[gnome-shell] theme-context: Use interface font instead of hardcoded default

[Florian Müllner <fmuellner src gnome org>]

commit f28f041a95dca2709ee43bdaa4762487588e3246
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon Apr 8 17:50:08 2019 +0200

    theme-context: Use interface font instead of hardcoded default
    
    With this, gnome-shell will now follow the interface setting instead
    of hardcoding a default font, unless when overwritten by the CSS.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=688288

 src/st/st-theme-context.c | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)
---
diff --git a/src/st/st-theme-context.c b/src/st/st-theme-context.c
index 7b1b03a45b..de112aa499 100644
--- a/src/st/st-theme-context.c
+++ b/src/st/st-theme-context.c
@@ -22,6 +22,7 @@
 #include <config.h>
 
 #include "st-private.h"
+#include "st-settings.h"
 #include "st-texture-cache.h"
 #include "st-theme.h"
 #include "st-theme-context.h"
@@ -42,8 +43,6 @@ struct _StThemeContext {
   int scale_factor;
 };
 
-#define DEFAULT_FONT "sans-serif 10"
-
 enum
 {
   PROP_0,
@@ -61,6 +60,10 @@ static guint signals[LAST_SIGNAL] = { 0, };
 
 G_DEFINE_TYPE (StThemeContext, st_theme_context, G_TYPE_OBJECT)
 
+static PangoFontDescription *get_interface_font_description (void);
+static void on_font_name_changed (StSettings     *settings,
+                                  GParamSpec     *pspec,
+                                  StThemeContext *context);
 static void on_icon_theme_changed (StTextureCache *cache,
                                    StThemeContext *context);
 static void st_theme_context_changed (StThemeContext *context);
@@ -79,6 +82,9 @@ st_theme_context_finalize (GObject *object)
 {
   StThemeContext *context = ST_THEME_CONTEXT (object);
 
+  g_signal_handlers_disconnect_by_func (st_settings_get (),
+                                        (gpointer) on_font_name_changed,
+                                        context);
   g_signal_handlers_disconnect_by_func (st_texture_cache_get_default (),
                                        (gpointer) on_icon_theme_changed,
                                        context);
@@ -134,8 +140,12 @@ st_theme_context_class_init (StThemeContextClass *klass)
 static void
 st_theme_context_init (StThemeContext *context)
 {
-  context->font = pango_font_description_from_string (DEFAULT_FONT);
+  context->font = get_interface_font_description ();
 
+  g_signal_connect (st_settings_get (),
+                    "notify::font-name",
+                    G_CALLBACK (on_font_name_changed),
+                    context);
   g_signal_connect (st_texture_cache_get_default (),
                     "icon-theme-changed",
                     G_CALLBACK (on_icon_theme_changed),
@@ -215,6 +225,16 @@ st_theme_context_new (void)
   return context;
 }
 
+static PangoFontDescription *
+get_interface_font_description (void)
+{
+  StSettings *settings = st_settings_get ();
+  g_autofree char *font_name = NULL;
+
+  g_object_get (settings, "font-name", &font_name, NULL);
+  return pango_font_description_from_string (font_name);
+}
+
 static void
 on_stage_destroy (ClutterStage *stage)
 {
@@ -237,6 +257,17 @@ st_theme_context_changed (StThemeContext *context)
     g_object_unref (old_root);
 }
 
+static void
+on_font_name_changed (StSettings     *settings,
+                      GParamSpec     *pspect,
+                      StThemeContext *context)
+{
+  PangoFontDescription *font_desc = get_interface_font_description ();
+  st_theme_context_set_font (context, font_desc);
+
+  pango_font_description_free (font_desc);
+}
+
 static gboolean
 changed_idle (gpointer userdata)
 {