[gtk+/wip/events: 14/16] xxx: sequence tracker

[Benjamin Otte <otte src gnome org>]

commit f353210ed8de6980ec682a21b70a5d6a940c392d
Author: Benjamin Otte <otte redhat com>
Date:   Sat Mar 10 17:26:45 2012 +0100

    xxx: sequence tracker

 gtk/gtksequencetracker.c        |   18 ++++++++++++++++++
 gtk/gtksequencetrackerprivate.h |    5 +++++
 2 files changed, 23 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtksequencetracker.c b/gtk/gtksequencetracker.c
index bfc5f64..4071b42 100644
--- a/gtk/gtksequencetracker.c
+++ b/gtk/gtksequencetracker.c
@@ -257,3 +257,21 @@ _gtk_sequence_tracker_get_direction (GtkSequenceTracker *tracker)
 
   return tracker->history[tracker->history_index].dir;
 }
+
+void
+_gtk_sequence_tracker_compute_distance (GtkSequenceTracker *from,
+                                        GtkSequenceTracker *to,
+                                        double             *x,
+                                        double             *y)
+{
+  g_return_if_fail (from != NULL);
+  g_return_if_fail (to != NULL);
+  g_return_if_fail (from->klass == to->klass);
+  /* XXX: compare devices here? */
+
+  if (x)
+    *x = from->history[from->history_index].x - to->history[to->history_index].x;
+  if (y)
+    *y = from->history[from->history_index].y - to->history[to->history_index].y;
+}
+
diff --git a/gtk/gtksequencetrackerprivate.h b/gtk/gtksequencetrackerprivate.h
index 5ad632f..76d7bdf 100644
--- a/gtk/gtksequencetrackerprivate.h
+++ b/gtk/gtksequencetrackerprivate.h
@@ -47,6 +47,11 @@ double                _gtk_sequence_tracker_get_y_offset        (GtkSequenceTrac
 
 GtkMovementDirection  _gtk_sequence_tracker_get_direction       (GtkSequenceTracker *tracker);
 
+void                  _gtk_sequence_tracker_compute_distance    (GtkSequenceTracker *from,
+                                                                 GtkSequenceTracker *to,
+                                                                 double             *x,
+                                                                 double             *y);
+
 G_END_DECLS
 
 #endif /* __GTK_SEQUENCE_TRACKER_PRIVATE_H__ */