[nautilus] previewer: support reading the Visible property

[Cosimo Cecchi <cosimoc src gnome org>]

commit 46ca020c280fa14e8052e33852e8542bc3433ed0
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Sat Jul 6 22:49:24 2019 -0700

    previewer: support reading the Visible property
    
    From the NautilusPreviewer2 interface.

 src/nautilus-previewer.c | 19 +++++++++++++++++++
 src/nautilus-previewer.h |  2 ++
 2 files changed, 21 insertions(+)
---
diff --git a/src/nautilus-previewer.c b/src/nautilus-previewer.c
index 7f8867afe..0511dc991 100644
--- a/src/nautilus-previewer.c
+++ b/src/nautilus-previewer.c
@@ -186,3 +186,22 @@ nautilus_previewer_disconnect_selection_event (GDBusConnection *connection,
 {
     g_dbus_connection_signal_unsubscribe (connection, event_id);
 }
+
+gboolean
+nautilus_previewer_is_visible (void)
+{
+    g_autoptr(GVariant) variant = NULL;
+
+    if (!ensure_previewer_v2_proxy ())
+    {
+        return FALSE;
+    }
+
+    variant = g_dbus_proxy_get_cached_property (previewer_v2_proxy, "Visible");
+    if (variant)
+    {
+        return g_variant_get_boolean (variant);
+    }
+
+    return FALSE;
+}
diff --git a/src/nautilus-previewer.h b/src/nautilus-previewer.h
index 7de3d178f..73270fa46 100644
--- a/src/nautilus-previewer.h
+++ b/src/nautilus-previewer.h
@@ -33,6 +33,8 @@ void nautilus_previewer_call_show_file (const gchar *uri,
                                        gboolean     close_if_already_visible);
 void nautilus_previewer_call_close     (void);
 
+gboolean nautilus_previewer_is_visible (void);
+
 guint nautilus_previewer_connect_selection_event (GDBusConnection *connection);
 void  nautilus_previewer_disconnect_selection_event (GDBusConnection *connection,
                                                      guint            event_id);