clutter: Add API for retrieving gesture unaccelerated deltaswip/exalm/unaccel

This will be useful for better aligning behavior between scrolling and
swiping for gnome-shell swipe tracker.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1353>

3 files changed, 75 insertions, 9 deletions

diff --git a/clutter/clutter/clutter-event.c b/clutter/clutter/clutter-event.c
index d454b2ae5..8cfa983a4 100644
--- a/clutter/clutter/clutter-event.c
+++ b/clutter/clutter/clutter-event.c
@@ -2008,6 +2008,42 @@ clutter_event_get_gesture_motion_delta (const ClutterEvent *event,
 }
 
 /**
+ * clutter_event_get_gesture_motion_delta_unaccelerated:
+ * @event: A clutter touchpad gesture event
+ * @dx: (out) (allow-none): the displacement relative to the pointer
+ *      position in the X axis, or %NULL
+ * @dy: (out) (allow-none): the displacement relative to the pointer
+ *      position in the Y axis, or %NULL
+ *
+ * Returns the unaccelerated gesture motion deltas relative to the current
+ * pointer position. Unlike clutter_event_get_gesture_motion_delta(),
+ * pointer acceleration is ignored.
+ **/
+void
+clutter_event_get_gesture_motion_delta_unaccelerated (const ClutterEvent *event,
+                                                      gdouble            *dx,
+                                                      gdouble            *dy)
+{
+  g_return_if_fail (event != NULL);
+  g_return_if_fail (event->type == CLUTTER_TOUCHPAD_PINCH ||
+                    event->type == CLUTTER_TOUCHPAD_SWIPE);
+
+  if (event->type == CLUTTER_TOUCHPAD_PINCH)
+    {
+      if (dx)
+        *dx = event->touchpad_pinch.dx_unaccel;
+      if (dy)
+        *dy = event->touchpad_pinch.dy_unaccel;
+    }
+  else if (event->type == CLUTTER_TOUCHPAD_SWIPE)
+    {
+      if (dx)
+        *dx = event->touchpad_swipe.dx_unaccel;
+      if (dy)
+        *dy = event->touchpad_swipe.dy_unaccel;
+    }
+}
+/**
  * clutter_event_get_scroll_source:
  * @event: an scroll event
  *
diff --git a/clutter/clutter/clutter-event.h b/clutter/clutter/clutter-event.h
index 1974c4fbe..b77e64d15 100644
--- a/clutter/clutter/clutter-event.h
+++ b/clutter/clutter/clutter-event.h
@@ -414,6 +414,10 @@ struct _ClutterTouchEvent
  * @y: the Y coordinate of the pointer, relative to the stage
  * @dx: movement delta of the pinch focal point in the X axis
  * @dy: movement delta of the pinch focal point in the Y axis
+ * @dx_unaccel: unaccelerated movement delta of the pinch focal
+ *   point in the X axis
+ * @dy_unaccel: unaccelerated movement delta of the pinch focal
+ *   point in the Y axis
  * @angle_delta: angle delta in degrees, clockwise rotations are
  *   represented by positive deltas
  * @scale: the current scale
@@ -441,6 +445,8 @@ struct _ClutterTouchpadPinchEvent
   gfloat y;
   gfloat dx;
   gfloat dy;
+  gfloat dx_unaccel;
+  gfloat dy_unaccel;
   gfloat angle_delta;
   gfloat scale;
   guint n_fingers;
@@ -457,8 +463,12 @@ struct _ClutterTouchpadPinchEvent
  * @n_fingers: the number of fingers triggering the swipe
  * @x: the X coordinate of the pointer, relative to the stage
  * @y: the Y coordinate of the pointer, relative to the stage
- * @dx: movement delta of the pinch focal point in the X axis
- * @dy: movement delta of the pinch focal point in the Y axis
+ * @dx: movement delta of the swipe center point in the X axis
+ * @dy: movement delta of the swipe center point in the Y axis
+ * @dx_unaccel: unaccelerated movement delta of the swipe center
+ *   point in the X axis
+ * @dy_unaccel: unaccelerated movement delta of the swipe center
+ *   point in the Y axis
  *
  * Used for touchpad swipe gesture events. The current state of the
  * gesture will be determined by the @phase field.
@@ -479,6 +489,8 @@ struct _ClutterTouchpadSwipeEvent
   gfloat y;
   gfloat dx;
   gfloat dy;
+  gfloat dx_unaccel;
+  gfloat dy_unaccel;
 };
 
 struct _ClutterPadButtonEvent
@@ -778,6 +790,11 @@ void                    clutter_event_get_gesture_motion_delta       (const Clut
                                                                       gdouble                *dy);
 
 CLUTTER_EXPORT
+void                    clutter_event_get_gesture_motion_delta_unaccelerated (const ClutterEvent     *event,
+                                                                              gdouble                *dx,
+                                                                              gdouble                *dy);
+
+CLUTTER_EXPORT
 ClutterScrollSource      clutter_event_get_scroll_source             (const ClutterEvent     *event);
 
 CLUTTER_EXPORT
diff --git a/src/backends/native/meta-seat-impl.c b/src/backends/native/meta-seat-impl.c
index da87b086b..cce7cd33c 100644
--- a/src/backends/native/meta-seat-impl.c
+++ b/src/backends/native/meta-seat-impl.c
@@ -1249,6 +1249,8 @@ notify_pinch_gesture_event (ClutterInputDevice          *input_device,
                             uint64_t                     time_us,
                             double                       dx,
                             double                       dy,
+                            double                       dx_unaccel,
+                            double                       dy_unaccel,
                             double                       angle_delta,
                             double                       scale,
                             uint32_t                     n_fingers)
@@ -1268,6 +1270,8 @@ notify_pinch_gesture_event (ClutterInputDevice          *input_device,
   event->touchpad_pinch.time = us2ms (time_us);
   event->touchpad_pinch.dx = dx;
   event->touchpad_pinch.dy = dy;
+  event->touchpad_pinch.dx_unaccel = dx_unaccel;
+  event->touchpad_pinch.dy_unaccel = dy_unaccel;
   event->touchpad_pinch.angle_delta = angle_delta;
   event->touchpad_pinch.scale = scale;
   event->touchpad_pinch.n_fingers = n_fingers;
@@ -1286,7 +1290,9 @@ notify_swipe_gesture_event (ClutterInputDevice          *input_device,
                             uint64_t                     time_us,
                             uint32_t                     n_fingers,
                             double                       dx,
-                            double                       dy)
+                            double                       dy,
+                            double                       dx_unaccel,
+                            double                       dy_unaccel)
 {
   MetaSeatImpl *seat_impl;
   ClutterEvent *event = NULL;
@@ -1303,6 +1309,8 @@ notify_swipe_gesture_event (ClutterInputDevice          *input_device,
                                                &event->touchpad_swipe.y);
   event->touchpad_swipe.dx = dx;
   event->touchpad_swipe.dy = dy;
+  event->touchpad_swipe.dx_unaccel = dx_unaccel;
+  event->touchpad_swipe.dy_unaccel = dy_unaccel;
   event->touchpad_swipe.n_fingers = n_fingers;
 
   meta_xkb_translate_state (event, seat_impl->xkb, seat_impl->button_state);
@@ -2278,14 +2286,14 @@ process_device_event (MetaSeatImpl          *seat_impl,
         n_fingers = libinput_event_gesture_get_finger_count (gesture_event);
         device = libinput_device_get_user_data (libinput_device);
         time_us = libinput_event_gesture_get_time_usec (gesture_event);
-        notify_pinch_gesture_event (device, phase, time_us, 0, 0, 0, 0, n_fingers);
+        notify_pinch_gesture_event (device, phase, time_us, 0, 0, 0, 0, 0, 0, n_fingers);
         break;
       }
     case LIBINPUT_EVENT_GESTURE_PINCH_UPDATE:
       {
         struct libinput_event_gesture *gesture_event =
           libinput_event_get_gesture_event (event);
-        double angle_delta, scale, dx, dy;
+        double angle_delta, scale, dx, dy, dx_unaccel, dy_unaccel;
         uint32_t n_fingers;
         uint64_t time_us;
 
@@ -2296,10 +2304,13 @@ process_device_event (MetaSeatImpl          *seat_impl,
         scale = libinput_event_gesture_get_scale (gesture_event);
         dx = libinput_event_gesture_get_dx (gesture_event);
         dy = libinput_event_gesture_get_dy (gesture_event);
+        dx_unaccel = libinput_event_gesture_get_dx_unaccelerated (gesture_event);
+        dy_unaccel = libinput_event_gesture_get_dy_unaccelerated (gesture_event);
 
         notify_pinch_gesture_event (device,
                                     CLUTTER_TOUCHPAD_GESTURE_PHASE_UPDATE,
-                                    time_us, dx, dy, angle_delta, scale, n_fingers);
+                                    time_us, dx, dy, dx_unaccel, dy_unaccel,
+                                    angle_delta, scale, n_fingers);
         break;
       }
     case LIBINPUT_EVENT_GESTURE_SWIPE_BEGIN:
@@ -2321,7 +2332,7 @@ process_device_event (MetaSeatImpl          *seat_impl,
           phase = libinput_event_gesture_get_cancelled (gesture_event) ?
             CLUTTER_TOUCHPAD_GESTURE_PHASE_CANCEL : CLUTTER_TOUCHPAD_GESTURE_PHASE_END;
 
-        notify_swipe_gesture_event (device, phase, time_us, n_fingers, 0, 0);
+        notify_swipe_gesture_event (device, phase, time_us, n_fingers, 0, 0, 0, 0);
         break;
       }
     case LIBINPUT_EVENT_GESTURE_SWIPE_UPDATE:
@@ -2330,17 +2341,19 @@ process_device_event (MetaSeatImpl          *seat_impl,
           libinput_event_get_gesture_event (event);
         uint32_t n_fingers;
         uint64_t time_us;
-        double dx, dy;
+        double dx, dy, dx_unaccel, dy_unaccel;
 
         device = libinput_device_get_user_data (libinput_device);
         time_us = libinput_event_gesture_get_time_usec (gesture_event);
         n_fingers = libinput_event_gesture_get_finger_count (gesture_event);
         dx = libinput_event_gesture_get_dx (gesture_event);
         dy = libinput_event_gesture_get_dy (gesture_event);
+        dx_unaccel = libinput_event_gesture_get_dx_unaccelerated (gesture_event);
+        dy_unaccel = libinput_event_gesture_get_dy_unaccelerated (gesture_event);
 
         notify_swipe_gesture_event (device,
                                     CLUTTER_TOUCHPAD_GESTURE_PHASE_UPDATE,
-                                    time_us, n_fingers, dx, dy);
+                                    time_us, n_fingers, dx, dy, dx_unaccel, dy_unaccel);
         break;
       }
     case LIBINPUT_EVENT_TABLET_TOOL_AXIS: