theme: Add MetaStyleInfo for wrapping frame style context

Our current use of style contexts is fairly limited - we don't
use them for much more than picking up some color information.
We will soon start to make more elaborate use of GTK style
information, but a single context will no longer be enough
to draw a frame then.
To prepare for this, add a simple ref-counted type to wrap
style information.

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

src/ui/frames.c

@@ -170,41 +170,41 @@ prefs_changed_callback (MetaPreference pref,
     }
 }
 
-static GtkStyleContext *
+static MetaStyleInfo *
 meta_frames_get_theme_variant (MetaFrames  *frames,
                                const gchar *variant)
 {
-  GtkStyleContext *style;
+  MetaStyleInfo *style_info;
 
-  style = g_hash_table_lookup (frames->style_variants, variant);
-  if (style == NULL)
+  style_info = g_hash_table_lookup (frames->style_variants, variant);
+  if (style_info == NULL)
     {
-      style = meta_theme_create_style_context (gtk_widget_get_screen (GTK_WIDGET (frames)), variant);
-      g_hash_table_insert (frames->style_variants, g_strdup (variant), style);
+      style_info = meta_theme_create_style_info (gtk_widget_get_screen (GTK_WIDGET (frames)), variant);
+      g_hash_table_insert (frames->style_variants, g_strdup (variant), style_info);
     }
 
-  return style;
+  return style_info;
 }
 
 static void
 update_style_contexts (MetaFrames *frames)
 {
-  GtkStyleContext *style;
+  MetaStyleInfo *style_info;
   GList *variants, *variant;
   GdkScreen *screen;
 
   screen = gtk_widget_get_screen (GTK_WIDGET (frames));
 
   if (frames->normal_style)
-    g_object_unref (frames->normal_style);
-  frames->normal_style = meta_theme_create_style_context (screen, NULL);
+    meta_style_info_unref (frames->normal_style);
+  frames->normal_style = meta_theme_create_style_info (screen, NULL);
 
   variants = g_hash_table_get_keys (frames->style_variants);
   for (variant = variants; variant; variant = variants->next)
     {
-      style = meta_theme_create_style_context (screen, (char *)variant->data);
+      style_info = meta_theme_create_style_info (screen, (char *)variant->data);
       g_hash_table_insert (frames->style_variants,
-                           g_strdup (variant->data), style);
+                           g_strdup (variant->data), style_info);
     }
   g_list_free (variants);
 }
@@ -217,7 +217,7 @@ meta_frames_init (MetaFrames *frames)
   frames->frames = g_hash_table_new (unsigned_long_hash, unsigned_long_equal);
 
   frames->style_variants = g_hash_table_new_full (g_str_hash, g_str_equal,
-                                                  g_free, g_object_unref);
+                                                  g_free, (GDestroyNotify)meta_style_info_unref);
 
   update_style_contexts (frames);
 
@@ -258,7 +258,7 @@ meta_frames_destroy (GtkWidget *object)
 
   if (frames->normal_style)
     {
-      g_object_unref (frames->normal_style);
+      meta_style_info_unref (frames->normal_style);
       frames->normal_style = NULL;
     }
 
@@ -531,8 +531,8 @@ meta_frames_attach_style (MetaFrames  *frames,
   gboolean has_frame;
   char *variant = NULL;
 
-  if (frame->style != NULL)
-    g_object_unref (frame->style);
+  if (frame->style_info != NULL)
+    meta_style_info_unref (frame->style_info);
 
   meta_core_get (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()),
                  frame->xwindow,
@@ -541,10 +541,10 @@ meta_frames_attach_style (MetaFrames  *frames,
                  META_CORE_GET_END);
 
   if (variant == NULL || strcmp(variant, "normal") == 0)
-    frame->style = g_object_ref (frames->normal_style);
+    frame->style_info = meta_style_info_ref (frames->normal_style);
   else
-    frame->style = g_object_ref (meta_frames_get_theme_variant (frames,
-                                                                variant));
+    frame->style_info = meta_style_info_ref (meta_frames_get_theme_variant (frames,
+                                                                            variant));
 }
 
 void
@@ -562,7 +562,7 @@ meta_frames_manage_window (MetaFrames *frames,
 
   gdk_window_set_user_data (frame->window, frames);
 
-  frame->style = NULL;
+  frame->style_info = NULL;
 
   /* Don't set event mask here, it's in frame.c */
 
@@ -602,7 +602,7 @@ meta_frames_unmanage_window (MetaFrames *frames,
 
       g_hash_table_remove (frames->frames, &frame->xwindow);
 
-      g_object_unref (frame->style);
+      meta_style_info_unref (frame->style_info);
 
       gdk_window_destroy (frame->window);
 
@@ -1833,7 +1833,7 @@ meta_frames_paint (MetaFrames   *frames,
   meta_prefs_get_button_layout (&button_layout);
 
   meta_theme_draw_frame (meta_theme_get_current (),
-                         frame->style,
+                         frame->style_info,
                          cr,
                          type,
                          flags,

src/ui/frames.h

@@ -74,7 +74,7 @@ struct _MetaUIFrame
 {
   Window xwindow;
   GdkWindow *window;
-  GtkStyleContext *style;
+  MetaStyleInfo *style_info;
   MetaFrameStyle *cache_style;
   PangoLayout *layout;
   int text_height;
@@ -97,7 +97,7 @@ struct _MetaFrames
   GHashTable *frames;
   MetaUIFrame *last_motion_frame;
 
-  GtkStyleContext *normal_style;
+  MetaStyleInfo *normal_style;
   GHashTable *style_variants;
 
   MetaGrabOp current_grab_op;

src/ui/theme-private.h

@@ -27,6 +27,11 @@
 #include <meta/common.h>
 #include <gtk/gtk.h>
 
+/**
+ * MetaStyleInfo: (skip)
+ *
+ */
+typedef struct _MetaStyleInfo MetaStyleInfo;
 /**
  * MetaFrameStyle: (skip)
  *
@@ -676,6 +681,19 @@ typedef enum
   META_BUTTON_TYPE_LAST
 } MetaButtonType;
 
+typedef enum
+{
+  META_STYLE_ELEMENT_FRAME,
+  META_STYLE_ELEMENT_LAST
+} MetaStyleElement;
+
+struct _MetaStyleInfo
+{
+  int refcount;
+
+  GtkStyleContext *styles[META_STYLE_ELEMENT_LAST];
+};
+
 typedef enum
 {
   /* Listed in the order in which the textures are drawn.
@@ -1024,11 +1042,13 @@ double meta_theme_get_title_scale (MetaTheme     *theme,
                                    MetaFrameType  type,
                                    MetaFrameFlags flags);
 
-GtkStyleContext * meta_theme_create_style_context (GdkScreen   *screen,
-                                                   const gchar *variant);
+MetaStyleInfo * meta_theme_create_style_info (GdkScreen   *screen,
+                                              const gchar *variant);
+MetaStyleInfo * meta_style_info_ref          (MetaStyleInfo *style);
+void            meta_style_info_unref        (MetaStyleInfo  *style_info);
 
 void meta_theme_draw_frame (MetaTheme              *theme,
-                            GtkStyleContext        *style_gtk,
+                            MetaStyleInfo          *style_info,
                             cairo_t                *cr,
                             MetaFrameType           type,
                             MetaFrameFlags          flags,

src/ui/theme.c

@@ -4158,7 +4158,7 @@ get_button_rect (MetaButtonType           type,
 
 static void
 meta_frame_style_draw_with_style (MetaFrameStyle          *style,
-                                  GtkStyleContext         *style_gtk,
+                                  MetaStyleInfo           *style_info,
                                   cairo_t                 *cr,
                                   const MetaFrameGeometry *fgeom,
                                   int                      client_width,
@@ -4327,7 +4327,7 @@ meta_frame_style_draw_with_style (MetaFrameStyle          *style,
               MetaRectangle m_rect;
               m_rect = meta_rect (rect.x, rect.y, rect.width, rect.height);
               meta_draw_op_list_draw_with_style (op_list,
-                                                 style_gtk,
+                                                 style_info->styles[META_STYLE_ELEMENT_FRAME],
                                                  cr,
                                                  &draw_info,
                                                  m_rect);
@@ -4368,7 +4368,7 @@ meta_frame_style_draw_with_style (MetaFrameStyle          *style,
                                           rect.width, rect.height);
 
                       meta_draw_op_list_draw_with_style (op_list,
-                                                         style_gtk,
+                                                         style_info->styles[META_STYLE_ELEMENT_FRAME],
                                                          cr,
                                                          &draw_info,
                                                          m_rect);
@@ -4999,11 +4999,12 @@ meta_theme_get_title_scale (MetaTheme     *theme,
   return style->layout->title_scale;
 }
 
-GtkStyleContext *
-meta_theme_create_style_context (GdkScreen   *screen,
-                                 const gchar *variant)
+MetaStyleInfo *
+meta_theme_create_style_info (GdkScreen   *screen,
+                              const gchar *variant)
 {
   GtkWidgetPath *path;
+  MetaStyleInfo *style_info;
   GtkStyleContext *style;
   char *theme_name;
 
@@ -5011,11 +5012,17 @@ meta_theme_create_style_context (GdkScreen   *screen,
                 "gtk-theme-name", &theme_name,
                 NULL);
 
-  style = gtk_style_context_new ();
+  style_info = g_new0 (MetaStyleInfo, 1);
+  style_info->refcount = 1;
+
   path = gtk_widget_path_new ();
+
+  style_info->styles[META_STYLE_ELEMENT_FRAME] = style = gtk_style_context_new ();
   gtk_widget_path_append_type (path, META_TYPE_FRAMES);
   gtk_widget_path_iter_add_class (path, -1, GTK_STYLE_CLASS_BACKGROUND);
+  gtk_widget_path_iter_add_class (path, -1, "window-frame");
   gtk_style_context_set_path (style, path);
+
   gtk_widget_path_unref (path);
 
   if (theme_name && *theme_name)
@@ -5030,12 +5037,37 @@ meta_theme_create_style_context (GdkScreen   *screen,
 
   g_free (theme_name);
 
-  return style;
+  return style_info;
+}
+
+MetaStyleInfo *
+meta_style_info_ref (MetaStyleInfo *style_info)
+{
+  g_return_val_if_fail (style_info != NULL, NULL);
+  g_return_val_if_fail (style_info->refcount > 0, NULL);
+
+  g_atomic_int_inc ((volatile int *)&style_info->refcount);
+  return style_info;
+}
+
+void
+meta_style_info_unref (MetaStyleInfo *style_info)
+{
+  g_return_if_fail (style_info != NULL);
+  g_return_if_fail (style_info->refcount > 0);
+
+  if (g_atomic_int_dec_and_test ((volatile int *)&style_info->refcount))
+    {
+      int i;
+      for (i = 0; i < META_STYLE_ELEMENT_LAST; i++)
+        g_object_unref (style_info->styles[i]);
+      g_free (style_info);
+    }
 }
 
 void
 meta_theme_draw_frame (MetaTheme              *theme,
-                       GtkStyleContext        *style_gtk,
+                       MetaStyleInfo          *style_info,
                        cairo_t                *cr,
                        MetaFrameType           type,
                        MetaFrameFlags          flags,
@@ -5069,7 +5101,7 @@ meta_theme_draw_frame (MetaTheme              *theme,
                                    theme);
 
   meta_frame_style_draw_with_style (style,
-                                    style_gtk,
+                                    style_info,
                                     cr,
                                     &fgeom,
                                     client_width, client_height,