[libshumate] scale: Update when the reference map source changes

[Corentin Noël <corentinnoel src gnome org>]

commit 327cabb76c7316fcfe18ba71ffea75c4519f322b
Author: James Westman <james jwestman net>
Date:   Wed Mar 10 14:30:49 2021 -0600

    scale: Update when the reference map source changes
    
    Previously, if you set the scale's viewport before you set the
    viewport's reference map source, the scale would start out at 1ft/1m.

 shumate/shumate-scale.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)
---
diff --git a/shumate/shumate-scale.c b/shumate/shumate-scale.c
index 0b9da5d..ff91d0f 100644
--- a/shumate/shumate-scale.c
+++ b/shumate/shumate-scale.c
@@ -212,22 +212,14 @@ shumate_scale_on_scale_changed (ShumateScale *self)
 }
 
 static void
-on_latitude_changed (ShumateScale *self,
-                     G_GNUC_UNUSED GParamSpec *pspec,
-                     ShumateViewport *viewport)
+on_viewport_props_changed (ShumateScale *self,
+                           G_GNUC_UNUSED GParamSpec *pspec,
+                           ShumateViewport *viewport)
 {
   shumate_scale_on_scale_changed (self);
 }
 
 
-static void
-on_zoom_level_changed (ShumateScale *self,
-                       G_GNUC_UNUSED GParamSpec *pspec,
-                       ShumateViewport *viewport)
-{
-  shumate_scale_on_scale_changed (self);
-}
-
 static void
 shumate_scale_get_property (GObject *object,
     guint prop_id,
@@ -477,8 +469,9 @@ shumate_scale_set_viewport (ShumateScale    *scale,
       g_object_notify_by_pspec(G_OBJECT (scale), obj_properties[PROP_VIEWPORT]);
       if (scale->viewport)
         {
-          g_signal_connect_swapped (scale->viewport, "notify::latitude", G_CALLBACK (on_latitude_changed), 
scale);
-          g_signal_connect_swapped (scale->viewport, "notify::zoom-level", G_CALLBACK 
(on_zoom_level_changed), scale);
+          g_signal_connect_swapped (scale->viewport, "notify::latitude", G_CALLBACK 
(on_viewport_props_changed), scale);
+          g_signal_connect_swapped (scale->viewport, "notify::zoom-level", G_CALLBACK 
(on_viewport_props_changed), scale);
+          g_signal_connect_swapped (scale->viewport, "notify::reference-map-source", G_CALLBACK 
(on_viewport_props_changed), scale);
         }
 
       shumate_scale_on_scale_changed (scale);