[PATCH libinput 3/3] touchpad: don't set the axis for a 0.0 value in a scroll event

[Peter Hutterer]

Once we trigger diagonal scrolling, the device's scroll direction is set as
horiz+vert. From then on, both axes will be set on every subsequent scroll
event, even when the actual delta for an axis is 0.

This causes continuous scroll stop events in clients that care about these
things.

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 src/evdev.c     |  9 ++++++++-
 test/touchpad.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/src/evdev.c b/src/evdev.c
index 4933185..55641c5 100644
--- a/src/evdev.c
+++ b/src/evdev.c
@@ -2548,9 +2548,16 @@ evdev_post_scroll(struct evdev_device *device,
 
 	if (!normalized_is_zero(event)) {
 		const struct discrete_coords zero_discrete = { 0.0, 0.0 };
+		uint32_t axes = device->scroll.direction;
+
+		if (event.y == 0.0)
+			axes &= ~AS_MASK(LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL);
+		if (event.x == 0.0)
+			axes &= ~AS_MASK(LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL);
+
 		evdev_notify_axis(device,
 				  time,
-				  device->scroll.direction,
+				  axes,
 				  source,
 				  &event,
 				  &zero_discrete);
diff --git a/test/touchpad.c b/test/touchpad.c
index e024ace..7bc99e9 100644
--- a/test/touchpad.c
+++ b/test/touchpad.c
@@ -144,6 +144,54 @@ START_TEST(touchpad_2fg_scroll)
 }
 END_TEST
 
+START_TEST(touchpad_2fg_scroll_diagonal)
+{
+	struct litest_device *dev = litest_current_device();
+	struct libinput *li = dev->libinput;
+	struct libinput_event *event;
+	struct libinput_event_pointer *ptrev;
+	int i;
+
+	if (!litest_has_2fg_scroll(dev))
+		return;
+
+	litest_enable_2fg_scroll(dev);
+	litest_drain_events(li);
+
+	litest_touch_down(dev, 0, 45, 30);
+	litest_touch_down(dev, 1, 55, 30);
+
+	litest_touch_move_two_touches(dev, 45, 30, 55, 30, 10, 10, 10, 0);
+	libinput_dispatch(li);
+	litest_wait_for_event_of_type(li,
+				      LIBINPUT_EVENT_POINTER_AXIS,
+				      -1);
+	litest_drain_events(li);
+
+	/* get rid of any touch history still adding x deltas sideways */
+	for (i = 0; i < 5; i++)
+		litest_touch_move(dev, 0, 55, 41 + i);
+	litest_drain_events(li);
+
+	for (i = 6; i < 10; i++) {
+		litest_touch_move(dev, 0, 55, 41 + i);
+		libinput_dispatch(li);
+
+		event = libinput_get_event(li);
+		ptrev = litest_is_axis_event(event,
+				LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL,
+				LIBINPUT_POINTER_AXIS_SOURCE_FINGER);
+		ck_assert(!libinput_event_pointer_has_axis(ptrev,
+				LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL));
+		libinput_event_destroy(event);
+	}
+
+	litest_touch_up(dev, 1);
+	litest_touch_up(dev, 0);
+	libinput_dispatch(li);
+}
+END_TEST
+
 START_TEST(touchpad_2fg_scroll_slow_distance)
 {
 	struct litest_device *dev = litest_current_device();
@@ -3500,6 +3548,7 @@ litest_setup_tests(void)
 	litest_add("touchpad:motion", touchpad_2fg_no_motion, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH);
 
 	litest_add("touchpad:scroll", touchpad_2fg_scroll, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH);
+	litest_add("touchpad:scroll", touchpad_2fg_scroll_diagonal, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH|LITEST_SEMI_MT);
 	litest_add("touchpad:scroll", touchpad_2fg_scroll_slow_distance, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH);
 	litest_add("touchpad:scroll", touchpad_2fg_scroll_return_to_motion, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH);
 	litest_add("touchpad:scroll", touchpad_2fg_scroll_source, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH);
-- 
2.5.0