[gimp] app: don't detroy cached data when disabling filter-tool preview

[Ell <ell src gnome org>]

commit 912b36a8f813551f3da1f8151f3af14266954e9a
Author: Ell <ell_se yahoo com>
Date:   Thu Apr 2 18:50:58 2020 +0300

    app: don't detroy cached data when disabling filter-tool preview
    
    In GimpFilterTool, use gimp_drawable_filter_set_preview(), added in
    the previous commit, to toggle the filter's preview, instead of
    removing and re-adding the filter.  This avoids destroying cached
    results when disabling the preview, allowing to quickly toggle the
    preview on and off to compare the result.

 app/tools/gimpfiltertool.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/app/tools/gimpfiltertool.c b/app/tools/gimpfiltertool.c
index b107054e04..c349772c66 100644
--- a/app/tools/gimpfiltertool.c
+++ b/app/tools/gimpfiltertool.c
@@ -713,6 +713,8 @@ gimp_filter_tool_options_notify (GimpTool         *tool,
   if (! strcmp (pspec->name, "preview") &&
       filter_tool->filter)
     {
+      gimp_filter_tool_update_filter (filter_tool);
+
       if (filter_options->preview)
         {
           gimp_drawable_filter_apply (filter_tool->filter, NULL);
@@ -722,8 +724,6 @@ gimp_filter_tool_options_notify (GimpTool         *tool,
         }
       else
         {
-          gimp_drawable_filter_abort (filter_tool->filter);
-
           if (filter_options->preview_split)
             gimp_filter_tool_remove_guide (filter_tool);
         }
@@ -1394,6 +1394,8 @@ gimp_filter_tool_update_filter (GimpFilterTool *filter_tool)
                                           clip);
   gimp_drawable_filter_set_region        (filter_tool->filter,
                                           options->region);
+  gimp_drawable_filter_set_preview       (filter_tool->filter,
+                                          options->preview);
   gimp_drawable_filter_set_preview_split (filter_tool->filter,
                                           options->preview_split,
                                           options->preview_alignment,