forked from mirrors/qmk_firmware
[Docs] New section to modifier docs: Checking Modifier State (#10550)
* Added new section to docs: Checking Modifier State * Added id anchors to all headers in modifiers docs * Added a Wikipedia link to bitwise operators and... crosslinked to the QMK macro docs. * Added an explanation on the format of mod bitmask * Added .md extension to hyperlinks to macros docs * Corrected mod mask order and changed notation * Documented add_oneshot_mods and del_oneshot_mods * Mentioned modifier checks in the macro docs * Explained strict modifier checking i.e. using `get_mods() & MOD_MASK == MOD_MASK` instead of simply `get_mods() & MOD_MASK` * Added (un)register_mods to the docs * Put left term of comparison in parens
This commit is contained in:
precondition
GitHub
parent
032dfddb6b
commit
2395069b0b
2 changed files with 136 additions and 1 deletions
|
|
@ -23,6 +23,141 @@ These allow you to combine a modifier with a keycode. When pressed, the keydown
|
|||
|
||||
You can also chain them, for example `LCTL(LALT(KC_DEL))` or `C(A(KC_DEL))` makes a key that sends Control+Alt+Delete with a single keypress.
|
||||
|
||||
# Checking Modifier State :id=checking-modifier-state
|
||||
|
||||
The current modifier state can mainly be accessed with two functions: `get_mods()` for normal modifiers and modtaps and `get_oneshot_mods()` for one-shot modifiers (unless they're held, in which case they act like normal modifier keys).
|
||||
|
||||
The presence of one or more specific modifiers in the current modifier state can be detected by ANDing the modifier state with a mod mask corresponding to the set of modifiers you want to match for. The reason why bitwise operators are used is that the modifier state is stored as a single byte in the format (GASC)<sub>R</sub>(GASC)<sub>L</sub>.
|
||||
|
||||
Thus, to give an example, `01000010` would be the internal representation of LShift+RAlt.
|
||||
For more information on bitwise operators in C, click [here](https://en.wikipedia.org/wiki/Bitwise_operations_in_C) to open the Wikipedia page on the topic.
|
||||
|
||||
In practice, this means that you can check whether a given modifier is active with `get_mods() & MOD_BIT(KC_<modifier>)` (see the [list of modifier keycodes](keycodes_basic.md#modifiers)) or with `get_mods() & MOD_MASK_<modifier>` if the difference between left and right hand modifiers is not important and you want to match both. Same thing can be done for one-shot modifiers if you replace `get_mods()` with `get_oneshot_mods()`.
|
||||
|
||||
To check that *only* a specific set of mods is active at a time, AND the modifier state and your desired mod mask as explained above and compare the result to the mod mask itself: `get_mods() & <mod mask> == <mod mask>`.
|
||||
|
||||
For example, let's say you want to trigger a piece of custom code if one-shot left control and one-shot left shift are on but every other one-shot mods are off. To do so, you can compose the desired mod mask by combining the mod bits for left control and shift with `(MOD_BIT(KC_LCTL) | MOD_BIT(KC_LSFT))` and then plug it in: `get_oneshot_mods & (MOD_BIT(KC_LCTL) | MOD_BIT(KC_LSFT)) == (MOD_BIT(KC_LCTL) | MOD_BIT(KC_LSFT))`. Using `MOD_MASK_CS` instead for the mod bitmask would have forced you to press four modifier keys (both versions of control and shift) to fulfill the condition.
|
||||
|
||||
The full list of mod masks is as follows:
|
||||
|
||||
| Mod Mask Name | Matching Modifiers |
|
||||
|--------------------|------------------------------------------------|
|
||||
| `MOD_MASK_CTRL` | LCTRL , RCTRL |
|
||||
| `MOD_MASK_SHIFT` | LSHIFT , RSHIFT |
|
||||
| `MOD_MASK_ALT` | LALT , RALT |
|
||||
| `MOD_MASK_GUI` | LGUI , RGUI |
|
||||
| `MOD_MASK_CS` | CTRL , SHIFT |
|
||||
| `MOD_MASK_CA` | (L/R)CTRL , (L/R)ALT |
|
||||
| `MOD_MASK_CG` | (L/R)CTRL , (L/R)GUI |
|
||||
| `MOD_MASK_SA` | (L/R)SHIFT , (L/R)ALT |
|
||||
| `MOD_MASK_SG` | (L/R)SHIFT , (L/R)GUI |
|
||||
| `MOD_MASK_AG` | (L/R)ALT , (L/R)GUI |
|
||||
| `MOD_MASK_CSA` | (L/R)CTRL , (L/R)SHIFT , (L/R)ALT |
|
||||
| `MOD_MASK_CSG` | (L/R)CTRL , (L/R)SHIFT , (L/R)GUI |
|
||||
| `MOD_MASK_CAG` | (L/R)CTRL , (L/R)ALT , (L/R)GUI |
|
||||
| `MOD_MASK_SAG` | (L/R)SHIFT , (L/R)ALT , (L/R)GUI |
|
||||
| `MOD_MASK_CSAG` | (L/R)CTRL , (L/R)SHIFT , (L/R)ALT , (L/R)GUI |
|
||||
|
||||
Aside from accessing the currently active modifiers using `get_mods()`, there exists some other functions you can use to modify the modifier state, where the `mods` argument refers to the modifiers bitmask.
|
||||
|
||||
* `add_mods(mods)`: Enable `mods` without affecting any other modifiers
|
||||
* `register_mods(mods)`: Like `add_mods` but send a keyboard report immediately.
|
||||
* `del_mods(mods)`: Disable `mods` without affecting any other modifiers
|
||||
* `unregister_mods(mods)`: Like `del_mods` but send a keyboard report immediately.
|
||||
* `set_mods(mods)`: Overwrite current modifier state with `mods`
|
||||
* `clear_mods()`: Reset the modifier state by disabling all modifiers
|
||||
|
||||
Similarly, in addition to `get_oneshot_mods()`, there also exists these functions for one-shot mods:
|
||||
|
||||
* `add_oneshot_mods(mods)`: Enable `mods` without affecting any other one-shot modifiers
|
||||
* `del_oneshot_mods(mods)`: Disable `mods` without affecting any other one-shot modifiers
|
||||
* `set_oneshot_mods(mods)`: Overwrite current one-shot modifier state with `mods`
|
||||
* `clear_oneshot_mods()`: Reset the one-shot modifier state by disabling all one-shot modifiers
|
||||
|
||||
## Examples :id=examples
|
||||
|
||||
The following examples use [advanced macro functions](feature_macros.md#advanced-macro-functions) which you can read more about in the [documentation page on macros](feature_macros.md).
|
||||
|
||||
### Alt + Escape for Alt + Tab :id=alt-escape-for-alt-tab
|
||||
|
||||
Simple example where chording Left Alt with `KC_ESC` makes it behave like `KC_TAB` for alt-tabbing between applications. This example strictly checks if only Left Alt is active, meaning you can't do Alt+Shift+Esc to switch between applications in reverse order. Also keep in mind that this removes the ability to trigger the actual Alt+Escape keyboard shortcut, though it keeps the ability to do AltGr+Escape.
|
||||
|
||||
```c
|
||||
bool process_record_user(uint16_t keycode, keyrecord_t *record) {
|
||||
switch (keycode) {
|
||||
|
||||
case KC_ESC:
|
||||
// Detect the activation of only Left Alt
|
||||
if ((get_mods() & MOD_BIT(KC_LALT)) == MOD_BIT(KC_LALT)) {
|
||||
if (record->event.pressed) {
|
||||
// No need to register KC_LALT because it's already active.
|
||||
// The Alt modifier will apply on this KC_TAB.
|
||||
register_code(KC_TAB);
|
||||
} else {
|
||||
unregister_code(KC_TAB);
|
||||
}
|
||||
// Do not let QMK process the keycode further
|
||||
return false;
|
||||
}
|
||||
// Else, let QMK process the KC_ESC keycode as usual
|
||||
return true;
|
||||
|
||||
}
|
||||
return true;
|
||||
};
|
||||
```
|
||||
|
||||
### Shift + Backspace for Delete :id=shift-backspace-for-delete
|
||||
|
||||
Advanced example where the original behaviour of shift is cancelled when chorded with `KC_BSPC` and is instead fully replaced by `KC_DEL`. Two main variables are created to make this work well: `mod_state` and `delkey_registered`. The first one stores the modifier state and is used to restore it after registering `KC_DEL`. The second variable is a boolean variable (true or false) which keeps track of the status of `KC_DEL` to manage the release of the whole Backspace/Delete key correctly.
|
||||
|
||||
As opposed to the previous example, this doesn't use strict modifier checking. Pressing `KC_BSPC` while one or two shifts are active is enough to trigger this custom code, regardless of the state of other modifiers. That approach offers some perks: Ctrl+Shift+Backspace lets us delete the next word (Ctrl+Delete) and Ctrl+Alt+Shift+Backspace lets us execute the Ctrl+Alt+Del keyboard shortcut.
|
||||
|
||||
```c
|
||||
// Initialize variable holding the binary
|
||||
// representation of active modifiers.
|
||||
uint8_t mod_state;
|
||||
bool process_record_user(uint16_t keycode, keyrecord_t *record) {
|
||||
// Store the current modifier state in the variable for later reference
|
||||
mod_state = get_mods();
|
||||
switch (keycode) {
|
||||
|
||||
case KC_BSPC:
|
||||
{
|
||||
// Initialize a boolean variable that keeps track
|
||||
// of the delete key status: registered or not?
|
||||
static bool delkey_registered;
|
||||
if (record->event.pressed) {
|
||||
// Detect the activation of either shift keys
|
||||
if (mod_state & MOD_MASK_SHIFT) {
|
||||
// First temporarily canceling both shifts so that
|
||||
// shift isn't applied to the KC_DEL keycode
|
||||
del_mods(MOD_MASK_SHIFT);
|
||||
register_code(KC_DEL);
|
||||
// Update the boolean variable to reflect the status of KC_DEL
|
||||
delkey_registered = true;
|
||||
// Reapplying modifier state so that the held shift key(s)
|
||||
// still work even after having tapped the Backspace/Delete key.
|
||||
set_mods(mod_state);
|
||||
return false;
|
||||
}
|
||||
} else { // on release of KC_BSPC
|
||||
// In case KC_DEL is still being sent even after the release of KC_BSPC
|
||||
if (delkey_registered) {
|
||||
unregister_code(KC_DEL);
|
||||
delkey_registered = false;
|
||||
return false;
|
||||
}
|
||||
}
|
||||
// Let QMK process the KC_BSPC keycode as usual outside of shift
|
||||
return true;
|
||||
}
|
||||
|
||||
}
|
||||
return true;
|
||||
};
|
||||
```
|
||||
|
||||
# Legacy Content :id=legacy-content
|
||||
|
||||
This page used to encompass a large set of features. We have moved many sections that used to be part of this page to their own pages. Everything below this point is simply a redirect so that people following old links on the web find what they're looking for.
|
||||
|
|
|
|||
|
|
@ -209,7 +209,7 @@ SEND_STRING(".."SS_TAP(X_END));
|
|||
|
||||
There are some functions you may find useful in macro-writing. Keep in mind that while you can write some fairly advanced code within a macro, if your functionality gets too complex you may want to define a custom keycode instead. Macros are meant to be simple.
|
||||
|
||||
?> You can also use the functions described in [Useful functions](ref_functions.md) for additional functionality. For example `reset_keyboard()` allows you to reset the keyboard as part of a macro.
|
||||
?> You can also use the functions described in [Useful function](ref_functions.md) and [Checking modifier state](feature_advanced_keycodes#checking-modifier-state) for additional functionality. For example, `reset_keyboard()` allows you to reset the keyboard as part of a macro and `get_mods() & MOD_MASK_SHIFT` lets you check for the existence of active shift modifiers.
|
||||
|
||||
### `record->event.pressed`
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue