Events management

Events are the basis for writing interactive applications in MacroLibX. So it’s essential that you understand this chapter thoroughly, as it will come in handy in your future graphics projects.

All MacroLibX hooks are nothing more than a function that is called whenever an event is triggered.

The base of all MacroLibX events is mlx_on_event. This function is used to manage all of the events, from keyboard to window events. It’s is used to attach a function hook to a specific event like keyboard down, or mouse wheel event. That hook will be called every time this specific event is triggerd.

⌨️ Keyboard

To get keyboard events, we need to use MLX_KEYDOWN or MLX_KEYUP when calling mlx_on_event to set the correct hook. Here’s how we could do it :

#include "MacroLibX/includes/mlx.h"

int key_hook(int key, void* mlx)
{
    if(key == 41) // 41 is the key code for escape
        mlx_loop_end(mlx); // if escape is pressed we stop the mlx_loop and so we continue in the main function
    return (0); // Note that the return is ignored, it is just for compatibility with old minilibx
}

int main(void)
{
    void* mlx = mlx_init();
    void* win = mlx_new_window(mlx, 400, 400, "Hello world!");

    // we pass the mlx pointer as the last param so it can be used in the key_hook function
    mlx_on_event(mlx, win, MLX_KEYDOWN, key_hook, mlx);

    mlx_loop(mlx);

    mlx_destroy_window(mlx, win);
    mlx_destroy_display(mlx);
}

🖱️ Mouse

Same thing that keyboard events, we need to use MLX_MOUSEDOWN, MLX_MOUSEUP or MLX_MOUSEWHEEL when calling mlx_on_event to set the correct hook. Here’s how we could do it :

#include "MacroLibX/includes/mlx.h"

int mouse_hook(int button, void* param)
{
    /* Do stuffs */
    return (0);
}

int mouse_wheel_hook(int button, void* param)
{
    /* Do stuffs */
    return (0);
}

int main(void)
{
    void* mlx = mlx_init();
    void* win = mlx_new_window(mlx, 400, 400, "Hello world!");

    mlx_on_event(mlx, win, MLX_MOUSEDOWN, mouse_hook, NULL);
    mlx_on_event(mlx, win, MLX_MOUSEWHEEL, mouse_wheel_hook, NULL);

    mlx_loop(mlx);

    mlx_destroy_window(mlx, win);
    mlx_destroy_display(mlx);
}

🖥️ Window events

The last type of events we can handle are window events (window moved, window maximized, window focused, window closed, … ).

#include "MacroLibX/includes/mlx.h"

int window_hook(int event, void* param)
{
    if(event == 0) // 0 is when we trigger the close of the window (by clicking the cross for example)
        mlx_loop_end(param);
    return (0);
}

int main(void)
{
    void* mlx = mlx_init();
    void* win = mlx_new_window(mlx, 400, 400, "Hello world!");

    mlx_on_event(mlx, win, MLX_WINDOW_EVENT, window_hook, mlx);

    mlx_loop(mlx);

    mlx_destroy_window(mlx, win);
    mlx_destroy_display(mlx);
}