synaptics 3/4 finger gestures

[ethician]

First, thanks for the hard work in keeping this project up!

Would you consider adding handling of Synaptics' poor reporting of multitouch gestures?

As evidenced by evtest, Synaptics unfortunately reports third, and higher, tap as a sequence of BTN_TOUCH (or BTN_FINGER) followed by BTN_TOOL_TRIPLETAP (or BTN_TOOL_QUADTAP, etc...).

Event: time 1513311070.511217, type 3 (EV_ABS), code 47 (ABS_MT_SLOT), value 0
Event: time 1513311070.511217, type 3 (EV_ABS), code 57 (ABS_MT_TRACKING_ID), value 1892
Event: time 1513311070.511217, type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 3141
Event: time 1513311070.511217, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 3851
Event: time 1513311070.511217, type 3 (EV_ABS), code 47 (ABS_MT_SLOT), value 1
Event: time 1513311070.511217, type 3 (EV_ABS), code 57 (ABS_MT_TRACKING_ID), value 1893
Event: time 1513311070.511217, type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 4276
Event: time 1513311070.511217, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 1984
Event: time 1513311070.511217, type 3 (EV_ABS), code 58 (ABS_MT_PRESSURE), value 48
Event: time 1513311070.511217, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 1
Event: time 1513311070.511217, type 3 (EV_ABS), code 0 (ABS_X), value 3141
Event: time 1513311070.511217, type 3 (EV_ABS), code 1 (ABS_Y), value 3851
Event: time 1513311070.511217, type 3 (EV_ABS), code 24 (ABS_PRESSURE), value 56
Event: time 1513311070.511217, type 1 (EV_KEY), code 334 (BTN_TOOL_TRIPLETAP), value 1

libinput does handle it correctly (relevant code in libinput/src/evdev-mt-touchpad.c around tp_fake_finger...) but lacks mtrack's other features, notably superb kinetic scrolling.

Thanks for the consideration!

[p2rkw]

Your device can track 2 fingers at once. How does synaptics report movement after that 3 finger tap (BTN_TOOL_TRIPLETAP=1) ? Does it generate events for slot 0, 1 or for both?

What value evtest report for ABS_MT_SLOT Max ? Is it 2?

[ethician]

Well, it can and it can do more than that. The log I posted from my own device shows that it uses both slots 0 and 1, but it also reports the other touches using BTN_TOUCH (sometimes BTN_FINGER) in conjunction with the number-of-fingers event like BTN_TOOL_TRIPLETAP.

The code in libinput I pointed to does handle these compound events and correctly reports 3 and 4 finger gestures via libinput-debug-events.

If this is something worth considering, let me know what additional info I can provide you with.