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| author | Haoran S. Diao (刁浩然) <0@hairydiode.xyz> | 2025-08-19 14:10:12 -0700 |
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| committer | Haoran S. Diao (刁浩然) <0@hairydiode.xyz> | 2025-08-19 14:10:12 -0700 |
| commit | df5df87632439a47d28214d3b155535259eec2ec (patch) | |
| tree | 8117d97f00cfd7f84ba391e0499f7b5c201e621e | |
| parent | 7a701578b0dbd700dc0330eafbd3a8faf3990beb (diff) | |
xbabuse.html
| -rw-r--r-- | index.html | 1 | ||||
| -rw-r--r-- | xkbabuse.html | 132 |
2 files changed, 133 insertions, 0 deletions
@@ -43,6 +43,7 @@ Where's all the other stuff you host from this domain? <a href="https://social.hairydiode.xyz">My Mastodon Instance</a> Where's all the content? Scroll Down +<a href="https://hairydiode.xyz/xkbabuse">[Abusing X11's xkb for fun and profit] 08-19-2025</a> <a href="https://hairydiode.xyz/fourcorners">[Four Corners Input Method for ibus-table] 11-25-2023</a> <a href="https://hairydiode.xyz/unihome">[We Have Unicode at Home] 6-30-2023</a> <a href="https://hairydiode.xyz/jankime">[Janky IME] 6-29-2023</a> diff --git a/xkbabuse.html b/xkbabuse.html new file mode 100644 index 0000000..ae8ff5c --- /dev/null +++ b/xkbabuse.html @@ -0,0 +1,132 @@ +<!DOCTYPE html> +<head> +<title>Abusing X11's xkb for fun and profit</title> +<meta charset="utf-8"/> +<link rel="stylesheet" href="https://hairydiode.xyz/style.css"/> +<link rel="icon" type="image/png" href="https://hairydiode.xyz/img/fav/logo.png"/> +</head> +<body> +<div class="content"> +<pre> +<!-- +123456789-223456789-323456789-423456789-523456789-623456789-723456789-8234567890 +一二三四 +-->-------------------------------------------------------------------------------- + +<a href="https://hairydiode.xyz">>HairyDiode</a> + +-------------------------------------------------------------------------------- +<!-- +123456789-223456789-323456789-423456789-523456789-623456789-723456789-8234567890 +一二三四-->Abusing X11's xkb for fun and profit 08-19-2025 +-------------------------------------------------------------------------------- + +Yesterday I was playing around with xkb keyboard layouts before I discovered +that compose functionality for European (and other languages that use accents) +keyboard layouts is implemented as a 5227 line long table that maps key symbols +to unicode strings. + +ex: /usr/share/X11/locale/en_US.UTF-8/Compose on my computer +# UTF-8 (Unicode) Compose sequences +# +# Spacing versions of accents (mostly) +<dead_tilde> <space> : "~" asciitilde # TILDE +<dead_tilde> <dead_tilde> : "~" asciitilde # TILDE +<Multi_key> <minus> <space> : "~" asciitilde # TILDE +<Multi_key> <space> <minus> : "~" asciitilde # TILDE +<dead_acute> <space> : "'" apostrophe # APOSTROPHE +... +<dead_circumflex> <o> : "ồ ocircumflex # LATIN SMALL LETTER O WITH CIRCUMFLEX +... +<Multi_key> <colon> <U2395> : "⍠́ U2360 # : ⎕ APL FUNCTIONAL SYMBOL QUAD COLON + +For those of you who are unaware, if you use for example a German keyboard +layout, pressing "^" followed by "o" will produce "ô". The circumflex "^" key is +called a "dead key" in xkb terminology because it does not produce any +characters by itself. In addition if you were to bind any key on your keyboard +to "compose" it would allow you to type basically a wide range of unicode +characters via various sequences of key presses. + +This got me thinking, this functionality is identical to how ibus-table IMs work +and would allow me to implement Chinese IMs in a way that requires no extra +software and which would presumbaly be compatible with a far greater range of +software since the functionality is built into X11. The fact that the default +file is 5000 lines long tells me that X11 is more than capable of handling long +tables. + +My first step was to take the <a href="https://github.com/jdh8/ibus-boshiamy">ibus boshiamy implementation</a> I already have on my +computer and mutilate it into the above format using convoluted regex commands +and a lot of whack a mole to turn 46000 lines of: + +aaa 100 鑫 +aaa 99 龘 +aaa 98 鑆 + + into + +<a> <a> <a> <space> : "鑫" +<a> <a> <a> <1> : "龘" +<a> <a> <a> <2> : "鑆" + + +To my surprise, after moving this file to ~/.XCompose it worked exactly as I +expected with no lag. The only issue then, is that there's no way to switch +between compose sets in xkb. This explains why the en_US.UTF-8 compose set was +so long, it had to essentially handle every possible dead-key or compose +sequence for every keyboard layout. + +There's an easy solution to this though, which is to create a custom keyboard +layout where the keys are mapped to custom key symbols (xkb's layer of +abstraction above a physical keycode and below a text string) and have my +compose table use those as the inputs instead of qwerty keys. + +Since I started this whole thing by messing with xkb layouts, it didn't take +long for me to edit the us layout into something like this: + + key <AD01> {[ U9AD8, Q ]}; # 高 + key <AD02> {[ U4E94, W ]}; # 五 + key <AD03> {[ U4E00, E ]}; # 一 + key <AD04> {[ U4E8C, R ]}; # 二 + key <AD05> {[ U901A, T ]}; # 通 + key <AD06> {[ U76CA, Y ]}; # 益 + key <AD07> {[ U4EE5, U ]}; # 以 + key <AD08> {[ U5F8C, I ]}; # 後 + key <AD09> {[ U3007, O ]}; # 〇 + key <AD10> {[ U5099, P ]}; # 備 + +And my compose table to look something like this: + +<U5C0D> <U5C0D> <U5C0D> <U4E8C> <space> : "鑆" +<U5C0D> <U5C0D> <U5C0D> <space> : "鑫" +<U5C0D> <U5C0D> <U5C0D> <U8981> <space> : "龘" + +Now if I set my keyboard layout to "boshiamy", it will be sending these custom +key symbols which will be interpreted by my custom compose rules, and if I +switch it back to the us layout the compose rules don't apply. + +The only issues there are with this method is that the functionality for user +specific keyboard layouts is incredibly broken in xkb, so I had to add my +custom layout to the system xkb data directory. Otherwise this whole +implementation would consist entirely of two config files in the home directory. + +Also if you have ibus installed make sure to check "use system keyboard layout" +in settings or else it'll keep switching your keyboard layout around. + +Also for those unfamilair with component based input methods, unlike phonetic +input methods like Pinyin (derogatory) or Zhuyin (derogatory), the mapping for +key presses to characters has very few if any conflicts, and therefore the +system works in an open loop way. You can easily use somethign like CangJie or +Boshiamy without the preview window or without any sort of predictive text. + + +The files I've created and further reading are in a git repo <a href="https://hairydiode.xyz/cgit/xkb-boshiamy">here</a> + +</pre> +</div> +<br> +<br> +</body> +<!-- +if you're digging in the src you might be interested in how this site works +here: https://hairydiode.xyz/meta2 +--> |