[pango/font-list] fontmap: Emit GListModel::changed

[Matthias Clasen <matthiasc src gnome org>]

commit d82d4093c083e087ccd6823bfad836f25249eeb9
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Dec 4 23:32:04 2019 -0500

    fontmap: Emit GListModel::changed
    
    Emit the list model changed signal when the font map changes.
    Since font map changes are rare, we don't keep track of detailed
    changes and assume everything has changed.

 pango/pango-fontmap.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)
---
diff --git a/pango/pango-fontmap.c b/pango/pango-fontmap.c
index a8b9f426..8f4d7bc7 100644
--- a/pango/pango-fontmap.c
+++ b/pango/pango-fontmap.c
@@ -37,9 +37,16 @@ static PangoFontset *pango_font_map_real_load_fontset (PangoFontMap
 static PangoFontFamily *pango_font_map_real_get_family (PangoFontMap *fontmap,
                                                         const char   *name);
 
+static void pango_font_map_real_changed (PangoFontMap *fontmap);
+
 static void pango_font_map_list_model_init (GListModelInterface *iface);
 
+typedef struct {
+  guint n_families;
+} PangoFontMapPrivate;
+
 G_DEFINE_ABSTRACT_TYPE_WITH_CODE (PangoFontMap, pango_font_map, G_TYPE_OBJECT,
+                                  G_ADD_PRIVATE (PangoFontMap)
                                   G_IMPLEMENT_INTERFACE (G_TYPE_LIST_MODEL, pango_font_map_list_model_init))
 
 static void
@@ -47,6 +54,7 @@ pango_font_map_class_init (PangoFontMapClass *class)
 {
   class->load_fontset = pango_font_map_real_load_fontset;
   class->get_family = pango_font_map_real_get_family;
+  class->changed = pango_font_map_real_changed;
 }
 
 static void
@@ -120,9 +128,13 @@ pango_font_map_list_families (PangoFontMap      *fontmap,
                              PangoFontFamily ***families,
                              int               *n_families)
 {
+  PangoFontMapPrivate *priv = pango_font_map_get_instance_private (fontmap);
   g_return_if_fail (fontmap != NULL);
 
   PANGO_FONT_MAP_GET_CLASS (fontmap)->list_families (fontmap, families, n_families);
+  
+  /* keep this value for GListModel::changed */
+  priv->n_families = *n_families;
 }
 
 /**
@@ -327,6 +339,18 @@ pango_font_map_get_serial (PangoFontMap *fontmap)
     return 1;
 }
 
+static void
+pango_font_map_real_changed (PangoFontMap *fontmap)
+{
+  PangoFontMapPrivate *priv = pango_font_map_get_instance_private (fontmap);
+  guint removed, added;
+
+  removed = priv->n_families;
+  added = g_list_model_get_n_items (G_LIST_MODEL (fontmap));
+
+  g_list_model_items_changed (G_LIST_MODEL (fontmap), 0, removed, added);  
+}
+
 /**
  * pango_font_map_changed:
  * @fontmap: a #PangoFontMap
@@ -420,7 +444,7 @@ pango_font_map_get_item (GListModel *list,
 {
   PangoFontMap *fontmap = PANGO_FONT_MAP (list);
   PangoFontFamily **families;
-  guint n_families;
+  int n_families;
   PangoFontFamily *family;
 
   pango_font_map_list_families (fontmap, &families, &n_families);