[eog] EogZoomEntry: Disable the entry if no zooming is possible

[Felix Riemann <friemann src gnome org>]

commit 788ec755964bddc5cea58f2a7ab45569d28afb94
Author: Felix Riemann <friemann gnome org>
Date:   Wed Feb 15 20:33:05 2017 +0100

    EogZoomEntry: Disable the entry if no zooming is possible

 src/eog-zoom-entry.c |   36 ++++++++++++++++++++++++++++++++++--
 1 files changed, 34 insertions(+), 2 deletions(-)
---
diff --git a/src/eog-zoom-entry.c b/src/eog-zoom-entry.c
index 2edd38c..02bb78d 100644
--- a/src/eog-zoom-entry.c
+++ b/src/eog-zoom-entry.c
@@ -74,10 +74,9 @@ static const struct {
 
 G_DEFINE_TYPE_WITH_PRIVATE (EogZoomEntry, eog_zoom_entry, GTK_TYPE_BOX);
 
-//static guint signals[LAST_SIGNAL] = { 0 };
-
 static void eog_zoom_entry_reset_zoom_level (EogZoomEntry *entry);
 static void eog_zoom_entry_set_zoom_level (EogZoomEntry *entry, gdouble zoom);
+static void eog_zoom_entry_update_sensitivity (EogZoomEntry *entry);
 
 
 static void
@@ -198,6 +197,16 @@ eog_zoom_entry_view_zoom_changed_cb (EogScrollView *view, gdouble zoom,
 }
 
 static void
+button_sensitivity_changed_cb (GObject    *gobject,
+                               GParamSpec *pspec,
+                               gpointer    user_data)
+{
+       g_return_if_fail (EOG_IS_ZOOM_ENTRY (user_data));
+
+       eog_zoom_entry_update_sensitivity (EOG_ZOOM_ENTRY (user_data));
+}
+
+static void
 eog_zoom_entry_constructed (GObject *object)
 {
        EogZoomEntry *zoom_entry = EOG_ZOOM_ENTRY (object);
@@ -214,6 +223,14 @@ eog_zoom_entry_constructed (GObject *object)
                        g_menu_model_get_item_link (G_MENU_MODEL (zoom_entry->priv->menu),
                                                    1, G_MENU_LINK_SECTION);
        eog_zoom_entry_populate_free_zoom_section (zoom_entry);
+
+       g_signal_connect (zoom_entry->priv->btn_zoom_in, "notify::sensitive",
+                         G_CALLBACK (button_sensitivity_changed_cb),
+                         zoom_entry);
+       g_signal_connect (zoom_entry->priv->btn_zoom_out, "notify::sensitive",
+                         G_CALLBACK (button_sensitivity_changed_cb),
+                         zoom_entry);
+       eog_zoom_entry_update_sensitivity (zoom_entry);
 }
 
 static void
@@ -271,6 +288,21 @@ eog_zoom_entry_reset_zoom_level (EogZoomEntry *entry)
 }
 
 static void
+eog_zoom_entry_update_sensitivity (EogZoomEntry *entry)
+{
+       const gboolean current_state =
+                       gtk_widget_is_sensitive (entry->priv->value_entry);
+       const gboolean new_state =
+                       gtk_widget_is_sensitive (entry->priv->btn_zoom_in)
+                       | gtk_widget_is_sensitive (entry->priv->btn_zoom_out);
+
+       if (current_state != new_state) {
+               gtk_widget_set_sensitive (entry->priv->value_entry, new_state);
+       }
+
+}
+
+static void
 eog_zoom_entry_class_init (EogZoomEntryClass *klass)
 {
        GObjectClass *object_class = G_OBJECT_CLASS (klass);