Added emacs as an "operating system" for input mode.

[chewxy]

I added a new unicode input mode: emacs.

While strictly not an operating system, inserting unicode characters in emacs has its own keybinding. The most usual way is C-x-8 RET followed by the unicode in hex. As a person who works across different OSes but with the constant being emacs, this was the most straightforward way forwards.

Of course, the main credit goes to TrentinQuarantino in this emacs stack exchange post.

Description

I added a new unicode input mode in quantum/process_unicode_common.(c|h). Then I updated all the programmer friendly numbers of the enums, and added documentation too.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

Additional notes

I'm unfamiliar with the testing protocols of this project. If I could get some help that'd be great. I'm reasonably familiar with C. However, what I have done is I have flashed two ergodox-EZs with this and tested it on emacs on both linux and macos. My Windows computer isn't quite available right now, so I'm unable to test on Windows.

[zvecr]

Previous implementation, #8358.

[drashna]

Is there a reason that the "linux" mode can't be used, with a custom start/finish option?

Eg

void unicode_input_start(void) {
    unicode_saved_caps_lock = host_keyboard_led_state().caps_lock;
    unicode_saved_num_lock  = host_keyboard_led_state().num_lock;

    if (unicode_config.input_mode == UC_LNX && unicode_saved_caps_lock) {
        tap_code(KC_CAPS_LOCK);
    }

    unicode_saved_mods = get_mods(); // Save current mods
    clear_mods();                    // Unregister mods to start from a clean state

    switch (unicode_config.input_mode) {
        case UC_MAC:
            register_code(UNICODE_KEY_MAC);
            break;
        case UC_LNX:
            tap_code16(LCTL(KC_X));
            tap_code16(KC_8);
            tap_code16(KC_ENTER);
            break;
        case UC_WIN:
            // For increased reliability, use numpad keys for inputting digits
            if (!unicode_saved_num_lock) {
                tap_code(KC_NUM_LOCK);
            }
            register_code(KC_LEFT_ALT);
            wait_ms(UNICODE_TYPE_DELAY);
            tap_code(KC_KP_PLUS);
            break;
        case UC_WINC:
            tap_code(UNICODE_KEY_WINC);
            tap_code(KC_U);
            break;
    }

    wait_ms(UNICODE_TYPE_DELAY);
}

[chewxy]

@drashna as far as I am aware, ibus on linux only allows Alt+HEXCODE entries, whereas emacs in general requires the C-x-8 RET sequence followed by the hex code

[chewxy]

(having said that, if you have gnome-tweak-tool or gconf-editor on any linux with gnome (e.g. ubuntu), you can turn on Emacs Input and the Ctrl+x+8 ENTER sequence also allows you to type unicode.)

But we'd probably still want to keep the default ibus settings for normal people