add a custom refresh-view signal

Now we can trigger a gtk page refresh calling refresh_view. This
function triggers a custom signal refresh-view, whose handler copies the
position from the document object to the adjustments.

callbacks.c

@@ -176,6 +176,32 @@ cb_view_vadjustment_changed(GtkAdjustment* adjustment, gpointer data)
   zathura_adjustment_set_value_from_ratio(adjustment, ratio);
 }
 
+void
+cb_refresh_view(GtkWidget* GIRARA_UNUSED(view), gpointer data)
+{
+  zathura_t* zathura = data;
+  if (zathura == NULL || zathura->document == NULL) {
+    return;
+  }
+
+  unsigned int page_id = zathura_document_get_current_page_number(zathura->document);
+  zathura_page_t* page = zathura_document_get_page(zathura->document, page_id);
+  if (page == NULL) {
+    return;
+  }
+
+  GtkAdjustment* vadj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(zathura->ui.session->gtk.view));
+  GtkAdjustment* hadj = gtk_scrolled_window_get_hadjustment(GTK_SCROLLED_WINDOW(zathura->ui.session->gtk.view));
+
+  double position_x = zathura_document_get_position_x(zathura->document);
+  double position_y = zathura_document_get_position_y(zathura->document);
+
+  zathura_adjustment_set_value_from_ratio(vadj, position_y);
+  zathura_adjustment_set_value_from_ratio(hadj, position_x);
+
+  statusbar_page_number_update(zathura);
+}
+
 void
 cb_adjustment_track_value(GtkAdjustment* adjustment, gpointer data)
 {

callbacks.h

@@ -61,6 +61,17 @@ void cb_view_hadjustment_changed(GtkAdjustment *adjustment, gpointer data);
  */
 void cb_view_vadjustment_changed(GtkAdjustment *adjustment, gpointer data);
 
+/**
+ * This function gets called when the program need to refresh the document view.
+ *
+ * It adjusts the value of the scrollbars, triggering a redraw in the new
+ * position.
+ *
+ * @param view The view GtkWidget
+ * @param data The zathura instance
+ */
+void cb_refresh_view(GtkWidget* view, gpointer data);
+
 /* This function gets called when the value of the adjustment changes.
  *
  * It updates the value of the tracking adjustment, only if the bounds of the

zathura.c

@@ -141,6 +141,21 @@ zathura_init(zathura_t* zathura)
   zathura->ui.session->events.buffer_changed  = cb_buffer_changed;
   zathura->ui.session->events.unknown_command = cb_unknown_command;
 
+  /* zathura signals */
+  zathura->signals.refresh_view = g_signal_new("refresh-view",
+                                               GTK_TYPE_WIDGET,
+                                               G_SIGNAL_RUN_LAST,
+                                               0,
+                                               NULL,
+                                               NULL,
+                                               g_cclosure_marshal_generic,
+                                               G_TYPE_NONE,
+                                               1,
+                                               G_TYPE_POINTER);
+
+  g_signal_connect(G_OBJECT(zathura->ui.session->gtk.view), "refresh-view",
+                   G_CALLBACK(cb_refresh_view), zathura);
+
   /* page view */
 #if (GTK_MAJOR_VERSION == 3)
   zathura->ui.page_widget = gtk_grid_new();
@@ -1195,6 +1210,16 @@ position_set(zathura_t* zathura, double position_x, double position_y)
   }
 }
 
+
+void
+refresh_view(zathura_t* zathura) {
+  g_return_if_fail(zathura != NULL);
+
+  /* emit a custom refresh-view signal */
+  g_signal_emit(zathura->ui.session->gtk.view, zathura->signals.refresh_view,
+                0, zathura);
+}
+
 static void
 zathura_jumplist_hide_inputbar(zathura_t* zathura)
 {

zathura.h

@@ -132,6 +132,11 @@ struct zathura_s
     unsigned int max_size;
   } jumplist;
 
+  struct
+  {
+    guint refresh_view;
+  } signals;
+
   struct
   {
     gchar* file;
@@ -321,6 +326,13 @@ void position_set_delayed(zathura_t* zathura, double position_x, double position
  */
 void position_set(zathura_t* zathura, double position_x, double position_y);
 
+/**
+ * Refresh the page view
+ *
+ * @param zathura Zathura session
+ */
+void refresh_view(zathura_t* zathura);
+
 /**
  * Builds the box structure to show the rendered pages
  *