1 Keymap framework - how to define your keymap
2 ============================================
3 ***NOTE: This is updated for QMK but this is still work in progress. This may still be inconsistent with the source code.***
5 QMK is based on TMK. Understanding the essential changes made should help you understand variable names etc.
10 |---------------------------|-----------------------|-------------------------|
11 | Maintainer |hasu |Jack Humbert et al. |
12 | Build path customization | `TMK_DIR = ...` | `include .../Makefile` |
13 | `keymaps` data | 3D array of `uint8_t` holding **keycode** | 3D array of `uint16_t` holding **action code** |
14 | `fn_actions` data | 1D array of `uint16_t` holding **action code** | 1D array of `uint16_t` holding **action code** |
16 Since QMK is based on TMK and uses major portion of TMK code as is, understanding the essential changes made should help you understand the code.
18 ## 0. Keymap and layers
19 In QMK, **`const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS]`** holds multiple **layers** of keymap information in **16 bit** data holding the **action code**. You can define **32 layers** at most.
21 For trivial key definitions, the higher 8 bits of the **action code** are all 0 and the lower 8 bits holds the USB HID usage code generated by the key as **keycode**.
23 Respective layers can be validated simultaneously. Layers are indexed with 0 to 31 and higher layer has precedence.
25 Keymap: 32 Layers Layer: action code matrix
26 ----------------- ---------------------
27 stack of layers array_of_action_code[row][column]
28 ____________ precedence _______________________
29 / / | high / ESC / F1 / F2 / F3 ....
30 31 /___________// | /-----/-----/-----/-----
31 30 /___________// | / TAB / Q / W / E ....
32 29 /___________/ | /-----/-----/-----/-----
33 : _:_:_:_:_:__ | : /LCtrl/ A / S / D ....
34 : / : : : : : / | : / : : : :
35 2 /___________// | 2 `--------------------------
36 1 /___________// | 1 `--------------------------
37 0 /___________/ V low 0 `--------------------------
40 Sometimes, the action code stored in keymap may be referred as keycode in some documents due to the TMK history.
42 ### 0.1 Keymap layer status
43 Keymap layer has its state in two 32 bit parameters:
45 * **`default_layer_state`** indicates a base keymap layer(0-31) which is always valid and to be referred.
46 * **`layer_state`** () has current on/off status of the layer on its each bit.
48 Keymap has its state in two parameter **`default_layer`** indicates a base keymap layer(0-31) which is always valid and to be referred, **`keymap_stat`** is 16bit variable which has current on/off status of layers on its each bit.
49 Keymap layer '0' is usually `default_layer` and which is the only valid layer and other layers is initially off after boot up firmware, though, you can configured them in `config.h`.
50 To change `default_layer` will be useful when you switch key layout completely, say you want Colmak instead of Qwerty.
52 Initial state of Keymap Change base layout
53 ----------------------- ------------------
61 1 / / ,->1 /___________/
62 ,->0 /___________/ | 0
64 `--- default_layer = 0 `--- default_layer = 1
65 layer_state = 0x00000001 layer_state = 0x00000002
67 On the other hand, you shall change `layer_state` to overlay base layer with some layers for feature such as navigation keys, function key(F1-F12), media keys or special actions.
70 --------------------- bit|status
71 ____________ ---+------
73 30 /___________// -----> 30 | 1
74 29 /___________/ -----> 29 | 1
78 ,->1 /___________/ -----> 1 | 1
81 `--- default_layer = 1 |
82 layer_state = 0x60000002 <-'
86 ### 0.2 Layer Precedence and Transparency
87 Note that ***higher layer has higher priority on stack of layers***, namely firmware falls down from top layer to bottom to look up keycode. Once it spots keycode other than **`KC_TRNS`**(transparent) on a layer it stops searching and lower layers aren't referred.
89 You can place `KC_TRANS` on overlay layer changes just part of layout to fall back on lower or base layer.
90 Key with `KC_TRANS` (`KC_TRNS` and `_______` are the alias) doesn't has its own keycode and refers to lower valid layers for keycode, instead.
94 ### 0.3 Keymap Example
95 Keymap in this QMK is **`static const uint16_t PROGMEM keymaps[]`** C array in fact and you can define layers in it with **`KEYMAP()`** C macro and keycodes. To use complex actions you need to define `Fn` keycode in **`fn_actions[]`** array. It holds the 16 bit quantum keycode (action code).
97 > Please note that keymap in the TMK, which QMK was forked from, is **`static const uint8_t PROGMEM keymaps[]`** C array which holds the 8 bit keycode (~USB HID usage code).
99 This is a keymap example for [HHKB](http://en.wikipedia.org/wiki/Happy_Hacking_Keyboard) keyboard.
100 This example has three layers, 'QWERTY' as base layer, 'FN' and 'MOUSE'.
104 `MO(layer)` is a **momentary layer switching** key.
106 You can find other keymap definitions in file `keymap.c` located on project directories.
109 * dbroqua HHKB Layout
117 const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
118 /* BASE Level: Default Layer
119 * ,-----------------------------------------------------------------------------------------.
120 * | Esc | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | - | = | \ | ` |
121 * |-----------------------------------------------------------------------------------------+
122 * | Tab | Q | W | E | R | T | Y | U | I | O | P | [ | ] | Bksp |
123 * |-----------------------------------------------------------------------------------------+
124 * | Ctrl | A | S | D | F | G | H | J | K | L | ; | ' | Enter |
125 * |-----------------------------------------------------------------------------------------+
126 * | Shift | Z | X | C | V | B | N | M | , | . | / | Shift | fn |
127 * +-----------------------------------------------------------------------------------------+
128 * | Gui | Alt | Space | AltGr |Mouse|
129 * `----------------------------------------------------------------´
132 KC_ESC, KC_1, KC_2, KC_3, KC_4, KC_5, KC_6, KC_7, KC_8, KC_9, KC_0, KC_MINS, KC_EQL, KC_BSLS, KC_GRV, \
133 KC_TAB, KC_Q, KC_W, KC_E, KC_R, KC_T, KC_Y, KC_U, KC_I, KC_O, KC_P, KC_LBRC, KC_RBRC, KC_BSPC, \
134 KC_LCTL, KC_A, KC_S, KC_D, KC_F, KC_G, KC_H, KC_J, KC_K, KC_L, KC_SCLN, KC_QUOT, KC_ENT, \
135 KC_LSFT, KC_Z, KC_X, KC_C, KC_V, KC_B, KC_N, KC_M, KC_COMM, KC_DOT, KC_SLSH, KC_RSFT, MO(FN), \
136 KC_LGUI, KC_LALT, /* */ KC_SPC, KC_RALT, MO(MOUSE)
140 * ,-----------------------------------------------------------------------------------------.
141 * | Pwr | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F0 | F11 | F12 | Ins | Del|
142 * |-----------------------------------------------------------------------------------------+
143 * | Caps | | | | | | | |PrtSc| Slck| Paus| Up | | |
144 * |-----------------------------------------------------------------------------------------+
145 * | | Vol-| Vol+| Mute| | | * | / | Home| PgUp| Left |Right| |
146 * |-----------------------------------------------------------------------------------------+
147 * | | Prev| Play| Next| | | + | - | End |PgDwn| Down| | |
148 * +-----------------------------------------------------------------------------------------+
150 * `----------------------------------------------------------------´
153 KC_PWR, KC_F1, KC_F2, KC_F3, KC_F4, KC_F5, KC_F6, KC_F7, KC_F8, KC_F9, KC_F10, KC_F11, KC_F12, KC_INS, KC_DEL, \
154 KC_CAPS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_PSCR, KC_SLCK, KC_PAUS, KC_UP, KC_TRNS, KC_TRNS, \
155 KC_TRNS, KC_VOLD, KC_VOLU, KC_MUTE, KC_TRNS, KC_TRNS, KC_PAST, KC_PSLS, KC_HOME, KC_PGUP, KC_LEFT, KC_RGHT, KC_TRNS, \
156 KC_TRNS, KC_MPRV, KC_MPLY, KC_MNXT, KC_TRNS, KC_TRNS, KC_PPLS, KC_PMNS, KC_END, KC_PGDN, KC_DOWN, KC_TRNS, KC_TRNS, \
157 KC_TRNS, KC_TRNS, KC_TRNS, KC_MSTP, KC_TRNS
161 * ,-----------------------------------------------------------------------------------------.
162 * | | | | | | | | | | | | | | | |
163 * |-----------------------------------------------------------------------------------------+
164 * | | | WUp | | | | | | | | Btn1| Up | Btn2| |
165 * |-----------------------------------------------------------------------------------------+
166 * | | WLt | WDn | WRt | | | | | | | Left |Right| |
167 * |-----------------------------------------------------------------------------------------+
168 * | | | | | | | | | | Btn3| Down| | |
169 * +-----------------------------------------------------------------------------------------+
171 * `----------------------------------------------------------------´
174 KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, \
175 KC_TRNS, KC_TRNS, KC_WH_U, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_BTN1, KC_MS_U, KC_BTN2, KC_TRNS, \
176 KC_TRNS, KC_WH_L, KC_WH_D, KC_WH_R, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_MS_L, KC_MS_R, KC_TRNS, \
177 KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_BTN3, KC_MS_D, KC_TRNS, KC_TRNS, \
178 KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS
182 const uint16_t PROGMEM fn_actions[] = {
186 const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt)
188 // MACRODOWN only works in this function
191 if (record->event.pressed) {
192 register_code(KC_RSFT);
194 unregister_code(KC_RSFT);
204 See [`tmk_core/common/keycode.h`](../tmk_core/common/keycode.h) or keycode table below for the detail. Keycode is internal **8bit code** to indicate action performed on key in keymap. Keycodes are based on [HID Usage Keyboard/Keypad Page(0x07)](http://www.usb.org/developers/hidpage/Hut1_12v2.pdf) plus special codes in the `0xA5-DF` range.
206 Keycode has `KC_` prefixed symbol respectively. Most of keycodes like `KC_A` have simple action registers key to host on press and unregister on release, while some of other keycodes has some special actions like `Fn` keys, Media control keys, System control keys and Mousekeys.
210 In `KEYMAP()` macro, TMK recommends you to keep prefix part `KC_` of keycode to keep keymap compact. For example, just use `A` instead you place `KC_A` in `KEYMAP()`. But this doesn't apply for QMK.
212 The `KEYMAP()` macro defines correspondence between the physical key location to the electrical key connection.
214 Some keycodes has 7-letter **short name** such as `KC_COMM` in addition to descriptive name `KC_COMMA`, you'll prefer short one in `KEYMAP()`.
217 - `KC_NO` for no action
218 - `KC_TRNS` for layer transparency (See above)
221 - `KC_A` to `KC_Z`, `KC_1` to `KC_0` for alpha numeric key
222 - `KC_MINS`, `KC_EQL`, `KC_GRV`, `KC_RBRC`, `KC_LBRC`, `KC_COMM`, `KC_DOT`, `KC_BSLS`, `KC_SLSH`, `KC_SCLN`, `KC_QUOT`
223 - `KC_ESC`, `KC_TAB`, `KC_SPC`, `KC_BSPC`, `KC_ENT`, `KC_DEL`, `KC_INS`
224 - `KC_UP`, `KC_DOWN`, `KC_RGHT`, `KC_LEFT`, `KC_PGUP`, `KC_PGDN`, `KC_HOME`, `KC_END`
225 - `KC_CAPS`, `KC_NLCK`, `KC_SLCK`, `KC_PSCR`, `KC_PAUS`, `KC_APP`, `KC_F1` to `KC_F24`
226 - `KC_P1` to `KC_P0`, `KC_PDOT`, `KC_PCMM`, `KC_PSLS`, `KC_PAST`, `KC_PMNS`, `KC_PPLS`, `KC_PEQL`, `KC_PENT` for keypad.
229 There are 8 modifiers which has discrimination between left and right.
231 - `KC_LCTL` and `KC_RCTL` for Control
232 - `KC_LSFT` and `KC_RSFT` for Shift
233 - `KC_LALT` and `KC_RALT` for Alt
234 - `KC_LGUI` and `KC_RGUI` for Windows key or Command key in Mac
237 - `KC_MS_U`, `KC_MS_D`, `KC_MS_L`, `KC_MS_R` for mouse cursor
238 - `KC_WH_U`, `KC_WH_D`, `KC_WH_L`, `KC_WH_R` for mouse wheel
239 - `KC_BTN1`, `KC_BTN2`, `KC_BTN3`, `KC_BTN4`, `KC_BTN5` for mouse buttons
241 ### 1.4 System & Media key
242 - `KC_PWR`, `KC_SLEP`, `KC_WAKE` for Power, Sleep, Wake
243 - `KC_MUTE`, `KC_VOLU`, `KC_VOLD` for audio volume control
244 - `KC_MNXT`, `KC_MPRV`, `KC_MSTP`, `KC_MPLY`, `KC_MSEL` for media control
245 - `KC_MAIL`, `KC_CALC`, `KC_MYCM` for application launch
246 - `KC_WSCH`, `KC_WHOM`, `KC_WBAK`, `KC_WFWD`, `KC_WSTP`, `KC_WREF`, `KC_WFAV` for web browser operation
249 You don't need to use this functionality under QMK since this is a backward compatibility functionality. Unlike TMK, you can write action code itself directly in **`static const uint16_t PROGMEM keymaps[]`** C array using `MO(layer)`, etc.
251 `KC_FNnn` are keycodes for `Fn` key which not given any actions at the beginning unlike most of keycodes has its own inborn action. To use these keycodes in `KEYMAP()` you need to assign action you want at first. Action of `Fn` key is defined in `fn_actions[]` and its index of the array is identical with number part of `KC_FNnn`. Thus `KC_FN0` keycode indicates the action defined in first element of the array. ***Only 32 `Fn` keys can be defined at most.***
254 ### 1.6 Keycode Table
255 See keycode table in [`doc/keycode.txt`](./keycode.txt) for description of keycodes.
257 In regard to implementation side most of keycodes are identical with [HID usage][HID_usage](pdf) sent to host for real and some virtual keycodes are defined to support special actions.
258 [HID_usage]: http://www.usb.org/developers/hidpage/Hut1_12v2.pdf
263 See [`common/action_code.h`](../common/action_code.h). Action is a **16bit code** and defines function to perform on events of a key like press, release, holding and tapping.
265 Most of keys just register 8bit scancode to host, but to support other complex features needs 16bit extended action codes internally. However, using 16bit action codes in keymap results in double size in memory compared to using just keycodes. To avoid this waste 8bit keycodes are used in `KEYMAP()` instead of action codes.
267 ***You can just use keycodes of `Normal key`, `Modifier`, `Mousekey` and `System & Media key` in keymap*** to indicate corresponding actions instead of using action codes. While ***to use other special actions you should use keycode of `Fn` key defined in `fn_actions[]`.***
271 This is a simple action that registers scancodes(HID usage in fact) to host on press event of key and unregister on release.
274 + **mods**: { ` MOD_LCTL`, ` MOD_LSFT`, ` MOD_LALT`, ` MOD_LGUI`,
275 ` MOD_RCTL`, ` MOD_RSFT`, ` MOD_RALT`, ` MOD_RGUI` }
279 #### 2.1.1 Normal key and Modifier
280 ***This action usually won't be used expressly in keymap*** because you can just use keycodes in `KEYMAP()` instead.
282 You can define these actions on *'A'* key and *'left shift'* modifier with:
287 #### 2.1.2 Modified key
288 This action is comprised of strokes of modifiers and a key. `Macro` action is needed if you want more complex key strokes.
290 Say you want to assign a key to `Shift + 1` to get character *'!'* or `Alt + Tab` to switch application windows.
292 ACTION_MODS_KEY(MOD_LSFT, KC_1)
293 ACTION_MODS_KEY(MOD_LALT, KC_TAB)
295 Or `Alt,Shift + Tab` can be defined. `ACTION_MODS_KEY(mods, key)` requires **4-bit modifier state** and a **keycode** as arguments. See `keycode.h` for `MOD_BIT()` macro.
297 ACTION_MODS_KEY(MOD_LALT | MOD_LSFT, KC_TAB)
299 #### 2.1.3 Multiple Modifiers
300 Registers multiple modifiers with pressing a key. To specify multiple modifiers use `|`.
302 ACTION_MODS(MOD_ALT | MOD_LSFT)
304 #### 2.1.3 Modifier with Tap key([Dual role][dual_role])
305 Works as a modifier key while holding, but registers a key on tap(press and release quickly).
308 ACTION_MODS_TAP_KEY(MOD_RCTL, KC_ENT)
313 These actions operate layers of keymap.
316 You can specify a **target layer** of action and **when the action is executed**. Some actions take a **bit value** for bitwise operation.
319 + **layer**: `0`-`31`
320 + **on**: { `ON_PRESS` | `ON_RELEASE` | `ON_BOTH` }
321 + **bits**: 4-bit value and 1-bit mask bit
324 #### 2.2.1 Default Layer
325 Default Layer is a layer which always is valid and referred to when actions is not defined on other overlay layers.
327 This sets Default Layer to given parameter `layer` and activate it.
329 ACTION_DEFAULT_LAYER_SET(layer)
333 Turns on `layer` momentarily while holding, in other words it activates when key is pressed and deactivate when released.
335 ACTION_LAYER_MOMENTARY(layer)
338 #### 2.2.3 Toggle Switch
339 Turns on `layer` with first type(press and release) and turns off with next.
341 ACTION_LAYER_TOGGLE(layer)
344 #### 2.2.4 Momentary Switch with tap key
345 Turns on `layer` momentary while holding, but registers key on tap(press and release quickly).
347 ACTION_LAYER_TAP_KEY(layer, key)
350 #### 2.2.5 Momentary Switch with tap toggle
351 Turns on `layer` momentary while holding and toggles it with serial taps.
353 ACTION_LAYER_TAP_TOGGLE(layer)
356 #### 2.2.6 Invert state of layer
357 Inverts current state of `layer`. If the layer is on it becomes off with this action.
359 ACTION_LAYER_INVERT(layer, on)
362 #### 2.2.7 Turn On layer
363 Turns on layer state.
365 ACTION_LAYER_ON(layer, on)
367 Turns on layer state on press and turns off on release.
369 ACTION_LAYER_ON_OFF(layer)
372 #### 2.2.8 Turn Off layer
373 Turns off layer state.
375 ACTION_LAYER_OFF(layer, on)
377 Turns off layer state on press and activates on release.
379 ACTION_LAYER_OFF_ON(layer)
384 `layer_state = (1<<layer) [layer: 0-31]`
386 ACTION_LAYER_SET(layer, on)
388 Turns on layer only and clear all layer on release..
390 ACTION_LAYER_SET_CLEAR(layer)
393 #### 2.2.10 Bitwise operation
395 **part** indicates which part of 32bit layer state(0-7). **bits** is 5-bit value. **on** indicates when the action is executed.
397 ACTION_LAYER_BIT_AND(part, bits, on)
398 ACTION_LAYER_BIT_OR(part, bits, on)
399 ACTION_LAYER_BIT_XOR(part, bits, on)
400 ACTION_LAYER_BIT_SET(part, bits, on)
402 These actions works with parameters as following code.
404 uint8_t shift = part*4;
405 uint32_t mask = (bits&0x10) ? ~(0xf<<shift) : 0;
406 uint32_t layer_state = layer_state <bitop> ((bits<<shift)|mask);
409 Default Layer also has bitwise operations, they are executed when key is released.
411 ACTION_DEFAULT_LAYER_BIT_AND(part, bits)
412 ACTION_DEFAULT_LAYER_BIT_OR(part, bits)
413 ACTION_DEFAULT_LAYER_BIT_XOR(part, bits)
414 ACTION_DEFAULT_LAYER_BIT_SET(part, bits)
421 `Macro` action indicates complex key strokes.
423 MACRO( D(LSHIFT), D(D), END )
424 MACRO( U(D), U(LSHIFT), END )
425 MACRO( I(255), T(H), T(E), T(L), T(L), W(255), T(O), END )
427 #### 2.3.1 Macro Commands
428 - **I()** change interval of stroke.
430 - **U()** release key
431 - **T()** type key(press and release)
437 ***TODO: sample implementation***
438 See `keyboards/hhkb/keymap.c` for sample.
442 ### 2.4 Function action
445 There are two type of action, normal `Function` and tappable `Function`.
446 These actions call user defined function with `id`, `opt`, and key event information as arguments.
449 To define normal `Function` action in keymap use this.
451 ACTION_FUNCTION(id, opt)
453 #### 2.4.2 Function with tap
454 To define tappable `Function` action in keymap use this.
456 ACTION_FUNCTION_TAP(id, opt)
458 #### 2.4.3 Implement user function
459 `Function` actions can be defined freely with C by user in callback function:
461 void keymap_call_function(keyrecord_t *event, uint8_t id, uint8_t opt)
463 This C function is called every time key is operated, argument `id` selects action to be performed and `opt` can be used for option. Function `id` can be 0-255 and `opt` can be 0-15.
465 `keyrecord_t` is comprised of key event and tap count. `keyevent_t` indicates which and when key is pressed or released. From `tap_count` you can know tap state, 0 means no tap. These information will be used in user function to decide how action of key is performed.
483 ***TODO: sample implementation***
484 See `keyboards/hhkb/keymap.c` for sample.
488 ### 2.5 Backlight Action
489 These actions control the backlight.
491 #### 2.5.1 Change backlight level
492 Increase backlight level.
494 ACTION_BACKLIGHT_INCREASE()
496 Decrease backlight level.
498 ACTION_BACKLIGHT_DECREASE()
500 Step through backlight levels.
502 ACTION_BACKLIGHT_STEP()
504 Turn a specific backlight level on or off.
506 ACTION_BACKLIGHT_LEVEL(1)
508 #### 2.5.2 Turn on / off backlight
509 Turn the backlight on and off without changing level.
511 ACTION_BACKLIGHT_TOGGLE()
515 ### 2.6 Swap-Hands Action
516 The swap-hands action allows support for one-handed keyboards without requiring a separate layer. Set `ONEHAND_ENABLE` in the Makefile and define a `hand_swap_config` entry in your keymap. Now whenever the `ACTION_SWAP_HANDS` command key is pressed the keyboard is mirrored. For instance, to type "Hello, World" on QWERTY you would type `^Ge^s^s^w^c W^wr^sd`
518 ### 2.6.1 Configuration
519 The configuration table is a simple 2-dimensional array to map from column/row to new column/row. Example `hand_swap_config` for Planck:
522 const keypos_t hand_swap_config[MATRIX_ROWS][MATRIX_COLS] = {
523 {{11, 0}, {10, 0}, {9, 0}, {8, 0}, {7, 0}, {6, 0}, {5, 0}, {4, 0}, {3, 0}, {2, 0}, {1, 0}, {0, 0}},
524 {{11, 1}, {10, 1}, {9, 1}, {8, 1}, {7, 1}, {6, 1}, {5, 1}, {4, 1}, {3, 1}, {2, 1}, {1, 1}, {0, 1}},
525 {{11, 2}, {10, 2}, {9, 2}, {8, 2}, {7, 2}, {6, 2}, {5, 2}, {4, 2}, {3, 2}, {2, 2}, {1, 2}, {0, 2}},
526 {{11, 3}, {10, 3}, {9, 3}, {8, 3}, {7, 3}, {6, 3}, {5, 3}, {4, 3}, {3, 3}, {2, 3}, {1, 3}, {0, 3}},
530 Note that the array indices are reversed same as the matrix and the values are of type `keypos_t` which is `{col, row}` and all values are zero-based. In the example above, `hand_swap_config[2][4]` (third row, fifth column) would return {7, 2} (third row, eighth column).
532 ### 2.6.2 Advanced Swap Commands
533 - **`ACTION_SWAP_HANDS()`** Swaps hands when pressed, returns to normal when released (momentary).
534 - **`ACTION_SWAP_HANDS_TOGGLE()`** Toggles swap on and off with every keypress.
535 - **`ACTION_SWAP_HANDS_TAP_TOGGLE()`** Toggles with a tap; momentary when held.
536 - **`ACTION_SWAP_HANDS_TAP_KEY(key)`** Sends `key` with a tap; momentary swap when held.
537 - **`ACTION_SWAP_HANDS_ON_OFF()`** Alias for `ACTION_SWAP_HANDS()`
538 - **`ACTION_SWAP_HANDS_OFF_ON()`** Momentarily turns off swap.
539 - **`ACTION_SWAP_HANDS_ON()`** Turns on swapping and leaves it on.
540 - **`ACTION_SWAP_HANDS_OFF()`** Turn off swapping and leaves it off. Good for returning to a known state.
544 ## 3. Layer switching Example
545 There are some ways to switch layer with 'Layer' actions.
547 ### 3.1 Momentary switching
548 Momentary switching changes layer only while holding Fn key.
550 This action makes 'Layer 1' active(valid) on key press event and inactive on release event. Namely you can overlay a layer on lower layers or default layer temporarily with this action.
552 ACTION_LAYER_MOMENTARY(1)
555 Note that after switching on press the actions on destination layer(Layer 1) are performed.
556 ***Thus you shall need to place an action to go back on destination layer***, or you will be stuck in destination layer without way to get back. Usually you need to place same action or 'KC_TRNS` on destination layer to get back.
559 ### 3.2 Toggle switching
560 Toggle switching performed after releasing a key. With this action you can keep staying on the destination layer until you type the key again to return.
562 This performs toggle switching action of 'Layer 2'.
564 ACTION_LAYER_TOGGLE(2)
568 ### 3.3 Momentary switching with Tap key
569 These actions switch a layer only while holding a key but register the key on tap. **Tap** means to press and release a key quickly.
571 ACTION_LAYER_TAP_KEY(2, KC_SCLN)
573 With this you can place a layer switching action on normal key like ';' without losing its original key register function. This action allows you to have layer switching action without necessity of a dedicated key. It means you can have it even on home row of keyboard.
577 ### 3.4 Momentary switching with Tap Toggle
578 This switches layer only while holding a key but toggle layer with several taps. **Tap** means to press and release key quickly.
580 ACTION_LAYER_TAP_TOGGLE(1)
582 Number of taps can be configured with `TAPPING_TOGGLE` in `config.h`, `5` by default.
586 ### 3.5 Momentary switching with Modifiers
587 This registers modifier key(s) simultaneously with layer switching.
589 ACTION_LAYER_MODS(2, MOD_LSFT | MOD_LALT)
594 Tapping is to press and release a key quickly. Tapping speed is determined with setting of `TAPPING_TERM`, which can be defined in `config.h`, 200ms by default.
597 This is a feature to assign normal key action and modifier including layer switching to just same one physical key. This is a kind of [Dual role key][dual_role]. It works as modifier when holding the key but registers normal key when tapping.
599 Modifier with tap key:
601 ACTION_MODS_TAP_KEY(MOD_RSFT, KC_GRV)
603 Layer switching with tap key:
605 ACTION_LAYER_TAP_KEY(2, KC_SCLN)
607 [dual_role]: http://en.wikipedia.org/wiki/Modifier_key#Dual-role_keys
609 When user hold a key after tap, it repeat the tapped key rather to hold a modifier key.
610 If you prefer to hold a modifier instead, define `TAPPING_FORCE_HOLD` in `config.h`.
611 See https://github.com/qmk/qmk_firmware/issues/889 for the detail.
614 This is a feature to assign both toggle layer and momentary switch layer action to just same one physical key. It works as momentary layer switch when holding a key but toggle switch with several taps.
616 ACTION_LAYER_TAP_TOGGLE(1)
619 ### 4.3 Oneshot Modifier
620 This runs onetime effects which modify only on just one following key. It works as normal modifier key when holding down while oneshot modifier when tapping. The behavior of oneshot modifiers is similar to the [sticky keys](https://en.wikipedia.org/wiki/StickyKeys) functionality found in most operating systems.
622 ACTION_MODS_ONESHOT(MOD_LSFT)
626 ACTION_LAYER_ONESHOT(MY_LAYER)
628 Say you want to type 'The', you have to push and hold Shift key before type 't' then release it before type 'h' and 'e', otherwise you'll get 'THe' or 'the' unintentionally. With Oneshot Modifier you can tap Shift then type 't', 'h' and 'e' normally, you don't need to holding Shift key properly here. This mean you can release Shift before 't' is pressed down.
630 Oneshot effect is cancel unless following key is pressed down within `ONESHOT_TIMEOUT` of `config.h`. No timeout when it is `0` or not defined.
632 Most implementations of sticky keys allow you to lock a modifier by double tapping the modifier. The layer then remains locked untill the modifier is tapped again. To enable this behaviour for oneshot modifiers set `ONESHOT_TAP_TOGGLE` to the number taps required. The feature is disabled if `ONESHOT_TAP_TOGGLE<2` or not defined.
635 ### 4.4 Tap Toggle Mods
636 Similar to layer tap toggle, this works as a momentary modifier when holding, but toggles on with several taps. A single tap will 'unstick' the modifier again.
638 ACTION_MODS_TAP_TOGGLE(MOD_LSFT)
644 In QMK, `tmk_core/common/keymap.c` is missing and its replacement `quantum/keymap_common.c` lacks Legacy Keymap support.
646 Legacy Keymap uses two arrays `fn_layer[]` and `fn_keycode[]` to define Fn key. The index of arrays corresponds with postfix number of `Fn` key. Array `fn_layer[]` indicates destination layer to switch and `fn_keycode[]` has keycodes to send when tapping `Fn` key.
648 In the following legacy keymap setting example, `Fn0`, `Fn1` and `Fn2` switch layer to 1, 2 and 2 respectively. `Fn2` registers `Space` key when tapping while `Fn0` and `Fn1` doesn't send any key.
650 static const uint8_t PROGMEM fn_layer[] = {
656 static const uint8_t PROGMEM fn_keycode[] = {
662 Under QMK, these can be realized using action code ACTION_LAYER_TAP_KEY(1, KC_NO), ACTION_LAYER_TAP_KEY(2, KC_NO), and ACTION_LAYER_TAP_KEY(2, KC_SPC) in the `keymaps` directly.
667 is comprised of multiple layers.
669 is matrix of keycodes.
671 is physical button on keyboard or logical switch on software.
673 is codes used on firmware.
675 is a function assigned on a key.
676 ### layer transparency
677 Using transparent keycode one layer can refer key definition on other lower layer.
679 Top layer has higher precedence than lower layers.
681 is to press and release a key quickly.
683 is key which executes a special action like layer switching, mouse key, macro or etc.
685 <http://en.wikipedia.org/wiki/Modifier_key#Dual-role_keys>