app, libgimp*, pdb, plug-ins: GimpContext is now using only GeglColor.

- app: gimp_context_get_(foreground|background)() are now returning a GeglColor.
- libgimp: PDB functions named similarly in libgimp are returning a newly
  allocated GeglColor too.
- A few other PDB functions (the ones using these functions) were updated and
  their signature changed to use GeglColor too, when relevant. Plug-ins which
  use any of the changed libgimp functions were fixed.
- GimpContext: signals "(foreground|background)-changed" are now passing a
  GeglColor.
- libgimpconfig: new macro GIMP_CONFIG_PROP_COLOR using gegl_param_spec_color().
- GimpContext: properties "foreground" and "background" are now GeglParamColor
  properties.
- app: All code interacting with GimpContext objects were updated to receive a
  GeglColor (that they may still convert, or no, to GimpRGB for now).
- app: gimp_prop_gegl_color_button_new() was added as an alternative to
  gimp_prop_color_button_new() when the property is a GeglParamColor. Eventually
  the former should replace completely the latter.
- libgimpwidgets: gimp_prop_color_area_new() now works on GeglParamColor
  properties only.
- libgimp: gimp_procedure_dialog_get_widget() will generate a GimpColorArea for
  GeglTypeParamColor arguments.

libgimp/gimpcontext_pdb.c

@@ -328,7 +328,6 @@ gimp_context_set_stroke_method (GimpStrokeMethod stroke_method)
 
 /**
  * gimp_context_get_foreground:
- * @foreground: (out caller-allocates): The foreground color.
  *
  * Get the current GIMP foreground color.
  *
@@ -336,16 +335,16 @@ gimp_context_set_stroke_method (GimpStrokeMethod stroke_method)
  * used in a variety of tools such as paint tools, blending, and bucket
  * fill.
  *
- * Returns: TRUE on success.
+ * Returns: (transfer full): The foreground color.
  *
  * Since: 2.2
  **/
-gboolean
-gimp_context_get_foreground (GimpRGB *foreground)
+GeglColor *
+gimp_context_get_foreground (void)
 {
   GimpValueArray *args;
   GimpValueArray *return_vals;
-  gboolean success = TRUE;
+  GeglColor *foreground = NULL;
 
   args = gimp_value_array_new_from_types (NULL,
                                           G_TYPE_NONE);
@@ -355,14 +354,12 @@ gimp_context_get_foreground (GimpRGB *foreground)
                                                args);
   gimp_value_array_unref (args);
 
-  success = GIMP_VALUES_GET_ENUM (return_vals, 0) == GIMP_PDB_SUCCESS;
-
-  if (success)
-    GIMP_VALUES_GET_RGB (return_vals, 1, &*foreground);
+  if (GIMP_VALUES_GET_ENUM (return_vals, 0) == GIMP_PDB_SUCCESS)
+    foreground = g_value_dup_object (gimp_value_array_index (return_vals, 1));
 
   gimp_value_array_unref (return_vals);
 
-  return success;
+  return foreground;
 }
 
 /**
@@ -404,7 +401,6 @@ gimp_context_set_foreground (GeglColor *foreground)
 
 /**
  * gimp_context_get_background:
- * @background: (out caller-allocates): The background color.
  *
  * Get the current GIMP background color.
  *
@@ -412,16 +408,16 @@ gimp_context_set_foreground (GeglColor *foreground)
  * used in a variety of tools such as blending, erasing (with non-alpha
  * images), and image filling.
  *
- * Returns: TRUE on success.
+ * Returns: (transfer full): The background color.
  *
  * Since: 2.2
  **/
-gboolean
-gimp_context_get_background (GimpRGB *background)
+GeglColor *
+gimp_context_get_background (void)
 {
   GimpValueArray *args;
   GimpValueArray *return_vals;
-  gboolean success = TRUE;
+  GeglColor *background = NULL;
 
   args = gimp_value_array_new_from_types (NULL,
                                           G_TYPE_NONE);
@@ -431,14 +427,12 @@ gimp_context_get_background (GimpRGB *background)
                                                args);
   gimp_value_array_unref (args);
 
-  success = GIMP_VALUES_GET_ENUM (return_vals, 0) == GIMP_PDB_SUCCESS;
-
-  if (success)
-    GIMP_VALUES_GET_RGB (return_vals, 1, &*background);
+  if (GIMP_VALUES_GET_ENUM (return_vals, 0) == GIMP_PDB_SUCCESS)
+    background = g_value_dup_object (gimp_value_array_index (return_vals, 1));
 
   gimp_value_array_unref (return_vals);
 
-  return success;
+  return background;
 }
 
 /**

libgimp/gimpcontext_pdb.h

@@ -40,9 +40,9 @@ gchar*                        gimp_context_get_paint_method               (void)
 gboolean                      gimp_context_set_paint_method               (const gchar                   *name);
 GimpStrokeMethod              gimp_context_get_stroke_method              (void);
 gboolean                      gimp_context_set_stroke_method              (GimpStrokeMethod               stroke_method);
-gboolean                      gimp_context_get_foreground                 (GimpRGB                       *foreground);
+GeglColor*                    gimp_context_get_foreground                 (void);
 gboolean                      gimp_context_set_foreground                 (GeglColor                     *foreground);
-gboolean                      gimp_context_get_background                 (GimpRGB                       *background);
+GeglColor*                    gimp_context_get_background                 (void);
 gboolean                      gimp_context_set_background                 (GeglColor                     *background);
 gboolean                      gimp_context_set_default_colors             (void);
 gboolean                      gimp_context_swap_colors                    (void);

libgimp/gimpproceduredialog.c

@@ -606,6 +606,7 @@ gimp_procedure_dialog_set_ok_label (GimpProcedureDialog *dialog,
  *         Please use gimp_procedure_dialog_get_color_widget() for a
  *         non-editable color area with a label.
  *     * %GIMP_TYPE_COLOR_BUTTON: a color button with no label.
+ * - %GEGL_TYPE_COLOR:
  *     * %GIMP_TYPE_COLOR_AREA: a color area with no label.
  * - %G_TYPE_PARAM_FILE:
  *     * %GTK_FILE_CHOOSER_BUTTON (default): generic file chooser button
@@ -755,7 +756,10 @@ gimp_procedure_dialog_get_widget (GimpProcedureDialog *dialog,
           gtk_widget_set_vexpand (widget, FALSE);
           gtk_widget_set_hexpand (widget, FALSE);
         }
-      else if (widget_type == GIMP_TYPE_COLOR_AREA)
+    }
+  else if (G_PARAM_SPEC_TYPE (pspec) == GEGL_TYPE_PARAM_COLOR)
+    {
+      if (widget_type == G_TYPE_NONE || widget_type == GIMP_TYPE_COLOR_AREA)
         {
           widget = gimp_prop_color_area_new (G_OBJECT (dialog->priv->config),
                                              property, 20, 20,