[gtk/wip/otte/dnd2] dnd: Add gdk_drag_action_is_unique()

[Benjamin Otte <otte src gnome org>]

commit 29b7160854df09735f68483cbf694f510c2b5720
Author: Benjamin Otte <otte redhat com>
Date:   Sat May 12 00:13:11 2018 +0200

    dnd: Add gdk_drag_action_is_unique()
    
    This will be necessary once we remove the ASK action.

 docs/reference/gdk/gdk4-sections.txt |  3 +++
 gdk/gdkdnd.c                         | 19 +++++++++++++++++++
 gdk/gdkdnd.h                         |  3 +++
 3 files changed, 25 insertions(+)
---
diff --git a/docs/reference/gdk/gdk4-sections.txt b/docs/reference/gdk/gdk4-sections.txt
index 2948955fb8..6ebf719e32 100644
--- a/docs/reference/gdk/gdk4-sections.txt
+++ b/docs/reference/gdk/gdk4-sections.txt
@@ -799,6 +799,9 @@ gdk_drag_context_get_dest_surface
 gdk_drag_context_get_drag_surface
 gdk_drag_context_set_hotspot
 
+<SUBSECTION>
+gdk_drag_action_is_unique
+
 <SUBSECTION Standard>
 GDK_DRAG_CONTEXT
 GDK_TYPE_DRAG_CONTEXT
diff --git a/gdk/gdkdnd.c b/gdk/gdkdnd.c
index 47da69eda3..98801fcde3 100644
--- a/gdk/gdkdnd.c
+++ b/gdk/gdkdnd.c
@@ -876,3 +876,22 @@ gdk_drag_context_handle_dest_event (GdkEvent *event)
   gdk_drag_context_commit_drag_status (context);
   return TRUE;;
 }
+
+/**
+ * gdk_drag_action_is_unique:
+ * @action: a #GdkDragAction
+ *
+ * Checks if @action represents a single action or if it
+ * includes multiple flags that can be selected from.
+ *
+ * When @action is 0 - ie no action was given, %TRUE
+ * is returned.
+ *
+ * Returns: %TRUE if exactly one action was given
+ **/
+GdkDragAction
+gdk_drag_action_is_unique (GdkDragAction action)
+{
+  return (action & (action - 1)) == 0;
+}
+
diff --git a/gdk/gdkdnd.h b/gdk/gdkdnd.h
index 74c65e4f67..f153af44a1 100644
--- a/gdk/gdkdnd.h
+++ b/gdk/gdkdnd.h
@@ -97,6 +97,9 @@ GdkSurface       *gdk_drag_context_get_source_surface    (GdkDragContext *contex
 GDK_AVAILABLE_IN_ALL
 GdkSurface       *gdk_drag_context_get_dest_surface      (GdkDragContext *context);
 
+GDK_AVAILABLE_IN_ALL
+GdkDragAction     gdk_drag_action_is_unique            (GdkDragAction   action);
+
 /* Destination side */
 GDK_AVAILABLE_IN_ALL
 void             gdk_drag_status        (GdkDragContext   *context,