audgui: Use scalable+themable icons for the preferences window.

Makefile

@@ -13,7 +13,14 @@ DATA = AUTHORS \
        images/connectivity.png \
        images/info.png \
        images/playlist.png \
-       images/plugins.png
+       images/plugins.png \
+       images/applications-graphics.svg \
+       images/applications-internet.svg \
+       images/applications-system.svg \
+       images/audio-volume-medium.svg \
+       images/audio-x-generic.svg \
+       images/dialog-information.svg \
+       images/preferences-system.svg
 
 include buildsys.mk
 include extra.mk

src/libaudgui/init.cc

@@ -127,6 +127,38 @@ void audgui_hide_unique_window (int id)
         gtk_widget_destroy (windows[id]);
 }
 
+static void load_fallback_icon (const char * icon, int size)
+{
+    const char * data_dir = aud_get_path (AudPath::DataDir);
+    StringBuf svg_name = str_concat ({icon, ".svg"});
+    StringBuf path = filename_build ({data_dir, "images", svg_name});
+    auto pixbuf = gdk_pixbuf_new_from_file_at_size (path, size, size, nullptr);
+
+    if (pixbuf)
+    {
+        gtk_icon_theme_add_builtin_icon (icon, size, pixbuf);
+        g_object_unref (pixbuf);
+    }
+}
+
+static void load_fallback_icons ()
+{
+    /* keep this in sync with the list in prefs-window.cc */
+    static const char * const categories[] = {
+        "applications-graphics",
+        "applications-internet",
+        "applications-system",
+        "audio-volume-medium",
+        "audio-x-generic",
+        "dialog-information",
+        "preferences-system"
+    };
+
+    int category_size = audgui_to_native_dpi (48);
+    for (const char * icon : categories)
+        load_fallback_icon (icon, category_size);
+}
+
 static void playlist_set_playing_cb (void *, void *)
 {
     audgui_pixbuf_uncache ();
@@ -140,13 +172,20 @@ static void playlist_position_cb (void * list, void *)
 
 EXPORT void audgui_init ()
 {
+    static bool icons_loaded = false;
     assert (aud_get_mainloop_type () == MainloopType::GLib);
 
     if (init_count ++)
         return;
 
     gtk_init (nullptr, nullptr);
 
+    if (! icons_loaded)
+    {
+        load_fallback_icons ();
+        icons_loaded = true;
+    }
+
     aud_config_set_defaults ("audgui", audgui_defaults);
 
     status_init ();

src/libaudgui/prefs-window.cc

@@ -46,7 +46,7 @@ enum CategoryViewCols {
 };
 
 struct Category {
-    const char * icon_path;
+    const char * icon;
     const char * name;
 };
 
@@ -77,14 +77,15 @@ enum {
     CATEGORY_ADVANCED
 };
 
+/* keep this in sync with the list in load_fallback_icons (init.cc) */
 static const Category categories[] = {
-    { "appearance.png", N_("Appearance") },
-    { "audio.png", N_("Audio") },
-    { "connectivity.png", N_("Network") },
-    { "playlist.png", N_("Playlist")} ,
-    { "info.png", N_("Song Info") },
-    { "plugins.png", N_("Plugins") },
-    { "advanced.png", N_("Advanced") }
+    { "applications-graphics", N_("Appearance") },
+    { "audio-volume-medium", N_("Audio") },
+    { "applications-internet", N_("Network") },
+    { "audio-x-generic", N_("Playlist")} ,
+    { "dialog-information", N_("Song Info") },
+    { "applications-system", N_("Plugins") },
+    { "preferences-system", N_("Advanced") }
 };
 
 static const PluginCategory plugin_categories[] = {
@@ -480,7 +481,8 @@ static void fill_category_list (GtkTreeView * treeview, GtkNotebook * notebook)
      GDK_TYPE_PIXBUF, G_TYPE_STRING, G_TYPE_INT);
     gtk_tree_view_set_model (treeview, (GtkTreeModel *) store);
 
-    const char * data_dir = aud_get_path (AudPath::DataDir);
+    GtkIconTheme * icon_theme = gtk_icon_theme_get_default ();
+    int icon_size = audgui_to_native_dpi (48);
 
     for (const Category & category : categories)
     {
@@ -492,8 +494,8 @@ static void fill_category_list (GtkTreeView * treeview, GtkNotebook * notebook)
         gtk_list_store_set (store, & iter, CATEGORY_VIEW_COL_NAME,
          gettext (category.name), -1);
 
-        StringBuf path = filename_build ({data_dir, "images", category.icon_path});
-        AudguiPixbuf img (gdk_pixbuf_new_from_file (path, nullptr));
+        AudguiPixbuf img (gtk_icon_theme_load_icon (icon_theme,
+         category.icon, icon_size, (GtkIconLookupFlags) 0, nullptr));
 
         if (img)
             gtk_list_store_set (store, & iter, CATEGORY_VIEW_COL_ICON, img.get (), -1);