gdk/wayland: Avoid relayout with the same properties

When a popup is already showing, and gdk_surface_present_popup() is
called, if the layout didn't change, we're not really interested in
relayouting.

In the future, we'll be able to get notified if position of the popup
would change by some environmental changes, but until then, just don't
support it.

gdk/gdkpopuplayout.c

@@ -129,6 +129,31 @@ gdk_popup_layout_copy (GdkPopupLayout *layout)
   return new_layout;
 }
 
+/**
+ * gdk_popup_layout_equal:
+ * @layout: a #GdkPopupLayout
+ * @other: another #GdkPopupLayout
+ *
+ * Check whether @layout and @other has identical layout properties.
+ *
+ * Returns: %TRUE if @layout and @other have identical layout properties,
+ * otherwise %FALSE.
+ */
+gboolean
+gdk_popup_layout_equal (GdkPopupLayout *layout,
+                        GdkPopupLayout *other)
+{
+  g_return_val_if_fail (layout, FALSE);
+  g_return_val_if_fail (other, FALSE);
+
+  return (gdk_rectangle_equal (&layout->anchor_rect, &other->anchor_rect) &&
+          layout->rect_anchor == other->rect_anchor &&
+          layout->surface_anchor == other->surface_anchor &&
+          layout->anchor_hints == other->anchor_hints &&
+          layout->dx == other->dx &&
+          layout->dy == other->dy);
+}
+
 /**
  * gdk_popup_layout_set_anchor_rect:
  * @layout: a #GdkPopupLayout

gdk/gdkpopuplayout.h

@@ -93,6 +93,10 @@ void                    gdk_popup_layout_unref                  (GdkPopupLayout
 GDK_AVAILABLE_IN_ALL
 GdkPopupLayout *        gdk_popup_layout_copy                   (GdkPopupLayout         *layout);
 
+GDK_AVAILABLE_IN_ALL
+gboolean                gdk_popup_layout_equal                  (GdkPopupLayout         *layout,
+                                                                 GdkPopupLayout         *other);
+
 GDK_AVAILABLE_IN_ALL
 void                    gdk_popup_layout_set_anchor_rect        (GdkPopupLayout         *layout,
                                                                  const GdkRectangle     *anchor_rect);

gdk/wayland/gdksurface-wayland.c

@@ -2819,6 +2819,11 @@ gdk_wayland_surface_present_popup (GdkSurface     *surface,
     }
   else
     {
+      if (impl->popup.unconstrained_width == width &&
+          impl->popup.unconstrained_height == height &&
+          gdk_popup_layout_equal (impl->popup.layout, layout))
+        return TRUE;
+
       reposition_popup (surface, width, height, layout);
     }