[gimp] libgimp: add the concept of "argument sync" to GimpProcedure

[Michael Natterer <mitch src gnome org>]

commit 5a235fae69dcc908b8bec8b46a2f77e7b12d7e74
Author: Michael Natterer <mitch gimp org>
Date:   Mon Jun 15 22:55:58 2020 +0200

    libgimp: add the concept of "argument sync" to GimpProcedure
    
    which can be set to GIMP_ARGUMENT_SYNC_NONE (the default) or
    GIMP_ARGUMENT_SYNC_PARASITE, which indicates that the argument should
    be synced with an image parasite of the same name.

 libgimp/gimp.def        |  2 ++
 libgimp/gimpprocedure.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++
 libgimp/gimpprocedure.h | 24 ++++++++++++++
 3 files changed, 113 insertions(+)
---
diff --git a/libgimp/gimp.def b/libgimp/gimp.def
index 26a8bcc983..d8b1f141f1 100644
--- a/libgimp/gimp.def
+++ b/libgimp/gimp.def
@@ -708,6 +708,7 @@ EXPORTS
        gimp_procedure_find_argument
        gimp_procedure_find_aux_argument
        gimp_procedure_find_return_value
+       gimp_procedure_get_argument_sync
        gimp_procedure_get_arguments
        gimp_procedure_get_authors
        gimp_procedure_get_aux_arguments
@@ -732,6 +733,7 @@ EXPORTS
        gimp_procedure_new_arguments
        gimp_procedure_new_return_values
        gimp_procedure_run
+       gimp_procedure_set_argument_sync
        gimp_procedure_set_attribution
        gimp_procedure_set_documentation
        gimp_procedure_set_icon_file
diff --git a/libgimp/gimpprocedure.c b/libgimp/gimpprocedure.c
index 04f8b52366..542b960d50 100644
--- a/libgimp/gimpprocedure.c
+++ b/libgimp/gimpprocedure.c
@@ -1537,6 +1537,93 @@ gimp_procedure_get_return_values (GimpProcedure *procedure,
   return procedure->priv->values;
 }
 
+/**
+ * gimp_procedure_set_argument_sync:
+ * @procedure: a #GimpProcedure.
+ * @arg_name:  the name of one of @procedure's arguments or auxiliary arguments.
+ * @sync:      how to sync the argument or auxiliary argument.
+ *
+ * When using #GimpProcedureConfig, gimp_procedure_config_begin_run()
+ * and gimp_procedure_config_end_run(), a #GimpProcedure's arguments
+ * or auxiliary arguments can be automatically synced with a
+ * #GimpParasite of the #GimpImage the procedure is running on.
+ *
+ * In order to enable this, set @sync to %GIMP_ARGUMENT_SYNC_PARASITE.
+ *
+ * Currently, it is possible to sync a string argument of type
+ * #GParamSpecString with an image parasite of the same name, for
+ * example the "gimp-comment" parasite in file save procedures.
+ *
+ * Since: 3.0
+ **/
+void
+gimp_procedure_set_argument_sync (GimpProcedure    *procedure,
+                                  const gchar      *arg_name,
+                                  GimpArgumentSync  sync)
+{
+  GParamSpec *pspec;
+
+  g_return_if_fail (GIMP_IS_PROCEDURE (procedure));
+  g_return_if_fail (arg_name != NULL);
+
+  pspec = gimp_procedure_find_argument (procedure, arg_name);
+
+  if (! pspec)
+    pspec = gimp_procedure_find_aux_argument (procedure, arg_name);
+
+  g_return_if_fail (pspec != NULL);
+
+  switch (sync)
+    {
+    case GIMP_ARGUMENT_SYNC_NONE:
+      gegl_param_spec_set_property_key (pspec, "gimp-argument-sync", NULL);
+      break;
+
+    case GIMP_ARGUMENT_SYNC_PARASITE:
+      gegl_param_spec_set_property_key (pspec, "gimp-argument-sync", "parasite");
+      break;
+    }
+}
+
+/**
+ * gimp_procedure_get_argument_sync:
+ * @procedure: a #GimpProcedure
+ * @arg_name:  the name of one of @procedure's arguments or auxiliary arguments
+ *
+ * Returns: The #GimpArgumentSync value set with
+ *          gimp_procedure_set_argument_sync():
+ *
+ * Since: 3.0
+ **/
+GimpArgumentSync
+gimp_procedure_get_argument_sync (GimpProcedure *procedure,
+                                  const gchar   *arg_name)
+{
+  GParamSpec       *pspec;
+  GimpArgumentSync  sync = GIMP_ARGUMENT_SYNC_NONE;
+  const gchar      *value;
+
+  g_return_val_if_fail (GIMP_IS_PROCEDURE (procedure), GIMP_ARGUMENT_SYNC_NONE);
+  g_return_val_if_fail (arg_name != NULL, GIMP_ARGUMENT_SYNC_NONE);
+
+  pspec = gimp_procedure_find_argument (procedure, arg_name);
+
+  if (! pspec)
+    pspec = gimp_procedure_find_aux_argument (procedure, arg_name);
+
+  g_return_val_if_fail (pspec != NULL, GIMP_ARGUMENT_SYNC_NONE);
+
+  value = gegl_param_spec_get_property_key (pspec, "gimp-argument-sync");
+
+  if (value)
+    {
+      if (! strcmp (value, "parasite"))
+        sync = GIMP_ARGUMENT_SYNC_PARASITE;
+    }
+
+  return sync;
+}
+
 GimpValueArray *
 gimp_procedure_new_arguments (GimpProcedure *procedure)
 {
diff --git a/libgimp/gimpprocedure.h b/libgimp/gimpprocedure.h
index ca09215b2d..23acc5a8c0 100644
--- a/libgimp/gimpprocedure.h
+++ b/libgimp/gimpprocedure.h
@@ -49,6 +49,22 @@ typedef GimpValueArray * (* GimpRunFunc) (GimpProcedure        *procedure,
                                           gpointer              run_data);
 
 
+/**
+ * GimpArgumentSync:
+ * @GIMP_ARGUMENT_SYNC_NONE:     Don't sync this argument
+ * @GIMP_ARGUMENT_SYNC_PARASITE: Sync this argument with an image parasite
+ *
+ * Methods of syncing procedure arguments.
+ *
+ * Since: 3.0
+ **/
+typedef enum
+{
+  GIMP_ARGUMENT_SYNC_NONE,
+  GIMP_ARGUMENT_SYNC_PARASITE
+} GimpArgumentSync;
+
+
 #define GIMP_TYPE_PROCEDURE            (gimp_procedure_get_type ())
 #define GIMP_PROCEDURE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_PROCEDURE, 
GimpProcedure))
 #define GIMP_PROCEDURE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_PROCEDURE, 
GimpProcedureClass))
@@ -170,12 +186,14 @@ GParamSpec     * gimp_procedure_add_argument_from_property
                                                    (GimpProcedure        *procedure,
                                                     GObject              *config,
                                                     const gchar          *prop_name);
+
 GParamSpec     * gimp_procedure_add_aux_argument   (GimpProcedure        *procedure,
                                                     GParamSpec           *pspec);
 GParamSpec     * gimp_procedure_add_aux_argument_from_property
                                                    (GimpProcedure        *procedure,
                                                     GObject              *config,
                                                     const gchar          *prop_name);
+
 GParamSpec     * gimp_procedure_add_return_value   (GimpProcedure        *procedure,
                                                     GParamSpec           *pspec);
 GParamSpec     * gimp_procedure_add_return_value_from_property
@@ -197,6 +215,12 @@ GParamSpec    ** gimp_procedure_get_aux_arguments  (GimpProcedure        *proced
 GParamSpec    ** gimp_procedure_get_return_values  (GimpProcedure        *procedure,
                                                     gint                 *n_return_values);
 
+void             gimp_procedure_set_argument_sync  (GimpProcedure        *procedure,
+                                                    const gchar          *arg_name,
+                                                    GimpArgumentSync      sync);
+GimpArgumentSync gimp_procedure_get_argument_sync  (GimpProcedure        *procedure,
+                                                    const gchar          *arg_name);
+
 GimpValueArray * gimp_procedure_new_arguments      (GimpProcedure        *procedure);
 GimpValueArray * gimp_procedure_new_return_values  (GimpProcedure        *procedure,
                                                     GimpPDBStatusType     status,