theme: Use a singleton theme

Different themes don't make sense when we are always using the current
GTK+ theme for everything, so adapt the MetaTheme API to use a singleton.

https://bugzilla.gnome.org/show_bug.cgi?id=741917

src/core/main.c

@@ -431,42 +431,6 @@ meta_run (void)
   meta_prefs_init ();
   meta_prefs_add_listener (prefs_changed_callback, NULL);
 
-  meta_ui_set_current_theme (meta_prefs_get_theme ());
-
-  /* Try to find some theme that'll work if the theme preference
-   * doesn't exist.  First try Simple (the default theme) then just
-   * try anything in the themes directory.
-   */
-  if (!meta_ui_have_a_theme ())
-    meta_ui_set_current_theme ("Simple");
-
-  if (!meta_ui_have_a_theme ())
-    {
-      const char *dir_entry = NULL;
-      GError *err = NULL;
-      GDir   *themes_dir = NULL;
-
-      if (!(themes_dir = g_dir_open (MUTTER_DATADIR"/themes", 0, &err)))
-        {
-          meta_fatal (_("Failed to scan themes directory: %s\n"), err->message);
-          g_error_free (err);
-        }
-      else
-        {
-          while (((dir_entry = g_dir_read_name (themes_dir)) != NULL) &&
-                 (!meta_ui_have_a_theme ()))
-            {
-              meta_ui_set_current_theme (dir_entry);
-            }
-
-          g_dir_close (themes_dir);
-        }
-    }
-
-  if (!meta_ui_have_a_theme ())
-    meta_fatal (_("Could not find a theme! Be sure %s exists and contains the usual themes.\n"),
-                MUTTER_DATADIR"/themes");
-
   if (!meta_display_open ())
     meta_exit (META_EXIT_ERROR);
 
@@ -513,9 +477,7 @@ prefs_changed_callback (MetaPreference pref,
 {
   switch (pref)
     {
-    case META_PREF_THEME:
     case META_PREF_DRAGGABLE_BORDER_WIDTH:
-      meta_ui_set_current_theme (meta_prefs_get_theme ());
       meta_display_retheme_all ();
       break;
 

src/meta/theme.h

@@ -30,8 +30,7 @@
  */
 typedef struct _MetaTheme MetaTheme;
 
-MetaTheme* meta_theme_get_current (void);
-void       meta_theme_set_current (const char *name);
+MetaTheme* meta_theme_get_default (void);
 
 MetaTheme* meta_theme_new      (void);
 void       meta_theme_free     (MetaTheme *theme);

src/ui/frames.c

@@ -395,8 +395,7 @@ meta_frames_ensure_layout (MetaFrames  *frames,
                  META_CORE_GET_FRAME_TYPE, &type,
                  META_CORE_GET_END);
 
-  style = meta_theme_get_frame_style (meta_theme_get_current (),
-                                      type, flags);
+  style = meta_theme_get_frame_style (meta_theme_get_default (), type, flags);
 
   if (style != frame->cache_style)
     {
@@ -480,7 +479,7 @@ meta_frames_calc_geometry (MetaFrames        *frames,
 
   meta_prefs_get_button_layout (&button_layout);
 
-  meta_theme_calc_geometry (meta_theme_get_current (),
+  meta_theme_calc_geometry (meta_theme_get_default (),
                             frame->style_info,
                             type,
                             frame->text_height,
@@ -648,7 +647,7 @@ meta_ui_frame_get_borders (MetaFrames *frames,
    * by the core move/resize code to decide on the client
    * window size
    */
-  meta_theme_get_frame_borders (meta_theme_get_current (),
+  meta_theme_get_frame_borders (meta_theme_get_default (),
                                 frame->style_info,
                                 type,
                                 frame->text_height,
@@ -1560,7 +1559,7 @@ get_visible_frame_border_region (MetaUIFrame *frame)
                  META_CORE_GET_FRAME_RECT, &frame_rect,
                  META_CORE_GET_END);
 
-  meta_theme_get_frame_borders (meta_theme_get_current (), frame->style_info,
+  meta_theme_get_frame_borders (meta_theme_get_default (), frame->style_info,
                                 type, frame->text_height, flags,
                                 &borders);
 
@@ -1751,7 +1750,7 @@ meta_frames_paint (MetaFrames   *frames,
 
   meta_prefs_get_button_layout (&button_layout);
 
-  meta_theme_draw_frame (meta_theme_get_current (),
+  meta_theme_draw_frame (meta_theme_get_default (),
                          frame->style_info,
                          cr,
                          type,

src/ui/theme.c

@@ -4573,23 +4573,19 @@ meta_frame_style_set_validate  (MetaFrameStyleSet *style_set,
 }
 
 /**
- * meta_theme_get_current: (skip)
+ * meta_theme_get_default: (skip)
  *
  */
 MetaTheme*
-meta_theme_get_current (void)
-{
-  return meta_current_theme;
-}
-
-void
-meta_theme_set_current (const char *name)
+meta_theme_get_default (void)
 {
+  static MetaTheme *theme = NULL;
   int i, j, frame_type;
 
-  if (meta_current_theme)
-    return;
-  meta_current_theme = meta_theme_new ();
+  if (theme)
+    return theme;
+
+  theme = meta_theme_new ();
 
   for (frame_type = 0; frame_type < META_FRAME_TYPE_LAST; frame_type++)
     {
@@ -4650,8 +4646,9 @@ meta_theme_set_current (const char *name)
         }
 
       meta_frame_style_unref (style);
-      meta_current_theme->style_sets_by_type[frame_type] = style_set;
+      theme->style_sets_by_type[frame_type] = style_set;
     }
+  return theme;
 }
 
 /**

src/ui/ui.c

@@ -599,7 +599,7 @@ meta_ui_theme_get_frame_borders (MetaUI *ui,
 
       text_height = meta_pango_font_desc_get_text_height (font_desc, context);
 
-      meta_theme_get_frame_borders (meta_theme_get_current (),
+      meta_theme_get_frame_borders (meta_theme_get_default (),
                                     style_info, type, text_height, flags,
                                     borders);
 
@@ -615,17 +615,10 @@ meta_ui_theme_get_frame_borders (MetaUI *ui,
     meta_style_info_unref (style_info);
 }
 
-void
-meta_ui_set_current_theme (const char *name)
-{
-  meta_theme_set_current (name);
-  meta_invalidate_default_icons ();
-}
-
 gboolean
 meta_ui_have_a_theme (void)
 {
-  return meta_theme_get_current () != NULL;
+  return meta_theme_get_default () != NULL;
 }
 
 gboolean

src/ui/ui.h

@@ -111,7 +111,6 @@ GdkPixbuf* meta_gdk_pixbuf_get_from_pixmap (Pixmap       xpixmap,
 gboolean  meta_ui_window_should_not_cause_focus (Display *xdisplay,
                                                  Window   xwindow);
 
-void     meta_ui_set_current_theme (const char *name);
 gboolean meta_ui_have_a_theme      (void);
 
 gboolean meta_ui_window_is_widget (MetaUI *ui,