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touchpad: reset motion history when nfingers changes on semi-mt pads

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On semi-mt touchpads the reported position of the first finger down may
jump when the pad switches from st to mt mode. When this happens a large
delta gets seen on the first finger at the same time the second fingers
is first seen down, causing a spurious 2 finger scroll event.

Reset the motion history when nfingers changes on semi-mt pads to avoid this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
This commit is contained in:
Hans de Goede 2014-07-21 15:25:47 +02:00 • committed by Peter Hutterer
parent d429da529c
commit 3264dde8c0
2 changed files with 10 additions and 0 deletions
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8
src/evdev-mt-touchpad.c
View file

@ -406,6 +406,11 @@ tp_process_state(struct tp_dispatch *tp, uint64_t time)
for (i = 0; i < tp->ntouches; i++) {
t = tp_get_touch(tp, i);
/* semi-mt finger postions may "jump" when nfingers changes */
if (tp->semi_mt && tp->nfingers_down != tp->old_nfingers_down)
tp_motion_history_reset(t);
if (i >= tp->real_touches && t->state != TOUCH_NONE) {
t->x = first->x;
t->y = first->y;
@ -454,6 +459,7 @@ tp_post_process_state(struct tp_dispatch *tp, uint64_t time)
t->dirty = false;
}
tp->old_nfingers_down = tp->nfingers_down;
tp->buttons.old_state = tp->buttons.state;
tp->queued = TOUCHPAD_EVENT_NONE;
@ -668,6 +674,8 @@ tp_init_slots(struct tp_dispatch *tp,
tp->has_mt = false;
}
tp->semi_mt = libevdev_has_property(device->evdev, INPUT_PROP_SEMI_MT);
ARRAY_FOR_EACH(max_touches, m) {
if (libevdev_has_event_code(device->evdev,
EV_KEY,

2
src/evdev-mt-touchpad.h
View file

@ -152,8 +152,10 @@ struct tp_dispatch {
struct evdev_dispatch base;
struct evdev_device *device;
unsigned int nfingers_down; /* number of fingers down */
unsigned int old_nfingers_down; /* previous no fingers down */
unsigned int slot; /* current slot */
bool has_mt;
bool semi_mt;
unsigned int real_touches; /* number of slots */
unsigned int ntouches; /* no slots inc. fakes */