[PATCH libinput 3/3] touchpad: change tap motion threshold to 3 mm

[Peter Hutterer]

Previous code used a device coordinate threshold of 300 which won't work on
Elantech touchpads (1280 vs the ~4000 that synaptics has).
Convert to normalized DPI and reduce the threshold to 3mm.

https://bugs.freedesktop.org/show_bug.cgi?id=89206

[note that because of the MAGIC in the accel code this is currently
more than 3mm]

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 src/evdev-mt-touchpad-tap.c | 12 +++++++++---
 src/evdev-mt-touchpad.h     |  1 +
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/evdev-mt-touchpad-tap.c b/src/evdev-mt-touchpad-tap.c
index 228eb84..62d3c80 100644
--- a/src/evdev-mt-touchpad-tap.c
+++ b/src/evdev-mt-touchpad-tap.c
@@ -37,7 +37,8 @@
 #define CASE_RETURN_STRING(a) case a: return #a;
 
 #define DEFAULT_TAP_TIMEOUT_PERIOD 180
-#define DEFAULT_TAP_MOVE_THRESHOLD 30
+/* in mm for touchpads with resolution, see tp_init_accel() */
+#define DEFAULT_TAP_MOVE_THRESHOLD 3 * 25.4
 
 enum tap_event {
 	TAP_EVENT_TOUCH = 12,
@@ -527,12 +528,15 @@ tp_tap_handle_event(struct tp_dispatch *tp,
 }
 
 static bool
-tp_tap_exceeds_motion_threshold(struct tp_dispatch *tp, struct tp_touch *t)
+tp_tap_exceeds_motion_threshold(struct tp_dispatch *tp,
+				struct tp_touch *t)
 {
 	int threshold = DEFAULT_TAP_MOVE_THRESHOLD;
 	double dx, dy;
 
-	tp_get_delta(t, &dx, &dy);
+	dx = abs(t->tap.initial_x - t->x);
+	dy = abs(t->tap.initial_y - t->y);
+	tp_normalize_delta(tp, &dx, &dy);
 
 	return dx * dx + dy * dy > threshold * threshold;
 }
@@ -568,6 +572,8 @@ tp_tap_handle_state(struct tp_dispatch *tp, uint64_t time)
 
 		if (t->state == TOUCH_BEGIN) {
 			t->tap.state = TAP_TOUCH_STATE_TOUCH;
+			t->tap.initial_x = t->x;
+			t->tap.initial_y = t->y;
 			tp_tap_handle_event(tp, t, TAP_EVENT_TOUCH, time);
 		} else if (t->state == TOUCH_END) {
 			tp_tap_handle_event(tp, t, TAP_EVENT_RELEASE, time);
diff --git a/src/evdev-mt-touchpad.h b/src/evdev-mt-touchpad.h
index 1b8b560..65581ae 100644
--- a/src/evdev-mt-touchpad.h
+++ b/src/evdev-mt-touchpad.h
@@ -162,6 +162,7 @@ struct tp_touch {
 
 	struct {
 		enum tp_tap_touch_state state;
+		int32_t initial_x, initial_y;
 	} tap;
 
 	struct {
-- 
2.1.0