theme-viewer: use the same GtkStyleContext as mutter usually renders

https://bugzilla.gnome.org/show_bug.cgi?id=690317

src/meta/preview-widget.h

@@ -44,6 +44,8 @@ struct _MetaPreview
 {
   GtkBin bin;
 
+  GtkStyleContext *style_context;
+
   MetaTheme *theme;
   char *title;
   MetaFrameType type;

src/ui/frames.c

@@ -185,38 +185,6 @@ prefs_changed_callback (MetaPreference pref,
     }
 }
 
-static GtkStyleContext *
-create_style_context (MetaFrames  *frames,
-                      const gchar *variant)
-{
-  GtkStyleContext *style;
-  GdkScreen *screen;
-  char *theme_name;
-
-  screen = gtk_widget_get_screen (GTK_WIDGET (frames));
-  g_object_get (gtk_settings_get_for_screen (screen),
-                "gtk-theme-name", &theme_name,
-                NULL);
-
-  style = gtk_style_context_new ();
-  gtk_style_context_set_path (style,
-                              gtk_widget_get_path (GTK_WIDGET (frames)));
-
-  if (theme_name && *theme_name)
-    {
-      GtkCssProvider *provider;
-
-      provider = gtk_css_provider_get_named (theme_name, variant);
-      gtk_style_context_add_provider (style,
-                                      GTK_STYLE_PROVIDER (provider),
-                                      GTK_STYLE_PROVIDER_PRIORITY_SETTINGS);
-    }
-
-  g_free (theme_name);
-
-  return style;
-}
-
 static GtkStyleContext *
 meta_frames_get_theme_variant (MetaFrames  *frames,
                                const gchar *variant)
@@ -226,7 +194,7 @@ meta_frames_get_theme_variant (MetaFrames  *frames,
   style = g_hash_table_lookup (frames->style_variants, variant);
   if (style == NULL)
     {
-      style = create_style_context (frames, variant);
+      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);
     }
 
@@ -238,15 +206,18 @@ update_style_contexts (MetaFrames *frames)
 {
   GtkStyleContext *style;
   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 = create_style_context (frames, NULL);
+  frames->normal_style = meta_theme_create_style_context (screen, NULL);
 
   variants = g_hash_table_get_keys (frames->style_variants);
   for (variant = variants; variant; variant = variants->next)
     {
-      style = create_style_context (frames, (char *)variant->data);
+      style = meta_theme_create_style_context (screen, (char *)variant->data);
       g_hash_table_insert (frames->style_variants,
                            g_strdup (variant->data), style);
     }

src/ui/preview-widget.c

@@ -39,6 +39,8 @@ static void     meta_preview_size_allocate (GtkWidget        *widget,
                                             GtkAllocation    *allocation);
 static gboolean meta_preview_draw          (GtkWidget        *widget,
                                             cairo_t          *cr);
+static void     meta_preview_realize       (GtkWidget        *widget);
+static void     meta_preview_dispose       (GObject          *object);
 static void     meta_preview_finalize      (GObject          *object);
 
 G_DEFINE_TYPE (MetaPreview, meta_preview, GTK_TYPE_BIN);
@@ -51,8 +53,10 @@ meta_preview_class_init (MetaPreviewClass *class)
 
   widget_class = (GtkWidgetClass*) class;
 
+  gobject_class->dispose = meta_preview_dispose;
   gobject_class->finalize = meta_preview_finalize;
 
+  widget_class->realize = meta_preview_realize;
   widget_class->draw = meta_preview_draw;
   widget_class->get_preferred_width = meta_preview_get_preferred_width;
   widget_class->get_preferred_height = meta_preview_get_preferred_height;
@@ -107,6 +111,16 @@ meta_preview_new (void)
   return GTK_WIDGET (preview);
 }
 
+static void
+meta_preview_dispose (GObject *object)
+{
+  MetaPreview *preview = META_PREVIEW (object);
+
+  g_clear_object (&preview->style_context);
+
+  G_OBJECT_CLASS (meta_preview_parent_class)->dispose (object);
+}
+
 static void
 meta_preview_finalize (GObject *object)
 {
@@ -212,7 +226,7 @@ meta_preview_draw (GtkWidget *widget,
         client_height = 1;  
       
       meta_theme_draw_frame (preview->theme,
-                             gtk_widget_get_style_context (widget),
+                             preview->style_context,
                              cr,
                              preview->type,
                              preview->flags,
@@ -231,6 +245,17 @@ meta_preview_draw (GtkWidget *widget,
   return GTK_WIDGET_CLASS (meta_preview_parent_class)->draw (widget, cr);
 }
 
+static void
+meta_preview_realize (GtkWidget *widget)
+{
+  MetaPreview *preview = META_PREVIEW (widget);
+
+  GTK_WIDGET_CLASS (meta_preview_parent_class)->realize (widget);
+
+  preview->style_context = meta_theme_create_style_context (gtk_widget_get_screen (widget),
+                                                            NULL);
+}
+
 #define NO_CHILD_WIDTH 80
 #define NO_CHILD_HEIGHT 20
 

src/ui/theme-private.h

@@ -1022,6 +1022,9 @@ double meta_theme_get_title_scale (MetaTheme     *theme,
                                    MetaFrameType  type,
                                    MetaFrameFlags flags);
 
+GtkStyleContext * meta_theme_create_style_context (GdkScreen   *screen,
+                                                   const gchar *variant);
+
 void meta_theme_draw_frame (MetaTheme              *theme,
                             GtkStyleContext        *style_gtk,
                             cairo_t                *cr,

src/ui/theme-viewer.c

@@ -854,7 +854,8 @@ main (int argc, char **argv)
                     G_CALLBACK (gtk_main_quit), NULL);
 
   gtk_widget_realize (window);
-  style = gtk_widget_get_style_context (window);
+
+  style = meta_theme_create_style_context (gtk_widget_get_screen (window), NULL);
   gtk_style_context_get (style, GTK_STATE_FLAG_NORMAL, "font", &font_desc, NULL);
 
   g_assert (style);
@@ -927,13 +928,12 @@ get_flags (GtkWidget *widget)
 }
 
 static int
-get_text_height (GtkWidget *widget)
+get_text_height (GtkWidget       *widget,
+                 GtkStyleContext *style)
 {
-  GtkStyleContext *style;
   PangoFontDescription *font_desc;
   int text_height;
 
-  style = gtk_widget_get_style_context (widget);
   gtk_style_context_get (style, GTK_STATE_FLAG_NORMAL, "font", &font_desc, NULL);
   text_height = meta_pango_font_desc_get_text_height (font_desc,
                                                       gtk_widget_get_pango_context (widget));
@@ -955,6 +955,7 @@ static void
 run_theme_benchmark (void)
 {
   GtkWidget* widget;
+  GtkStyleContext *style_context;
   cairo_surface_t *pixmap;
   MetaFrameBorders borders;
   MetaButtonState button_states[META_BUTTON_TYPE_LAST] =
@@ -979,9 +980,11 @@ run_theme_benchmark (void)
   widget = gtk_window_new (GTK_WINDOW_TOPLEVEL);
   gtk_widget_realize (widget);
 
+  style_context = meta_theme_create_style_context (gtk_widget_get_screen (widget), NULL);
+
   meta_theme_get_frame_borders (global_theme,
                                 META_FRAME_TYPE_NORMAL,
-                                get_text_height (widget),
+                                get_text_height (widget, style_context),
                                 get_flags (widget),
                                 &borders);
 
@@ -1024,13 +1027,13 @@ run_theme_benchmark (void)
       cr = cairo_create (pixmap);
 
       meta_theme_draw_frame (global_theme,
-                             gtk_widget_get_style_context (widget),
+                             style_context,
                              cr,
                              META_FRAME_TYPE_NORMAL,
                              get_flags (widget),
                              client_width, client_height,
                              layout,
-                             get_text_height (widget),
+                             get_text_height (widget, style_context),
                              &button_layout,
                              button_states,
                              meta_preview_get_mini_icon (),
@@ -1058,6 +1061,7 @@ run_theme_benchmark (void)
 
   g_timer_destroy (timer);
   g_object_unref (G_OBJECT (layout));
+  g_object_unref (style_context);
   gtk_widget_destroy (widget);
 
 #undef ITERATIONS

src/ui/theme.c

@@ -37,6 +37,7 @@
 
 #include <config.h>
 #include "theme-private.h"
+#include "frames.h" /* for META_TYPE_FRAMES */
 #include <meta/util.h>
 #include <meta/gradient.h>
 #include <meta/prefs.h>
@@ -5438,6 +5439,37 @@ meta_theme_get_title_scale (MetaTheme     *theme,
   return style->layout->title_scale;
 }
 
+GtkStyleContext *
+meta_theme_create_style_context (GdkScreen   *screen,
+                                 const gchar *variant)
+{
+  GtkWidgetPath *path;
+  GtkStyleContext *style;
+  char *theme_name;
+
+  g_object_get (gtk_settings_get_for_screen (screen),
+                "gtk-theme-name", &theme_name,
+                NULL);
+
+  style = gtk_style_context_new ();
+  path = gtk_widget_path_new ();
+  gtk_widget_path_append_type (path, META_TYPE_FRAMES);
+  gtk_style_context_set_path (style, path);
+  gtk_widget_path_unref (path);
+
+  if (theme_name && *theme_name)
+    {
+      GtkCssProvider *provider;
+
+      provider = gtk_css_provider_get_named (theme_name, variant);
+      gtk_style_context_add_provider (style,
+                                      GTK_STYLE_PROVIDER (provider),
+                                      GTK_STYLE_PROVIDER_PRIORITY_SETTINGS);
+    }
+
+  return style;
+}
+
 void
 meta_theme_draw_frame (MetaTheme              *theme,
                        GtkStyleContext        *style_gtk,