[pango/misc-speedups2: 1/4] pango-view: Avoid an assertion when running headless

[Matthias Clasen <matthiasc src gnome org>]

commit 5d45281892f598b79878905105465adbdd5d7a73
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Mar 29 12:55:41 2021 -0400

    pango-view: Avoid an assertion when running headless
    
    The cairo debug cleanup function asserts that all cairo
    resources have been released, but with PangoFcFontMap
    now doing work in threads, some of those threads may
    still be active, holding a reference to the fontmap,
    and thereby keeping cairo objects alive. To fix this
    without giving up on the cleanup entirely, use a
    weak notify to defer it until the fontmap is going
    away.

 utils/viewer-pangocairo.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/utils/viewer-pangocairo.c b/utils/viewer-pangocairo.c
index ac3b49c3..ff9314a1 100644
--- a/utils/viewer-pangocairo.c
+++ b/utils/viewer-pangocairo.c
@@ -79,6 +79,13 @@ pangocairo_view_create (const PangoViewer *klass G_GNUC_UNUSED)
   return instance;
 }
 
+static void
+clear_cairo_data (gpointer  data,
+                  GObject  *dead)
+{
+  cairo_debug_reset_static_data ();
+}
+
 static void
 pangocairo_view_destroy (gpointer instance)
 {
@@ -86,12 +93,12 @@ pangocairo_view_destroy (gpointer instance)
 
   cairo_font_options_destroy (c->font_options);
 
+  g_object_weak_ref (G_OBJECT (c->fontmap), clear_cairo_data, NULL);
+
   g_object_unref (c->fontmap);
 
   c->iface->backend_class->destroy (c->backend);
 
-  cairo_debug_reset_static_data ();
-
   g_slice_free (CairoViewer, c);
 }