app: do not warn for stray images from command lines.

The INFO message "a stray image seems to have been left around by a
plug-in" was annoying when GIMP is run non-interactively, and when it
was about images open from command lines. Typically this message would
be visible on our CI when the various gimp-data scripts would fail. This
could only confuse script developers.

The fact is that while a plug-in (or batch script) should definitely
clean after itself by deleting images it created (unless it gave it a
display, in which case ownership is moved to the GUI), it is absolutely
expected that images opened through the command line would still exist
at exit.

app/app.c

@@ -321,15 +321,15 @@ app_run (const gchar         *full_prog_name,
   if (gimp->be_verbose)
     g_print ("EXIT: %s\n", G_STRFUNC);
 
+  while (g_main_context_pending (NULL))
+    g_main_context_iteration (NULL, TRUE);
+
   g_clear_object (&app);
 
   gimp_gegl_exit (gimp);
 
   errors_exit ();
 
-  while (g_main_context_pending (NULL))
-    g_main_context_iteration (NULL, TRUE);
-
   g_object_unref (gimp);
 
   gimp_debug_instances ();

app/core/gimp.c

@@ -28,6 +28,8 @@
 
 #include "core-types.h"
 
+#include "gimpcoreapp.h"
+
 #include "config/gimprc.h"
 
 #include "gegl/gimp-babl.h"
@@ -1368,9 +1370,20 @@ gimp_exit_idle_cleanup_stray_images (Gimp *gimp)
     {
       GimpImage *image = image_iter->data;
 
-      /* TODO: localize after string freeze. */
-      g_printerr ("INFO: a stray image seems to have been left around by a plug-in: \"%s\"",
-                  gimp_image_get_display_name (image));
+      /* Plug-in developers are expected to free the images they
+       * created, unless they add a display (while in GUI mode), in
+       * which case the user gets ownership of the image and it will be
+       * freed as any other image by the GUI.
+       * On the other hand, images created from command lines are very
+       * likely to still exist when the software exits, if it was closed
+       * by the --quit argument, or run without an interface. This is
+       * normal use case.
+       */
+      if (! gimp_image_get_from_command_line (image) ||
+          (! gimp->no_interface && ! gimp_core_app_get_quit (GIMP_CORE_APP (gimp->app))))
+        /* TODO: localize after string freeze. */
+        g_printerr ("INFO: a stray image seems to have been left around by a plug-in: \"%s\"\n",
+                    gimp_image_get_display_name (image));
 
       g_object_unref (image);
     }

app/core/gimpimage-private.h

@@ -148,6 +148,8 @@ struct _GimpImagePrivate
 
   /*  Signal emission accumulator  */
   GimpImageFlushAccumulator  flush_accum;
+
+  gboolean                   from_command_line;
 };
 
 #define GIMP_IMAGE_GET_PRIVATE(image) (((GimpImage *) (image))->priv)

app/core/gimpimage.c

@@ -909,6 +909,8 @@ gimp_image_init (GimpImage *image)
   private->flush_accum.mask_changed               = FALSE;
   private->flush_accum.floating_selection_changed = FALSE;
   private->flush_accum.preview_invalidated        = FALSE;
+
+  private->from_command_line                      = FALSE;
 }
 
 static void
@@ -6408,3 +6410,28 @@ gimp_image_get_converting (GimpImage *image)
 
   return private->converting;
 }
+
+void
+gimp_image_set_from_command_line (GimpImage *image,
+                                  gboolean   from_command_line)
+{
+  GimpImagePrivate *private;
+
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  private->from_command_line = from_command_line;
+}
+
+gboolean
+gimp_image_get_from_command_line (GimpImage *image)
+{
+  GimpImagePrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_IMAGE (image), FALSE);
+
+  private = GIMP_IMAGE_GET_PRIVATE (image);
+
+  return private->from_command_line;
+}

app/core/gimpimage.h

@@ -508,3 +508,7 @@ void            gimp_image_invalidate_previews   (GimpImage          *image);
 void            gimp_image_set_converting        (GimpImage          *image,
                                                   gboolean            converting);
 gboolean        gimp_image_get_converting        (GimpImage          *image);
+
+void            gimp_image_set_from_command_line (GimpImage          *image,
+                                                  gboolean            from_command_line);
+gboolean        gimp_image_get_from_command_line (GimpImage          *image);

app/file/file-open.c

@@ -690,6 +690,7 @@ file_open_from_command_line (Gimp     *gimp,
     {
       success = TRUE;
 
+      gimp_image_set_from_command_line (image, TRUE);
       g_object_set_data_full (G_OBJECT (gimp), GIMP_FILE_OPEN_LAST_FILE_KEY,
                               g_object_ref (file),
                               (GDestroyNotify) g_object_unref);