pdb, libgimp, app: add gimp_drawable_get_thumbnail_format()

so plug-ins can allocate buffers and stuff before getting the actual
thumbnail data.

app/pdb/drawable-cmds.c

@@ -90,6 +90,36 @@ drawable_get_format_invoker (GimpProcedure         *procedure,
   return return_vals;
 }
 
+static GimpValueArray *
+drawable_get_thumbnail_format_invoker (GimpProcedure         *procedure,
+                                       Gimp                  *gimp,
+                                       GimpContext           *context,
+                                       GimpProgress          *progress,
+                                       const GimpValueArray  *args,
+                                       GError               **error)
+{
+  gboolean success = TRUE;
+  GimpValueArray *return_vals;
+  GimpDrawable *drawable;
+  gchar *format = NULL;
+
+  drawable = gimp_value_get_drawable (gimp_value_array_index (args, 0), gimp);
+
+  if (success)
+    {
+      format = g_strdup (babl_format_get_encoding (gimp_drawable_get_preview_format (drawable)));
+
+    }
+
+  return_vals = gimp_procedure_get_return_values (procedure, success,
+                                                  error ? *error : NULL);
+
+  if (success)
+    g_value_take_string (gimp_value_array_index (return_vals, 1), format);
+
+  return return_vals;
+}
+
 static GimpValueArray *
 drawable_type_invoker (GimpProcedure         *procedure,
                        Gimp                  *gimp,
@@ -994,6 +1024,37 @@ register_drawable_procs (GimpPDB *pdb)
   gimp_pdb_register_procedure (pdb, procedure);
   g_object_unref (procedure);
 
+  /*
+   * gimp-drawable-get-thumbnail-format
+   */
+  procedure = gimp_procedure_new (drawable_get_thumbnail_format_invoker);
+  gimp_object_set_static_name (GIMP_OBJECT (procedure),
+                               "gimp-drawable-get-thumbnail-format");
+  gimp_procedure_set_static_strings (procedure,
+                                     "gimp-drawable-get-thumbnail-format",
+                                     "Returns the drawable's thumbnail Babl format",
+                                     "This procedure returns the drawable's thumbnail Babl format.\n"
+                                     "Thumbnails are always 8-bit images, see 'gimp-drawable-thumbnail' and 'gimp-drawable-sub-thmbnail'.",
+                                     "Michael Natterer <mitch@gimp.org>",
+                                     "Michael Natterer",
+                                     "2019",
+                                     NULL);
+  gimp_procedure_add_argument (procedure,
+                               gimp_param_spec_drawable_id ("drawable",
+                                                            "drawable",
+                                                            "The drawable",
+                                                            pdb->gimp, FALSE,
+                                                            GIMP_PARAM_READWRITE));
+  gimp_procedure_add_return_value (procedure,
+                                   gimp_param_spec_string ("format",
+                                                           "format",
+                                                           "The drawable's thumbnail Babl format",
+                                                           FALSE, FALSE, FALSE,
+                                                           NULL,
+                                                           GIMP_PARAM_READWRITE));
+  gimp_pdb_register_procedure (pdb, procedure);
+  g_object_unref (procedure);
+
   /*
    * gimp-drawable-type
    */

app/pdb/internal-procs.c

@@ -28,7 +28,7 @@
 #include "internal-procs.h"
 
 
-/* 734 procedures registered total */
+/* 735 procedures registered total */
 
 void
 internal_procs_init (GimpPDB *pdb)

libgimp/gimp.def

@@ -212,6 +212,7 @@ EXPORTS
 	gimp_drawable_get_sub_thumbnail_data
 	gimp_drawable_get_thumbnail
 	gimp_drawable_get_thumbnail_data
+	gimp_drawable_get_thumbnail_format
 	gimp_drawable_get_tile
 	gimp_drawable_has_alpha
 	gimp_drawable_height

libgimp/gimpdrawable.c

@@ -437,3 +437,24 @@ gimp_drawable_get_format (gint32 drawable_ID)
 
   return format;
 }
+/**
+ * gimp_drawable_get_thumbnail_format:
+ * @drawable_ID: the ID of the #GimpDrawable to get the thumbnail format for.
+ *
+ * Returns the #Babl thumbnail format of the drawable.
+ *
+ * Return value: The #Babl thumbnail format.
+ *
+ * Since: 2.10.14
+ */
+const Babl *
+gimp_drawable_get_thumbnail_format (gint32 drawable_ID)
+{
+  const Babl *format     = NULL;
+  gchar      *format_str = _gimp_drawable_get_thumbnail_format (drawable_ID);
+
+  if (format_str)
+    format = babl_format (format_str);
+
+  return format;
+}

libgimp/gimpdrawable.h

@@ -46,6 +46,7 @@ GeglBuffer   * gimp_drawable_get_buffer             (gint32         drawable_ID)
 GeglBuffer   * gimp_drawable_get_shadow_buffer      (gint32         drawable_ID);
 
 const Babl   * gimp_drawable_get_format             (gint32         drawable_ID);
+const Babl   * gimp_drawable_get_thumbnail_format   (gint32         drawable_ID);
 
 GIMP_DEPRECATED_FOR(gimp_drawable_get_buffer)
 GimpDrawable * gimp_drawable_get                    (gint32         drawable_ID);

libgimp/gimpdrawable_pdb.c

@@ -71,6 +71,40 @@ _gimp_drawable_get_format (gint32 drawable_ID)
   return format;
 }
 
+/**
+ * _gimp_drawable_get_thumbnail_format:
+ * @drawable_ID: The drawable.
+ *
+ * Returns the drawable's thumbnail Babl format
+ *
+ * This procedure returns the drawable's thumbnail Babl format.
+ * Thumbnails are always 8-bit images, see gimp_drawable_thumbnail()
+ * and gimp_drawable_sub_thmbnail().
+ *
+ * Returns: The drawable's thumbnail Babl format.
+ *
+ * Since: 2.10.14
+ **/
+gchar *
+_gimp_drawable_get_thumbnail_format (gint32 drawable_ID)
+{
+  GimpParam *return_vals;
+  gint nreturn_vals;
+  gchar *format = NULL;
+
+  return_vals = gimp_run_procedure ("gimp-drawable-get-thumbnail-format",
+                                    &nreturn_vals,
+                                    GIMP_PDB_DRAWABLE, drawable_ID,
+                                    GIMP_PDB_END);
+
+  if (return_vals[0].data.d_status == GIMP_PDB_SUCCESS)
+    format = g_strdup (return_vals[1].data.d_string);
+
+  gimp_destroy_params (return_vals, nreturn_vals);
+
+  return format;
+}
+
 /**
  * gimp_drawable_type:
  * @drawable_ID: The drawable.

libgimp/gimpdrawable_pdb.h

@@ -33,6 +33,7 @@ G_BEGIN_DECLS
 
 
 G_GNUC_INTERNAL gchar*   _gimp_drawable_get_format           (gint32                      drawable_ID);
+G_GNUC_INTERNAL gchar*   _gimp_drawable_get_thumbnail_format (gint32                      drawable_ID);
 GimpImageType            gimp_drawable_type                  (gint32                      drawable_ID);
 GimpImageType            gimp_drawable_type_with_alpha       (gint32                      drawable_ID);
 gboolean                 gimp_drawable_has_alpha             (gint32                      drawable_ID);

pdb/groups/drawable.pdb

@@ -307,6 +307,38 @@ CODE
     );
 }
 
+sub drawable_get_thumbnail_format {
+    $blurb = "Returns the drawable's thumbnail Babl format";
+
+    $help = <<'HELP';
+This procedure returns the drawable's thumbnail Babl format.
+
+Thumbnails are always 8-bit images, see gimp_drawable_thumbnail() and
+gimp_drawable_sub_thmbnail().
+HELP
+
+    &mitch_pdb_misc('2019', '2.10.14');
+
+    @inargs = (
+	{ name => 'drawable', type => 'drawable',
+	  desc => 'The drawable' }
+    );
+
+    @outargs = (
+	{ name => 'format', type => 'string', wrap => 1,
+	  desc => "The drawable's thumbnail Babl format" }
+    );
+
+    %invoke = (
+	code => <<'CODE'
+{
+  format = g_strdup (babl_format_get_encoding (gimp_drawable_get_preview_format (drawable)));
+
+}
+CODE
+    );
+}
+
 sub drawable_type {
     $blurb = "Returns the drawable's type.";
     $help  = "This procedure returns the drawable's type.";
@@ -994,6 +1026,7 @@ CODE
               "gimp-intl.h");
 
 @procs = qw(drawable_get_format
+            drawable_get_thumbnail_format
             drawable_type
             drawable_type_with_alpha
             drawable_has_alpha