repeat_key.h

// Copyright 2022-2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

/**
 * @file repeat_key.h
 * @brief Repeat Key - an extensible "repeat last key" implementation.
 *
 * @note Repeat Key is now a core QMK feature! See
 * <https://docs.qmk.fm/#/feature_repeat_key>
 *
 * Repeat Key performs the action of last pressed key. Tapping the Repeat Key
 * after tapping the Z key types another "z." Repeat Key remembers the modifiers
 * that were active with the last key press. These modifiers are combined with
 * any additional active modifiers while pressing the Repeat Key. For instance,
 * if the last press key was Ctrl + Z, then Shift + Repeat Key performs Ctrl +
 * Shift + Z.
 *
 * Also included is an Alternate Repeat Key, performing the "alternate" if there
 * is one for the last key. By default it is defined for navigation keys to act
 * in the reverse direction. If Page Down was the last key, the Alternate Repeat
 * performs Page Up.
 *
 * The implementation is a generic event-plumbing strategy that interoperates
 * predictably with most QMK features, including tap-hold keys, Auto Shift,
 * Combos, and userspace macros.
 *
 * For full documentation, see
 * <https://getreuer.info/posts/keyboards/repeat-key>
 */

#pragma once

#include "quantum.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Handler function for Repeat Key. Call either this function or
 * `process_repeat_key_with_rev()` (but not both) from `process_record_user()`
 * to implement Repeat Key in your keymap.
 *
 * If your `process_record_user()` has other handlers or macros, Repeat Key’s
 * handler `process_repeat_key()` should preferably be called before anything
 * else. (If you also use Achordion, then call Achordion's handler first, Repeat
 * Key's handler second, and then other handlers.)
 */
bool process_repeat_key(uint16_t keycode, keyrecord_t* record,
                        uint16_t repeat_keycode);

/** Handler function for Repeat Key and Alternate Repeat Key. */
bool process_repeat_key_with_alt(uint16_t keycode, keyrecord_t* record,
                                 uint16_t repeat_keycode,
                                 uint16_t alt_repeat_keycode);

/**
 * @brief Signed count of times the key has been repeated or alternate repeated.
 *
 * @note The count is nonzero only while a repeated or alternate-repeated key is
 * being processed.
 *
 * When a key is pressed normally, the count is 0. When the Repeat Key is used
 * to repeat a key, the count is 1 on the first repeat, 2 on the second repeat,
 * and continuing up to 127.
 *
 * Negative counts are used similarly for alternate repeating. When the
 * Alternate Repeat Key is used, the count is -1 on the first alternate repeat,
 * -2 on the second, continuing down to -127.
 */
int8_t get_repeat_key_count(void);

/** @brief Keycode of the last key. */
uint16_t get_last_keycode(void);
/** @brief Mods that were active with the last key. */
uint8_t get_last_mods(void);
/** @brief Sets the last keycode. */
void set_last_keycode(uint16_t keycode);
/** @brief Sets the last mods. */
void set_last_mods(uint8_t mods);

/**
 * @brief Callback defining which keys are remembered.
 *
 * @param keycode          Keycode that was just pressed
 * @param record           keyrecord_t structure
 * @param remembered_mods  Mods that will be remembered with this key
 * @return true            Key is remembered (eligible for repeating)
 * @return false           Key is ignored
 *
 * Modifier and layer switch keys are always ignored. For all other keys, this
 * callback is called on every key press. Returning true means that the key is
 * remembered, false means it is ignored. By default, all non-modifier,
 * non-layer switch keys are remembered.
 *
 * The `remembered_mods` arg represents the mods that will be remembered with
 * this key. It can be modified to forget certain mods, for instance to forget
 * capitalization when repeating shifted letters:
 *
 *     // Forget Shift on letter keys.
 *     if (KC_A <= keycode && keycode <= KC_Z &&
 *         (*remembered_mods & ~MOD_MASK_SHIFT) == 0) {
 *       *remembered_mods = 0;
 *     }
 */
bool remember_last_key_user(uint16_t keycode, keyrecord_t* record,
                            uint8_t* remembered_mods);

/**
 * @brief Keycode to be used for alternate repeating.
 *
 * Alternate Repeat performs this keycode based on the last eligible pressed key
 * and mods, get_last_keycode() and get_last_mods(). For example, when the last
 * key was KC_UP, this function returns KC_DOWN. The function returns KC_NO if
 * the last key doesn't have a defined alternate.
 */
uint16_t get_alt_repeat_key_keycode(void);

/**
 * @brief Optional user callback to define additional alternate keys.
 *
 * When `get_alt_repeat_key_keycode()` is called, it first calls this callback.
 * It should return a keycode representing the "alternate" of the given keycode
 * and mods. Returning KC_NO defers to the default definitions in
 * `get_alt_repeat_key_keycode()`.
 *
 * This callback can be used to define additional pairs of keys that "reverse"
 * each other. More generally, Alternate Repeat can be configured to perform an
 * action that "complements" the last key---Alternate Repeat not limited to
 * reverse repeating, and it need not be symmetric. For instance, you can use it
 * to eliminate the worst same-finger bigrams in your layout.
 */
uint16_t get_alt_repeat_key_keycode_user(uint16_t keycode, uint8_t mods);

/**
 * Registers (presses down) the Repeat Key. This is useful for invoking Repeat
 * as part of a tap dance or other custom handler. Note that if doing so, you
 * likely want to define `repeat_key_press_user()` to ignore the key associated
 * with that handler so that the Repeat Key does not attempt to repeat itself.
 */
void repeat_key_register(void);

/** Unregisters (releases) the Repeat Key. */
void repeat_key_unregister(void);

/** Taps the Repeat Key with a delay of `TAP_CODE_DELAY`. */
void repeat_key_tap(void);

/**
 * Registers (presses down) the Alternate Repeat Key, performing the alternate,
 * if there is one, for the last pressed key. If no alternate is found, the
 * function takes no action and returns false.
 *
 * @return True if an alternate key was found.
 */
bool alt_repeat_key_register(void);

/**
 * Unregisters (releases) the Alternate Repeat Key.
 *
 * @return True if an alternate key was found.
 */
bool alt_repeat_key_unregister(void);

/**
 * Taps the Alternate Repeat Key with a delay of TAP_CODE_DELAY.
 *
 * @return True if an alternate key was found.
 */
bool alt_repeat_key_tap(void);

// Deprecated APIs.

/** @deprecated Use `process_repeat_key_with_alt()` instead. */
static inline bool process_repeat_key_with_rev(uint16_t keycode,
                                               keyrecord_t* record,
                                               uint16_t repeat_keycode,
                                               uint16_t rev_repeat_keycode) {
  return process_repeat_key_with_alt(keycode, record, repeat_keycode,
                                     rev_repeat_keycode);
}

/** @deprecated Use `get_repeat_key_count()` instead. */
static inline int8_t repeat_key_count(void) { return get_repeat_key_count(); }

/** @deprecated Use `get_last_keycode()` instead. */
static inline uint16_t get_repeat_key_keycode(void) {
  return get_last_keycode();
}
/** @deprecated Use `get_last_keycode()` instead. */
static inline uint16_t repeat_key_keycode(void) { return get_last_keycode(); }
/** @deprecated Use `get_last_mods()` instead. */
static inline uint8_t get_repeat_key_mods(void) { return get_last_mods(); }
/** @deprecated Use `get_last_mods()` instead. */
static inline uint8_t repeat_key_mods(void) { return get_last_mods(); }
/** @deprecated Use `set_last_keycode()` instead. */
static inline void set_repeat_key_keycode(uint16_t keycode) {
  set_last_keycode(keycode);
}
/** @deprecated Use `set_last_mods()` instead. */
static inline void set_repeat_key_mods(uint8_t mods) { set_last_mods(mods); }

/** @deprecated Use `remember_last_key_user()` instead. */
bool get_repeat_key_eligible_user(uint16_t keycode, keyrecord_t* record,
                                  uint8_t* remembered_mods);
/** @deprecated Use `remember_last_key_user()` instead. */
bool get_repeat_key_eligible(uint16_t keycode, keyrecord_t* record);

/** @deprecated Use `get_alt_repeat_key_keycode()` instead. */
static inline uint16_t rev_repeat_key_keycode(void) {
  return get_alt_repeat_key_keycode();
}
/** @deprecated Use `get_alt_repeat_key_keycode()` instead. */
static inline uint16_t get_rev_repeat_key_keycode(void) {
  return get_alt_repeat_key_keycode();
}

/** @deprecated Use `get_alt_repeat_key_keycode_user()` instead. */
uint16_t get_rev_repeat_key_keycode_user(uint16_t keycode, uint8_t mods);

/** @deprecated Use `alt_repeat_key_register()` instead. */
static inline bool rev_repeat_key_register(void) {
  return alt_repeat_key_register();
}

/** @deprecated Use `alt_repeat_key_unregister()` instead. */
static inline bool rev_repeat_key_unregister(void) {
  return alt_repeat_key_unregister();
}

/** @deprecated Use `alt_repeat_key_tap()` instead. */
static inline bool rev_repeat_key_tap(void) { return alt_repeat_key_tap(); }

#ifdef __cplusplus
}
#endif