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 1e5749e60e77cce3b5c5b69425f1dcf658cb668b..fb18504d4ace9ca674cae4ff1690a0639cb33575 100644 (file)
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -616,6 +616,8 @@ struct _GtkStateData
 {
   guint         flags_to_set;
   guint         flags_to_unset;
+
+  gint          old_scale_factor;
 };
 
 /* --- prototypes --- */
@@ -8778,6 +8780,7 @@ 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;
 
@@ -9436,6 +9439,8 @@ 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;
@@ -9531,6 +9536,8 @@ 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()
    */
 
@@ -12791,6 +12798,7 @@ gtk_widget_propagate_state (GtkWidget    *widget,
   GtkWidgetPrivate *priv = widget->priv;
   GtkStateFlags new_flags, old_flags = priv->state_flags;
   GtkStateType old_state;
+  gint new_scale_factor = gtk_widget_get_scale_factor (widget);
 
   G_GNUC_BEGIN_IGNORE_DEPRECATIONS;
   old_state = gtk_widget_get_state (widget);
@@ -12815,6 +12823,9 @@ 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);
@@ -12872,6 +12883,7 @@ gtk_widget_propagate_state (GtkWidget    *widget,
           GtkStateData child_data;
 
           /* 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;