Question: How to toggle layer in ACTION_FUNCTION?

[tywtyw2002]

Is someone give me some example for how to toggle a layer in ACTION_FUNCTION?

I would like to change some LEDs then toggle a layer.

The follow code did not work.

void action_function(keyrecord_t *record, uint8_t id, uint8_t opt){

    static bool led = false;
    switch (id) {
        case TOGGLE_ARROW_LAYER:
            if (led) {
                gh60_esc_led_off();
            }else{
                gh60_esc_led_on();
                led = true;
            }
            return (action_t) ACTION_LAYER_TOGGLE(2);
            break;
    }
}

[tmk]

You have to implement toggle logic in action function your self. You will want to know how built-in ACTION_LAYER_TOGGLE action is implemented in tmk_core. First check common/action_code.h to know how the action code is defined. In the end you will know the action is identified as ACT_LAYER.
https://github.com/tmk/tmk_keyboard/blob/master/tmk_core/common/action_code.h#L266

#define ACTION_LAYER_TOGGLE(layer)                  ACTION_LAYER_INVERT(layer, ON_RELEASE)
#define ACTION_LAYER_INVERT(layer, on)              ACTION_LAYER_BIT_XOR((layer)/4,   1<<((layer)%4),  (on))
...
#define ACTION_LAYER_BIT_XOR(part, bits, on)        ACTION_LAYER_BITOP(OP_BIT_XOR, (part), (bits), (on))
...
#define ACTION_LAYER_BITOP(op, part, bits, on)      ACTION(ACT_LAYER, (op)<<10 | (on)<<8 | (part)<<5 | ((bits)&0x1f))

Next, you can find code of the built-in action in common/action.c using word ACT_LAYER and OP_BIT_XOR.
https://github.com/tmk/tmk_keyboard/blob/master/tmk_core/common/action.c#L216-L245

        case ACT_LAYER:
            if (action.layer_bitop.on == 0) {
                /* Default Layer Bitwise Operation */
                if (!event.pressed) {
                    uint8_t shift = action.layer_bitop.part*4;
                    uint32_t bits = ((uint32_t)action.layer_bitop.bits)<<shift;
                    uint32_t mask = (action.layer_bitop.xbit) ? ~(((uint32_t)0xf)<<shift) : 0;
                    switch (action.layer_bitop.op) {
                        case OP_BIT_AND: default_layer_and(bits | mask); break;
                        case OP_BIT_OR:  default_layer_or(bits | mask);  break;
                        case OP_BIT_XOR: default_layer_xor(bits | mask); break;
                        case OP_BIT_SET: default_layer_and(mask); default_layer_or(bits); break;
                    }
                }
            } else {
                /* Layer Bitwise Operation */
                if (event.pressed ? (action.layer_bitop.on & ON_PRESS) :
                                    (action.layer_bitop.on & ON_RELEASE)) {
                    uint8_t shift = action.layer_bitop.part*4;
                    uint32_t bits = ((uint32_t)action.layer_bitop.bits)<<shift;
                    uint32_t mask = (action.layer_bitop.xbit) ? ~(((uint32_t)0xf)<<shift) : 0;
                    switch (action.layer_bitop.op) {
                        case OP_BIT_AND: layer_and(bits | mask); break;
                        case OP_BIT_OR:  layer_or(bits | mask);  break;
                        case OP_BIT_XOR: layer_xor(bits | mask); break;
                        case OP_BIT_SET: layer_and(mask); layer_or(bits); break;
                    }
                }
            }
            break;

You will find something useful if you explore this code more deeply. Search definition of layer_xor() function you will find layer_state_set() finally.

https://github.com/tmk/tmk_keyboard/blob/master/tmk_core/common/action_layer.c#L105-L108
https://github.com/tmk/tmk_keyboard/blob/master/tmk_core/common/action_layer.c#L62-L70

void layer_xor(uint32_t state)
{
    layer_state_set(layer_state ^ state);
}
...
static void layer_state_set(uint32_t state)
{
    dprint("layer_state: ");
    layer_debug(); dprint(" to ");
    layer_state = state;
    hook_layer_change(layer_state);
    layer_debug(); dprintln();
    clear_keyboard_but_mods(); // To avoid stuck keys
}

What you want to do is inverting a bit of layer_state in the end.

I think this code will work in your case probably.

layer_state ^= (1<<2);