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From ae9d1112b78ebc2a6c57212fa289d3161c6dd735 Mon Sep 17 00:00:00 2001
From: abc def <24701-abcdef@users.noreply.gitlab.freedesktop.org>
Date: Thu, 6 Jan 2022 13:22:42 +0100
Subject: [PATCH 3/3] TFD: add debounce state for touch count decrease
Don't allow motion events within a certain interval from a touch count decrease (to 1 finger) to finish the drag. This should make even very quick drags remain in drag-lock instead of being unintentionally finished by the last finger.
Signed-off-by: Temp Name <test@example.com>
---
src/evdev-mt-touchpad-tfd.c | 93 ++++++++++++++++++++++++++++++++++---
src/evdev-mt-touchpad.h | 13 ++++--
2 files changed, 96 insertions(+), 10 deletions(-)
diff --git a/src/evdev-mt-touchpad-tfd.c b/src/evdev-mt-touchpad-tfd.c
index c12bc27b..49c576bd 100644
--- a/src/evdev-mt-touchpad-tfd.c
+++ b/src/evdev-mt-touchpad-tfd.c
@@ -44,6 +44,7 @@ tfd_state_to_str(enum tp_tfd_state state)
CASE_RETURN_STRING(TFD_STATE_IDLE);
CASE_RETURN_STRING(TFD_STATE_POSSIBLE_DRAG);
CASE_RETURN_STRING(TFD_STATE_DRAG);
+ CASE_RETURN_STRING(TFD_STATE_POSSIBLE_ZERO_FINGERS);
CASE_RETURN_STRING(TFD_STATE_AWAIT_RESUME);
CASE_RETURN_STRING(TFD_STATE_POSSIBLE_RESUME);
}
@@ -275,6 +276,8 @@ tp_tfd_possible_drag_handle_event(struct tp_dispatch *tp,
}
break;
case TFD_EVENT_MOTION:
+ /* this event must ensure it fires upon cursor movement -- alternatively, if
+ impossible, TODO: cursor should be pinned in this state to ensure this */
switch (nfingers_down) {
default:
log_tfd_bug(tp, event, nfingers_down);
@@ -303,6 +306,12 @@ tp_tfd_possible_drag_handle_event(struct tp_dispatch *tp,
}
}
+
+ /* TODO: Future improvement: When one finger moves considerably
+ faster than the others, don't average their deltas for cursor
+ position updates -- use the fastest finger only */
+
+
static void
tp_tfd_drag_handle_event(struct tp_dispatch *tp,
struct tp_touch *t,
@@ -315,10 +324,7 @@ tp_tfd_drag_handle_event(struct tp_dispatch *tp,
case TFD_EVENT_TOUCH_COUNT_DECREASE:
switch (nfingers_down) {
case 0:
- case 1:
tp_tfd_pin_fingers(tp);
- /* removing all, or all but one, fingers gives you ~0.7 seconds to
- place three fingers back on the touchpad before the drag ends */
tp_tfd_set_await_resume_timer(tp, time);
tp->tfd.state = TFD_STATE_AWAIT_RESUME;
@@ -327,15 +333,18 @@ tp_tfd_drag_handle_event(struct tp_dispatch *tp,
// tp_tfd_set_await_more_fingers_timer(tp, time);
// tp->tfd.state = TFD_STATE_POSSIBLE_RESUME;
+ break;
+ case 1:
+ tp_tfd_pin_fingers(tp);
+ tp_tfd_set_await_resume_timer(tp, time);
+ tp_tfd_set_await_more_fingers_timer(tp, time);
+ tp->tfd.state = TFD_STATE_POSSIBLE_ZERO_FINGERS;
break;
default:
break;
}
break;
case TFD_EVENT_MOTION:
- /* TODO: Future improvement: When one finger moves considerably
- faster than the others, don't average their deltas for cursor
- position updates -- use the fastest finger only */
break;
case TFD_EVENT_RESUME_TIMEOUT:
case TFD_EVENT_TIMEOUT:
@@ -352,6 +361,73 @@ tp_tfd_drag_handle_event(struct tp_dispatch *tp,
}
}
+
+/* Waiting for zero fingers. Drag has decreased to 1 finger, but it might be
+a transitory phase towards 0 fingers. Allow a small amount of time for that
+before allowing one finger to break out of the drag in the AWAIT state. Makes it
+harder to end very fast, brief drags. */
+static void
+tp_tfd_possible_zero_fingers_handle_event(struct tp_dispatch *tp,
+ struct tp_touch *t,
+ enum tfd_event event, uint64_t time,
+ int nfingers_down)
+{
+ switch (event) {
+ case TFD_EVENT_TOUCH_COUNT_DECREASE:
+ switch (nfingers_down) {
+ case 0:
+ tp_tfd_clear_timer(tp);
+ tp->tfd.state = TFD_STATE_AWAIT_RESUME;
+ break;
+ default:
+ log_tfd_bug(tp, event, nfingers_down);
+ break;
+ }
+ break;
+ case TFD_EVENT_MOTION:
+ break;
+ case TFD_EVENT_RESUME_TIMEOUT:
+ /* this shouldn't have time to happen */
+ log_tfd_bug(tp, event, nfingers_down);
+ tp->tfd.state = TFD_STATE_IDLE;
+ tp_tfd_clear_timer(tp);
+ tp_tfd_unpin_fingers(tp);
+ break;
+ case TFD_EVENT_TOUCH_COUNT_INCREASE:
+ /* an increase forces immediate evaluation as if the timer had fired */
+ tp_tfd_clear_timer(tp);
+ /* fallthrough */
+ case TFD_EVENT_TIMEOUT:
+ /* time to (most probably) transition to the AWAIT state with 0 or 1 fingers */
+ switch (nfingers_down) {
+ case 0:
+ case 1:
+ case 2:
+ tp->tfd.state = TFD_STATE_AWAIT_RESUME;
+ break;
+ case 3:
+ tp_tfd_set_await_more_fingers_timer(tp, time);
+ tp->tfd.state = TFD_STATE_POSSIBLE_RESUME;
+ break;
+ default:
+ tp_tfd_unpin_fingers(tp);
+ tp->tfd.state = TFD_STATE_IDLE;
+ tp_tfd_clear_resume_timer(tp);
+ tp_tfd_notify(tp, time, 1, LIBINPUT_BUTTON_STATE_RELEASED);
+ break;
+ }
+ break;
+ case TFD_EVENT_TAP:
+ case TFD_EVENT_BUTTON:
+ tp_tfd_unpin_fingers(tp);
+ tp->tfd.state = TFD_STATE_IDLE;
+ tp_tfd_clear_resume_timer(tp);
+ tp_tfd_clear_timer(tp);
+ tp_tfd_notify(tp, time, 1, LIBINPUT_BUTTON_STATE_RELEASED);
+ break;
+ }
+}
+
/* Drag-lock; After leaving 3 finger dragging there's a small time window where you can
resume the drag with 3 fingers. */
static void
@@ -621,6 +697,10 @@ tp_tfd_handle_event(struct tp_dispatch *tp,
tp_tfd_drag_handle_event(tp, t, event, time, nfingers_down);
break;
+ case TFD_STATE_POSSIBLE_ZERO_FINGERS:
+ tp_tfd_possible_zero_fingers_handle_event(tp, t, event, time, nfingers_down);
+ break;
+
case TFD_STATE_AWAIT_RESUME:
tp_tfd_await_resume_handle_event(tp, t, event, time, nfingers_down);
break;
@@ -816,6 +896,7 @@ void
tp_tfd_handle_tap(struct tp_dispatch *tp, uint64_t time)
{
switch (tp->tfd.state) {
+ case TFD_STATE_POSSIBLE_ZERO_FINGERS:
case TFD_STATE_AWAIT_RESUME:
case TFD_STATE_POSSIBLE_RESUME:
tp_tfd_handle_event(tp, NULL, TFD_EVENT_TAP, time, tp->tfd.finger_count);
diff --git a/src/evdev-mt-touchpad.h b/src/evdev-mt-touchpad.h
index 12403ca3..ccd38bc4 100644
--- a/src/evdev-mt-touchpad.h
+++ b/src/evdev-mt-touchpad.h
@@ -136,15 +136,20 @@ enum tp_tap_state {
enum tp_tfd_state {
+ /* [debounce] = brief states anticipating a further increase/decrease in finger
+ count, preventing unintended drops on account of motion events */
+
/* waiting for 3 fingers */
TFD_STATE_IDLE,
- /* 3 fingers down, possible 4+ f gesture */
+ /* 3 fingers touching, possible 4+ f gesture */
TFD_STATE_POSSIBLE_DRAG,
- /* 3 fingers down and button press has been output */
+ /* 3 fingers touching and button press has been output */
TFD_STATE_DRAG,
- /* drag-lock; waiting for drag continuation */
+ /* [debounce] drag-lock; 1 finger touching, possibly going to 0 fingers */
+ TFD_STATE_POSSIBLE_ZERO_FINGERS,
+ /* drag-lock; waiting for 3 finger drag continuation */
TFD_STATE_AWAIT_RESUME,
- /* disambiguate between drag continuation and a possible 4+ gesture */
+ /* [debounce] disambiguate between drag continuation and a possible 4+ gesture */
TFD_STATE_POSSIBLE_RESUME,
};
--
2.41.0
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