[clutter] event: Add distance and angle accessors

[Emmanuele Bassi <ebassi src gnome org>]

commit 695621f5eaa82b931be7b6b817f7992073cf1259
Author: Emmanuele Bassi <ebassi linux intel com>
Date:   Thu Apr 19 12:16:54 2012 +0100

    event: Add distance and angle accessors
    
    Let's start using ClutterPoint in the API.

 clutter/clutter-event.c |  115 ++++++++++++++++++++++++++++++++++++++++-------
 clutter/clutter-event.h |    9 ++++
 clutter/clutter.symbols |    7 ++-
 3 files changed, 112 insertions(+), 19 deletions(-)
---
diff --git a/clutter/clutter-event.c b/clutter/clutter-event.c
index fb5587e..c878b5e 100644
--- a/clutter/clutter-event.c
+++ b/clutter/clutter-event.c
@@ -33,6 +33,8 @@
 #include "clutter-keysyms.h"
 #include "clutter-private.h"
 
+#include <math.h>
+
 /**
  * SECTION:clutter-event
  * @short_description: User and window system events
@@ -278,11 +280,34 @@ clutter_event_get_coords (const ClutterEvent *event,
                           gfloat             *x,
                           gfloat             *y)
 {
-  gfloat event_x, event_y;
+  ClutterPoint coords;
 
   g_return_if_fail (event != NULL);
 
-  event_x = event_y = 0;
+  clutter_event_get_position (event, &coords);
+
+  if (x != NULL)
+    *x = coords.x;
+
+  if (y != NULL)
+    *y = coords.y;
+}
+
+/**
+ * clutter_event_get_position:
+ * @event: a #ClutterEvent
+ * @position: a #ClutterPoint
+ *
+ * Retrieves the event coordinates as a #ClutterPoint.
+ *
+ * Since: 1.12
+ */
+void
+clutter_event_get_position (const ClutterEvent *event,
+                            ClutterPoint       *position)
+{
+  g_return_if_fail (event != NULL);
+  g_return_if_fail (position != NULL);
 
   switch (event->type)
     {
@@ -294,44 +319,35 @@ clutter_event_get_coords (const ClutterEvent *event,
     case CLUTTER_CLIENT_MESSAGE:
     case CLUTTER_DELETE:
     case CLUTTER_EVENT_LAST:
+      clutter_point_init (position, 0.f, 0.f);
       break;
 
     case CLUTTER_ENTER:
     case CLUTTER_LEAVE:
-      event_x = event->crossing.x;
-      event_y = event->crossing.y;
+      clutter_point_init (position, event->crossing.x, event->crossing.y);
       break;
 
     case CLUTTER_BUTTON_PRESS:
     case CLUTTER_BUTTON_RELEASE:
-      event_x = event->button.x;
-      event_y = event->button.y;
+      clutter_point_init (position, event->button.x, event->button.y);
       break;
 
     case CLUTTER_MOTION:
-      event_x = event->motion.x;
-      event_y = event->motion.y;
+      clutter_point_init (position, event->motion.x, event->motion.y);
       break;
 
     case CLUTTER_TOUCH_BEGIN:
     case CLUTTER_TOUCH_UPDATE:
     case CLUTTER_TOUCH_END:
     case CLUTTER_TOUCH_CANCEL:
-      event_x = event->touch.x;
-      event_y = event->touch.y;
+      clutter_point_init (position, event->touch.x, event->touch.y);
       break;
 
     case CLUTTER_SCROLL:
-      event_x = event->scroll.x;
-      event_y = event->scroll.y;
+      clutter_point_init (position, event->scroll.x, event->scroll.y);
       break;
     }
 
-  if (x)
-    *x = event_x;
-
-  if (y)
-    *y = event_y;
 }
 
 /**
@@ -1513,3 +1529,68 @@ clutter_event_get_axes (const ClutterEvent *event,
 
   return retval;
 }
+
+/**
+ * clutter_event_get_distance:
+ * @source: a #ClutterEvent
+ * @target: a #ClutterEvent
+ *
+ * Retrieves the distance between two events, a @source and a @target.
+ *
+ * Return value: the distance between two #ClutterEvent
+ *
+ * Since: 1.12
+ */
+float
+clutter_event_get_distance (const ClutterEvent *source,
+                            const ClutterEvent *target)
+{
+  ClutterPoint p0, p1;
+
+  clutter_event_get_position (source, &p0);
+  clutter_event_get_position (source, &p1);
+
+  return clutter_point_distance (&p0, &p1, NULL, NULL);
+}
+
+/**
+ * clutter_event_get_angle:
+ * @source: a #ClutterEvent
+ * @target: a #ClutterEvent
+ *
+ * Retrieves the angle relative from @source to @target.
+ *
+ * The direction of the angle is from the position X axis towards
+ * the positive Y axis.
+ *
+ * Return value: the angle between two #ClutterEvent
+ *
+ * Since: 1.12
+ */
+double
+clutter_event_get_angle (const ClutterEvent *source,
+                         const ClutterEvent *target)
+{
+  ClutterPoint p0, p1;
+  float x_distance, y_distance;
+  double angle;
+
+  clutter_event_get_position (source, &p0);
+  clutter_event_get_position (target, &p1);
+
+  if (clutter_point_equals (&p0, &p1))
+    return 0;
+
+  clutter_point_distance (&p0, &p1, &x_distance, &y_distance);
+
+  angle = atan2 (x_distance, y_distance);
+
+  /* invert the angle, and shift it by 90 degrees */
+  angle = (2.0 * G_PI) - angle;
+  angle += G_PI / 2.0;
+
+  /* keep the angle within the [ 0, 360 ] interval */
+  angle = fmod (angle, 2.0 * G_PI);
+
+  return angle;
+}
diff --git a/clutter/clutter-event.h b/clutter/clutter-event.h
index cb96257..b56da54 100644
--- a/clutter/clutter-event.h
+++ b/clutter/clutter-event.h
@@ -445,6 +445,15 @@ void                    clutter_event_set_coords                (ClutterEvent
 void                    clutter_event_get_coords                (const ClutterEvent     *event,
                                                                  gfloat                 *x,
                                                                  gfloat                 *y);
+CLUTTER_AVAILABLE_IN_1_12
+void                    clutter_event_get_position              (const ClutterEvent     *event,
+                                                                 ClutterPoint           *position);
+CLUTTER_AVAILABLE_IN_1_12
+float                   clutter_event_get_distance              (const ClutterEvent     *source,
+                                                                 const ClutterEvent     *target);
+CLUTTER_AVAILABLE_IN_1_12
+double                  clutter_event_get_angle                 (const ClutterEvent     *source,
+                                                                 const ClutterEvent     *target);
 
 gdouble *               clutter_event_get_axes                  (const ClutterEvent     *event,
                                                                  guint                  *n_axes);
diff --git a/clutter/clutter.symbols b/clutter/clutter.symbols
index 14f9937..2349829 100644
--- a/clutter/clutter.symbols
+++ b/clutter/clutter.symbols
@@ -619,6 +619,8 @@ clutter_effect_queue_repaint
 clutter_events_pending
 clutter_event_copy
 clutter_event_flags_get_type
+clutter_event_free
+clutter_event_get_angle
 clutter_event_get_axes
 clutter_event_get_button
 clutter_event_get_click_count
@@ -626,13 +628,13 @@ clutter_event_get_coords
 clutter_event_get_device
 clutter_event_get_device_id
 clutter_event_get_device_type
+clutter_event_get_distance
 clutter_event_get_event_sequence
 clutter_event_get_flags
-clutter_event_free
-clutter_event_get
 clutter_event_get_key_code
 clutter_event_get_key_symbol
 clutter_event_get_key_unicode
+clutter_event_get_position
 clutter_event_get_related
 clutter_event_get_scroll_delta
 clutter_event_get_scroll_direction
@@ -642,6 +644,7 @@ clutter_event_get_stage
 clutter_event_get_state
 clutter_event_get_type
 clutter_event_get_time
+clutter_event_get
 clutter_event_new
 clutter_event_peek
 clutter_event_put