touchscroll.py

#!/usr/bin/env python3
import time
import evdev
from evdev import ecodes

SCROLL_FRAC = 0.1

if __name__ == '__main__':
    devs = [evdev.InputDevice(path) for path in evdev.list_devices()]
    dev = None
    for d in devs:
        if 'eGalaxTouch' in d.name:
            dev = d
    assert dev is not None
    print('grabbing device', dev.name)
    dev.grab()
    abs_x_info = dev.absinfo(ecodes.ABS_X)
    abs_y_info = dev.absinfo(ecodes.ABS_Y)
    cap = {
        ecodes.EV_KEY: [ecodes.BTN_TOUCH, ecodes.BTN_LEFT],
        ecodes.EV_REL: [ecodes.REL_WHEEL],
        ecodes.EV_ABS: [
            (ecodes.ABS_X, abs_x_info),
            (ecodes.ABS_Y, abs_y_info),
        ],
    }
    print('creating ui')
    ui = evdev.UInput(cap, name='touchscroll', version=0x3)
    time.sleep(1)
    print(ui)
    last_pos = (None, None)
    quant_err = 0.
    for evt in dev.read_loop():
        evt = evdev.util.categorize(evt)
        if isinstance(evt, evdev.KeyEvent):
            if evt.keystate == evt.key_up:
                last_pos = (None, None)
                acc = 0.
        elif isinstance(evt, evdev.AbsEvent):
            if evt.event.code == ecodes.ABS_X:
                pos = (evt.event.value, last_pos[1])
            elif evt.event.code == ecodes.ABS_Y:
                pos = (last_pos[0], evt.event.value)
            else:
                continue
            if None in last_pos and None not in pos:
                print('move to', pos)
                ui.write(ecodes.EV_KEY, ecodes.BTN_LEFT, 1)
                ui.write(ecodes.EV_ABS, ecodes.ABS_X, pos[0])
                ui.write(ecodes.EV_ABS, ecodes.ABS_Y, pos[1])
                ui.syn()
                ui.write(ecodes.EV_KEY, ecodes.BTN_LEFT, 0)
                ui.syn()
            if last_pos[1] is not None:
                y_scroll = pos[1] - last_pos[1]
                print('scroll', y_scroll)
                adj = y_scroll * SCROLL_FRAC + quant_err
                adj_floor = int(adj)
                quant_err = adj - adj_floor
                ui.write(ecodes.EV_REL, ecodes.REL_WHEEL, adj_floor)
                ui.syn()
            last_pos = pos