[gtk+] widget: Make gtk_widget_pick() really slow

[Benjamin Otte <otte src gnome org>]

commit 994287b71fc208d9b810f15ef7fd6dfa6364737a
Author: Benjamin Otte <otte redhat com>
Date:   Sun Nov 5 04:05:55 2017 +0100

    widget: Make gtk_widget_pick() really slow
    
    We cannot fast-track picking by using gtk_widget_contains(). Child
    widgets may extend their parent using ie negative margins.
    
    This is not just a theoretical concern, this is what's happening right
    now with GtkScale's sliders relative to the trough.
    
    The problem is that we now iterate through all widgets, even when they
    aren't anywhere near the mouse pointer. So essentially every pick
    operation is now guaranteed O(N_WIDGETS) which used to be the worst case
    that pretty much never happened.

 gtk/gtkwidget.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 69dfe6d..5d41c2d 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -955,9 +955,6 @@ gtk_widget_real_pick (GtkWidget *widget,
 {
   GtkWidget *child;
 
-  if (!gtk_widget_contains (widget, x, y))
-    return NULL;
-
   for (child = _gtk_widget_get_last_child (widget);
        child;
        child = _gtk_widget_get_prev_sibling (child))
@@ -972,6 +969,9 @@ gtk_widget_real_pick (GtkWidget *widget,
         return picked;
     }
 
+  if (!gtk_widget_contains (widget, x, y))
+    return NULL;
+
   return widget;
 }
 
@@ -13186,6 +13186,11 @@ gtk_widget_pick (GtkWidget *widget,
 {
   g_return_val_if_fail (GTK_IS_WIDGET (widget), NULL);
 
+  if (gtk_widget_get_pass_through (widget) ||
+      !gtk_widget_is_sensitive (widget) ||
+      !gtk_widget_is_drawable (widget))
+    return NULL;
+
   return GTK_WIDGET_GET_CLASS (widget)->pick (widget, x, y);
 }