[gtk+] Allow selecting a dark variant with GTK_THEME

[Matthias Clasen <matthiasc src gnome org>]

commit 15004e59306de29b5a0cf3195ccf266100a423b2
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Mar 6 19:27:37 2014 -0500

    Allow selecting a dark variant with GTK_THEME
    
    Dark themes need to be debugged, too.
    
    Author:    Matthias Clasen <mclasen redhat com>

 docs/reference/gtk/running.sgml |    4 +++
 gtk/gtksettings.c               |   57 +++++++++++++++++++++++++-------------
 2 files changed, 41 insertions(+), 20 deletions(-)
---
diff --git a/docs/reference/gtk/running.sgml b/docs/reference/gtk/running.sgml
index 8065e19..05f0510 100644
--- a/docs/reference/gtk/running.sgml
+++ b/docs/reference/gtk/running.sgml
@@ -322,6 +322,10 @@ additional environment variables.
     that is specified by the gtk-theme-name setting. This is intended
     mainly for easy debugging of theme issues.
   </para>
+  <para>
+    It is also possible to specify a theme variant to load, by appending
+    the variant name with a colon, like this: `GTK_THEME=Adwaita:dark`.
+  </para>
 </formalpara>
 
 <para>
diff --git a/gtk/gtksettings.c b/gtk/gtksettings.c
index ea043e3..5c834ef 100644
--- a/gtk/gtksettings.c
+++ b/gtk/gtksettings.c
@@ -2976,47 +2976,63 @@ settings_update_provider (GdkScreen       *screen,
     }
 }
 
-static char *
-get_theme_name (GtkSettings *settings)
+static void
+get_theme_name (GtkSettings  *settings,
+                gchar       **theme_name,
+                gchar       **theme_variant)
 {
-  char *theme_name = NULL;
+  gboolean prefer_dark;
+
+  *theme_name = NULL;
+  *theme_variant = NULL;
 
   if (g_getenv ("GTK_THEME"))
-    theme_name = g_strdup (g_getenv ("GTK_THEME"));
+    *theme_name = g_strdup (g_getenv ("GTK_THEME"));
 
-  if (theme_name && *theme_name)
-    return theme_name;
+  if (*theme_name && **theme_name)
+    {
+      char *p;
+      p = strrchr (*theme_name, ':');
+      if (p) {
+        *p = '\0';
+        p++;
+        *theme_variant = g_strdup (p);
+      }
+
+g_print ("theme: %s variant: %s\n", *theme_name, *theme_variant);
+      return;
+    }
+
+  g_free (*theme_name);
 
-  g_free (theme_name);
   g_object_get (settings,
-                "gtk-theme-name", &theme_name,
+                "gtk-theme-name", theme_name,
+                "gtk-application-prefer-dark-theme", &prefer_dark,
                 NULL);
 
-  if (theme_name && *theme_name)
-    return theme_name;
+  if (prefer_dark)
+    *theme_variant = g_strdup ("dark");
 
-  g_free (theme_name);
-  return g_strdup (DEFAULT_THEME_NAME);
+  if (*theme_name && **theme_name)
+    return;
+
+  g_free (*theme_name);
+  *theme_name = g_strdup (DEFAULT_THEME_NAME);
 }
 
 static void
 settings_update_theme (GtkSettings *settings)
 {
   GtkSettingsPrivate *priv = settings->priv;
-  gboolean prefer_dark_theme;
   gchar *theme_name;
+  gchar *theme_variant;
   gchar *theme_dir;
   gchar *path;
 
-  g_object_get (settings,
-                "gtk-application-prefer-dark-theme", &prefer_dark_theme,
-                NULL);
-
-  theme_name = get_theme_name (settings);
+  get_theme_name (settings, &theme_name, &theme_variant);
 
   _gtk_css_provider_load_named (priv->theme_provider,
-                                theme_name,
-                                prefer_dark_theme ? "dark" : NULL);
+                                theme_name, theme_variant);
 
   /* reload per-theme settings */
   theme_dir = _gtk_css_provider_get_theme_dir ();
@@ -3026,6 +3042,7 @@ settings_update_theme (GtkSettings *settings)
     gtk_settings_load_from_key_file (settings, path, GTK_SETTINGS_SOURCE_THEME);
 
   g_free (theme_name);
+  g_free (theme_variant);
   g_free (theme_dir);
   g_free (path);
 }