[PATCH (diff only) libinput] touchpad: track touch sequences that ended

[Peter Hutterer]

Note: this patch is just for easier review, see below for the real patch (with
this one squashed in)
http://lists.freedesktop.org/archives/wayland-devel/2015-January/019352.html

A "touch" in the touchpad code refers to one on the touchpad. When we hover,
the touch ends but the touch sequence may still be active. Store whether the
HW sequence is still active in t->has_ended and then decide which touches to
hover based on that.

Not 100% happy with it, it doesn't quite feel right. But it does the job for
now and we'll likely have to revisit all this if/once we start handling
pressure thresholds.
---
 src/evdev-mt-touchpad.c | 38 ++++++++++++++++++++++++++++++++------
 src/evdev-mt-touchpad.h |  1 +
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
index a1d2274..066bbba 100644
--- a/src/evdev-mt-touchpad.c
+++ b/src/evdev-mt-touchpad.c
@@ -190,6 +190,7 @@ tp_new_touch(struct tp_dispatch *tp, struct tp_touch *t, uint64_t time)
 	 * after ABS_MT_TRACKING_ID */
 	tp_motion_history_reset(t);
 	t->dirty = true;
+	t->has_ended = false;
 	t->state = TOUCH_HOVERING;
 	t->pinned.is_pinned = false;
 	t->millis = time;
@@ -206,12 +207,17 @@ tp_begin_touch(struct tp_dispatch *tp, struct tp_touch *t, uint64_t time)
 	assert(tp->nfingers_down >= 1);
 }
 
+/**
+ * End a touch, even if the touch sequence is still active.
+ */
 static inline void
 tp_end_touch(struct tp_dispatch *tp, struct tp_touch *t, uint64_t time)
 {
 	switch (t->state) {
 	case TOUCH_HOVERING:
+		t->has_ended = true;
 		t->state = TOUCH_NONE;
+		/* fallthough */
 	case TOUCH_NONE:
 	case TOUCH_END:
 		return;
@@ -232,6 +238,16 @@ tp_end_touch(struct tp_dispatch *tp, struct tp_touch *t, uint64_t time)
 	tp->queued |= TOUCHPAD_EVENT_MOTION;
 }
 
+/**
+ * End the touch sequence on ABS_MT_TRACKING_ID -1 or when the BTN_TOOL_* 0 is received.
+ */
+static inline void
+tp_end_sequence(struct tp_dispatch *tp, struct tp_touch *t, uint64_t time)
+{
+	t->has_ended = true;
+	tp_end_touch(tp, t, time);
+}
+
 static double
 tp_estimate_delta(int x0, int x1, int x2, int x3)
 {
@@ -284,7 +300,7 @@ tp_process_absolute(struct tp_dispatch *tp,
 		if (e->value != -1)
 			tp_new_touch(tp, t, time);
 		else
-			tp_end_touch(tp, t, time);
+			tp_end_sequence(tp, t, time);
 	}
 }
 
@@ -330,7 +346,7 @@ tp_process_fake_touch(struct tp_dispatch *tp,
 		if (i < nfake_touches)
 			tp_new_touch(tp, t, time);
 		else
-			tp_end_touch(tp, t, time);
+			tp_end_sequence(tp, t, time);
 	}
 }
 
@@ -706,7 +722,13 @@ static void
 tp_post_process_state(struct tp_dispatch *tp, uint64_t time)
 {
 	struct tp_touch *t;
-	unsigned int i;
+	unsigned int i, active_real_touches = 0;
+
+	for (i = 0; i < tp->real_touches; i++) {
+		t = tp_get_touch(tp, i);
+		if (!t->has_ended)
+			active_real_touches++;
+	}
 
 	for (i = 0; i < tp->ntouches; i++) {
 		t = tp_get_touch(tp, i);
@@ -716,10 +738,13 @@ tp_post_process_state(struct tp_dispatch *tp, uint64_t time)
 
 		if (t->state == TOUCH_END) {
 			if (!tp_fake_finger_is_touching(tp) &&
-			    tp_fake_finger_count(tp) >= i + 1)
+			    active_real_touches > 0 &&
+			    tp_fake_finger_count(tp) >= active_real_touches) {
 				t->state = TOUCH_HOVERING;
-			else
+			} else {
 				t->state = TOUCH_NONE;
+				t->has_ended = true;
+			}
 		} else if (t->state == TOUCH_BEGIN) {
 			t->state = TOUCH_UPDATE;
 		}
@@ -903,7 +928,7 @@ tp_clear_state(struct tp_dispatch *tp)
 	tp_release_all_taps(tp, now);
 
 	tp_for_each_touch(tp, t) {
-		tp_end_touch(tp, t, now);
+		tp_end_sequence(tp, t, now);
 	}
 
 	tp_handle_state(tp, now);
@@ -1064,6 +1089,7 @@ tp_init_touch(struct tp_dispatch *tp,
 	      struct tp_touch *t)
 {
 	t->tp = tp;
+	t->has_ended = true;
 }
 
 static int
diff --git a/src/evdev-mt-touchpad.h b/src/evdev-mt-touchpad.h
index 0de2e62..7fe152a 100644
--- a/src/evdev-mt-touchpad.h
+++ b/src/evdev-mt-touchpad.h
@@ -131,6 +131,7 @@ struct tp_motion {
 struct tp_touch {
 	struct tp_dispatch *tp;
 	enum touch_state state;
+	bool has_ended;				/* TRACKING_ID == -1 */
 	bool dirty;
 	bool is_pointer;			/* the pointer-controlling touch */
 	int32_t x;
-- 
2.1.0