自打使用linux系统以来，触摸板这块的体验一只是个痛点：只支持基本的点击，双指垂直滚动。很久以来我就一直想要触摸板水平滚动的功能。今天终于实现了！
Synaptics
其实很久以前就照抄过一份xf86-input-synaptics驱动程序的触摸板配置：
# file: /etc/X11/xorg.conf.d/70-synaptics.conf
Section "InputClass"
Identifier "touchpad"
Driver "synaptics"
MatchIsTouchpad "on"
Option "TapButton1" "1"
Option "TapButton2" "3"
Option "TapButton3" "2"
Option "VertEdgeScroll" "on"
Option "VertTwoFingerScroll" "on"
Option "HorizonEdgeScroll" "on"
Option "HorizonTwoFingerScroll" "on"
Option "EmulateTwoFingerMinZ" "40"
Option "EmulateTwoFingerMinW" "8"
Option "FingerLow" "30"
Option "FingerHigh" "50"
Option "VertScrollDelta" "-111"
Option "HorizScrollDelta" "-111"
EndSection但很奇怪，一直以来水平滚动一直没生效。其实想来也是乌龙，是我抄错了：
# 正确的应该是Horiz而非Horizon
Option "HorizEdgeScroll" "on"
Option "HorizTwoFingerScroll" "on"其实只要改正并重启一下，事情就完美解决了。可惜我一直没发现，还尝试研究为啥水平滚动不生效呢，他文档明明这么写了，难道是诓我？
synclient是用于实时更改synaptics驱动参数的命令行工具，使用
synclient HorizTwoFingerScroll=1即可开启水平滚动。事情本应到此结束，但是我惊讶的发现synaptics驱动已经停止维护，archwiki上已经推荐大家使用libinput了。
Libinput
Cf. https://wiki.archlinux.org/title/Libinput
参考archwiki直接把触摸板输入驱动换成libinput，尤其值得注意，如果/etc/X11/xorg.conf.d中需要移除（最好先备份）之前的synaptic driver的配置文件，比如我的:
rm /etc/X11/xorg.conf.d/70-synaptics.conf删除之后像这样：
yychi@/etc/X11/xorg.conf.d> ls -al
总用量 12
drwxr-xr-x 2 root root 4096 3月 26 00:23 ./
drwxr-xr-x 4 root root 4096 1月 3 20:53 ../
-rw-r--r-- 1 root root 337 3月 26 00:23 00-keyboard.conf
lrwxrwxrwx 1 root root 43 3月 25 23:23 40-libinput.conf -> /usr/share/X11/xorg.conf.d/40-libinput.conf看下配置文件：
cat 40-libinput.conf
Section "InputClass"
Identifier "touchpad"
MatchIsTouchpad "on"
Driver "libinput"
Option "AccelerationProfile" "2"
Option "Sensitivity" "0.1"
Option "Tapping" "on"
Option "ClickMethod" "clickfinger"
Option "TappingButtonMap" "lrm"
Option "NaturalScrolling" "on"
EndSection特别注意
注意到文件夹中还有一个文件00-keyboard.conf，由于我们换了驱动，而libinput是所有输入的驱动，包括键盘，所以必须适当更改该文件，否则重启进来之后你会发现键盘失效！
ychi@/etc/X11/xorg.conf.d> cat 00-keyboard.conf
# Written by systemd-localed(8), read by systemd-localed and Xorg. It's
# probably wise not to edit this file manually. Use localectl(1) to
# instruct systemd-localed to update it.
Section "InputClass"
Identifier "system-keyboard"
MatchIsKeyboard "on"
Driver "libinput" # 这行必须指定driver为libinput，否则重启后键盘无法输入
Option "XkbLayout" "cn"
EndSection配置完成后用xinput看看：
yychi@/etc/X11/xorg.conf.d> xinput
⎡ Virtual core pointer id=2 [master pointer (3)]
⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
⎜ ↳ ELAN2301:00 04F3:306B Touchpad id=11 [slave pointer (2)]
⎣ Virtual core keyboard id=3 [master keyboard (2)]
↳ Virtual core XTEST keyboard id=5 [slave keyboard (3)]
↳ Power Button id=6 [slave keyboard (3)]
↳ Video Bus id=7 [slave keyboard (3)]
↳ Video Bus id=8 [slave keyboard (3)]
↳ Sleep Button id=9 [slave keyboard (3)]
↳ XiaoMi USB 2.0 Webcam: XiaoMi U id=10 [slave keyboard (3)]
↳ AT Translated Set 2 keyboard id=12 [slave keyboard (3)]
↳ Wireless hotkeys id=13 [slave keyboard (3)]
yychi@/etc/X11/xorg.conf.d> xinput list-props 11 # 由上可知id=11为触摸板
Device 'ELAN2301:00 04F3:306B Touchpad':
Device Enabled (189): 1
Coordinate Transformation Matrix (191): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000
libinput Tapping Enabled (327): 1
libinput Tapping Enabled Default (328): 0
libinput Tapping Drag Enabled (329): 1
libinput Tapping Drag Enabled Default (330): 1
libinput Tapping Drag Lock Enabled (331): 0
libinput Tapping Drag Lock Enabled Default (332): 0
libinput Tapping Button Mapping Enabled (333): 1, 0
libinput Tapping Button Mapping Default (334): 1, 0
libinput Natural Scrolling Enabled (335): 1
libinput Natural Scrolling Enabled Default (336): 0
libinput Disable While Typing Enabled (337): 1
libinput Disable While Typing Enabled Default (338): 1
libinput Scroll Methods Available (339): 1, 1, 0
libinput Scroll Method Enabled (340): 1, 0, 0
libinput Scroll Method Enabled Default (341): 1, 0, 0
libinput Click Methods Available (342): 1, 1
libinput Click Method Enabled (343): 0, 1
libinput Click Method Enabled Default (344): 1, 0
libinput Middle Emulation Enabled (345): 0
libinput Middle Emulation Enabled Default (346): 0
libinput Accel Speed (347): 0.000000
libinput Accel Speed Default (348): 0.000000
libinput Accel Profiles Available (349): 1, 1
libinput Accel Profile Enabled (350): 1, 0
libinput Accel Profile Enabled Default (351): 1, 0
libinput Left Handed Enabled (352): 0
libinput Left Handed Enabled Default (353): 0
libinput Send Events Modes Available (312): 1, 1
libinput Send Events Mode Enabled (313): 0, 0
libinput Send Events Mode Enabled Default (314): 0, 0
Device Node (315): "/dev/input/event6"
Device Product ID (316): 1267, 12395
libinput Drag Lock Buttons (354): <no items>
libinput Horizontal Scroll Enabled (355): 1
libinput Scrolling Pixel Distance (356): 15
libinput Scrolling Pixel Distance Default (357): 15
libinput High Resolution Wheel Scroll Enabled (358): 1发现驱动已经成功更换为libinput，并且
libinput Horizontal Scroll Enabled (355): 1表明已成功开启水平滚动。
Libinput-gestures
libinput-gestures是一个脚本工具，它可以接收libinput的event并作出相应的action，进而达到手势操作的目地。具体可参考3.