Shadowblitz Allegro5

#include <string>
#include <stdio>
#include "allegro5/allegro.h"

ALLEGRO_BITMAP *allegro;


ALLEGRO_EVENT_QUEUE* queue;
ALLEGRO_TIMER* timer;

ALLEGRO_DISPLAY *display;



class App
{
    public:
        static void init(int w = 256, int h = 240, std::string title = "Untitled", int fps = 60, bool noDisplay = false);
        static void bindInit(void (*init)());
        static void bindTick(void (*tick)());
        static void bindDraw(void (*draw)());
        static void bindFree(void (*free)());

    protected:


    private:

        static void (*onInit)();
        static void (*onTick)();
        static void (*onDraw)();
        static void (*onFree)();


};


void App::init(int w, int h, std::string title, int fps, bool noDisplay)
{
    if (!al_init())
    {
        fprintf(stderr, "failed to initalize allegro!\n");
        return;
    }

    al_install_keyboard();
    al_install_mouse();

    if (!noDisplay)
    {
        bool update = false;


        timer = al_create_timer(1.0 / fps);
        if (!timer) {
            fprintf(stderr, "failed to create timer!\n");
            return;
        }

        display = al_create_display(w, h);
        if (!display)
        {
            fprintf(stderr, "failed to create display!\n");
            if (timer != nullptr) al_destroy_timer(timer);
            return;
        }

        queue = al_create_event_queue();
        if (!queue)
        {
            fprintf(stderr, "failed to create event_queue!\n");
            if (timer   != nullptr) al_destroy_timer(timer);
            if (display != nullptr) al_destroy_display(display);
            return;
        }

        al_register_event_source(queue, al_get_display_event_source(display));
        al_register_event_source(queue, al_get_timer_event_source(timer));
        al_start_timer(timer);

        while (true)
        {
            ALLEGRO_EVENT   event; //why in this loop?
            ALLEGRO_TIMEOUT timeout;
            al_init_timeout(&timeout, 0.06);
            bool get_event = al_wait_for_event_until(&queue, &event, &timeout);

            if (get_event)
            {
                if (event.type == ALLEGRO_EVENT_TIMER)
                {
                    update = true;
                }

                if (event.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
                {
                    break;
                }
            }

            if (update)
            {
                al_clear_to_color(al_map_rgb(0, 0, 0));

                if (App::onTick != nullptr) App::onFree();
                if (App::onDraw != nullptr) App::onFree();

                al_flip_display();
            }
        }
    }

    if (App::onFree  != nullptr) App::onFree();
    if (App::timer   != nullptr) al_destroy_timer(timer);
    if (App::queue   != nullptr) al_destroy_event_queue(queue);
    if (App::display != nullptr) al_destroy_display(display);
}

void App::bindInit(void(*init)())
{
    App::onInit = init;
}
void App::bindTick(void(*tick)())
{
    App::onTick = tick;
}
void App::bindDraw(void(*draw)())
{
    App::onDraw = draw;
}
void App::bindFree(void(*free)())
{
    App::onFree = free;
}

void (*App::onInit)() = nullptr;
void (*App::onTick)() = nullptr;
void (*App::onDraw)() = nullptr;
void (*App::onFree)() = nullptr;


int main()
{

    {
        App::init(256,240, "Title");
        al_init_primitives_addon();
        al_install_keyboard();
        al_install_mouse();

    }

    al_destroy_bitmap(allegro);

    al_destroy_event_queue(queue);
    al_destroy_timer(timer);
    al_destroy_display(display);

    return 0;
}