This function draw a rectangle in a framebuffer.
void dg_fb_putrectangle(dg_framebuffer_t *fb, sfVector2u position, sfVector2u size, sfColor color);
dg_fb_putrectangle(fb, pos, size, sfBlue);
void dg_fb_putrectangle(dg_framebuffer_t *fb, sfVector2u position,
sfVector2u size, sfColor color)
{
for (int i = position.x; i < position.x + size.x; i++)
for (int j = position.y; j < position.y + size.y; j++)
dg_fb_putpx(fb, i, j, color);
}