Add Compose support #36
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Thanks for putting up the PR! I do have some early questions. Why it's necessary to set locale explicitly? Per systemd manual:
Also, the dbus service Overall, I feel if we were introducing a dependency on sd-bus in C, I think it's better to completely get rid of the helper script/program and have the ability directly built into the main executable behind a compile time switch. |
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I was actually hoping for feedback, thanks for that. I read systemd-localed(8), which was a bit sparse, but you're right, systemd takes care of it itself. It might make sense to roll the querying of |
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Let's drop ef1310e for now then. We can reconsider this in the future when kmscon has more use of dbus internally. |
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Also, let me know when you are ready for me to review other parts. |
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I've dropped the launcher commit. The rest is ready for review. One thing I'd like your view on is what to do with cancelled sequences (https://xkbcommon.org/doc/current/group__compose.html#compose-cancellation). Right now the cancelling keysym is swallowed, but perhaps it should be let through? I've followed @snakeroot's example for now. |
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You're absolutely right, it's even in their repository. |
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Overall looks good! I have just a few nitpicks marked inline.
Also, please make sure to credit @bluetech in the commit message. Or even better, incorporate some lines in the original commit message bluetech@89aeb0f. It provides a good overview of the feature. Maybe that should also go into the man page?
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I have force-pushed some changes you asked for. I have credited @bluetech in the first commit and used part of their commit message as well. Should I add credits in the other two commits as well? |
The code is partially based on and partially inspired by Ran Benita's code at bluetech@89aeb0f. The main difference is that Compose support is enabled by default, instead of requiring an extra command-line option. Dead keys are special keys which have no immediate effect when pressed, but instead they modify the result of subsequent keys. For example, pressing the <`> key (the dead key) and then <u> may produce the symbol ú. Such sequences can be more elaborate and consist of several keysyms. The compose mechanism has two main pieces of configuration: 1. The Compose file, which defines the compose sequences. It is picked by the user's locale. See the Compose(5) man page; most of it is supported. These files are currently a part of libX11, but some users write their own. For example: /usr/share/X11/locale/en_US.UTF-8/Compose 2. The user's XKB keymap, which defines which keys are dead keys (that is, produce keysyms of the form dead_*, which are normally used in Compose sequences) and which key is the Compose key (which starts many Compose sequences). For example, the us 'intl' variant. This feature (and more) is usually provided by an input method. But we use the lightweight support provided by xkbcommon.
Analogously to --xkb-keymap this allows a user to directly specify an Xkb compose file. This overrides the automatic creation of a compose table from the current locale.
Feed all key events into the Compose state and use the resulting keysyms.
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It should be alright now. I've tested it myself over the last few days and it seems to work so far. |
@snakeroot linked to their implementation in #23. I had independently written a (worse) patch as well. I've taken inspiration from both @snakeroot's and my own implementation for this PR. The main functional difference between their version and this one is that this PR does not require a command-line option to enable Compose support.
Only the first and fourth commits are actually needed. The second commit adds a new launcher to also query the locale information from systemd-localed. The third commit allows the user to specify a Compose file explicitly, but I don't know if that's really useful?