[gtk+/smooth-scrolling: 2/16] gdk: Add delta_x/y to scroll events

[Carlos Garnacho <carlosg src gnome org>]

commit ba0e69f5d80047cf88d1121a59c646dc499a754b
Author: Michael Natterer <mitch lanedo com>
Date:   Mon Jan 23 23:37:44 2012 +0100

    gdk: Add delta_x/y to scroll events
    
    gdk_event_get_scroll_deltas() can be used to retrieve those
    values on smooth scroll events.

 gdk/gdkevents.c |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 gdk/gdkevents.h |    6 ++++++
 2 files changed, 54 insertions(+), 0 deletions(-)
---
diff --git a/gdk/gdkevents.c b/gdk/gdkevents.c
index 4a5394d..8eee7c6 100644
--- a/gdk/gdkevents.c
+++ b/gdk/gdkevents.c
@@ -467,6 +467,8 @@ gdk_event_new (GdkEventType type)
       new_event->scroll.y = 0.;
       new_event->scroll.x_root = 0.;
       new_event->scroll.y_root = 0.;
+      new_event->scroll.delta_x = 0.;
+      new_event->scroll.delta_y = 0.;
       break;
     case GDK_ENTER_NOTIFY:
     case GDK_LEAVE_NOTIFY:
@@ -1220,6 +1222,52 @@ gdk_event_get_scroll_direction (const GdkEvent *event,
 }
 
 /**
+ * gdk_event_get_scroll_deltas:
+ * @event: a #GdkEvent
+ * @delta_x: return location for X delta
+ * @delta_y: return location for Y delta
+ *
+ * Retrieves the scroll deltas from a #GdkEvent
+ *
+ * Returns: %TRUE if the event contains smooth scroll information
+ *
+ * Since: 3.4
+ **/
+gboolean
+gdk_event_get_scroll_deltas (const GdkEvent *event,
+                             gdouble        *delta_x,
+                             gdouble        *delta_y)
+{
+  gboolean fetched = TRUE;
+  gdouble dx = 0.0;
+  gdouble dy = 0.0;
+
+  switch (event->type)
+    {
+    case GDK_SCROLL:
+      if (event->scroll.direction == GDK_SCROLL_SMOOTH)
+        {
+          dx = event->scroll.delta_x;
+          dy = event->scroll.delta_y;
+        }
+      else
+        fetched = FALSE;
+      break;
+    default:
+      fetched = FALSE;
+      break;
+    }
+
+  if (delta_x)
+    *delta_x = dx;
+
+  if (delta_y)
+    *delta_y = dy;
+
+  return fetched;
+}
+
+/**
  * gdk_event_get_axis:
  * @event: a #GdkEvent
  * @axis_use: the axis use to look for
diff --git a/gdk/gdkevents.h b/gdk/gdkevents.h
index 2f3e9a4..cdce112 100644
--- a/gdk/gdkevents.h
+++ b/gdk/gdkevents.h
@@ -750,6 +750,8 @@ struct _GdkEventScroll
   GdkScrollDirection direction;
   GdkDevice *device;
   gdouble x_root, y_root;
+  gdouble delta_x;
+  gdouble delta_y;
 };
 
 /**
@@ -1189,6 +1191,10 @@ gboolean  gdk_event_get_keycode         (const GdkEvent *event,
                                          guint16        *keycode);
 gboolean gdk_event_get_scroll_direction (const GdkEvent *event,
                                          GdkScrollDirection *direction);
+gboolean  gdk_event_get_scroll_deltas   (const GdkEvent *event,
+                                         gdouble         *delta_x,
+                                         gdouble         *delta_y);
+
 gboolean  gdk_event_get_axis            (const GdkEvent  *event,
                                          GdkAxisUse       axis_use,
                                          gdouble         *value);