filter: enforce minimum velocity

In the current code, a timeout or direction change on the first tracker will
result in a velocity of 0. Really slow movements will thus always be zero, and
the first event after a direction is swallowed.

Enforce a minimum velocity:
In the case of a timeout, assume the current velocity is that of
distance/timeout. In the case of a direction change, the velocity is simply
that since the last tracker.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

diff --git a/src/filter.c b/src/filter.c
index 3845c7f..c54d866 100644 (file)
--- a/src/filter.c
+++ b/src/filter.c
@@ -144,6 +144,24 @@ calculate_tracker_velocity(struct pointer_tracker *tracker, uint64_t time)
        return normalized_length(tracker->delta) / tdelta; /* units/ms */
 }
 
+static inline double
+calculate_velocity_after_timeout(struct pointer_tracker *tracker)
+{
+       /* First movement after timeout needs special handling.
+        *
+        * When we trigger the timeout, the last event is too far in the
+        * past to use it for velocity calculation across multiple tracker
+        * values.
+        *
+        * Use the motion timeout itself to calculate the speed rather than
+        * the last tracker time. This errs on the side of being too fast
+        * for really slow movements but provides much more useful initial
+        * movement in normal use-cases (pause, move, pause, move)
+        */
+       return calculate_tracker_velocity(tracker,
+                                         tracker->time + MOTION_TIMEOUT);
+}
+
 static double
 calculate_velocity(struct pointer_accelerator *accel, uint64_t time)
 {
@@ -163,15 +181,23 @@ calculate_velocity(struct pointer_accelerator *accel, uint64_t time)
 
                /* Stop if too far away in time */
                if (time - tracker->time > MOTION_TIMEOUT ||
-                   tracker->time > time)
+                   tracker->time > time) {
+                       if (offset == 1)
+                               result = calculate_velocity_after_timeout(tracker);
                        break;
+               }
+
+               velocity = calculate_tracker_velocity(tracker, time);
 
                /* Stop if direction changed */
                dir &= tracker->dir;
-               if (dir == 0)
+               if (dir == 0) {
+                       /* First movement after dirchange - velocity is that
+                        * of the last movement */
+                       if (offset == 1)
+                               result = velocity;
                        break;
-
-               velocity = calculate_tracker_velocity(tracker, time);
+               }
 
                if (initial_velocity == 0.0) {
                        result = initial_velocity = velocity;

diff --git a/test/touchpad.c b/test/touchpad.c
index 5579c04..a747910 100644 (file)
--- a/test/touchpad.c
+++ b/test/touchpad.c
@@ -2959,7 +2959,7 @@ START_TEST(touchpad_edge_scroll)
        litest_touch_up(dev, 0);
 
        libinput_dispatch(li);
-       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL, 10);
+       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL, 4);
        litest_assert_empty_queue(li);
 
        litest_touch_down(dev, 0, 99, 80);
@@ -2967,7 +2967,7 @@ START_TEST(touchpad_edge_scroll)
        litest_touch_up(dev, 0);
 
        libinput_dispatch(li);
-       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL, -10);
+       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL, -4);
        litest_assert_empty_queue(li);
 
        litest_touch_down(dev, 0, 20, 99);
@@ -2975,7 +2975,7 @@ START_TEST(touchpad_edge_scroll)
        litest_touch_up(dev, 0);
 
        libinput_dispatch(li);
-       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL, 10);
+       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL, 4);
        litest_assert_empty_queue(li);
 
        litest_touch_down(dev, 0, 70, 99);
@@ -2983,7 +2983,7 @@ START_TEST(touchpad_edge_scroll)
        litest_touch_up(dev, 0);
 
        libinput_dispatch(li);
-       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL, -10);
+       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL, -4);
        litest_assert_empty_queue(li);
 }
 END_TEST
@@ -3065,7 +3065,7 @@ START_TEST(touchpad_edge_scroll_no_motion)
        litest_touch_up(dev, 0);
        libinput_dispatch(li);
 
-       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL, 5);
+       litest_assert_scroll(li, LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL, 4);
        litest_assert_empty_queue(li);
 }
 END_TEST