Double Typing Characters when using Hardware Keyboard

[canadiannomad]

I've been running into an issue for a while now, and I'm not sure what is triggering it.
I'll be working in Termux on my Android device with a bluetooth keyboard connected, everything fine, then randomly it will start sending double chacters to the terminal when I type. Ie I type "a" and "aa" will appear, if I hit "backspace" it will delete the 2 previous characters. I'm not able to get out of this state without restarting my Android device.
This happens on both a Logitech K780 as well as an Apple Magic Keyboard on a Samsung S21 Ultra, as well as a BigMe EInk device. (Tested the 4 combinations)
If I use other apps then typing is still fine, only Termux gets into this state.
If I try exiting the session + termux, I will still have this issue when I open the app again. Only reboot seems to resolve it.
On screen keyboard still works while it is in this state.

Samsung:
Android version 13
Termux 0.118.0
Termux tools: 1.29.3

BigMe:
Android version 11
Termux 0.118.0
Termux tools: 1.31.0

Oddly enough it seems to have resolved itself while I was writing this report, but it is a recurring issue for me.

[Yellow-Subroutine]

This also just happened to me.

Logitech K380 keyboard
Lenovo Tab m8 (4ht gen) - Android 12
Termux 0.118.0

[Yellow-Subroutine]

Also happening with 0.118.0 on a Galaxy A7 Lite (Android 13) with a K380 keyboard and 2 no-name keyboards.
And it happens when I emulate a bluetooth keyboard on my phone using an app - so it seems it is a generic problem with bluethooth keyboards.

In all cases only termux is affected, other apps work fine.

This is clearly a termux-bug that is becoming a serious problem for me as the use of an external keyboard is not reliably possible.

I would very much appreciate it if this could be fixed.

[agnostic-apollo]

Enable Terminal View Key Logging and check if duplicate events are being received by termux in logcat or if termux is duplicating keys.

https://github.com/termux/termux-app#debugging

[Yellow-Subroutine]

Thanks a lot for taking an interest.

I have enabled the key logging and produced the attached log with "logcat | grep TerminalView" to suppress irrelevant log-message (I hope this did not supress relevant suff - please let me know if I should do it any other way).

The log shows the events when typing "termux" in the "bad" keyboard state.

It looks like there is a keydown and a keyup event for every character but it does not appear termux would receive the letters twice - it seems to do the duplication itself...

But I leave it to the experts...

termux-log.txt

[agnostic-apollo]

It seems that both commitText() and onKeyDown() are getting called for some reason, even though ideally only one should be called, hence termux is duplicating. Maybe softkeyboard is causing some problem or bluetooth keyboard is triggering both. Firstly try to disable software keyboard from settings and restart app and also try both values for enforce-char-based-input.

https://wiki.termux.com/wiki/Terminal_Settings#Workaround_issues_with_some_keyboards

https://github.com/termux/termux-app/blob/v0.118.0/terminal-view/src/main/java/com/termux/view/TerminalView.java#L602

https://github.com/termux/termux-app/blob/v0.118.0/terminal-view/src/main/java/com/termux/view/TerminalView.java#L306

Termux:TerminalView: onKeyPreIme(keyCode=49, event=KeyEvent { action=ACTION_DOWN, keyCode=KEYCODE_U, scanCode=22, metaState=0, flags=0x8, repeatCount=0, eventTime=312605320093000, downTime=312605320093000, deviceId=49, source=0x101, displayId=-1 })
...
Termux:TerminalView: IME: finishComposingText()
...
Termux:TerminalView: IME: commitText("u", 1)
Termux:TerminalView: inputCodePoint(codePoint=117, controlDownFromEvent=false, leftAltDownFromEvent=false)
...
Termux:TerminalView: onKeyDown(keyCode=49, isSystem()=false, event=KeyEvent { action=ACTION_DOWN, keyCode=KEYCODE_U, scanCode=22, metaState=0, flags=0x8, repeatCount=0, eventTime=312605320093000, downTime=312605320093000, deviceId=49, source=0x101, displayId=-1 })
Termux:TerminalView: KeyEvent#getUnicodeChar(0) returned: 117
Termux:TerminalView: inputCodePoint(codePoint=117, controlDownFromEvent=false, leftAltDownFromEvent=false)
...
Termux:TerminalView: onKeyPreIme(keyCode=49, event=KeyEvent { action=ACTION_UP, keyCode=KEYCODE_U, scanCode=22, metaState=0, flags=0x8, repeatCount=0, eventTime=312605322224000, downTime=312605320093000, deviceId=49, source=0x101, displayId=-1 })

[Yellow-Subroutine]

Disabling the software keyboard makes the problem go away.
Enabling it again makes the problem re-appear, that is absolutely reproducible.

Setting "enforce-char-based-input" to either true or false has no impact on the problem.

[agnostic-apollo]

Disabling the software keyboard makes the problem go away.

Great! And what will make you go away? ;)

Which soft keyboard are you (both) using? Try changing to some other like Gboard or OpenBoard and test while enabled.

[Yellow-Subroutine]

I will test further when the problem manifests itself again (I cannot provoke it and at the moment everything is fine) but I have been using mostly Swiftkey and sometimes "Hacker's keyboard" and "Unexpected keyboard".

As far as I can remember you would run into this problem with all these keyboards, so I assume it is a termux-bug and does not depend on the softkeyboard used.

But I may be wrong here and as I said, I will test further as soon as I can.

[agnostic-apollo]

Note that deviceId is 49 for all the entries. If soft keyboard generated the events it would have been -1. Termux is only processing the events sent. As a workaround if needed, I think it should be possible to ignore onKeyDown() for non -1 devices with a user property.

https://developer.android.com/reference/android/view/KeyEvent.html

[Yellow-Subroutine]

Just a little update...
Currently (unfortunately) I don't experience this bug.
In the recent days it happened only once when I was using Swiftkey as softkeyboard.
I then switched to "Hacker's keyboard" but it seems that when you switch keyboards something gets reset that also makes the bug go away. So after switching to "Hacker's keyboard" everything was fine again, and it stayed fine even when switching back to Swiftkey.
So it seems to me that when this bug appears, both disabling the softkeyboard as well as switching to another softkeyboard gets the device back to a sane state (for a while, until it happens again).

[Jon8RFC]

I have this issue using scrcpy and a hardware keyboard with Swiftkey.

I'm unsure where the culprit actually lies (maybe it's swiftkey?), but you all may be able to help me figure it out.

With Swiftkey, I get duplicated keystrokes in scrcpy with the hardware keyboard; clicking with mouse through scrcpy does not duplicate.

With Swiftkey, SPACEBAR must be pressed for the final character to be part of the command; switching to google keyboard and then back to swiftkey eliminates that necessary step:
service call nfc 2
will omit the "2" unless SPACEBAR is pressed before ENTER, or, if switching to google keyboard then back to swiftkey, just pressing ENTER works. The keyboard must be switched each time before sending a command if Swiftkey is used.

EDIT
And I'm embarrassed that I can't figure out where the "Termux app settings" is accessed:

I don't see three dots or three lines, I've swiped on the edges, I've long-pressed. I feel really dumb since editing termux.properties would say "edit termux.properties", so I'm stuck.

EDIT2

Ah, so the play store app doesn't have "settings" and I found out I shouldn't use that version anymore. And the github version doesn't duplicate keystrokes in swiftkey, no spacebar is necessary for the final keystroke. I'm good to go.