, and the different
    upper/lower-half behavior is gone. Instead, the behavior depends
    on the mouse button and modifier used:

    - left-click is used for absolute adjustment,
    - Shift + left-click + drag changes value in small increments,
    - Ctrl + left-click + drag changes value in large increments,
    - middle-click enables numeric input mode;
    - right-click enables numeric input mode and selects the value.

  - The "You can drop dockable dialogs here" message is gone from the
    toolbox for good. Instead, highlight dockable areas when a user
    starts dragging a dockable dialog, and intensify the highlight as
    the dialog goes over a dockable area.

  - Consolidate UI for merging down and anchoring layers:
    As they are both mutually exclusive and serve an almost identical
    purpose, the "Merge down" and "Anchor Layer" are given mutually
    exclusive visibility in menus, and the anchor button is replaced
    with a merge down button in the Layers dockable whenever there is
    no active floating selection. Modifier keys are available:

    - Shift: merge layer group
    - Ctrl: merge visible layers
    - Ctrl + Shift: merge visible layers from last used values

Plugins:

  - In plug_in_compat.pdb, when wrapping an op node inside a graph,
    set the op node as the graph node's underlying operation. This
    allows gimp_gegl_apply_operation() to perform certain
    optimizations.

  - The Spyrogimp plugin now features a Visual tab where the inner
    mechanics of a spirograph is abstracted away, and you operate on
    amount of petals etc. The plugin now also allows saving a pattern
    as a path rather than rendering it to a layer as a bitmap.

  - Improve the loading speed for PSD files, mostly by eliminating
    excessive copies.

Filters:

  - Don't disable gegl:color-to-alpha (which has "needs-alpha") 
    when the drawable doesn't have an alpha channel, if one can be
    added.

  - Don't disable color-to-alpha for grayscale drawable, since the
    operation is applicable to grayscale images (in particular, it
    doesn't add color where there was none), and since GIMP no longer
    distinguishes between layers and channels according to the
    drawable format when updating the filters actions.

Windows:

  - Installer: unofficial languages, ghostscript 9.50.
  - Installer: skip .debug files when they don't exist.
  - Installer: properly remove old icons on 32-bit installs and
    per-user installs.

macOS:

  - Set required variables if it is running from Apple application
    bundle.
  - The macOS build now ships with the dashboard dock for displaying
    perfomance graphs.

Updated translations:

  - British English, Catalan, Danish, French, German, Hungarian,
    Icelandic, Italian, Japanese, Polish, Russian, Spanish, Swedish,
    Turkish, Ukrainian.

Bugfixes:

   - #4172, #4194, #4205, #4218, #2543, #4185, #4246, #2794, #4209,
     #4278, #4372, #4187, #4392, #2674, #4338, #2862, #4203, #4204,
     #4354, #1266, #4584, #4174, #4285, #4366, #1975, #4605

Developers:

  - Alex Samorukov, Cyril Richard, Elad Shahar, Ell, Elle Stone,
    Jehan, Jernej Simončič, lillolollo, Massimo Valentini, Michael
    Natterer, Pascal Terjan, woob.

Translators:

  - Alan Mortensen, Alexandre Prokoudine, Anders Jonsson, Balázs
    Meskó, Balázs Úr, Bruce Cowan, Daniel Korostil, Jordi Mas, Julien
    Hardelin, Marco Ciampa, Piotr Drąg, Rodrigo Lledó Milanca, Ryuta
    Fujii, Sabri Ünal, sicklylife, Sveinn í Felli, Tim Sabsch, Zander
    Brown.


Overview of Changes from GIMP 2.10.12 to GIMP 2.10.14
=====================================================

Core:

  - New "Selected areas continue outside the image" toggle option to
    the "Feather Selection" dialog.
  - New "Allow editing on non-visible layers" setting in Preferences
    to allow painting, transforming, and selecting on layers with
    toggled off visibility.
  - XCF loading a bit more resilient to corruption: it doesn't stop
    any more at the first layer or channel error; instead it tries to
    load more layers/channels to salvage as much data as possible from
    a corrupted XCF file.
  - In gimp:gradient, fix dithering to correspond to how we actually
    round float values to 8-bit. In particular, this avoids
    introducing noise when a component is fixed at 0 or 1 along a
    segment.
  - New "Show All" view mode allowing to show pixels outside the
    canvas boundary.
  - New "Show Canvas Boundary" option to render a dotted line around
    the canvas boundary.
  - New "Keep Padding in "Show All" Mode" option, also available as a
    default option via Preferences, to preserve the padding color
    instead of displaying the checkerboard.
  - Several features updated to react as expected when run
    out-of-canvas: color-picking, canvas grid, transform tools, bucket
    fill, and more.
  - Loaded images' pixel density will now default to 72 PPI when no
    explicit resolution information was stored in the imported file.
    Newly created images' default pixel density will continue to be
    based on the default image template (with value 300 PPI if it has
    not be changed), yet not loaded images anymore. 72 PPI is the
    common default in most software (and in standards such as Exif) so
    it makes sense we stick to it, only for loaded images.

Tools:

  - Free Select tool: fast copy|cut-paste modifiers (Alt + Ctrl|Shift)
    are now working even when the selection is not committed. Starting
    a fast copy|cut-paste will automatically close the polygon and
    commit the selection, accelerating fast usage of free selections.
  - Foreground Select tool: new "Grayscale" Preview Mode. Also, a
    color selector for "Color" preview (original preview mode) now
    available, to select any color and opacity for the preview.
  - Add a new "Image" transform type to the transform tools, in
    addition to the existing "Layer", "Selection", and "Path"
    transform types.  The "Image" mode transforms the entire image,
    rather than a single item. In tools with a preview, the preview
    shows the transformed image projection.  The clipping mode
    controls how the canvas is clipped during the transform; in
    particular, the ADJUST clipping mode resizes the canvas to fit its
    transformed size.
  - In GimpFilterTool, add a new "clipping" option, which can be
    either Adjust or Clip.  This option is controllable for layers,
    when there's no selection mask.
    When set to Adjust, which is used by default, the filter's output
    may extent past the drawable's boundary, and the drawable will be
    resized to match the output when committed.
  - Gradient tool: offest support in shaped gradients

Plug-ins:

  - Simple 8-bit port of filters to GEGL: nl-filter, film,
    fractal-explorer, flame, blinds, jigsaw, gradient-flare,
    checkerboard, tile-small, curve-bend, sample-colorize, map-object,
    lighting, grid, despeckle, sphere-designer, contrast-retinex, hot,
    sparkle, cml-explorer, destripe, twain, animation-optimize,
    depth-merge, warp, imagemap, gimpressionist
  - Port of filters to GEGL with float support: van-gogh-lic.
  - Add color profile support for HEIF (only when libheif 1.4.0 is
    available).
  - TIFF import will now ask (in interactive mode) how to process
    unspecified TIFF channels: non-premultiplied (used to be the
    default) alpha, premultiplied alpha, or just import as generic
    channel.
  - HEIF export now improved with same profile logics as JPEG or WebP
    (it can actually export higher bit-depth data, so profile logics
    should be the one as in PNG, but we only support 8 bpc HEIF for
    the time being).
  - HEIF export dialog now has a "Save color profile" checkbox
    allowing to not export with a profile when needed (needs libheif
    1.4.0 or higher).
  - PDF exporting: text layers in layer groups are now exported as
    proper text.
  - Cleaned up the file-dds GUI, removed the "Advanced" expander.
  - gimptool external tool now install plug-ins into subfolders (this
    is not mandatory in GIMP 2.10 yet, unlike future GIMP 3, but is
    already the recommended folder structure for plug-ins).
  - 3 procedures ("color-decode-ycocg", "color-decode-ycocg-scaled"
    and "color-decode-alpha-exp") removed from file-dds plug-in
    because they are hacks which should stay internal to the plug-in
    and are semantically wrong because colors in drawables are never
    in such formats.

Filters:

  - New "Normal Map" filter to generate normal maps from height maps
    in the Generic section.
  - Replace old filters with GEGL operation counterparts: edge-neon
    (gegl:edge-neon), contrast-normalize (gegl:stretch-contrast),
    oilify (gegl:oilify)
  - Add gegl:bayer-matrix and gegl:linear-sinusoid to Filters ->
    Render -> Pattern.
  - Add gegl:newsprint to Filters -> Distorts.
  - Add gegl:mean-curvature-blur to Filters -> Blur.

Performance:

  - Add an active-thread variable to the dashboard's misc group,
    showing the number of active worker threads.
  - Reduce time complexity of layer-group translation. When
    translating a layer group, avoid separately updating the original
    area of the child layers before translating them (as per the fix
    to issue #3484), as this results in quadratic time complexity
    w.r.t. to the maximal subgroup nesting level. Instead, simply
    defer the updating of the group's offset until *after* translating
    the child layers, so that their original area isn't clipped by the
    parent, while their new area is still properly updated even if the
    parent's size changes.

User interface:

  - Many mnemonics added in various dialogs.
  - Add a gimp-rotate-image-arbitrary action, and a corresponding
    "Image -> Transform -> Arbitrary Rotation..." menu entry, which
    activates the rotate tool in image mode (similarly to the
    corresponding action for layers).
  - On Windows, minimized GIMP window is now deiconified when GIMP is
    run again (clicking its shortcut or otherwise).

Preferences:

  - New "Swap compression" option: explicit control over the tile-swap
    compression algorithm in GEGL. "Best performance" is used by
    default, "Balanced", "Best compression", and "None" (disables
    compression) are available.

Devel docs:

  - Update the libgimpconfig and libgimpbase docs.
  - Update docs with missing symbols and types.
  - New docs for structs and enums.

Installers:

  - Install 64-bit Python on 64-bit Windows (until now, the installer
    used to install 32-bit Python for all architectures).
  - Windows installer now supports per-user install.

Debugging:

  - New mnemonic-clashes tool to help looking for mnemonic clashes.

Translations:

  - Basque, Brazilian Portuguese, British English, Catalan, Chinese
    (Taiwan), Croatian, Danish, Dutch, French, German, Greek,
    Hungarian, Icelandic, Indonesian, Italian, Latvian, Polish,
    Russian, Slovenian, Spanish, Swedish, Turkish.

Bugfixes:

   - #3630, #3226, #3610, #1725, #3093, #3599, #3597, #3082, #3553, #3435,
     #3503, #3532, #3164, #3560, #3500, #3493, #3514, #3512, #2685, #3641,
     #1002, #360,  #3263, #2221, #3893, #2708, #3100, #2873, #3655, #2206,
     #3341, #3718, #3763, #3112, #3723, #4049, #4068, #3663, #4119, #4008,
     #2837, #3994, #3990, #1283, #2561

Code contributors:

   Alexandre Prokoudine, Ell, Federico Mena Quintero, Jehan, Jernej
   Simončič, Lionel, Massimo Valentini, Michael Natterer, Michael
   Schumacher, Oleksii Samorukov, Sabri Ünal, Sergio Jiménez Herena,
   Thomas Manni, lillolollo, sarah, woob, Øyvind Kolås.

Translators:

   Alan Mortensen, Alexandre Prokoudine, Anders Jonsson, Andika
   Triwidada, Asier Sarasua Garmendia, Balázs Meskó, Balázs Úr, Bruce
   Cowan, Claude Paroz, Daniel Mustieles García, Dimitris Spingos,
   Emin Tufan Çetin, Hannie Dumoleyn, Jordi Mas, Julia Dronova, Julien
   Hardelin, Marco Ciampa, Martin Srebotnjak, Milo Ivir, pesder, Piotr
   Drąg, Rafael Fontenelle, Rodrigo Lledó Milanca, Rūdolfs Mazurs,
   Sabri Ünal, Sveinn í Felli, Tim Sabsch, Zander Brown.


Overview of Changes from GIMP 2.10.10 to GIMP 2.10.12
=====================================================

Core:

  - Add an "Incremental" option to the Dodge/Burn tool, which,
    similarly to the Paintbrush, Pencil, and Eraser tools, applies the
    effect incrementally as the pointer moves.
  - Curves now have a concept of smooth vs corner points: smooth
    points produce a smooth curve, while corner points produce a sharp
    curve (previously, all points were smooth).
  - Search the user font directory path on Windows (since Windows 10,
    non-admin users have the ability to install fonts). This is only a
    temporary hack until fontconfig adds proper upstream support:
    https://gitlab.freedesktop.org/fontconfig/fontconfig/issues/144
  - In gimp_brush_core_get_paint_buffer(), when allocating a new paint
    buffer, clear the old buffer *before* allocating the new one, to
    reduce the amount of simultaneously allocated memory.
  - In GimpPaintbrush, avoid refilling the paint buffer at each dab if
    the paint color/pixmap hasn't changed, hence allowing faster
    painting in some specific cases.
  - Add hygon cpu detection and enable MMX/SSE support.
  - Add a GimpSymmetry::get_transform() virtual function and a
    corresponding gimp_symmetry_get_transform() function which return
    the brush transform corresponding to a given symmetry stroke in
    terms of the rotation angle and reflection flag (in contrast to
    gimp_symmetry_get_operation() which returns the same transforation
    in terms of a GeglNode). This allows us to simplify, fix (artifact
    bugs, etc.), and improve the painting-code performance for several
    symmetry painting cases.
  - New gimp-brush-pipe-spacing parasite set by core code to preserve
    GIH brush's spacing across reloads.
  - Add a new Offset filter tool, as a front-end to gimp:offset. The
    tool replaces, and provides the same interface as the drawable-
    offset dialog while also providing live preview and on-canvas
    interaction.

Plug-ins:

  - Exported profile and data format strategy updated in several file
    plug-ins.

    * When not saving a profile, we always export as sRGB data, as most
      viewers would not display the image properly otherwise.
    * When saving a profile:
        * If a profile was manually assigned, we always export to the
          assigned format, hence pixel data is converted accordingly,
	  whatever the work format.
        * If no profile was assigned:
            * If the export format support high-bit depth, we export the
              work format as-is.
            * If the export format is 8-bit max, we convert the work
              format to sRGB, except if the work format is 8-bit linear.

    The following plug-ins were updated: JPEG, PNG, TIFF and WebP.

  - TIFF plug-in now supports layer export.
  - Add accelerator on "Save color _profile" item in JPEG export so
    that all items in the dialog have keyboard accelerators.
  - Add a "Save color profile" checkbox in WebP export and remove the
    "Advanced Options" expander (all metadata and profile writing
    options are now directly visible).
  - Process cases of non-conformant TIFF file with extra channels
    while ExtraSamples is not set by assuming the first extra channel
    is a non-premultiplied alpha channel and outputting a warning. In
    the future, this should be updated further by a dialog asking what
    to do with the non-defined dialog (consider as premultiplied or
    non-premultiplied alpha channel, or just save as extra channels).

Tools:

  - Add input/output spin-buttons to the Curves tool, which allow
    setting the selected point's coordinates numerically. When the image
    precision is greater than 8-bpc, use a 0.00-100.00 range for the
    point-coordinate spin-buttons instead of a 0-255 range.
  - In the Curves tool, allow changing the curve's point types (cf. new
    curve corner points in Core section). Corner points are displayed
    with a diamond shape instead of a circle.
  - Free Select tool now creates a selection as soon as the polygon is
    closed. This selection is updated when the polygon, or the relevant
    tool-options, change, similarly to GimpRectangleSelectTool.
  - Derive GimpEraser from GimpPaintbrush, instead of directly from
    GimpBrushCore.
    This allows GimpEraser to reuse the paint-buffer content across
    dabs, improving performance.
  - Allow moving an intersecting pair of guides with the Move tool.

User interface:

  - In GimpCurveView, when dragging an existing curve point, don't
    immediately move the point to the cursor position upon button
    press, but rather move it relative to its current position as the
    cursor moves. This allows selecting a point without moving it, and
    adjusting its position more easily.
  - when the cursor hovers above a point in GimpCurveView, or when
    dragging a point, have the coordinate indicator show the point's
    position, rather than the cursor's.
  - In GimpCurveView, when holding down Ctrl while adding/dragging a
    point, snap the y-coordinate to the original curve (at the start
    of the drag). This is particularly useful for adding points along
    the curve.
  - In GimpDashboard, don't show legend for groups with no meter.
  - Add a tile-alloc-total variable to the dashboard's memory and misc
    groups, showing the total amount of memory used by the tile
    allocator.
  - Add a "Save Keyboard Shortcuts Now" button to the Configure
    Keyboard Shortcuts dialog.

Installers:

  - Windows: enable InnoSetup "unofficial" translations. Otherwise we
    had a bunch of wasted work from our translators of several
    languages whose translations were never used in the installer.

Translations:

   - 12 translations were updated: Catalan, Chinese, French, German,
     Hungarian, Indonesian, Italian, Polish, Russian, Spanish, Swedish
     and Turkish.


Overview of Changes from GIMP 2.10.8 to GIMP 2.10.10
====================================================

Core:

  - Add gimp-scratch allocator, a fast memory allocator (on the order of
    magnitude of alloca()), suitable for small (up to a few megabytes),
    short-lived (usually, bound to the current stack-frame) allocations.
    Unlike alloca(), gimp-scratch doesn't use the stack, and is therefore
    safer, and will also serve bigger requests, by falling-back to malloc().
  - In gimp_drawable_transform_buffer_affine(), avoid modifying the
    clipping mode when transforming layer masks, since this function
    is used (among other things) to transform layer masks together with
    their layer, in which case they should use the same clipping mode
    as the layer. This fixes a regression introduced by commit 2ae823ba,
    causing layer masks to be transformed with a mismatched clipping mode
    during layer transforms, leading to discrepencies between the
    transformed layer and the transformed mask.
  - Moved swap/cache and temporary files out the GIMP user config dir and
    added new config file substitutions ${gimp_cache_dir} and
    ${gimp_temp_dir}.
  - Pass the GEGL tile-cache size, swap path, and thread-count to plug-ins
    as part of their config, and have libgimp set the plug-in's GeglConfig
    accordingly upon initialization.
  - Layer groups are now rendered in bigger chunks rather than tile-by-tile
    (which used to pretty much eliminate multithreading for groups), which
    improves the rendering speed.
  - Make saving/exporting files more robust to errors. In particular if
    an error occurs during the process (be it a bug, a memory error, or
    anything else), GIMP won't overwrite anymore any existing file with
    incomplete contents, so that you won't end up with no valid files at
    all.
  - Fix a regression on support of various graphics tablet.
  - Remove the "Edit -> Fade..." feature: it makes GIMP use two buffers
    instead of one (east into system resources), it's broken in 2.10, and
    we can make the UX better for filters.
  - New generic canvas modifier 'Alt + middle click' allowing to pick
    layers by clicking on pixels. The available layers will be looped
    through (starting from the upper one) while Alt key is hold and the
    picked layer name will be temporarily displayed in the status bar.
  - When clearing a channel, do nothing if the channel is already empty;
    otherwise, align the cleared rectangle to the channel buffer's tile
    grid, so that all affected tiles are dropped, rather than zeroed.
    Furthermore, only update the affected region of the channel.
  - Brush and pattern saving logics has been moved to core code (instead
    of plug-in).
  - Clipboard brushes and pattern can now be duplicated.
  - Parametric brushes are now 32-bit float to avoid posterization on
    large brushes.
    Note: raster brushes are still 8-bit and plug-ins only have access
    to 8-bit versions of high-precision brushes/patterns. New API will
    be required to handle high-precision data.
  - On-canvas preview while editing a color in the colormap of an
    indexed image.

User interface:

  - Enabled HiDPI/Retina support for the GTK2/OSX build, fixes blurry icons. 
  - Add a tooltip to the "better compression" checkbox in save dialog to
    make it clearer it does not mean that the file size is necessarily
    smaller in every cases. In particular some best/worst case are
    possible when an algorithm less efficient in general may end up
    better on a particular image.
  - Add basic support for cursors with a scale factor of 2 for HiDPI
    (artwork to be updated).
  - Foreground and background color icons, as well as color history will
    now display out-of-gamut warning on indexed images for colors
    outside of the palette, as well as on grayscale images, for non-gray
    colors.
  - Pack color picker and hexadecimal entry on same line in Color dock.
  - Add an "Open as Image" button to the brushes dialog.

Usability:

  - Attempting to transform locked layers or paint on them now results in
    blinking around the status bar (where the warning message is displayed)
    and around the toolbar where lock toggles are. The same applies to
    attempting to move a selection where there is none — GIMP will blink
    around the toolbar where the moving target (layer, selection, path)
    is chosen.
  - GIMP now allows selecting default export file type for new projects.
    The choice is limited to PNG, JPEG, WebP, PSD, ORA, TIFF, BMP.
  - GimpSpinScale widget now has an optional feature to constrain the
    value to integer when dragging with a pointer (even if the scale
    allows for fractional numbers), set with new function
    gimp_spin_scale_set_constrain_drag().
    This is useful for settings where fractional numbers are technically
    possible, yet most common use case are with integers (such as pixel
    sizes, angles in degrees, etc.) so you want the easy interface to be
    constrained. Fractional numbers are still settable, for instance by
    keyboard edit; and arrow incrementation won't drop fraction parts.
    This is currently only activated for brush options in paint tools.

Tools:

  - In scale tool, scale around center even when using numeric input.
  - New algorithm in the Bucket Fill tool when selecting the affected
    area "Fill by line art detection", based off the G'Mic algorithm for
    "smart colorization": https://hal.archives-ouvertes.fr/hal-01891876
    In a few words, it identifies painted pixels (either based on
    grayscale or opacity values) and tries to close line arts to allow
    filling even with not perfectly closed zones; the second step of the
    algorithm will flood the colors under line art pixels to prevent
    "holes" in the filling.
    It is possible to control a max size (in pixels) for the flooding,
    as well as max length of closing segments and splines.
  - The Bucket Fill tool got new interaction allowing to hold the click
    and move the mouse to fill based on several seed zones (for "Fill
    by line art detection" as well as "Fill similar colors"). You can
    now cancel the fill in progress with right click as in other tools.
  - The Bucket Fill tool now allows color picking with ctrl-click, same
    as every painting tool. It will pick either the foreground or
    background color depending on the selected Fill Type. The ctrl-alt
    modifier combination is also possible to pick the non-Fill Type
    color.
  - In the Bucket Fill tool, the Alt modifier will now switch to
    "FG color fill" when "Pattern fill" was set (instead of doing
    nothing).
  - In the Unified Transform tool, default to preserving aspect ratio
    when scaling up or down.
  - In the Healing tool, "Sample merged" now also work for the target
    pixels, allowing to draw in empty layers.
  - Selection by color is now parallelized, hence improving speed of the
    Select by Color tool (and any other processing which may share this
    piece of code now or in the future).
  - Add "Constrain handles" and "Around center" options to the
    perspective-transform tool's GUI, which are similar to the
    corresponding options of the unified-transform tool.
  - Improve color picking on indexed image to always select an indexed
    color corresponding to the picked pixel in the colormap.

Plug-ins:

  - file-pdf-save GUI now clearly indicates the order the layers will be
    used to make multi-page PDFs.
  - Add DDS loading/exporting plug-in originally developed by Shawn Kirst
    and Arne Reuter.
  - Rename the Guillotine plug-in to Slice Using Guides.
  - Add a new option saving a color profile when exporting PNG, JPEG, TIFF.
    Always save it when exporting to PSD.
  - Remove the "Advanced" expanders from the PNG and TIFF export dialogs.
  - Full rewrite of the Spyrogimp plug-in with much more options and
    better interaction.
  - Indexed TIFF with alpha channel now supported.

Filters:

  - Add on-canvas GUI (simple lines) for circular, linear, and zoom motion
    blur.

Help:

  - Link to the bugtracker directly from the Help menu, also link to the
    wiki and the roadmap. Remove the link to currently disabled
    registry.gimp.org.

Installers:

  - Windows: proper fix for libthai to stop GIMP from crashing in the
    Thai locale. 

Translations:

  - Czech, Danish, French, Italian, Japanese, Marathi, Polish, Russian,
    Spanish, Swedish, Ukrainian.

Build:

  - Bumping GTK+ dependency to the micro update GTK+ 2.24.32 to handle
    several bugs on Windows (broken shortcuts on non-latin layouts and
    broken vector icons).


Overview of Changes from GIMP 2.10.6 to GIMP 2.10.8
===================================================

Core:

  - Use adaptive chunk size in GimpProjection when rendering the
    projection asynchronously, rather than using a fixed chunk size.
    This provides a better trade-off between throughput and
    responsiveness dynamically, based on how fast the processing is.
  - Add xyY color space to the color spaces for sampling colors.

Tools:

  - In all selection tools, show error on attempt to
    subtract-from/intersect-with empty selection.
  - Fix text along path not working with vertical text.
  - Fix Text tool's frame position when undoing a move operation.
  - Streamline Text tool's drawing blocking/unblocking logic.
  - When moving a text layer using the text tool (through alt+drag),
    don't change the layer's box mode to "fixed", which is unnecessary,
    since the layer's size isn't affected.
  - Transform and deformation operations now maintain color for fully
    transparent pixels, making unerase and curves manipulation of alpha
    channel more reliable.
  - All transform tools now apply changes when you save or export/overwrite
    an image without pressing Enter first to confirm changes.
  - Heal, Dodge/Burn, Smudge, and Convolve tools now adjust the processed
    buffer and mask_buffer regions according to the changes made to the
    application region, as calculated by intersecting it with the
    drawable and mask extents. This fixes wrong application position
    when painting on a drawable whose origin is above/to the left of the
    image's origin, and there's a selection active.
  - New type of gradient interpolation called 'Step' for making multi-color
    hard-edge gradient fills.

Plug-ins:

  - Port all plug-ins to the new iterator API in GEGL.
  - Improve automatic detection of HEIC/HEIF files.
  - Improve RawTherapee discovery by looking up registry key (should
    become useful with RawTherapee 5.5 and more).

Usability and UI:

  - Compatibility information in the Save dialog is now more understandable.
    The minimum GIMP version for the XCF file is always written down when it
    is GIMP 2.8 or over. The list of features warranting the minimum version
    is now listed in an expander container rather than as tooltip, which
    makes it more discoverable. The warning on compression is now displayed
    as its own text under the checkbox and not as additional text to the
    minimum GIMP version label.
  - In all themes, fix the color of selected text, while editing a tree-view's
    item text (such as when renaming a layer), by overriding tree-view
    specific styling with the global text-entry style, for nested text entries
    inside tree-views. The text would previously use the same color as the
    selection background, making it unreadable.
  - Add option in the Windows menu to hide the image tab bar.

CLI:

  - New self-explanatory --enable-win32-debug-console CLI option

Debugging:

  - New GimpBacktrace API provides an interface for creating and
    traversing multi-threaded backtraces, as well as querying symbol
    information. Backends are available for Linux and Windows.
  - Performance log recording now available in the Dashboard dock.
    The log contains a series of samples of the dashboard variables,
    as well as the full program backtrace, when available. As such,
    it essentially acts as a built-in profiler, which allows us to
    correlate program execution with the information available
    through the Dashboard.
  - New performance-log-expand.py tool decodes a delta-encoded
    performance log by expanding the deltas, producing a log where
    each sample (and other relevant elements) contain complete
    information. The structure of expanded logs is identical to that
    of delta-encoded logs, the expanded log simply has no deltas.
  - New performance-log-resolve.py tool resolves symbol information
    in backtraces. The logs produced by GIMP only specify the program
    counter at each stack frame, providing an address-map to map
    program-counter addresses to actual symbols separately. This tool
    looks up each program-counter address in the address map,
    incorporating the relevant symbol information directly into the
    backtrace.
  - New performance-log-deduce.py tool that statistically deduces the
    correct thread states based on backtrace address frequency, fixing
    local inaccuracies.
  - New performance-log-viewer.py tool that is a viewer for GIMP
    performance logs, with a sample-selection area at the top and an
    information area at the bottom. The sample-selection area visualizes
    the sampled variables and markers using a simultaneous set of plots,
    and displays the currently selected samples. The information area
    shows global information stored in the log, as well as information
    specific to the currently selected samples, including variable listing
    and statistics, full backtrace, and profile/call-graph information.

Translations:

  - Updated translations: Danish, Dutch, Finnish, German, Hungarian,
    Italian, Marathi, Polish, Portuguese (Brazil), Russian, Spanish,
    Swedish, Ukrainian.


Overview of Changes from GIMP 2.10.4 to GIMP 2.10.6
===================================================

Core:

  - Render drawable previews asynchronously.
  - Merge the file view filter and file format lists in GimpFileDialog.
    The presence of 2 lists was very confusing.
  - DLL search priority is now updated before running a plug-in on
    Windows, depending on the executable bitness. This gets rid of one
    of the last remnant of DLL hell in GIMP, which was when running
    32-bit plug-ins from a 64-bit build of GIMP.

Filters:

  - New "Little Planet" (gegl:stereographic-projection) filter.
  - New "Long Shadow" (gegl:long-shadow) filter.

Tools:

  - Halt the Measure tool after straightening.
  - Add an "orientation" option to the measure tool, corresponding to
    the "orientation" property of GimpToolCompass (i.e., it controls the
    orientation against which the angle is measured, when not in 3-
    point mode.)  The orientation is "auto" by default, so that the
    angle is always <= 45 deg.  Note that the "orientation" option
    affects the tool's "straighten" function, so that the layer is
    rotated toward the current orientation.
  - Text layers can now represent vertical texts, with 4 variants:
    left-to-right and right-to-left lines, and forcing all characters to
    be upright or following Unicode's vertical orientation property.
    See also:
    * https://www.unicode.org/reports/tr50/
    * http://www.unicode.org/Public/UCD/latest/ucd/VerticalOrientation.txt

User Interface:

  - The Dashboard dockable dialog now has an "async" field to the
    dashboard's "misc" group, showing the number of async operations
    currently in the "running" state.
  - New Preferences option to enable/disable layer-group previews, since
    these can get quite time-expensive.

Translations:

  - New language: Marathi
  - 12 translations were updated: Brazilian Portuguese, Dutch, French,
    German, Greek, Italian, Latvian, Polish, Romanian, Slovenian,
    Spanish, Swedish.

Build:

  - Add --with-win32-32bit-dll-folder configuration option to override
    the folder where 32-bit versions of DLL will be installed (default:
    32/bin/).
  - Install all plug-ins in their own directories. Unlike on master,
    this is not mandatory to do so, but it would protect our core
    plug-ins against any DLL installed directly under plug-ins/ by
    third-party plug-ins (cf. Windows DLL hell).


Overview of Changes from GIMP 2.10.2 to GIMP 2.10.4
===================================================

Core:

  - Remove gimp_display_shell_draw_background() and all clipping hacks
    for drawing the canvas background. This optimizes away one entire
    step of drawing of image size, for each expose.
  - Font loading does not block startup anymore. Only consequence is
    that the Text tool may not be usable immediately if fonts are not
    fully loaded yet (and will output an appropriate error if you do
    so). All non-text related activities can be performed right away.
  - Change of the URL from bugzilla to gitlab where appropriate.
  - New tool option manager to better keep track of user context and
    paint options in a consistent manner.

User Interface:

  - The Dashboard dockable dialog now has a 'Memory' group that shows
    memory-usage information: the currently used memory size, the
    available physical memory size, and the total physical memory
    size.  It can also show the tile-cache size, for comparison
    against the other memory stats. Note that the upper-bound of the
    meter is the physical memory size, so the memory usage may be over
    100% when GIMP uses the swap.
  - The Dashboard dockable dialog now has "read" and "written" fields in
    the dashboard swap group, which report the total amount of data
    read-from/written-to the tile swap, respetively. Additionally, the
    swap busy indicator (used as the meter's LED) has been improved,
    so that it's active whenever data has been read-from/written-to
    the swap during the last sampling interval, rather than at the
    point of sampling.
  - Fonts can now be tagged. The user interface is the same as for
    brushes, patterns etc.
  - Some icons fixed: larger spacing between broken chains and
    gimp-tool-ellipse-select made symmetrical.

Usability:

  - When a plug-in cannot be applied to an image because of mismatch
    in image types (e.g. layer has no alpha or image is greyscale),
    GIMP now displays a message listing supported image types for this
    plug-in.

Tools:

  - The Measurement tool now has an "Auto straighten" option allowing
    to rotate the active drawable (layer, channel…) so that the
    measurement line is used as horizon. As other transform tools, the
    feature will work on linked drawables as well.
  - The Smudge tool now paints correctly on images with a color
    profile other than the GIMP's built-in one.

Build:

  - Installer: set compatibility options to run Python plugins in
    HiDPI-aware mode.
  - Put back compatibility DLLs for really old plugins.
  - Install binary tool `gimp-test-clipboard` on the system to allow
    people to help us debug clipboard bugs.
  - --enable-bundled-mypaint-brushes renamed
    --enable-relocatable-bundle and also make WMF fonts looked up on
    the runtime prefix of GIMP (instead of the build-time path) when
    this build option was set.
  
Plug-ins:

  - gimptool-2.0 binary now accepts source files with non-standard
    extensions if it can try to guess appropriate language from the
    compiler being used. It will also properly quote arguments for
    shell usage.
  - Run explicitly Python 2 as Python plug-in interpreter to prevent
    breakage on systems where Python 3 is the default.
  - raw_input()'s argument in Python console is now optional, and
    input() support has been added.

File Formats:

  - The PSD loader now provides an option to load "merged",
    pre-composited version of the images that becomes available when a
    PSD file was saved with "Maximize Compatibility" option enabled in
    Photoshop. This is useful when loading PSD files that use features
    that GIMP doesn't currently support, and therefore can't render
    correctly, such as adjustment layers. When loading the merged
    image version, we avoid loading certain additional data from the
    file, such as channels, paths, and guides, while still loading
    metadata. This option is currently exposed as an additional file
    type ("Photoshop image (merged)"), which has to be explicitly
    selected from the file-type list when opening the image.
  - Embedding GIMP's built-in sRGB color profile to exported files is
    now optional. The default choice can be set in the Preferences
    dialog.

Translations:

  - Updated translations: Catalan, Czech, Danish, Dutch, Finnish,
    Greek, Hungarian, Italian, Latvian, Polish, Romanian, Russian,
    Spanish, Swedish, Ukrainian.


Overview of Changes from GIMP 2.10.0 to GIMP 2.10.2
===================================================

Core:

  - Discard fonts which fail to load and popup an info dialog to allow
    people debug their fonts.
  - New API to suppress updates in UI until plug-ins are done
    introducing changes.
  - New API to calculate histograms in separate threads, with possible further
    extension to handle similar cases elsewhere in GIMP.
  - Tool options are now properly saved and reloaded per-device at
    startup.

Plug-ins:

  - New plug-in for importing and exporting HEIF images.
  - Enable visibility of rasterized vector layer from PSD.
  - Single-window screenshots in Windows fixed to correctly snap a
    window even when it is partly off-screen or covered by another
    window or when display scaling is not set to 100%.

Filters:

  - New Spherize filter to wrap an image around a spherical cap
  - New Recursive Transform filter to create Droste effect.

Usability:

  - Warn users, when alpha-only painting has no effect. E.g. when target
    drawable doesn't have an alpha channel, or the alpha channel is locked.
  - Make the splash texts dynamic, so they are larger on larger splashes.
  - Mention pressing Enter to complete Foreground selection in the status bar.
  - Make sure that clicking outside any selection prevents Rectangle Select
    and Ellipse Select tools from creating empty selections.
  - Improve mouse wheel zooming behavior to keep the same point
    centered under the pointer even if the image is completely visible
    in the canvas.
  - Add "View -> Center Image in Window" (Shift+J) as a quick way to
    center the image at any zoom level.

Translations:

  - Updated translations: Catalan, Danish, Dutch, French, German, Greek,
    Hungarian, Icelandic, Italian, Latvian, Polish, Russian, Spanish,
    Swedish, Ukrainian.
  - New translation of Windows installer: Chinese (Taiwan)

Build:

  - Add a --with-bug-report-url configure option allowing packagers to
    set the address of their own bug tracker. This address will be the
    one opened by the debug dialog for reporting bugs.
  - Add a flatpak manifest for the gtk3-port branch.
  - Remove the possibility to disable script-fu.
  - Add a --with-icc-directory configure option to customize the color
    profile directory. By default, it is set to the common path
    /usr/share/color/icc.

Documentation:

  - Updating the description of the XCF format "devel-docs/xcf.txt", for
    third-party readers wishing to support GIMP 2.10 XCF files.
  - Add documentation skeletons for all enums in libgimpbase/, there is
    much room for improvement.
