From 08c93a5478d32615ddbea8a119da3bbbfbb2ece9 Mon Sep 17 00:00:00 2001
From: Jehan <jehan@girinstud.io>
Date: Thu, 5 Jun 2025 01:08:01 +0200
Subject: [PATCH] app: make dark scheme the default when system scheme request
 fails.

If the DBus portal is not available or if any failure occurs when
querying the system scheme, let's default to dark theme (since it's
GIMP's default).
---
 app/gui/themes.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/app/gui/themes.c b/app/gui/themes.c
index cb7400a9ed..cf46535f04 100644
--- a/app/gui/themes.c
+++ b/app/gui/themes.c
@@ -276,12 +276,12 @@ static void
 themes_apply_theme (Gimp          *gimp,
                     GimpGuiConfig *config)
 {
-  GFile         *theme_css;
-  GOutputStream *output;
-  GError        *error = NULL;
-  gboolean       prefer_dark_theme;
-  guint32        color_scheme;
-  GVariant      *tuple_variant, *variant;
+  GFile           *theme_css;
+  GOutputStream   *output;
+  GError          *error = NULL;
+  gboolean         prefer_dark_theme;
+  GimpThemeScheme  color_scheme;
+  GVariant        *tuple_variant, *variant;
 
   g_return_if_fail (GIMP_IS_GIMP (gimp));
   g_return_if_fail (GIMP_IS_GUI_CONFIG (config));
@@ -332,14 +332,25 @@ themes_apply_theme (Gimp          *gimp,
            */
           prefer_dark_theme = (g_variant_get_uint32 (variant) == 1);
 
-          color_scheme = prefer_dark_theme ? GIMP_THEME_DARK : GIMP_THEME_SYSTEM;
+          /*
+           * Note that normally it's a tri-state flag, with a
+           * prefer-light and no-preference case too, except that it
+           * looks like both in KDE and GNOME at least, they only set
+           * prefer-dark or no-preference and for us, the latter should
+           * also mean dark.
+           * Therefore for this setting to actually mean something, we
+           * are currently breaking the spec by having no-preference
+           * mean prefer-light. This should be fixed if/when the main
+           * desktops actually implement all 3 options some day.
+           */
+          color_scheme = prefer_dark_theme ? GIMP_THEME_DARK : GIMP_THEME_LIGHT;
         }
       else
         {
           g_printerr ("%s\n", error->message);
           g_clear_error (&error);
 
-          color_scheme = config->theme_scheme;
+          color_scheme = (config->theme_scheme == GIMP_THEME_SYSTEM) ? GIMP_THEME_DARK : config->theme_scheme;
           prefer_dark_theme = (color_scheme == GIMP_THEME_DARK ||
                                color_scheme == GIMP_THEME_GRAY);
         }
@@ -347,7 +358,7 @@ themes_apply_theme (Gimp          *gimp,
   else
 #endif
     {
-      color_scheme = config->theme_scheme;
+      color_scheme = (config->theme_scheme == GIMP_THEME_SYSTEM) ? GIMP_THEME_DARK : config->theme_scheme;
       prefer_dark_theme = (color_scheme == GIMP_THEME_DARK ||
                            color_scheme == GIMP_THEME_GRAY);
     }
@@ -402,7 +413,6 @@ themes_apply_theme (Gimp          *gimp,
 
           switch (color_scheme)
             {
-            case GIMP_THEME_SYSTEM:
             case GIMP_THEME_LIGHT:
               if (light != NULL)
                 file = g_object_ref (light);
@@ -433,6 +443,8 @@ themes_apply_theme (Gimp          *gimp,
               else if (light != NULL)
                 file = g_object_ref (light);
               break;
+            case GIMP_THEME_SYSTEM:
+              g_return_if_reached ();
             }
 
           if (file != NULL)
@@ -465,7 +477,6 @@ themes_apply_theme (Gimp          *gimp,
 
           switch (color_scheme)
             {
-            case GIMP_THEME_SYSTEM:
             case GIMP_THEME_LIGHT:
               tmp = g_build_filename (gimp_data_directory (),
                                       "themes", "Default", "gimp-light.css",
@@ -481,6 +492,8 @@ themes_apply_theme (Gimp          *gimp,
                                       "themes", "Default", "gimp-dark.css",
                                       NULL);
               break;
+            case GIMP_THEME_SYSTEM:
+              g_return_if_reached ();
             }
 
           css_files = g_slist_prepend (css_files, g_file_new_for_path (tmp));