[gtk+/gtk-3-22] GtkMenu: Try using gdk_window_move_to_rect() more often

[Matthias Clasen <matthiasc src gnome org>]

commit 3ad1677a3a96c245ffc0d2090c4706e164dfb712
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Oct 14 16:41:50 2016 +0800

    GtkMenu: Try using gdk_window_move_to_rect() more often
    
    With best-effort, try to use gdk_window_move_to_rect() more often, when
    all pieces fit together. For the non-legacy paths to be triggered for
    when gtk_menu_popup_for_device() or gtk_menu_popup() were used, the
    following conditions must be met:
    
     1) There is no custom positioning function specified
     2) The menu is attached to a widget (using gtk_menu_attach_to_widget())
     3) There is a associated grab device
    
    https://bugzilla.gnome.org/show_bug.cgi?id=772922

 gtk/gtkmenu.c |   59 ++++++++++++++++++++++++++++++++++++++++++++++----------
 1 files changed, 48 insertions(+), 11 deletions(-)
---
diff --git a/gtk/gtkmenu.c b/gtk/gtkmenu.c
index 0488d1f..e77817f 100644
--- a/gtk/gtkmenu.c
+++ b/gtk/gtkmenu.c
@@ -5164,7 +5164,16 @@ gtk_menu_position (GtkMenu  *menu,
   GtkTextDirection text_direction = GTK_TEXT_DIR_NONE;
   GdkGravity rect_anchor;
   GdkGravity menu_anchor;
+  GdkAnchorHints anchor_hints;
+  gint rect_anchor_dx, rect_anchor_dy;
   GdkWindow *toplevel;
+  gboolean emulated_move_to_rect = FALSE;
+
+  rect_anchor = priv->rect_anchor;
+  menu_anchor = priv->menu_anchor;
+  anchor_hints = priv->anchor_hints;
+  rect_anchor_dx = priv->rect_anchor_dx;
+  rect_anchor_dy = priv->rect_anchor_dy;
 
   if (priv->rect_window)
     {
@@ -5177,6 +5186,36 @@ gtk_menu_position (GtkMenu  *menu,
       gtk_widget_get_allocation (priv->widget, &rect);
       text_direction = gtk_widget_get_direction (priv->widget);
     }
+  else if (!priv->position_func)
+    {
+      GtkWidget *attach_widget;
+      GdkDevice *grab_device;
+
+      /*
+       * One of the legacy gtk_menu_popup*() functions were used to popup but
+       * without a custom positioning function, so make an attempt to let the
+       * backend do the position constraining when required conditions are met.
+       */
+
+      grab_device = _gtk_menu_shell_get_grab_device (GTK_MENU_SHELL (menu));
+      attach_widget = gtk_menu_get_attach_widget (menu);
+
+      if (grab_device && attach_widget)
+        {
+          rect = (GdkRectangle) { 0, 0, 1, 1 };
+
+          rect_window = gtk_widget_get_window (attach_widget);
+          gdk_window_get_device_position (rect_window, grab_device,
+                                          &rect.x, &rect.y, NULL);
+          text_direction = gtk_widget_get_direction (attach_widget);
+          rect_anchor = GDK_GRAVITY_SOUTH_EAST;
+          menu_anchor = GDK_GRAVITY_NORTH_WEST;
+          anchor_hints = GDK_ANCHOR_FLIP | GDK_ANCHOR_SLIDE | GDK_ANCHOR_RESIZE;
+          rect_anchor_dx = 0;
+          rect_anchor_dy = 0;
+          emulated_move_to_rect = TRUE;
+        }
+    }
 
   if (!rect_window)
     {
@@ -5197,13 +5236,8 @@ gtk_menu_position (GtkMenu  *menu,
 
   if (text_direction == GTK_TEXT_DIR_RTL)
     {
-      rect_anchor = get_horizontally_flipped_anchor (priv->rect_anchor);
-      menu_anchor = get_horizontally_flipped_anchor (priv->menu_anchor);
-    }
-  else
-    {
-      rect_anchor = priv->rect_anchor;
-      menu_anchor = priv->menu_anchor;
+      rect_anchor = get_horizontally_flipped_anchor (rect_anchor);
+      menu_anchor = get_horizontally_flipped_anchor (menu_anchor);
     }
 
   toplevel = gtk_widget_get_window (priv->toplevel);
@@ -5211,15 +5245,18 @@ gtk_menu_position (GtkMenu  *menu,
   gdk_window_set_transient_for (toplevel, rect_window);
 
   g_signal_handlers_disconnect_by_func (toplevel, moved_to_rect_cb, menu);
-  g_signal_connect (toplevel, "moved-to-rect", G_CALLBACK (moved_to_rect_cb), menu);
+
+  if (!emulated_move_to_rect)
+    g_signal_connect (toplevel, "moved-to-rect", G_CALLBACK (moved_to_rect_cb),
+                      menu);
 
   GDK_PRIVATE_CALL (gdk_window_move_to_rect) (toplevel,
                                               &rect,
                                               rect_anchor,
                                               menu_anchor,
-                                              priv->anchor_hints,
-                                              priv->rect_anchor_dx,
-                                              priv->rect_anchor_dy);
+                                              anchor_hints,
+                                              rect_anchor_dx,
+                                              rect_anchor_dy);
 }
 
 static void