[gimp] Enhance GimpProcedureDialog have int combo widget for G_PARAM_SPEC_ENUM

[Lloyd Konneker <lkonneker src gnome org>]

commit 0c1b00b04c772b2c653144f19f5b24df49b4cfe8
Author: lloyd konneker <konnekerl gmail com>
Date:   Sat Aug 13 07:34:17 2022 -0400

    Enhance GimpProcedureDialog have int combo widget for G_PARAM_SPEC_ENUM
    
    Resolves #8488

 libgimp/gimpproceduredialog.c    | 20 ++++++++++++--
 libgimpwidgets/gimppropwidgets.c | 58 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 72 insertions(+), 6 deletions(-)
---
diff --git a/libgimp/gimpproceduredialog.c b/libgimp/gimpproceduredialog.c
index f3e126da1d..bd63b42d50 100644
--- a/libgimp/gimpproceduredialog.c
+++ b/libgimp/gimpproceduredialog.c
@@ -725,10 +725,26 @@ gimp_procedure_dialog_get_widget (GimpProcedureDialog *dialog,
                                                   property, NULL,
                                                   GTK_FILE_CHOOSER_ACTION_OPEN);
     }
+  else  if (G_PARAM_SPEC_TYPE (pspec) == G_TYPE_PARAM_ENUM)
+    {
+      GimpIntStore *store;
+
+      store = (GimpIntStore *) gimp_enum_store_new (G_PARAM_SPEC_VALUE_TYPE (pspec));
+
+      widget = gimp_prop_int_combo_box_new (G_OBJECT (dialog->priv->config),
+                                            property,
+                                            store);
+      gtk_widget_set_vexpand (widget, FALSE);
+      gtk_widget_set_hexpand (widget, TRUE);
+      widget = gimp_label_int_widget_new (g_param_spec_get_nick (pspec),
+                                          widget);
+    }
   else
     {
-      g_warning ("%s: parameter %s has non supported type %s",
-                 G_STRFUNC, property, G_PARAM_SPEC_TYPE_NAME (pspec));
+      g_warning ("%s: parameter %s has non supported type %s for value type %s",
+                 G_STRFUNC, property,
+                 G_PARAM_SPEC_TYPE_NAME (pspec),
+                 g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)));
       return NULL;
     }
 
diff --git a/libgimpwidgets/gimppropwidgets.c b/libgimpwidgets/gimppropwidgets.c
index a6f23af92a..1d79fd8507 100644
--- a/libgimpwidgets/gimppropwidgets.c
+++ b/libgimpwidgets/gimppropwidgets.c
@@ -55,6 +55,11 @@ static GParamSpec * get_param_spec     (GObject     *object);
 static GParamSpec * find_param_spec    (GObject     *object,
                                         const gchar *property_name,
                                         const gchar *strloc);
+static GParamSpec * check_param_spec_quiet (
+                                        GObject     *object,
+                                        const gchar *property_name,
+                                        GType        type,
+                                        const gchar *strloc);
 static GParamSpec * check_param_spec   (GObject     *object,
                                         const gchar *property_name,
                                         GType        type,
@@ -414,10 +419,36 @@ gimp_prop_int_combo_box_new (GObject      *config,
   g_return_val_if_fail (G_IS_OBJECT (config), NULL);
   g_return_val_if_fail (property_name != NULL, NULL);
 
-  param_spec = check_param_spec_w (config, property_name,
-                                   G_TYPE_PARAM_INT, G_STRFUNC);
-  if (! param_spec)
-    return NULL;
+  /* Require property is integer valued type: INT or ENUM, and is writeable. */
+  param_spec = check_param_spec_quiet (config, property_name,
+                                       G_TYPE_PARAM_INT, G_STRFUNC);
+  if (param_spec)
+    {
+      param_spec = check_param_spec_w (config, property_name,
+                                     G_TYPE_PARAM_INT, G_STRFUNC);
+      if (! param_spec)
+        return NULL;
+    }
+  else
+    {
+      param_spec = check_param_spec_quiet (config, property_name,
+                                          G_TYPE_PARAM_ENUM, G_STRFUNC);
+      if (param_spec)
+        {
+          param_spec = check_param_spec_w (config, property_name,
+                                           G_TYPE_PARAM_ENUM, G_STRFUNC);
+          if (! param_spec)
+            return NULL;
+        }
+      else
+        {
+          g_warning ("%s: property '%s' of %s is not integer valued.",
+                     G_STRFUNC,
+                     param_spec->name,
+                     g_type_name (param_spec->owner_type));
+          return NULL;
+        }
+    }
 
   combo_box = g_object_new (GIMP_TYPE_INT_COMBO_BOX,
                             "model", store,
@@ -4536,6 +4567,25 @@ find_param_spec (GObject     *object,
   return param_spec;
 }
 
+/* Compare GType of GParamSpec of object's property to GType.
+ * Return GParamSpec when equal, else NULL.
+ */
+static GParamSpec *
+check_param_spec_quiet (GObject     *object,
+                        const gchar *property_name,
+                        GType        type,
+                        const gchar *strloc)
+{
+  GParamSpec *param_spec;
+
+  param_spec = find_param_spec (object, property_name, strloc);
+
+  if (param_spec && ! g_type_is_a (G_TYPE_FROM_INSTANCE (param_spec), type))
+    return NULL;
+  else
+    return param_spec;
+}
+
 static GParamSpec *
 check_param_spec (GObject     *object,
                   const gchar *property_name,