From ed39721aa7435860f46da69998cf6cac4ae7e735 Mon Sep 17 00:00:00 2001
From: Emmanuele Bassi <ebassi@gnome.org>
Date: Tue, 15 Jan 2019 15:22:09 +0000
Subject: [PATCH] Add fallbacks for GtkSwitch state labels

While the IEC power symbols have been part of Unicode since version 9.0,
released in 2016, not every font supports them.

We can use the old symbols as a fallback, as they seem to have the
better coverage, if not the best appearance.
---
 gtk/gtkswitch.c | 41 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/gtk/gtkswitch.c b/gtk/gtkswitch.c
index bf63f34fd2..1d42f572a9 100644
--- a/gtk/gtkswitch.c
+++ b/gtk/gtkswitch.c
@@ -298,11 +298,48 @@ gtk_switch_create_pango_layouts (GtkSwitch *self)
 {
   GtkSwitchPrivate *priv = self->priv;
 
+  /* Glyphs for the ON state, in descending order of preference */
+  const char *on_glyphs[] = {
+    "⏽", /* U+23FD POWER ON SYMBOL */
+    "❙", /* U+2759 MEDIUM VERTICAL BAR */
+  };
+
+  /* Glyphs for the OFF state, in descending order of preference */
+  const char *off_glyphs[] = {
+    "⭘", /* U+2B58 HEAVY CIRCLE */
+    "○", /* U+25CB WHITE CIRCLE */
+  };
+  int i;
+
   g_clear_object (&priv->on_layout);
-  priv->on_layout = gtk_widget_create_pango_layout (GTK_WIDGET (self), "⏽");
+
+  for (i = 0; i < G_N_ELEMENTS (on_glyphs); i++)
+    {
+      PangoLayout *layout = gtk_widget_create_pango_layout (GTK_WIDGET (self), on_glyphs[i]);
+
+      if (pango_layout_get_unknown_glyphs_count (layout) == 0)
+        {
+          priv->on_layout = layout;
+          break;
+        }
+
+      g_object_unref (layout);
+    }
 
   g_clear_object (&priv->off_layout);
-  priv->off_layout = gtk_widget_create_pango_layout (GTK_WIDGET (self), "⭘");
+
+  for (i = 0; i < G_N_ELEMENTS (off_glyphs); i++)
+    {
+      PangoLayout *layout = gtk_widget_create_pango_layout (GTK_WIDGET (self), off_glyphs[i]);
+
+      if (pango_layout_get_unknown_glyphs_count (layout) == 0)
+        {
+          priv->off_layout = layout;
+          break;
+        }
+
+      g_object_unref (layout);
+    }
 }
 
 static void