app, libgimp, pdb: add GimpLinkLayer base API.

Still more to be done, but this is the basic, working API.

pdb/app.pl

@@ -391,6 +391,16 @@ gimp_param_spec_vector_layer ("$name",
                               "$blurb",
                               $none_ok,
                               $flags)
+CODE
+    }
+    elsif ($pdbtype eq 'link_layer') {
+	$none_ok = exists $arg->{none_ok} ? 'TRUE' : 'FALSE';
+	$pspec = <<CODE;
+gimp_param_spec_link_layer ("$name",
+                            "$nick",
+                            "$blurb",
+                            $none_ok,
+                            $flags)
 CODE
     }
     elsif ($pdbtype eq 'layer') {

pdb/groups.pl

@@ -1,18 +1,18 @@
 # This file is autogenerated
 @groups = qw(
-    brush
     brush_select
+    brush
     brushes
     buffer
     channel
     context
     debug
     display
-    drawable
     drawable_color
     drawable_edit
     drawable_filter
     drawable_select
+    drawable
     dynamics
     edit
     file
@@ -22,12 +22,11 @@
     fonts
     gimp
     gimprc
-    gradient
     gradient_select
+    gradient
     gradients
     group_layer
     help
-    image
     image_autocrop
     image_color_profile
     image_convert
@@ -37,17 +36,19 @@
     image_select
     image_transform
     image_undo
-    item
+    image
     item_transform
+    item
     layer
+    link_layer
     message
     paint_tools
-    palette
     palette_select
+    palette
     palettes
     path
-    pattern
     pattern_select
+    pattern
     patterns
     pdb
     plug_in

pdb/groups/item.pdb

@@ -248,6 +248,42 @@ CODE
     );
 }
 
+sub item_id_is_link_layer {
+    $blurb = 'Returns whether the item ID is a link layer.';
+
+    $help = <<'HELP';
+This procedure returns %TRUE if the specified item ID is a link layer.
+
+
+*Note*: in most use cases, you should not use this function. See
+[func@Gimp.Item.id_is_layer] for a discussion on alternatives.
+HELP
+
+    &jehan_pdb_misc('2025', '3.2');
+
+    @inargs = (
+        { name => 'item_id', type => 'int32',
+	  desc => 'The item ID' }
+    );
+
+    @outargs = (
+        { name => 'text_layer', type => 'boolean',
+	  desc => 'TRUE if the item is a text layer, FALSE otherwise.' }
+    );
+
+    %invoke = (
+        code => <<'CODE'
+{
+  GimpItem *item = gimp_item_get_by_id (gimp, item_id);
+
+  text_layer = (GIMP_IS_LAYER (item) &&
+                ! gimp_item_is_removed (item) &&
+                gimp_item_is_link_layer (item));
+}
+CODE
+    );
+}
+
 sub item_id_is_channel {
     $blurb = 'Returns whether the item ID is a channel.';
 
@@ -1090,6 +1126,7 @@ CODE
 
 @headers = qw("core/gimpgrouplayer.h"
               "core/gimplayermask.h"
+              "core/gimplinklayer.h"
               "core/gimplist.h"
               "core/gimpselection.h"
               "path/gimppath.h"
@@ -1105,6 +1142,7 @@ CODE
             item_id_is_text_layer
             item_id_is_vector_layer
             item_id_is_group_layer
+            item_id_is_link_layer
             item_id_is_channel
             item_id_is_layer_mask
             item_id_is_path

pdb/groups/link_layer.pdb

@@ -0,0 +1,225 @@
+# GIMP - The GNU Image Manipulation Program
+# Copyright (C) 1995 Spencer Kimball and Peter Mattis
+
+# New Link Layer PDB API
+# Copyright (C) 2025 Jehan
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+
+sub link_layer_new {
+    $blurb = 'Creates a new link layer.';
+
+    $help = <<'HELP';
+This procedure creates a link layer monitoring the specified @file.
+
+
+The new layer still needs to be added to the image as this is not
+automatic. Add the new layer with the [method@Image.insert_layer]
+method.
+
+
+The arguments are kept as simple as necessary for the basic case. All
+link attributes, however, can be modified with the appropriate
+`gimp_link_layer_set_*()` procedures.
+HELP
+
+    &jehan_pdb_misc('2025', '3.2');
+
+    @inargs = (
+        { name => 'image', type => 'image',
+          desc => 'The image' },
+        { name => 'file', type => 'file',
+          desc => 'The file this link layer will monitor' }
+    );
+
+    @outargs = (
+        { name => 'layer', type => 'link_layer',
+          desc => 'The new link layer. The object belongs to libgimp and you should not free it.' }
+    );
+
+    %invoke = (
+        code => <<'CODE'
+{
+  if (file == NULL)
+    {
+      g_set_error (error, GIMP_PDB_ERROR, GIMP_PDB_ERROR_INVALID_ARGUMENT,
+                   _("Failed to create link layer"));
+
+      success = FALSE;
+    }
+
+  if (success)
+    {
+      GimpLink *link;
+
+      link = gimp_link_new (gimp, file, 0, 0, TRUE, NULL, error);
+
+      if (link == NULL)
+        {
+          success = FALSE;
+        }
+      else
+        {
+          layer = GIMP_LINK_LAYER (gimp_link_layer_new (image, link));
+
+          if (! layer)
+            {
+              g_set_error (error, GIMP_PDB_ERROR, GIMP_PDB_ERROR_INVALID_ARGUMENT,
+                           _("Failed to create link layer"));
+
+              success = FALSE;
+            }
+        }
+
+      g_clear_object (&link);
+    }
+}
+CODE
+    );
+}
+
+sub link_layer_discard {
+    $blurb = 'Discard the link layer information.';
+
+    $help = <<'HELP';
+Discards the link information. This makes the layer behave like a normal layer.
+HELP
+
+    &jehan_pdb_misc('2025', '3.2');
+
+    @inargs = (
+        { name => 'layer', type => 'link_layer',
+          desc => 'The link layer' }
+    );
+
+    %invoke = (
+        code => <<'CODE'
+{
+  gimp_link_layer_discard (layer);
+}
+CODE
+    );
+}
+
+sub link_layer_monitor {
+    $blurb = 'Retrieve the link layer information.';
+
+    $help = <<'HELP';
+Retrieve the link information. This makes the layer behave like a link
+layer after the link information has been discarded.
+
+Since the source file will be monitored again, it may change the layer's render.
+HELP
+
+    &jehan_pdb_misc('2025', '3.2');
+
+    @inargs = (
+        { name => 'layer', type => 'link_layer',
+          desc => 'The link layer' }
+    );
+
+    %invoke = (
+        code => <<'CODE'
+{
+  gimp_link_layer_monitor (layer);
+}
+CODE
+    );
+}
+
+sub link_layer_get_file {
+    $blurb = 'Get the monitored file.';
+
+    $help = <<'HELP';
+This procedure returns the file which is being monitored.
+HELP
+
+    &jehan_pdb_misc('2025', '3.2');
+
+    @inargs = (
+        { name => 'layer', type => 'link_layer',
+          desc => 'The link layer' }
+    );
+
+    @outargs = (
+        { name => 'file', type => 'file',
+          desc => 'The monitored file' }
+    );
+
+    %invoke = (
+        code => <<'CODE'
+{
+  file = gimp_link_get_file (gimp_link_layer_get_link (layer), NULL, NULL);
+}
+CODE
+    );
+}
+
+sub link_layer_set_file {
+    $blurb = 'Set the monitored file.';
+
+    $help = <<'HELP';
+This procedure sets the file to be monitored.
+It may change the layer's render.
+HELP
+
+    &jehan_pdb_misc('2025', '3.2');
+
+    @inargs = (
+        { name => 'layer', type => 'link_layer',
+          desc => 'The link layer' },
+        { name => 'file', type => 'file',
+          desc => 'The file to monitor' }
+    );
+
+    %invoke = (
+        code => <<'CODE'
+{
+  GimpLink *link = gimp_link_new (gimp, file, 0, 0, TRUE, NULL, error);
+
+  if (link)
+    {
+      gimp_link_layer_set_link (layer, link, TRUE);
+    }
+  else
+    {
+      success = FALSE;
+    }
+
+  g_clear_object (&link);
+}
+CODE
+    );
+}
+
+@headers = qw("core/gimplink.h"
+              "core/gimplinklayer.h"
+              "gimppdberror.h"
+              "gimp-intl.h");
+
+@procs = qw(link_layer_new
+            link_layer_discard
+            link_layer_monitor
+            link_layer_get_file
+            link_layer_set_file);
+
+%exports = (app => [@procs], lib => [@procs]);
+
+$desc = 'Link layer procedures';
+$doc_title = 'gimplinklayer';
+$doc_short_desc = 'Functions for querying and manipulating link layers.';
+$doc_long_desc = 'Functions for querying and manipulating link layers.';
+
+1;

pdb/meson.build

@@ -42,6 +42,7 @@ pdb_names = [
   'item_transform',
   'item',
   'layer',
+  'link_layer',
   'message',
   'paint_tools',
   'palette_select',

pdb/pdb.pl

@@ -383,6 +383,18 @@ package Gimp::CodeGen::pdb;
 		     take_value_func => 'g_value_set_object ($value, $var)',
 		     headers         => [ qw("path/gimpvectorlayer.h") ] },
 
+    link_layer  => { name            => 'LINK_LAYER',
+		     gtype           => 'GIMP_TYPE_LINK_LAYER',
+		     type            => 'GimpLinkLayer *',
+		     const_type      => 'GimpLinkLayer *',
+		     init_value      => 'NULL',
+		     out_annotate    => '(transfer none)',
+		     get_value_func  => '$var = g_value_get_object ($value)',
+		     dup_value_func  => '$var = GIMP_VALUES_GET_LINK_LAYER ($value)',
+		     set_value_func  => 'g_value_set_object ($value, $var)',
+		     take_value_func => 'g_value_set_object ($value, $var)',
+		     headers         => [ qw("core/gimplinklayer.h") ] },
+
     group_layer => { name            => 'GROUP_LAYER',
 		     gtype           => 'GIMP_TYPE_GROUP_LAYER',
 		     type            => 'GimpGroupLayer *',