[gimp/gtk3-port: 268/274] app: allow to select if we prefer a dark variant of the current theme.

[Michael Natterer <mitch src gnome org>]

commit 428732d0970e4198b8b1f7dd7d5048f1ab55b911
Author: Jehan <jehan girinstud io>
Date:   Tue May 1 04:43:33 2018 +0200

    app: allow to select if we prefer a dark variant of the current theme.
    
    GTK+ has the concept of theme variants, and in particular if we prefer
    the dark variant of a theme. This can be chosen globally but also
    per-application. Make this choice customizable in the Theme tab of
    Preferences.
    By default, the dark variant will be prefered.

 app/config/gimpguiconfig.c       |   14 ++++++++++++++
 app/config/gimpguiconfig.h       |    1 +
 app/dialogs/preferences-dialog.c |    4 ++++
 app/gui/themes.c                 |   18 +++++++++++-------
 4 files changed, 30 insertions(+), 7 deletions(-)
---
diff --git a/app/config/gimpguiconfig.c b/app/config/gimpguiconfig.c
index 72e263d..816f4ca 100644
--- a/app/config/gimpguiconfig.c
+++ b/app/config/gimpguiconfig.c
@@ -76,6 +76,7 @@ enum
   PROP_TOOLBOX_WILBER,
   PROP_THEME_PATH,
   PROP_THEME,
+  PROP_PREFER_DARK_THEME,
   PROP_ICON_THEME_PATH,
   PROP_ICON_THEME,
   PROP_ICON_SIZE,
@@ -323,6 +324,13 @@ gimp_gui_config_class_init (GimpGuiConfigClass *klass)
                            GIMP_CONFIG_DEFAULT_THEME,
                            GIMP_PARAM_STATIC_STRINGS);
 
+  GIMP_CONFIG_PROP_BOOLEAN (object_class, PROP_PREFER_DARK_THEME,
+                            "prefer-dark-theme",
+                            "Prefer Dark Theme",
+                            THEME_BLURB,
+                            TRUE,
+                            GIMP_PARAM_STATIC_STRINGS);
+
   path = gimp_config_build_data_path ("icons");
   GIMP_CONFIG_PROP_PATH (object_class, PROP_ICON_THEME_PATH,
                          "icon-theme-path",
@@ -645,6 +653,9 @@ gimp_gui_config_set_property (GObject      *object,
       g_free (gui_config->theme);
       gui_config->theme = g_value_dup_string (value);
       break;
+    case PROP_PREFER_DARK_THEME:
+      gui_config->prefer_dark_theme = g_value_get_boolean (value);
+      break;
      case PROP_ICON_THEME_PATH:
       g_free (gui_config->icon_theme_path);
       gui_config->icon_theme_path = g_value_dup_string (value);
@@ -828,6 +839,9 @@ gimp_gui_config_get_property (GObject    *object,
     case PROP_THEME:
       g_value_set_string (value, gui_config->theme);
       break;
+    case PROP_PREFER_DARK_THEME:
+      g_value_set_boolean (value, gui_config->prefer_dark_theme);
+      break;
     case PROP_ICON_THEME_PATH:
       g_value_set_string (value, gui_config->icon_theme_path);
       break;
diff --git a/app/config/gimpguiconfig.h b/app/config/gimpguiconfig.h
index 316f1d2..7b42549 100644
--- a/app/config/gimpguiconfig.h
+++ b/app/config/gimpguiconfig.h
@@ -65,6 +65,7 @@ struct _GimpGuiConfig
   gboolean             toolbox_wilber;
   gchar               *theme_path;
   gchar               *theme;
+  gboolean             prefer_dark_theme;
   gchar               *icon_theme_path;
   gchar               *icon_theme;
   GimpIconSize         icon_size;
diff --git a/app/dialogs/preferences-dialog.c b/app/dialogs/preferences-dialog.c
index 5057ecb..2278eaf 100644
--- a/app/dialogs/preferences-dialog.c
+++ b/app/dialogs/preferences-dialog.c
@@ -1879,6 +1879,10 @@ prefs_dialog_new (Gimp       *gimp,
                       gimp);
   }
 
+  prefs_check_button_add (object, "prefer-dark-theme",
+                          _("Use dark theme variant if available"),
+                          GTK_BOX (vbox2));
+
   hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 6);
   gtk_box_pack_start (GTK_BOX (vbox2), hbox, FALSE, FALSE, 0);
   gtk_widget_show (hbox);
diff --git a/app/gui/themes.c b/app/gui/themes.c
index 54cf671..82801e4 100644
--- a/app/gui/themes.c
+++ b/app/gui/themes.c
@@ -131,11 +131,6 @@ themes_init (Gimp *gimp)
       g_list_free_full (path, (GDestroyNotify) g_object_unref);
     }
 
-
-  g_object_set (gtk_settings_get_for_screen (gdk_screen_get_default ()),
-                "gtk-application-prefer-dark-theme", TRUE,
-                NULL);
-
   themes_style_provider = GTK_STYLE_PROVIDER (gtk_css_provider_new ());
 
   /*  Use GTK_STYLE_PROVIDER_PRIORITY_APPLICATION + 1 so theme files
@@ -150,6 +145,9 @@ themes_init (Gimp *gimp)
   g_signal_connect (config, "notify::theme",
                     G_CALLBACK (themes_theme_change_notify),
                     gimp);
+  g_signal_connect (config, "notify::prefer-dark-theme",
+                    G_CALLBACK (themes_theme_change_notify),
+                    gimp);
 
   themes_theme_change_notify (config, NULL, gimp);
 }
@@ -382,8 +380,14 @@ themes_theme_change_notify (GimpGuiConfig *config,
                             GParamSpec    *pspec,
                             Gimp          *gimp)
 {
-  GFile  *theme_css;
-  GError *error = NULL;
+  GFile    *theme_css;
+  GError   *error = NULL;
+  gboolean  prefer_dark_theme;
+
+  g_object_get (config, "prefer-dark-theme", &prefer_dark_theme, NULL);
+  g_object_set (gtk_settings_get_for_screen (gdk_screen_get_default ()),
+                "gtk-application-prefer-dark-theme", prefer_dark_theme,
+                NULL);
 
   themes_apply_theme (gimp, config->theme);