repos/Callback_11/Callback_11.cpp

#include <array>
#include <vector>
#include <map>
#include <iostream>


/*
 *  https://stackoverflow.com/questions/2298242/callback-functions-in-c
 */

enum e_event_code { ALL, EVENT_PRESSED, EVENT_LONG_PRESSED, LV_EVENT_RELEASED, REDRAW } ;

class cEvents {
public:
    
    void* user_data = nullptr;
    void* param = nullptr;
    cEvents* prev = nullptr;

    enum e_event_code code; 
    uint16_t x;
    uint16_t y;

    cEvents* event_get_code(cEvents* e) {
        std::cout << e->code << std::endl;
        return this;
    }

    bool event_send_code(cEvents* e) {
        return true;
    }
};




void player_jump(cEvents &e) {

    std::cout << "player jump" << std::endl;
    std::cout << "x: " << e.x << " / y: " << e.y << std::endl;
    e.x = 36; 
    e.y = 47; 
};

void player_crouch(cEvents& e) {

    std::cout << "player crouch" << std::endl;
    std::cout << "x: " << e.x << " / y: " << e.y << std::endl;
}


class game_core : public cEvents
{
    // empty eventhandler (default)
    static void emptyEvent(cEvents& e) {
        std::cout << "empty event handler" << std::endl;
    }


public: 
    std::array<void(*)(cEvents&), 5> actions;

    game_core() {

        actions.fill(&emptyEvent); 
    }
    // 
    void execEvent(cEvents& e)
    {
        if (actions[e.code]) actions[e.code](e);
    }

    // update keybind from menu
    void addEventCb(enum e_event_code key_id, void(*new_action)(cEvents &))
    {
        actions[key_id] = new_action;
    }

};


int main() {
    game_core gc; 
    cEvents e;
    gc.addEventCb(REDRAW, &player_jump);
    gc.addEventCb(EVENT_PRESSED, &player_crouch);

    e.code = EVENT_PRESSED;
    e.x = 12;
    e.y = 24;
    gc.execEvent(e);

    e.code = REDRAW;
    e.x = 39;
    e.y = 41;
    gc.execEvent(e);

    e.code = ALL;
    e.x = 39;
    e.y = 41;
    gc.execEvent(e);

    return 1;
}