widget: propagate scale factor upon reparenting a widget

When a widget is created, its default scale is the scale of the
primary screen (for instance 2). But once parented to another widget
its scale factor should be the one of its parent (if parented to a
widget on a screen at scale factor 1, it should be 1).

The problem is that we don't emit the notify::scale-factor signal when
reparenting happens.

https://bugzilla.gnome.org/show_bug.cgi?id=776821

diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 5e406a5d6fe9e2fa40c6005c7f8c74f27fbcc870..838630d5f113526b744d44c1e610fcdc8b929e5c 100644 (file)
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -606,6 +606,8 @@ struct _GtkStateData
 {
   guint         flags_to_set;
   guint         flags_to_unset;
+
+  gint          old_scale_factor;
 };
 
 /* --- prototypes --- */
@@ -7882,6 +7884,7 @@ gtk_widget_update_state_flags (GtkWidget     *widget,
     {
       GtkStateData data;
 
+      data.old_scale_factor = gtk_widget_get_scale_factor (widget);
       data.flags_to_set = flags_to_set;
       data.flags_to_unset = flags_to_unset;
 
@@ -8304,6 +8307,8 @@ gtk_widget_set_sensitive (GtkWidget *widget,
     {
       GtkStateData data;
 
+      data.old_scale_factor = gtk_widget_get_scale_factor (widget);
+
       if (sensitive)
         {
           data.flags_to_set = 0;
@@ -8399,6 +8404,8 @@ gtk_widget_set_parent (GtkWidget *widget,
       return;
     }
 
+  data.old_scale_factor = gtk_widget_get_scale_factor (widget);
+
   /* keep this function in sync with gtk_menu_attach_to_widget()
    */
 
@@ -11120,6 +11127,7 @@ gtk_widget_propagate_state (GtkWidget    *widget,
   GtkStateFlags new_flags, old_flags = priv->state_flags;
   GtkStateData child_data;
   GtkWidget *child;
+  gint new_scale_factor = gtk_widget_get_scale_factor (widget);
 
   priv->state_flags |= data->flags_to_set;
   priv->state_flags &= ~(data->flags_to_unset);
@@ -11140,6 +11148,9 @@ gtk_widget_propagate_state (GtkWidget    *widget,
 
   new_flags = priv->state_flags;
 
+  if (data->old_scale_factor != new_scale_factor)
+    _gtk_widget_scale_changed (widget);
+
   if (old_flags != new_flags)
     {
       g_object_ref (widget);
@@ -11193,6 +11204,7 @@ gtk_widget_propagate_state (GtkWidget    *widget,
 
 
       /* Make sure to only propagate the right states further */
+      child_data.old_scale_factor = new_scale_factor;
       child_data.flags_to_set = data->flags_to_set & GTK_STATE_FLAGS_DO_PROPAGATE;
       child_data.flags_to_unset = data->flags_to_unset & GTK_STATE_FLAGS_DO_PROPAGATE;